Information
-
Patent Grant
-
6504950
-
Patent Number
6,504,950
-
Date Filed
Thursday, March 4, 199925 years ago
-
Date Issued
Tuesday, January 7, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 382 162
- 382 167
- 358 500
- 358 518
- 358 504
- 358 520
-
International Classifications
-
Abstract
An apparatus for creating an ICC profile in a simple manner without using a specialized measuring instrument. A display control unit reads out a dot pattern image from a pattern image data holding unit and a grayscale pattern image containing a plurality of grayscale patches of gradually varying gray scale from a grayscale image data holding unit, and presents the thus readout images for display on a display device. A user selects the grayscale patch having brightness closest to the brightness of the dot pattern image by operating a selection unit. Based on the selection, a gamma coefficient value is calculated by a gamma coefficient value calculation unit, and based on this gamma coefficient value, a profile creation unit modifies the ICC profile held in a common information holding unit and thus creates a customized ICC profile.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a terminal that has a keyboard and a display for a user to communicate with a data processing system or the like, and that adjusts the color reproduction of the screen of a display device.
The invention also relates to an input/output characteristic measurement method and an input/output characteristic calculation apparatus for obtaining the input/output characteristics, i.e., the electro-optical conversion characteristics, of a display such as a CRT display device or a liquid crystal display device.
The invention further relates to a display profile creation method and display profile creation apparatus for creating a profile relating to the color appearance of the display device.
Furthermore, the invention relates to a display calibration method and calibration apparatus that enable adjustments relating to the profile, etc. of the display device to be made in a simple manner.
The present invention further relates to a recording medium recording a program that may advantageously be used, for example, when adjusting the color appearance, etc. of a screen or when calculating the input/output characteristics of a display.
2. Description of the Related Art
With increasing prevalence of high-performance personal computers (hereinafter, personal computers may also be referred to as PCs) and the decreasing prices of image input devices such as scanners and image output devices such as color printers, the opportunities for individuals to handle color images are increasing. However, as more individuals have come to handle color images, color reproducibility is becoming a problem. That is, the problem concerns the difficulty in color matching between an original image and an image produced on a display, or between an original image and an image printed by a printer, or further between an image produced on a display and an image printed by a printer. Such a problem arises because color characteristics such as a color producing mechanism and a color gamut differ between different input/output devices.
A color management system (hereinafter sometimes referred to as the CMS) is a technique for matching color appearance between different input/output devices such as displays, scanners, color printers, etc. Using the CMS, it becomes possible to match color appearance between an image read by a scanner and an image displayed on a display and also between such an image and an image output by a color printer, and an image processing system can be constructed that does not give the user the feeling of unnaturalness about the color appearances of the various images output from different input/output devices.
In recent years, it has become common to incorporate a CMS framework at the OS level, such as ICM (Image Color Matching) 1.0 in Windows 95 and ColorSync 2.0 in the Macintosh environment. Manufacturers of input/output devices provide users with device profiles conforming to ICM 1.0 or ColorSync 2.0 so that the users can view color images without unnatural differences in color between images produced by different image output devices, for example, an image produced on a display and an image printed by a printer.
Device profiles for ICM 1.0 and ColorSync 2.0 conform to the ICC profiles proposed by the International Color Consortium (ICC). With manufacturers of input/output devices providing device profiles conforming to the ICC Profile Specification, users, in the Windows environment and the Macintosh environment alike, can obtain images free from unnaturalness in color appearance and can use various input/output devices without having to worry about differences in color appearance.
When using a CMS in a computing environment today, the ICC profiles are generally used as information holding the characteristics of input/output devices.
FIG. 51
conceptually shows the format of an ICC profile Ip.
FIG. 52
shows dump data in hexadecimal to illustrate the format of the ICC profile Ip in a specific example.
As shown in
FIGS. 51 and 52
, the ICC profile Ip consists of a fixed length 128-byte profile header Ph containing information on the profile itself and information on the target device (input/output device), a variable length tag table Tt indicating what information is stored where, and tag element data Ted of variable length containing actual information.
In the ICC profile Ip, each necessary data element is described within the tag table Tt using a 12-byte tag consisting of a 4-byte signature tag Ta, a 4-byte storage address tag Tb, and a 4-byte size tag Tc indicating the size of the data element. A 4-byte tag count tag Tn at the head of the tag table Tt contains a count of the number of tags, (n), in the tag table itself. It is therefore seen that the total number of bytes in the tag table Tt is given by 4+12n bytes. In the example of
FIG. 52
, the tag count n is 4 (that is, 00000004h (h indicating hexadecimal notation)).
To describe in further detail the contents of the first 12-byte tag labeled profileDescriptionTag PDT (see
FIG. 52
) following the 4-byte tag count tag Tn in the tag table Tt, the first four bytes (6465 7363) as the signature tag Ta indicate information (name) unique to the profile, and the next four bytes (0000 00b4) as the storage address tag Tb represent the starting address (row b and column 4) in the tag element data Ted. The last four bytes (0000 0074) as the size tag Tc show that the data size is 74h=116. The tag element data Ted having the size of 74h is also a Profile Description Tag PDT and contains information (name, etc.) unique to the profile.
The tag element data Ted specified by the next 12-byte tag labeled mediaWhitePointTag (also referred to as wtptTag) wtpt contains CIEXYZ values of white (w). The tag element data Ted specified by the next 12-byte tag labeled redColorantTag (also referred to as rXYZTag) rXYZ contains normalized CIEXYZ values of red (r). The last 12-byte tag labeled redTRCTag (also referred to as rTRCTag) rTRC stores input/output characteristic values of red (r); in the example of
FIG. 52
, values of 16 points are stored in the last 32 bytes (two bytes for each point). In the CCC profile Ip, the stored CIEXYZ values are normalized with respect to the standard illuminant of D50.
FIG. 53
shows the color gamut of a display, such as a CRT display, plotted on an u′, v′ chromaticity diagram. In
FIG. 53
, the horseshoe-shaped region containing the triangle bounding the range of reproducible colors (color gamut) indicates the limits of chromaticities distinguishable by the human eye.
FIG. 54
shows an example of CIEXYZ measurements. Further,
FIG. 55
shows an example of the gamma characteristic (electro-optical conversion characteristic) as an input/output characteristic of a display.
In the case of a display, if the CIEXYZ values (see
FIG. 54
) when the primary colors R, G, and B are at their maximum values (Rmax, Gmax, and Bmax), as shown in
FIG. 53
, and the input/output characteristic for each of the R, G, and B colors, such as shown in
FIG. 55
, are known, then a gamma coefficient value can be calculated using the gamma coefficient calculation formula (IEC 1966-3) shown in equation (1) below defined by the International Electrotechnical Commission (IEC), and the display characteristics of the display can be determined using equations (2) to (5) below which are known linear conversion equations. Here, the CIEXYZ values of the R, G, and B colors define the range of reproducible colors (color gamut), and the input/output characteristic of the display is represented by the gamma characteristic.
where
P
i
=log
10
x
i
(x
i
=input voltage)
q
i
=log
10
y
i
(y
i
=display luminance)
In equation (1), x
i
represents the value of input voltage and y
i
the value of displayed luminance.
x=X/
(
X+Y+Z
) (2)
y=Y/
(
X+Y+Z
) (3)
u′=
4
X/
(
X+
15
Y+
3
Z
) (4)
v′=
9
X/
(
X+
15
Y+
3
Z
) (5)
As earlier described, in the ICC profile Ip for a display, the CIEXYZ values of the R, G, and B colors (refer, for example, to
FIG. 54
) are stored in the rXYZ, gXYZ, and bXYZ tags (in
FIG. 52
, the rXYZ tag is shown as an example) as information indicating the range of reproducible colors. As for the gamma characteristic, the input/output point values for the R, G, and B colors are respectively stored in the rTRC, gTRC, and bTRC tags. When the number of points in the tag is 0, it means that the gamma coefficient for that color is 1.0, and when the number of points is 1, the gamma coefficient value itself is stored. When the number of points is 2 or larger, the same number of input/output point values as the number of points are stored. In the example of
FIG. 52
, input/output point values for 16 points are stored in the last 32 bytes, and 16 output values are shown for 16 inputs dividing the section 0.0 to 1.0 in 16 equal parts, i.e., 0, {fraction (1/16)}, {fraction (2/16)}, . . . , {fraction (15/16)}. In other words, when the stored data elements are Y
1
, Y
2
, . . . , Y
n
, for example, (in the example of
FIG. 52
, n=16), relations (input, output)=(0/n, Y
1
), (1/n, Y
2
), . . . , ((n−1)/n, Y
n
) are stored.
In addition to the above, the CIEXYZ values (refer, for example, to
FIG. 54
) when white is at its maximum value (Wmax) are contained in the wtpt tag as the standard white information of the display.
In the ICC profile Ip for a display, it is usual practice to store these seven items of information (the normalized CIEXYZ values of the R, G, and B colors, the input/output point values for the R, G, and B colors, and the normalized maximum value information of white). These seven items of information can be obtained by displaying colors on the display based on color data, and by measuring the displayed luminance and CIEXYZ values using a measuring instrument (colorimeter such as a spectroradiometer). Usually, at the manufacturer, a reference display is prepared and, using the just mentioned measuring instrument, the luminance and CIEXYZ values of displayed colors are measured on the reference display; based on the obtained values, an ICC profile Ip is created which is supplied to the user.
When creating a profile, such as the ICC profile Ip, for a display, the input/output characteristics of the display must be measured.
For example, when a manufacturer delivers a new display unit to a user or performs color matching on the existing display unit that the user has, the practice has been such that the manufacturer's staff carries color data of measurement colors to be displayed on the display unit, an application for displaying colors from the color data, a signal generator for directly displaying colors on the display unit, a measuring instrument for measuring the colors displayed on the display unit, etc. to the user site and, using these resources, measures the input/output characteristics of the display unit. Then, based on the measurement results, the manufacturer's staff calibrates the display unit or creates a profile for color display correction for the display unit and installs it on the system in which the display unit is used.
Of course, the calibration of the display or creation of a profile for the display may be done at factory before shipment or by sending the user's display unit to the factory, but since colors displayed on the display are greatly influenced by the reflection of ambient lighting (surrounding light) on the display, it is desirable that the display setup or the creation of the profile be done at the site where the display is actually used, that is, at the user site.
Further, the display calibration work by the manufacturer as described above would be costly and not practical for ordinary users who use their personal computers in their homes. Therefore, in most cases, a profile that comes with a purchased display unit or a profile conforming to the ICC profile Ip and included as standard with an operating system such as Windows 95 is used as the profile data for the display.
Manufacturers display images on a reference display using various image data, measure luminance and chromaticity on the display surface using a specialized measuring instrument, create a profile for color conversion, and supply the created profile to users.
However, not all display manufacturers provide profiles, and furthermore, even in the case of a display shipped with a profile, the attached profile may not match the display used because of variations among individual display units or may become unusable because of aging or other factors.
On the other hand, if the user desires to calibrate his display by himself, he will need a measuring instrument for measuring the luminance and chromaticity on the display and image data (special data used for calibration, also called reference data) for displaying images on the display for the measurement.
Color calibration of a display requires the use of calibration image display data as reference data for collecting display calibration data and a measuring instrument for measuring the displayed image. Color reproduction on the display must account for the effects of surrounding light, such as ambient lighting, as well as the color display characteristics unique to the display used.
Accordingly, it has been common practice for the manufacturer's staff to carry a special measuring instrument and other resources to the user site and calibrate the user's display on site.
However, since the task of creating a profile by measuring the display using a measuring instrument involves extremely complicated procedures, the display calibration work has been a cost increasing factor for both the manufacturer and the user.
For users who cannot afford the expense of display calibration using professional equipment, the only choice left is to use profiles provided by the manufacturer.
However, the color output of a display varies depending on the environment where the display is used, the production lot, aging, etc. Furthermore, because of variations among individual units, there is no guarantee that the profile provided by the manufacturer will always match the user's display.
Accordingly, if a profile is to be obtained that matches the user's display, a profile must be created from the color display characteristics of the user's display itself.
If the user desires to create a profile for his own display, however, he will need a specialized measuring instrument for measuring the luminance and chromaticity on his display and reference data for displaying images to obtain measurement data; the problem here is, as earlier described, such a measuring instrument is expensive and not readily purchasable by an individual user. Furthermore, the reference data for obtaining measurement data is quite special, and data suitable for use as such reference data has not been made public.
On the other hand, display characteristics not only vary depending on the make and model, but also differ even between units of the same model, depending on the lot number, the length of time used, the use environment (particularly, lighting environment), etc. It is therefore not too much to say that each individual display unit has unique display characteristics.
Accordingly, creation of a profile such as one conforming to the ICC profile format requires that the display characteristics unique to the display be measured and the measurement results be reflected into the profile, but for reasons of cost, space, etc., it is difficult for an individual user to own a measuring instrument capable of measuring the display characteristics of a display, and the user ends up being unable to create a profile for his display, that is, a profile unique to his own display.
SUMMARY OF THE INVENTION
The present invention has been devised in view of the above-enumerated problems, and it is an object of the present invention to provide a terminal that makes it possible to measure in a simple manner the input/output characteristics, i.e., the electro-optical conversion characteristics, of a display such as a CRT display device or a liquid crystal display device attached to it.
It is another object of the present invention to provide an input/output characteristic measurement method and input/output characteristic calculation apparatus for a display device that enable the input/output characteristics to be measured and calculated in a simple manner at the user side.
It is a further object of the present invention to provide a profile creation method and profile creation apparatus for a display device that enable the user to create a profile relating to the color appearance of the display without using a specialized measuring instrument.
It is still another object of the present invention to provide a calibration method and calibration apparatus for a display device that enable the user to perform calibration relating to the profile, etc. of the display without the need for special reference data.
It is yet another object of the present invention to provide a recording medium recording a program that makes it possible, for example, to adjust the color appearance, etc. of a screen, or to calculate the input/output characteristics of a display.
A terminal according to the present invention is configured to simultaneously display on a display device: a pattern image region consisting of first pixels of first luminance and second pixels of second luminance in prescribed proportions to provide prescribed luminance by an average luminance value taken over the first and second pixels; and a grayscale image region consisting of pixels of uniform luminance. According to this configuration, an input/output characteristic of the display device can be measured in a simple manner based on the displayed results.
In this case, the input/output characteristic measurement can be further simplified by subdividing the grayscale image region into smaller regions each having different luminance.
It is also possible to further simplify the input/output characteristic measurement by providing regularity in the arrangement of the first and second pixels in the pattern image region.
An input/output characteristic measurement method according to the present invention comprises: a displaying step for simultaneously displaying on a display device a pattern image consisting of a plurality of colors and a grayscale image consisting of a single color lying between the plurality of colors used for the formation of the pattern image; and an input/output characteristic deriving step for obtaining an input/output characteristic of the display device based on the displayed images. Since the pattern image and grayscale image are displayed simultaneously, the input/output characteristic can be calculated easily.
In this case, if the pattern image is displayed as an image consisting of first pixels of first luminance and second pixels of second luminance in prescribed proportions to provide prescribed luminance by an average luminance value taken over the first and second pixels, and the grayscale image is displayed as an image consisting of pixels of uniform luminance, the input/output characteristic can be obtained easily.
For example, a grayscale pattern image containing a plurality of grayscale patches of gradually varying gray scale may be displayed on the display device, simultaneously with the pattern image, or alternatively, while keeping the pattern image displayed on the display device, the grayscale patch images forming the grayscale pattern image may be sequentially presented for display one at a time.
In a preferred mode, the pattern image is displayed as a dot pattern image consisting of black pixels and white pixels and the grayscale image as a grayscale pattern image containing a plurality of patches consisting of gray pixels with the gray scale varying in steps from one patch to the next; then, the patch having brightness closest to the brightness of the dot pattern image is selected from the grayscale pattern image, and the input/output characteristic of the display device is obtained based on the selected patch. In this way, the input/output characteristic of the display device for gray color can be obtained easily.
Further, by displaying the pattern image as a dot pattern image consisting, for example, of black pixels and non-black pixels and the grayscale image as a grayscale pattern image containing a plurality of patches consisting of like non-black pixels with the gray scale varying in steps from one patch to the next, the input/output characteristic for an arbitrary color can be obtained.
Furthermore, if R, G, and B colors, for example, are sequentially selected as the color of the non-black pixels in the dot pattern image while sequentially presenting the grayscale image pattern of the same color as the selected color, the input/output characteristic for each of the R, G, and B colors can be obtained.
Moreover, the input/output characteristic obtained for white color or a predesignated non-black color (which may include any one of the R, G, and B colors), for example, may be substituted for all or part of the input/output characteristics for the R, G, and B colors.
If the dot pattern image is displayed as a checkerboard pattern image consisting, for example, of black pixels and non-black pixels, the image can advantageously be used for sequential scan type displays.
By determining the displayed size of each color of the checkerboard pattern image according to the resolution of the display device, an artifact such as moire can be prevented from being generated in the displayed image, and the measurement can thus be made easily.
If the ratio between the black pixels and non-black pixels in the dot pattern image is set at a value other than 1:1, the generation of moire, etc. in the displayed image can be prevented more effectively.
By determining the black/non-black pixel ratio according to the resolution of the display device, a dot pattern image optimized for the display device can be produced.
The input/output characteristic obtained in the above method is, for example, the gamma characteristic representing the electro-optical conversion characteristic of the display device. The method can thus be applied to almost all types of display device.
In another preferred mode, the pattern image is displayed as a stripe pattern image consisting of lines of first pixels of first luminance and lines of second pixels of second luminance, the lines running parallel to the horizontal scanning direction of the screen of the display device, and the grayscale image is displayed as an image consisting of pixels of uniform luminance. This serves to eliminate the difference between the density represented by a data value and the actually displayed density that occurs, for example, due to the horizontal scanning frequency of a raster scan type display device.
For example, the lines consisting of the first pixels of the first luminance can be constructed from lines of black pixels and the lines consisting of the second pixels of the second luminance from lines of white pixels. The same effect can also be obtained if the pattern image is displayed as a stripe pattern image consisting of lines of black pixels and lines of non-black pixels, the lines running parallel to the horizontal scanning direction of the screen of the display device.
In an input/output characteristic calculation apparatus according to the present invention, display control means presents the pattern image and grayscale image simultaneously for display on the display device based on the pattern image data and grayscale image data read out of pattern image data holding means and grayscale image data holding means, and input/output characteristic calculation means obtains the input/output characteristic of the display device based on the display of the pattern image and grayscale image. Since the pattern image and grayscale image are displayed simultaneously, the input/output characteristic can be easily calculated.
In this case, a grayscale pattern image containing a plurality of grayscale patches of gradually varying gray scale, for example, may be displayed on the display device, simultaneously with the pattern image, or alternatively, while keeping the pattern image displayed on the display device, the grayscale patch images forming the grayscale pattern image may be sequentially presented for display one at a time.
In a preferred mode, the pattern image is displayed as a dot pattern image consisting of black pixels and white pixels and the grayscale image as a grayscale pattern image containing a plurality of patches consisting of gray pixels with the gray scale varying in steps from one patch to the next; then, the patch having brightness closest to the brightness of the dot pattern image is selected from the grayscale pattern image, and the input/output characteristic of the display device is obtained based on the selected patch. In this way, the input/output characteristic of the display device for a gray can be obtained easily.
Further, if the pattern image is displayed as a checkerboard pattern image consisting, for example, of black pixels and non-black pixels, the image can be advantageously used, for example, for sequential scan type displays.
By determining the displayed size of each color of the checkerboard pattern image according, for example, to the resolution of the display device, an artifact such as moire can be prevented from being generated in the displayed image, and the measurement can thus be made easily.
Further, if, for example, the ratio between the black pixels and non-black pixels in the dot pattern image is set at a value other than 1:1, the generation of moire, etc. in the displayed image can be prevented more effectively.
Furthermore, by determining the black/non-black pixel ratio according, for example, to the resolution of the display device, a dot pattern image optimized for the display device can be produced.
The input/output characteristic calculated by the apparatus is, for example, the gamma characteristic representing the electro-optical conversion characteristic of the display device. The apparatus can thus be applied to almost all types of display device.
In another preferred mode, the pattern image is displayed as a stripe pattern image consisting of lines of first pixels of first luminance and lines of second pixels of second luminance, the lines running parallel to the horizontal scanning direction of the screen of the display device. This serves to eliminate the difference between the density represented by a data value and the actually displayed density that occurs, for example, due to the horizontal scanning frequency of a raster scan type display device.
When the pattern image is displayed as a stripe pattern image consisting, for example, of lines of black pixels and lines of white pixels, the lines running parallel to the horizontal scanning direction of the screen of the display device, it becomes possible to eliminate the difference between the density represented by a data value and the actually displayed density that occurs, for example, due to the horizontal scanning frequency of a raster scan type display device. The same effect can also be obtained if the pattern image is displayed as a stripe pattern image consisting of lines of black pixels and lines of non-black pixels, the lines running parallel to the horizontal scanning direction of the screen of the display device.
If, for example, the dot pattern image or the stripe pattern image, whichever is suitable, can be selected for display as the pattern image, the apparatus can be applied to a wide variety of display devices.
In a profile creation method for a display device according to the present invention, the pattern image and grayscale image are displayed on the display device, an input/output characteristic is obtained based on the display of the pattern image and grayscale image, and the profile of the display device is created based on the obtained input/output characteristic. Since the pattern image and grayscale image are displayed simultaneously on the display device, the profile of the display device can be created in a simple manner.
In this case, if the pattern image is displayed as an image consisting of first pixels of first luminance and second pixels of second luminance in prescribed proportions to provide prescribed luminance by an average luminance value taken over the first and second pixels, and the grayscale image is displayed as an image consisting of pixels of uniform luminance, the profile of the display device can be created in a simpler manner.
In a preferred mode, the pattern image is displayed as a dot pattern image consisting of black pixels and white pixels and the grayscale image as a grayscale pattern image containing a plurality of patches consisting of gray pixels with the gray scale varying in steps from one patch to the next; then, the patch having brightness closest to the brightness of the dot pattern image is selected from the grayscale pattern image, and the input/output characteristic of the display device is obtained based on the selected patch. In this way, the input/output characteristic of the display device for a gray color can be obtained easily, and a profile based on the input/output characteristic for the gray color can be created. The same effect can be obtained if the pattern image is displayed as a dot pattern image consisting, for example, of black pixels and non-black pixels.
In the profile creation step, the profile is created based on color gamut information as well as on the input/output characteristic. This enhances the accuracy of the created profile.
By holding color gamut information for a plurality of representative display devices, a profile can be created that matches the target display device.
Provisions may be made to modify the existing profile of the display device based, for example, on the obtained input/output characteristic. This enables quick and accurate creation of a customized profile.
If R, G, and B colors, for example, are sequentially selected as the color of the non-black pixels in the dot pattern image while sequentially presenting the grayscale image pattern of the same R, G, or B color as the selected color, the input/output characteristic for each of the R, G, and B colors can be obtained, thus making it possible to produce a profile with greater fidelity to the display device.
Further, if the input/output characteristic previously obtained for a predesignated color is employed, for example, for all or part of the input/output characteristics for the R, G, and B colors, the input/output characteristic can be obtained quickly, and as a result, the profile of the display device can be quickly created.
If the dot pattern image is presented, for example, as a checkerboard pattern image consisting of black pixels and non-black pixels, a profile with greater adaptability to a sequential scan type display, for example, can be created.
Furthermore, if the dot pattern image is presented, for example, as a dot pattern image consisting of black pixels and non-black pixels in proportions other than 1:1, the generation of moire or other artifacts is prevented, facilitating the measurement.
By employing the gamma characteristic as the input/output characteristic to be obtained, input/output characteristics applicable to almost all kinds of display devices can be calculated.
In this case, by calculating a plurality of input value versus output value relations based, for example, on the obtained gamma coefficient value, and by creating the profile of the display device by including therein the thus calculated input value versus output value relations, profiles applicable to almost all kinds of display devices can be created.
For example, by obtaining the input/output characteristic for gray color using a stripe pattern image consisting of lines of black pixels and lines of white pixels, a profile for a raster scan type display or the like can be created.
Further, by obtaining the input/output characteristic for an arbitrary color using a stripe pattern image consisting of lines of black pixels and lines of white pixels, for example, a profile for a raster scan type display or the like can be created.
In a profile creation apparatus for a display device according to the present invention, the pattern image and grayscale image are displayed on the display device, an input/output characteristic is obtained based on the display of the pattern image and grayscale image, and the profile of the display device is created based on the obtained input/output characteristic. Since the pattern image and grayscale image are displayed simultaneously on the display device, the profile of the display device can be created in a simple manner.
In this case, if the pattern image is displayed as an image consisting of first pixels of first luminance and second pixels of second luminance in prescribed proportions to provide prescribed luminance by an average luminance value taken over the first and second pixels, and the grayscale image is displayed as an image consisting of pixels of uniform luminance, the profile of the display device can be created in a simpler manner.
In a preferred mode, the pattern image is displayed as a dot pattern image consisting of black pixels and white pixels and the grayscale image as a grayscale pattern image containing a plurality of patches consisting of gray pixels with the gray scale varying in steps from one patch to the next; then, the patch having a brightness closest to the brightness of the dot pattern image is selected from the grayscale pattern image, and the input/output characteristic of the display device is obtained based on the selected patch. In this way, the input/output characteristic of the display device for gray color can be obtained easily, and a profile based on the input/output characteristic for the gray color can be created.
The same effect can be obtained if the pattern image is displayed as a dot pattern image consisting, for example, of black pixels and non-black pixels.
The profile creation means creates the profile based on color gamut information as well as on the input/output characteristic. This enhances the accuracy of the created profile.
By holding color gamut information for a plurality of representative display devices, a profile can be created that matches the target display device.
In this case, provisions may be made to modify the existing profile of the display device based, for example, on the obtained input/output characteristic. This enables quick and accurate creation of a customized profile.
If R, G, and B colors, for example, are sequentially selected as the color of the non-black pixels in the dot pattern image while sequentially presenting the grayscale image pattern of the same R, G, or B color as the selected color, the input/output characteristic for each of the R, G, and B colors can be obtained, thus making it possible to produce a profile with greater fidelity to the display device.
Further, if the input/output characteristic previously obtained for a predesignated color is employed, for example, for all or part of the input/output characteristics for the R, G, and B colors, the input/output characteristic can be obtained quickly, and as a result, the profile of the display device can be quickly created.
If the dot pattern image is presented, for example, as a checkerboard pattern image consisting of black pixels and non-black pixels, a profile with greater adaptability to a sequential scan type display, for example, can be created.
Furthermore, if the dot pattern image is presented, for example, as a dot pattern image consisting of black pixels and non-black pixels in proportions other than 1:1, the generation of moire or other artifacts is prevented, facilitating the measurement.
By employing the gamma characteristic as the input/output characteristic to be obtained, input/output characteristics applicable to almost all kinds of display devices can be calculated.
In this case, by calculating a plurality of input value versus output value relations based on the obtained gamma coefficient value, and by creating the profile of the display device by including therein the thus calculated input value versus output value relations, profiles applicable to almost all kinds of display devices can be created.
For example, by obtaining the input/output characteristic for gray color using a stripe pattern image consisting of lines of black pixels and lines of white pixels, a profile applicable, for example, to a raster scan type display or the like can be created.
Further, by obtaining the input/output characteristic for an arbitrary color using a stripe pattern image consisting of lines of black pixels and lines of white pixels, for example, a profile applicable, for example, to a raster scan type display or the like can be created.
In a calibration method for a display device according to the present invention, calibration data relating to a profile for a display device provided at second equipment is transmitted from first equipment to the second equipment via a network, and a calibration image and guidance based on the calibration data is displayed on the display device at the second equipment; thereafter, data relating to the profile of the display device is collected when an operation is performed in accordance with the guidance. In this way, the profile of the display device can be created easily based on the collected data. Text, pictorial symbols, voice, etc. can be included in the guidance. Here, the first equipment may be configured, for example, as a server, and the second equipment as a client.
In a preferred mode, a reference profile is held at the first equipment, and calibration data relating to the reference profile is transmitted to the second equipment; then, data relating to the profile is collected at the second equipment, and the collected data is transmitted as display calibration information to the server. Based on this display calibration information, the first equipment modifies and updates the reference profile and holds it as a new reference profile. Since the profile is modified based on the reference profile, an accurate, customized profile can be created in a simple manner.
In this case, the reference profile may be held at the second equipment, and the profile be modified at the first equipment.
Conversely, the reference profile may be held at the first equipment, and the profile be modified at the second equipment.
Alternatively, calibration data relating to the profile of the display device provided at the second equipment may be held at the first equipment, and data relating to the profile of the display device be collected at the second equipment based on the calibration data, thereby to modify the reference profile held at the second equipment.
In this case, provisions may be made to automatically incorporate the new modified reference profile into a profile created in compliance with an ICC profile in a color management system at the second equipment.
In another preferred mode, calibration data relating to the profile of the display device provided at the second equipment is transmitted from the first equipment to the second equipment via a network, and a calibration image and guidance based on this calibration data are displayed on the display device at the second equipment. When display adjusting means provided on the display device is operated, the setting of the display adjusting means is changed. Calibration of the display device can thus be done at the second equipment even when the calibration data is not held at the second equipment.
Preferably, data indicating the month, day, and year that the calibration data was sent to the second equipment is held at the first equipment, and when a predetermined period has elapsed from the calibration data transmission date, a notification reminding the second equipment of the arrival of time to calibrate the display device is sent to the second equipment so that the settings of the display device at the second equipment are periodically updated.
In a calibration apparatus for a display device according to the present invention, second equipment is connected to first equipment via a network, and the first equipment holds calibration data and transmits it to the second equipment. Display control means at the second equipment displays a calibration image and guidance based on the thus transmitted calibration data on the display device, and when an operation is performed in accordance with the guidance, data relating to the profile of the display device is modified by display calibration information collecting means at the second equipment. Adjustments relating to the profile can thus be made at the second equipment even when the calibration data is not held at the second equipment.
In a preferred mode, a reference profile is held at the first equipment, and calibration data relating to the reference profile is transmitted to the second equipment; then, data relating to the profile is collected at the second equipment, and the collected data is transmitted as display calibration information to the first equipment. Based on this display calibration information, the first equipment modifies and updates the reference profile and holds it as a new reference profile. Since the profile is modified based on the reference profile, an accurate, customized profile can be created in a simple manner.
In this case, the reference profile may be held at the second equipment, and the profile be modified at the first equipment.
Conversely, the reference profile may be held at the first equipment, and the profile be modified at the second equipment.
Of course, calibration data relating to the profile of the display device provided at the second equipment may be held at the first equipment, and data relating to the profile of the display device be collected at the second equipment based on the calibration data, thereby to modify the reference profile held at the second equipment.
In this case, provisions may be made to automatically incorporate the new modified reference profile into a profile created in compliance with an ICC profile in a color management system at the second equipment.
In another preferred mode, calibration data relating to the profile of the display device provided at the second equipment is transmitted from the first equipment to the second equipment via a network, and a calibration image and guidance based on this calibration data are displayed on the display device at the second equipment. When display adjusting means provided on the display device is operated, the setting of the display adjusting means is changed. Calibration of the display device can thus be done at the second equipment even when the calibration data is not held at the second equipment.
Preferably, data indicating the month, day, and year that the calibration data was sent to the second equipment is held at the first equipment, and when a predetermined period has elapsed from the calibration data transmission date, a notification reminding the second equipment of the arrival of time to calibrate the display device is sent to the second equipment so that the settings of the display device at the second equipment are periodically updated.
In this case, the transmission may be performed using electronic mail.
For example, the first equipment may be configured as a WWW server, and the display control means at the second equipment as a browser.
A recording medium according to the present invention records a program for implementing the steps of displaying pixels of first luminance and pixels of second luminance in prescribed proportions in a first region of a screen, and displaying a grayscale image consisting of pixels of uniform luminance in a second region of the screen. Accordingly, when the program is loaded into a computer, the color appearance of the screen, for example, can be adjusted using the computer.
Further, a recording medium recording a program for implementing the steps of displaying pixels of first luminance and pixels of second luminance in prescribed proportions in a first region of a screen of an apparatus, displaying in a second region of the screen a grayscale image consisting of a plurality of smaller regions each containing pixels of uniform luminance, the luminance varying from one smaller region to the next, determining which of the smaller regions has been selected from the grayscale image, and calculating an input/output characteristic of the apparatus in accordance with the selected smaller region. Accordingly, when the program is loaded into a computer, the input/output characteristic of the apparatus can be calculated using the computer.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present invention will be apparent from the following description with reference to the accompanying drawings, in which:
FIG. 1
is a diagram showing the configuration of a computer to which one embodiment of the present invention is applied;
FIG. 2
is a block diagram showing the configuration of a profile creation apparatus according to one embodiment of the present invention, as applied to the computer of
FIG. 1
;
FIG. 3
is a diagram showing an example of a screen display produced on the display device of the profile creation apparatus;
FIG. 4
is a diagram for explaining a grayscale image;
FIG. 5
is a diagram for explaining a pattern image;
FIG. 6
is a diagram for explaining another example of the pattern image;
FIG. 7
is a diagram showing an example of simultaneous display of a dot pattern image and grayscale pattern image;
FIG. 8
is a diagram for explaining how a gamma characteristic is calculated for an arbitrary color;
FIG. 9
is a diagram for explaining the relationship between grayscale patches and RGB values;
FIG. 10
is a diagram for explaining gamma characteristic offset and cutoff voltage;
FIG. 11
is a diagram showing an example of simultaneous display of a stripe pattern image and grayscale pattern image;
FIG. 12
is a diagram showing an example of simultaneous display of a stripe pattern image, with its white line/black line ratio changed, and grayscale pattern image;
FIG. 13
is a flowchart for explaining the operation of the profile creation apparatus of
FIG. 2
;
FIG. 14
is a block diagram showing the configuration of a profile creation apparatus according to another embodiment of the present invention;
FIG. 15
is a block diagram showing the configuration of a profile creation apparatus according to still another embodiment of the present invention;
FIG. 16
is a flowchart for explaining the operation of the profile creation apparatus of
FIG. 15
;
FIG. 17
is a flowchart showing a modified example of the profile creation process;
FIG. 18
is a flowchart showing a modified example of the profile creation process;
FIG. 19
is a flowchart showing a modified example of the profile creation process;
FIG. 20
is a diagram for explaining the calculation of a gamma coefficient value;
FIG. 21
is a diagram showing input/output values at six points, calculated from the calculated gamma characteristic and used for the creation of an ICC profile;
FIG. 22
is a diagram for explaining the calculation of a gamma coefficient value that matches the display luminance;
FIG. 23
is a flowchart for explaining the calculation of a gamma coefficient value that matches the display luminance;
FIG. 24
is a diagram showing examples of gamma coefficient values calculated according to the display luminance;
FIG. 25
is a flowchart for explaining a process for creating an ICC profile using a plurality of dot pattern images;
FIG. 26
is a diagram for explaining the process of
FIG. 25
;
FIG. 27
is a diagram showing data obtained for the creation of an ICC profile by the process of
FIG. 25
;
FIG. 28
is a diagram showing the conceptual configuration of a display calibration system to which another embodiment of the present invention is applied;
FIG. 29
is a block diagram showing a specific example of the configuration of the system of
FIG. 28
;
FIG. 30
is a flowchart for explaining the operation of the system shown in
FIGS. 28 and 29
;
FIG. 31
is a diagram showing an example of an image and guidance displayed on the displace device of a client in the system shown in
FIGS. 28 and 29
;
FIG. 32
is a diagram showing another example of an image and guidance displayed on the displace device of a client in the system shown in
FIGS. 28 and 29
;
FIG. 33
is a diagram showing the conceptual configuration of a display calibration system to which still another embodiment of the present invention is applied;
FIG. 34
is a block diagram showing a specific example of the configuration of the system of
FIG. 33
;
FIG. 35
is a flowchart for explaining the operation of the system shown in
FIGS. 33 and 34
;
FIG. 36
is a diagram showing a specific example of the configuration of a display calibration system to which yet another embodiment of the present invention is applied;
FIG. 37
is a diagram showing an example of calibration data in the form of an HTML source program;
FIG. 38
is a diagram showing the conceptual configuration of a display calibration system to which a further embodiment of the present invention is applied;
FIG. 39
is a block diagram showing a specific example of the configuration of the system of
FIG. 38
;
FIG. 40
is a flowchart for explaining the operation of the system shown in
FIGS. 38 and 39
;
FIG. 41
is a diagram showing a specific example of the configuration of a display calibration system to which a still further embodiment of the present invention is applied;
FIG. 42
is a diagram showing a specific example of the configuration of a display calibration system to which a still further embodiment of the present invention is applied;
FIG. 43
is a diagram showing the conceptual configuration of a display calibration system to which a still further embodiment of the present invention is applied;
FIG. 44
is a block diagram showing a specific example of the configuration of the system of
FIG. 43
;
FIG. 45
is a flowchart for explaining the operation of the system shown in
FIGS. 43 and 44
;
FIG. 46
is a diagram showing an example of a display calibration image and guidance;
FIG. 47
is a diagram showing the conceptual configuration of a display calibration system to which a still further embodiment of the present invention is applied;
FIG. 48
is a block diagram showing a specific example of the configuration of the system of
FIG. 47
;
FIG. 49
is a diagram showing an example of management table structure for managing the next calibration date;
FIG. 50
is a flowchart for explaining the operation of the system shown in
FIGS. 47 and 48
;
FIG. 51
is a diagram showing a generalized example of ICC profile format;
FIG. 52
is a diagram showing a specific example of ICC profile format;
FIG. 53
is a diagram for explaining the color gamut of a display;
FIG. 54
is diagram showing an example of CIEXYZ values, etc.; and
FIG. 55
is a graph for explaining the gamma characteristic.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will be described below. Throughout the description hereinafter given, like or corresponding parts are designated by like reference numerals.
FIG. 1
shows the configuration of a computer
10
as a user terminal to which the present invention is applied. As is well known, the computer
10
comprises a computer main unit
12
and a display (display means)
14
, keyboard
16
, and mouse
18
attached to the main unit
12
.
The computer main unit
12
contains, though not specifically shown here, a central processing unit (CPU) functioning as judging, calculating, and control means, a semiconductor memory device used to store control programs and application programs, a semiconductor memory device used to provide a work area, various other storage devices (holding means and storage means) such as a hard disk and other large-capacity auxiliary storage devices for storing image data, etc., input/output interfaces such as an AD converter and D/A converter, and various connecting interfaces providing connections with other devices.
The display device
14
such as a CRT display as an image output means, the keyboard
16
with cursor movement keys that functions as a data input means, selection means, or designating means, and a pointing device (input device, selection means) such as the mouse
18
are connected to the computer main unit
12
via the connecting interfaces.
FIG. 2
shows a functional block diagram showing the configuration of a profile creation apparatus
21
according to one embodiment of the present invention, as applied to the computer
10
shown in FIG.
1
. The constituent elements of the profile creation apparatus
21
, other than the selection unit
16
(
18
) and display device
14
, are means for implementing the functions carried out by the computer main unit
12
with software installed thereon. The software is recorded as a program on a recording medium such as a floppy disk
15
A or CD-ROM
15
B which is loaded into a floppy disk drive
17
A or CD-ROM drive
17
B in the computer
10
so that the program can be used by being installed, for example, on a hard disk or the like incorporated in the computer
10
.
The profile creation apparatus
21
includes a pattern image data holding unit
30
which holds therein pattern image data representing a pattern image consisting of a plurality of colors, a grayscale image data holding unit
32
which holds therein grayscale image data consisting of a single color, and a display control unit
31
which reads out the pattern image data and grayscale image data from the pattern image data holding unit
30
and grayscale image data holding unit
32
and presents the pattern image and grayscale image simultaneously for display on the screen of the display device
14
.
The profile creation apparatus
21
further includes the selection unit
16
(
18
) which, in accordance with user selection, selects a grayscale image patch of the brightness closest to the brightness of the pattern image displayed on the display device
14
, a gamma coefficient calculation unit
36
(input/output characteristic calculation means) which obtains a gamma coefficient associated with the input/output characteristic of the display device
14
based on the selected patch, a common information holding unit
39
which stores information other than the gamma coefficient, that is, common information such as color gamut information and standard white information, and a profile creation unit
38
which creates a profile for the display device
14
, for example, the ICC profile Ip (see examples of FIGS.
51
and
52
), based on the gamma coefficient value calculated by the gamma coefficient calculation unit
36
and on the common information stored in the common information holding unit
39
.
Next, a detailed explanation of the pattern image data and grayscale image data stored and held in the pattern image data holding unit
30
and grayscale image data holding unit
32
will be given in association with displays produced on the display device
14
.
As shown in
FIG. 3
, the pattern image
40
expressed by the pattern image data stored in the pattern image data holding unit
30
and the grayscale image
42
expressed by the grayscale image data stored in the grayscale image data holding unit
32
are presented via the display control unit
31
for display, separately, in different regions but simultaneously on the same screen of the display device
14
in the computer
10
(profile creation apparatus
21
). In the region of the pattern image
40
, first pixels
40
a
of first luminance (in the example of
FIG. 3
, sets of black pixels indicated by hatching) and second pixels
40
b
of second luminance (in the example of
FIG. 3
, sets of white pixels) are basically arranged in prescribed proportions (in the example
FIG. 3
, a checkerboard pattern consisting of black pixels and white pixels in proportions of 1:1) to provide prescribed luminance by an average luminance value taken over the first and second pixels (in the example of
FIG. 3
, a value intermediate between black and white).
FIG. 3
shows an example of the pattern image
40
constructed from a combination of two colors, black and white, but checkerboard patterns of other color combinations may be used, as will be described later. Further, the number of colors need not be limited to two, but three, four, or more colors may be used; in other words, the pattern image may be constructed from a combination of first to n-th pixels having first to n-th luminance values.
On the other hand, the region of the grayscale image
42
consists of one or more uniform luminance regions (in the example of
FIG. 3
, five regions).
While the pattern image
40
consists of a plurality of colors, each uniform luminance region of the grayscale image
42
consists of a single color lying between the plurality of colors. In the example of
FIG. 3
, the pattern image
40
consists of the black pixels
40
a
and white pixels
40
b,
and each region of the grayscale image
42
is displayed in gray, a color considered to lie between the black and white colors.
The construction of the pattern image
40
and grayscale image
42
will be described in further detail.
First, as shown in
FIG. 3
, the grayscale image
42
is an image that contains a grayscale patch
44
consisting of a plurality of regions with the gray scale varying in steps from one region to the next (in the example of
FIG. 3
, a total of five grayscale patches, i.e., a grayscale patch
44
a
of gray closest in tone to black, a grayscale patch
44
b
of gray slightly lighter than the grayscale patch
44
a,
a grayscale patch
44
c
of gray slightly lighter than the grayscale patch
44
b,
a grayscale patch
44
d
of gray slightly lighter than the grayscale patch
44
c,
and a grayscale patch
44
e
of gray slightly lighter than the grayscale patch
44
d,
in decreasing order of hatching density). That is, the color of the grayscale patches
44
a
to
44
e
forming the grayscale image
42
is gray, a color lying between the black and white colors, as described above.
When the plurality of grayscale patches
44
a
to
44
e
are displayed simultaneously on the same screen, the grayscale image
42
is then called a grayscale pattern image. Instead of displaying the grayscale image
42
as a grayscale pattern image, the grayscale patches
44
a
to
44
e
of varying gray scale may be presented for display one at a time, switching from one patch to another. When displaying the image by switching, a grayscale patch
44
of uniform density (one of the grayscale patches
44
a
to
44
e
) is displayed in the entire region where the five grayscale patches
44
a
to
44
e
are displayed in FIG.
3
. In either case, the pattern image
40
is displayed at all times, that is, simultaneously with the grayscale image
42
.
In
FIG. 3
, the grayscale patches
44
a
to
44
e
are shown by hatching to indicate varying tonal densities, but in actuality, each of the grayscale patches
44
(
44
a
to
44
e
) forming the grayscale pattern image
42
is displayed as an image consisting of a single color of uniform density (in the illustrated example, uniform luminance), as schematically shown in
FIG. 4
, and the density (luminance) of the grayscale patch
44
can be varied by varying input image data values (RGB values).
For example, in the computer
10
, the color of an image is expressed by R, G, and B colors each represented by 8-bit data. Therefore, in the case of the grayscale patch
44
of gray color, by varying the R, G, and B image data values such that (R, G, B)=(0, 0, 0), (1, 1, 1), (2, 2, 2), . . . , (255, 255, 255), the color of the grayscale patch
44
to be displayed can be varied from black with the RGB image data value (R, G, B)=(0, 0, 0) to white with the RGB image data value (R, G, B)=(255, 255, 255) by way of gray of intermediate shades with the RGB image data value (R, G, B)=(x, x, x).
In the display
14
, each of the R (red), G (green), and B (blue) colors forms one pixel, as is well known, but in the present embodiment, it is assumed that one RGB set forms one pixel to facilitate the understanding of the invention. It will be recognized, however, that the present invention is also applicable if it is assumed that each of the R, G, and B colors forms one pixel.
Next, a description will be given of the pattern image
40
. As shown in
FIG. 5
, the pattern image
40
is a dot pattern image
46
consisting of pixels of two colors, for example, black color pixels (also called black pixels) and non-black color pixels, for example, white color pixels (also called white pixels); more specifically, the image consists of white pixels, i.e., pixel dots with the RGB image data value (R, G, B)=(255, 255, 255), and black pixels, i.e., pixel dots with the RGB image data value (R, G, B)=(0, 0, 0).
The dot pattern image
46
consisting of such white pixels and black pixels is displayed on the display device
14
, as shown in
FIG. 3
, simultaneously with the grayscale pattern image
42
containing the grayscale patches
44
of varying gray scale levels. As earlier noted, the grayscale patches
44
forming the grayscale pattern image
42
may be presented for display one at a time.
The color used is not limited to gray, but other colors may be used for the pattern image
40
and grayscale image
42
. For example, in the case of red color, the color of the grayscale patches
44
in the grayscale pattern image
42
can be varied from black to red by varying the R, G, and B image data values such that (R, G, B)=(0, 0, 0), (1, 0, 0), (2, 0, 0), . . . , (255, 0, 0). In this case, the dot pattern image
46
should be presented as an image consisting of black pixels, i.e., pixel dots with the RGB image data value (R, G, B)=(0, 0, 0), and red color pixels (also called red pixels) as non-black pixels, i.e., pixel dots with the RGB image data value (R, G, B)=(255, 0, 0).
To facilitate understanding, the following description deals primarily with examples of the pattern image
40
consisting of white pixels and black pixels and its corresponding grayscale image
42
, but the same description is equally applicable for other color combinations such as red and black, blue and black, green and black, red and white, blue and white, and green and white.
The dot pattern arrangement in the dot pattern image
46
, for example, the dot ratio, can be varied as desired by varying the proportions of black pixels versus non-black pixels.
While the dot pattern image
46
shown in
FIG. 5
is a so-called checkerboard pattern image with a white/black dot ratio of 1:1, the dot pattern image
48
shown in
FIG. 6
has a white/black dot ratio of 3:1 with white pixels and black pixels contained in proportions of 3:1. In this way, the density of the dot pattern image, i.e., the pattern image
40
, can be varied. The size of each dot forming the dot pattern image
46
is chosen to be small enough that the image appears as if the entire image were a halftone image when the screen of the display
14
was viewed straight-on from a suitable distance.
By varying the dot ratio in the case of the pattern image
40
and RGB data values in the case of the grayscale image
42
, as described above, the image density (luminance) can be varied as desired.
Next, a description will be given of how gamma can be measured and calculated by the gamma coefficient calculation unit
36
based on the pattern image
40
and grayscale image
42
displayed on the display device
14
. Gamma characteristic characterizes a CRT display, but the method hereinafter described can be applied not only to the CRT display but also for the measurement and calculation of the input/output characteristics (electro-optical conversion characteristics) of various other display devices such as liquid crystal display devices and plasma display devices.
For simplicity, the following description is given by ignoring the offset value and cutoff voltage of the display device
14
as negligible values. Denoting the output of the display device
14
, i.e., the displayed luminance, as B(y), and the input to the display device
14
, i.e., the input voltage, as E(x), the displayed luminance B is given in relation to the input voltage E by the following equation (6). In any equation given hereinafter, including equation (6), the symbol “{circumflex over ( )}” is used to represent a power; for example, E{circumflex over ( )}γ means E raised to the power γ.
B=E{circumflex over ( )}γ
(6)
The value of γ in this equation is called the gamma coefficient value, and the input/output characteristic defined by γ is called the gamma characteristic (see FIG.
55
). If the input voltage E and displayed luminance B at any one point, except the points at (E, B)=(0, 0) and (1, 1), on the graph shown in
FIG. 55
are known, the gamma coefficient value can be obtained using the above equation (1), etc.
Here, suppose that when the checkerboard dot pattern image
46
and five-level grayscale pattern image
42
were simultaneously displayed on the display device
14
, as shown in
FIG. 7
, the grayscale patch
44
e
appeared the same in color (luminance) as the dot pattern image
46
. The displayed luminance B(yi) of the checkerboard dot pattern image
46
with a white/black ratio of 1:1 is yi=0.5. If, at this time, the RGB value of the tonal path
44
is RGB=(192, 192, 192), as shown in
FIG. 7
, then the input value E(xi) is xi=192/255=0.753. This means that the point with (input, output)=(E, B)=(xi, yi)=(0.753, 0.5) has been measured (determined) as one point on the gamma characteristic curve of the display device
14
.
Then, in the gamma coefficient calculation unit
36
, when the three points with (input, output)=(0, 0), (0.753, 0.5), and (1.0, 1.0) are substituted in equation (1) to solve for γ, γ=2.45 can be derived as the gamma coefficient value.
In this way, by simultaneously displaying the dot pattern image
46
and grayscale pattern image
42
for comparison on the screen of the display device
14
to be measured, or by sequentially displaying the grayscale patches
44
a
to
44
e
for comparison with the dot pattern image
46
displayed on the screen, one of the grayscale patches
44
a
to
44
e
that appears the same in color as the dot pattern image
46
is determined, and the gamma coefficient value can be derived using the known RGB value (see
FIG. 7
) of the thus determined grayscale patch
44
. By further comparing the grayscale pattern image
42
(or each grayscale patch
44
) with the dot pattern image
48
of a different luminance value such as shown in
FIG. 6
, a plurality of points can be obtained on the gamma characteristic curve; in this way, a gamma coefficient value (gamma characteristic) of higher accuracy can be obtained.
As previously stated, for the dot pattern image
46
(the pattern image
40
) and its corresponding grayscale pattern image
42
, not only the combination of white pixels and black pixels but other color combinations, such as red and black, blue and black, green and black, red and white, blue and white, and green and white, can also be used.
For example, as shown in
FIG. 8
, when two colors each having the same image data value for R, G, and B are displayed in the form of a gray dot pattern image
46
with (R, G, B)=K
1
(C
1
, C
1
, C
1
) and K
2
(C
2
, C
2
, C
2
) (C
1
and C
2
are different values), the luminance of the dot pattern image
46
is given by (C
1
{circumflex over ( )}γ+C
2
{circumflex over ( )}γ)/2.
If this dot pattern image
46
appears the same in color as a gray grayscale patch
44
with an RGB image data value of (R, G, B)=K
3
(C
3
, C
3
, C
3
), then the relation (C
1
{circumflex over ( )}γ+C
2
{circumflex over ( )}γ)/2=C
3
{circumflex over ( )}γ holds. From this equation, the gamma coefficient value can be derived.
Accordingly, (R, G, B)=K
1
(C
1
,
0
,
0
), K
2
(C
2
,
0
,
0
), and K
3
(C
3
,
0
,
0
) should be used as the RGB image data values to obtain the gamma coefficient value for red, (R, G, B)=K
1
(
0
, C
1
,
0
), K
2
(
0
, C
2
,
0
), and K
3
(
0
, C
3
,
0
) should be used as the RGB image data values to obtain the gamma coefficient value for green, and (R, G, B)=K
1
(
0
,
0
, C
1
), K
2
(
0
,
0
, C
2
), and K
3
(
0
,
0
, C
3
) should be used as the RGB image data values to obtain the gamma coefficient value for blue.
In the above example, the offset value and cutoff voltage of the display device
14
have been ignored as negligible values when obtaining the gamma coefficient value, but depending on the type of display device
14
, there can occur a situation where a profile with high accuracy cannot be created if these values are ignored. In such cases, the gamma coefficient value must be calculated using an equation that takes the offset value and cutoff voltage into account.
Here, denoting the offset values for R, G, and B as Kor, Kog, and Kob, and the cutoff voltages as Ro, Go, and Bo, respectively, the outputs of R, G, and B, denoted Er, Eg, and Eb (in
FIG. 55
, letter B was used to denote displayed luminance, but to avoid confusion with B in RGB, letter E is used here) can be expressed by the following equations (7), (8), and (9), respectively.
Er=
(
R−Ro
){circumflex over ( )}γ
R+Kor
(7)
Eg=
(
G−Go
){circumflex over ( )}γ
G+Kog
(8)
Eb=
(
B−Bo
){circumflex over ( )}γ
B+Kob
(9)
where {circumflex over ( )}γR, {circumflex over ( )}γG, and {circumflex over ( )}γB are the gamma coefficient values for R, G, and B, respectively. The cutoff voltages Ro, Go, and Bo represent the input value (RGB value) at which the output luminance E begins to change when the input RGB value is applied to the display device under measurement.
More specifically, when a plurality of grayscale patches with different RGB values are arranged in increasing order of the RGB value and displayed with the blackest patch at the leftmost end as shown in
FIG. 9
(in the example of
FIG. 9
, nine grayscale patches are displayed), the RGB value at the point where color appears to change is the cutoff RGB value, which is (R, G, B)=(50, 50, 50) in the example of FIG.
9
. In the example of
FIG. 9
, the four grayscale patches at the left all appear black, as shown in the figure.
As for the offset value, the screen of the display device 14 when power is cut off is compared with the screen when a black image (RGB value is (RGB)=(0, 0, 0)) is displayed, and if the difference is not distinguishable, the offset value can be assumed to be zero and be ignored. If the difference is distinguishable, brightness or contrast should be adjusted on the display device
14
, before starting the measurement, to vary the brightness or contrast setting so that the offset value can be ignored. By making measurements on the display device
14
in this condition, the characteristics of the display device
14
can be measured under good conditions where there is no need to consider the offset value.
FIG. 10
shows the offset values Kor, Kog, and Kob and cutoff voltages (cutoff values) Ro, Go, and Bo in relation to the gamma characteristic. When the display is successfully adjusted to a point where the offset values Kor, Kog, and Kob can be ignored, the offset values Kor, Kog, and Kob become zero, i.e., Kor=Kog=Kob=0.
In the above embodiment, the pattern image data stored in the pattern image data holding unit
30
has been described as being image data representing the checkerboard dot pattern image
46
(see
FIG. 5
) with a black/non-black pixel ratio of 1:1 or pattern image data representing the dot pattern image
48
(see
FIG. 6
) consisting of black pixels and non-black pixels in proportions other than 1:1. However, depending on the type of display device
14
, there are cases where a gamma coefficient value with higher accuracy can be obtained if a stripe pattern image
50
is used that consists of lines
50
a
of black pixels and lines
50
b
of non-black pixels running parallel to the horizontal scanning direction of the display device
14
, as schematically shown in
FIG. 11
(in the example of
FIG. 11
, the black pixel lines
50
a
are equal in thickness to the non-black pixel lines
50
b
(in this example, white lines), and the ratio between the black pixels and white pixels is 1:1). In
FIG. 11
, the grayscale pattern image
42
is displayed as an image consisting of a plurality of grayscale patches
44
(
44
a
to
44
i
) like the one shown in FIG.
9
.
Generally, in a raster scan display device such as a CRT display, as the horizontal scanning frequency increases, the possibility that the input RGB value may not match the display RGB value increases in the case of the dot pattern image
46
or
48
; accordingly, the gamma coefficient value can be measured and calculated with higher accuracy if the stripe pattern image
50
shown in
FIG. 11
is used in place of the dot pattern image
46
or
48
.
In this case also, the accuracy of the gamma coefficient value can be enhanced by making measurements using a stripe pattern image
52
consisting of black pixel lines
52
a
and non-black pixel lines
52
b
with black pixels and white pixels contained in proportions other than 1:1, as shown in FIG.
12
.
In contrast, in a sequential scan display device such as a liquid crystal display device or a plasma display device, the input and display RGB values are generally in good agreement compared with the CRT display; therefore, in most cases it is preferable to use the dot pattern image
46
, etc.
For example, in a liquid crystal display device or a plasma display device, since the gamma coefficient value is close to 1.0 compared with the CRT display or the like, the dot pattern image
46
, consisting of black pixels ((R, G, B)=(0, 0, 0)) and white pixels ((R, G, B)=(255, 255, 255)), appears close in color to the grayscale patch
44
of the intermediate gray color ((R, G, B)=(128, 128, 128)).
Accordingly, if the pattern image data representing the dot pattern images
46
and
48
and the pattern image data representing the stripe pattern images
50
and
52
are both stored in the pattern image data holding unit
30
with provisions made to selectively supply the pattern image data to the display device
14
through the selection unit
16
(
18
) which also functions as a pattern image selection means, it becomes possible to supply optimum pattern image data to the display device
14
, whether it is a CRT display, a liquid crystal display device, or a plasma display device.
Next, the operation of the profile creation apparatus
21
of the embodiment shown in
FIG. 2
will be described with reference to the flowchart of FIG.
13
.
First, the display control unit
31
reads out the pattern image data from the pattern image holding unit
30
and presents the pattern image
40
, represented by the pattern image data, for display on the display device
14
(step S
1
), and also reads out the grayscale image data from the pattern image holding unit
30
and presents the grayscale image
42
, represented by the grayscale image data, for display (step S
2
).
At this time, while keeping the pattern image
40
displayed on the screen, either the grayscale image
42
is displayed by sequentially presenting the grayscale patches
44
of varying tonal densities, or the grayscale pattern image
42
consisting of a plurality of grayscale patches
44
of varying tonal densities is displayed; in this condition, the grayscale patch
44
that appears the same in color (brightness) as the pattern image
40
is determined and measured (step S
3
). This determination can be made with high accuracy by using a specialized measuring instrument, but since the measurement is made through a comparison, the determination can also be made with fairly high accuracy by the human eye. In other words, according to the present invention, the grayscale patch that definitely appears the same to the human eye can be determined.
Using the selection unit
16
(
18
) such as the keyboard
16
or the mouse
18
, the mouse cursor, not shown, is pointed at the grayscale patch
44
that appears the same in color, and the mouse
18
is clicked on it. In this way, the determination can be made with high accuracy without using a specialized measuring instrument.
When the result of the determination and selection made by operating the selection unit
16
(
18
) is fed back to the display control unit
31
, the RGB value of the grayscale patch
44
determined to be the same in color (brightness) as the pattern image
40
is supplied from the display control unit
31
to the gamma coefficient calculation unit
36
. The gamma coefficient calculation unit
36
obtains from the RGB value a coordinate point on the gamma characteristic curve, as previously described, and calculates from the obtained coordinate point the gamma coefficient characteristic as the input/output characteristic (step S
4
).
Next, based on the thus obtained gamma coefficient value, an ICC profile Ip (see
FIG. 52
) is created by the profile creation unit
38
(step S
5
).
As explained with reference to
FIG. 52
, the ICC profile Ip contains white color information and color gamut information as well as the gamma characteristic. However, unlike the gamma characteristic, the white color and color gamut of a display device
14
do not vary substantially among display devices
14
of the same kind and the same model; therefore, a profile having adequate precision can be created by using the white color and color gamut information of a reference display device without strictly measuring the white color and color gamut of each individual display device
14
. In view of this, in the profile creation apparatus
21
of
FIG. 2
, reference white color information and reference color gamut information are stored in advance as common information in the common information holding unit
39
. The profile creation unit
38
can thus create the ICC profile Ip by using the measured gamma coefficient value unique to the display device
14
and the common information such as the white color information and color gamut information common to the display devices
14
of the same model.
The following program is recorded on a recording medium such as the floppy disk
15
A or CD-ROM
15
B shown in FIG.
1
. Referring, for example, to
FIG. 3
, the program contains instructions for executing the step of displaying the pixels
40
a
of a first luminance and pixels
40
b
of a second luminance in prescribed proportions in a first region of the screen (the region of the pattern image
40
) (step S
1
) and the step of displaying the grayscale image
42
, consisting of pixels of uniform luminance, in a second region of the screen (the region of the grayscale image
42
) (step S
2
). By loading this program into the computer
10
, the color appearance of the screen of the display device
14
, for example, can be adjusted using the computer
10
.
Further, a recording medium such as the floppy disk
15
A or CD-ROM
15
B records a program for executing the step of displaying the pixels
40
a
of first luminance and pixels
40
b
of second luminance in prescribed proportions in a first region (for example, the region of the pattern image
40
) of the screen of the display device
14
(see
FIG. 3
) (step S
1
), the step of displaying in a second region of the screen (for example, the region of the grayscale image
42
) the grayscale image
42
consisting of a plurality of smaller regions (for example, the grayscale patches
44
a
to
44
e
) each containing pixels of uniform luminance, the luminance being different for each smaller region (for each of the grayscale patches
44
a
to
44
e
) (step S
2
), the step of determining which smaller region has been selected from among the smaller regions
44
a
to
44
e
of the grayscale image
42
(step S
3
), and the step of calculating the input/output characteristic of the display device
14
in accordance with the selected smaller region (step S
4
). By loading this program into the computer
10
, the gamma coefficient value as the input/output characteristic of the display device (the display device
14
of the computer
10
) can be calculated using the computer
10
. A program for executing the step of creating the ICC profile Ip may also be recorded on the recording medium.
FIG. 14
shows the configuration of a profile creation apparatus
22
according to another embodiment of the present invention.
The profile creation apparatus
22
includes a common information selection unit
54
which is interposed between the common information holding unit
39
and the profile creation unit
38
. The common information holding unit
39
holds therein reference white color information and reference color gamut information for a plurality of representative display devices, for example, display devices classified by manufacturer. The user can select the common information corresponding to the type of his display device
14
via the common information selection unit
54
.
Rather than having the user make the selection, provisions may be made so that the OS or the profile creation apparatus
22
itself makes the selection. For example, in the computer
10
in which an OS such as Windows 95 is installed, the display device
14
sends ID information to identify itself to the OS. Though not shown here, the computer
10
(the profile creation apparatus
22
) can be configured to automatically respond to the ID information and selects, via the common information selection unit
54
, the common information that best matches the ID information originating display unit
14
from among the information held in the common information holding unit
39
.
As earlier described, under PC environments, color management systems using ICC profiles Ip have begun to be used, and manufacturers are selling display devices with their ICC profiles Ip included with them or attached to the OS. These existing ICC profiles Ip do not always match every individual user's display device
14
but are considered to have a certain level of precision.
One possible approach here is to produce a customized ICC profile Ip for the display device
14
by modifying an existing ICC profile, rather than creating an ICC profile Ip.
FIG. 15
shows the configuration of a profile creation apparatus
23
in accordance with an embodiment in which a customized ICC profile Ip is produced by modifying an existing ICC profile Ip. The profile creation apparatus
23
differs from the profile creation apparatus
22
of
FIG. 14
in that the profile creation unit
38
is replaced by a profile modification unit
58
, and in that a profile holding unit
56
holding therein existing ICC profiles Ip is connected to the profile modification unit
58
.
The operation of the profile creation apparatus
23
will be described with reference to the flowchart of FIG.
16
.
First, the display control unit
31
presents the pattern image
40
for display on the display device
14
(step S
11
), and also presents the grayscale image
42
for display (step S
12
). The profile modification unit
58
reads out an existing ICC profile Ip from the profile holding unit
56
(step S
13
).
The display control unit
31
measures display characteristics (step S
14
), and the gamma coefficient calculation unit
36
calculates the gamma coefficient value based on the measured display characteristics (step S
15
).
The profile modification unit
58
alters the contents of gamma characteristic information (the contents of the rTRC tag, gTRC tag, and bTRC tag, etc.) in the existing Icc profile Ip, but the contents of other information (rXYZ, gXYZ, bXYZ) are not altered and the existing values are used without modification. In this way, the profile modification unit
58
produces a customized ICC profile Ip by modifying the existing ICC profile Ip (step S
16
).
Using an existing ICC profile Ip, it becomes possible to create an ICC profile Ip with higher accuracy. It should, however, be noted that the display characteristics of the display device
14
change with age; therefore, by making provisions to store the customized ICC profile Ip in the profile holding unit
56
as an existing ICC profile Ip in case there arises a need to regenerate the ICC profile Ip in future, the accuracy of the ICC profile Ip can be maintained over a long period of time.
A description will be given below of modified examples of the input/output characteristic calculation and profile creation process that are applicable to any of the profile creation apparatuses
21
to
23
shown in
FIGS. 2
,
14
, and
15
.
The processing example shown in
FIG. 17
obtains the gamma characteristic for each of the R, G, and B colors. First, based on the color selection made via the selection unit
16
(
18
), the display control unit
31
presents the pattern image
40
, consisting, for example, of black pixels and red (R) pixels as non-black pixels, and the: grayscale pattern image
42
of red (R) for display on the display device
14
(steps S
21
, S
22
, S
23
), measures the display characteristic for red (step S
24
), and calculates the input/output characteristic for red (step S
25
).
Next, the pattern image
40
, consisting of black. pixels and green (G) pixels, and the grayscale pattern image
42
of green are displayed, the display characteristic for green is measured, and the input/output characteristic for green is calculated (steps S
21
to S
25
).
Finally, the pattern image
40
, consisting of black pixels and blue (B) pixels, and the grayscale pattern image
42
of blue are displayed, the display characteristic for blue is measured, and the input/output characteristic for blue is calculated (steps S
21
to S
25
).
In this way, by obtaining the gamma characteristics for all of the R, G, B primaries producing color on the display device
14
, an ICC profile Ip with higher accuracy can be created (step S
26
).
However, since the displayed luminance of the display device
14
is lower for blue than for red and green, and since the human eye is less sensitive to blue, there are cases where a highly accurate measurement cannot be made for blue. In such cases, the input/output characteristic measured for red or green may be substituted for the input/output characteristic for blue.
In view of this situation, the processing example shown in
FIG. 18
specifies an arbitrary color by means of the selection unit
16
(
18
) from among prestored colors (step S
31
). Next, the pattern image
40
, consisting of black pixels and pixels of the specified color as non-black pixels, and the grayscale pattern image
42
of the specified color are presented for display (steps S
31
, S
32
, S
33
), the display characteristic for the specified color is measured (step S
34
), and the input/output characteristic for the specified color is calculated and is used directly as the input/output characteristic for a desired color (step S
35
). Then, the ICC profile Ip is created (step S
36
).
It will be appreciated that the color to be specified and the color to be measured can be interchanged, and also that, though not shown in the flowchart, the gamma characteristic for an already measured color can be substituted for the gamma characteristic for the specified color.
The gamma coefficient value storing field (rTRC tag, gTRC tag, bTRC tag) of the ICC profile Ip shown in
FIG. 51
is capable of holding not only the gamma coefficient value itself, but also two or more input/output point values, as earlier described.
In the processing example shown in
FIG. 19
, the dot pattern image
46
(see
FIG. 5
) is displayed as the pattern image
40
, and at the same time, the grayscale image
42
is displayed (steps S
41
, S
42
) (see the display shown in FIG.
7
).
In the displayed condition of
FIG. 7
, the grayscale patch
44
that matches the brightness of the dot pattern image
46
is determined, and the gamma characteristic value is measured (step S
43
). In this example, it is assumed that the grayscale patch of (R, G, B)=(192, 192, 192) designated by reference numeral
44
e
in
FIG. 7
matches the color appearance of the dot pattern image
46
having a white/black ratio of 1:1.
In this case, three points with (input, output)=(x, y)=(0, 0), (0.753, 0.5), and (1.0, 1.0) are obtained as values for measuring the gamma coefficient value, as shown in FIG.
20
. Here, the numerical value B(y)=0.5 represents the displayed luminance of the dot pattern image
46
with a white/black ratio of 1:1, and the numerical value E(x)=0.753 represents the ratio of the measured RGB value 192 to the maximum value 255 of the input RGB value (192/255).
FIG. 20
shows point A (0.5, 0.5) where the input RGB value E(x) is x=0.5 and the displayed luminance B(y) is y=0.5, point C (x, 0) where E(x) is x=x, and point B (x, 0.5) on a gamma characteristic curve whose gamma coefficient value is unknown, where the input RGB value E(x) is x=x and the displayed luminance B(y) is y=0.5.
By substituting the values of the above three points into equation (1), a gamma coefficient value of 2.443 is calculated (step S
44
).
Using the input/output characteristic equation (6), six outputs E{circumflex over ( )}2.443=(0, 0.0196, 0.1066, 0.2871, 0.5798, 1.0) are calculated for six inputs E=(0, 0.2, 0.4, 0.6, 0.8, 1.0), as shown in
FIG. 21
(step S
45
). By storing the thus calculated input/output values for six points (input/output sets) in the ICC profile Ip, a new ICC profile Ip can be produced (step S
46
).
The gamma characteristic of the display device
14
generally obeys the relation B=E{circumflex over ( )}γ previously shown in equation (6). However, in a low luminance region where the luminance is relatively low (for example, the region of the displayed luminance B(y)=0 to 0.35 in FIG.
22
), or in a high luminance region where the luminance is relatively high (for example, the region of the displayed luminance B(y)=0.65 to 1.0 in FIG.
22
), the luminance may deviate from the relation B=E{circumflex over ( )}γ (6) obtained for the luminance B(y)=0.5.
A processing example that solves this problem is shown in FIG.
23
. First, the gamma characteristic of the display device
14
is divided into a plurality of regions, that is, the low luminance region (the region of B(y)=0 to 0.35), the middle luminance region (the region of B(y)=0.35 to 0.65), and the high luminance region (the region of B(y)=0.65 to 1.0). Then, the pattern image
40
with a white/black ratio of 1:1 (in this case, the dot pattern image
46
) and the grayscale pattern image
42
are displayed, the grayscale patch
44
that matches the brightness of the pattern image
40
is determined, and the input RGB value E
2
=E
2
(x
2
,
0
) in the middle luminance region is measured (steps S
51
to S
54
).
Next, the white/black ratio in the pattern image
40
to be displayed is changed to 1:3 (step S
55
), and the input RGB value E
1
=E
1
(x
1
,
0
) in the low luminance region is measured (steps S
51
to S
54
).
Finally, the white/black ratio in the pattern image
40
to be displayed is changed to 3:1 (step S
55
), and the input RGB value E
3
=E
3
(x
3
,
0
) in the high luminance region is measured (steps S
51
to S
54
).
Next, the gamma coefficient value for each luminance region is calculated in accordance with equation (1) (step S
56
). That is, as shown in
FIG. 24
, the gamma coefficient value γ
1
for the low luminance region is calculated from the input/output relations (input, output)=(0, 0), (x
1
, 0.25), and (1.0, 1.0), the gamma coefficient value γ
2
for the middle luminance region is calculated from the input/output relations (input, output)=(0, 0), (x
2
, 0.5), and (1.0, 1.0), and the gamma coefficient value γ
3
for the high luminance region is calculated from the input/output relations (input, output)=(0, 0), (x
3
, 0.75), and (1.0, 1.0).
Then, using the thus calculated gamma coefficient values γ
1
, γ
2
, and γ
3
, the input/output relations in the respective luminance regions are calculated from the results of equation (6) obtained for the respective luminance regions (step S
57
). That is, as shown in
FIG. 24
, for inputs E(x)=0.1, 0.2, 0.3, 0.4, 0.5, and 0.6, outputs B(y)=B
11
, B
12
, B
13
, B
14
, B
15
, and B
16
are calculated based on the gamma coefficient value γ
1
; for inputs E(x)=0.7 and 0.8, outputs B(y)=B
17
and B
18
are calculated based on the gamma coefficient value γ
2
; and for an input E(x)=0.9, an output B(y)=B
19
is calculated based on the gamma coefficient value γ
3
.
By storing these values in the ICC profile Ip, a new ICC profile Ip is produced (step S
58
). The thus produced ICC profile Ip has extremely high accuracy, faithfully reproducing the characteristics of the display device
14
.
Since the ICC profile Ip is capable of storing the relations between the input and output values of the gamma characteristic, as described above, the measurement points obtained by comparing the pattern image
40
and grayscale pattern image
42
may be stored directly.
This is illustrated in the processing example shown in
FIG. 25
, in which dot pattern images
46
with white/black ratios of 1:4, 2:3, 3:2, and 4:1, respectively, are sequentially presented for display as the pattern image
40
, and input values E(x)=x
1
, x
2
, x
3
, and x
4
are obtained for four points with output values B(y)=0.2 (⅕), 0.4 (⅖), 0.6 (⅗), and 0.8 (⅘), as shown in
FIG. 26
(steps S
61
to S
65
).
After completing the measurement for the input values E(x) corresponding to the output values B(y) of the predetermined four points, the relations between the input and output values (see
FIG. 27
) are stored in the ICC profile Ip, and the ICC profile Ip is thus produced (step S
66
).
FIGS. 28 and 29
show the configuration of still another embodiment of the present invention.
FIG. 28
illustrates the conceptual configuration of a display calibration system
100
according to this embodiment, and
FIG. 29
shows a specific example of the configuration of the display calibration system
100
according to this embodiment (the same reference numeral
100
is used between the two figures).
In
FIGS. 28 and 29
, the display calibration system
100
comprises a server
102
as first equipment responsible for data storage, management, etc. and one or more clients.
106
as second equipment connected to the server
102
via a network
104
which is a communications circuit such as a LAN or the Internet. Each individual equipment is, basically, a computer by itself. The server
102
performs processing in response to various requests made from the clients
106
, and the clients
106
use the functions of the server
102
. The network
104
is responsible for data transfers between the server
102
and the clients
106
.
Since the server
102
and clients
106
are computers by themselves, each of them comprises a computer main unit
12
, display device
14
, keyboard
16
, and mouse
18
, as previously shown in FIG.
1
.
The server
102
includes a calibration data holding unit
110
for holding therein calibration data
108
relating to the ICC profile Ip of the display device
14
provided at each client
106
, and a transmitting unit
112
for transmitting the calibration data
108
to the target client
106
via the network
104
.
Each client
106
includes a receiving unit
114
for receiving the calibration data
108
transmitted over the network
104
, a display control unit
31
as a display producing application for displaying an image corresponding to the received calibration data
108
(including a calibration image displayed based on the calibration data
108
and characters displayed as guidance) on the display device
14
, and a display calibration information collection unit
118
for collecting data relating to the profile of the display device
14
in response to the operation of the keyboard
16
, etc. by a user
116
.
In the display calibration system
100
of
FIGS. 28 and 29
, the calibration data
108
used for making adjustments relating to the profile of the display device
14
is stored only at the server
102
.
Next, the operation of the display calibration system
100
shown in
FIGS. 28 and 29
will be described with reference to the flowchart of FIG.
30
.
First, when the user
116
wants to calibrate the display device
14
of the client
106
, he sends a request to the server
102
via the receiving unit
113
of the client
106
for the transfer of the calibration data
108
held in the calibration data holding unit
110
(step S
71
).
In response to the transfer request, the server
102
sends the calibration data
108
to the receiving unit
114
of the client
106
via the transmitting unit
112
and via the network
104
(step S
72
).
The display control unit
31
, upon detecting the arrival of the calibration data
108
through the receiving unit
114
, displays a calibration image based on the calibration data
108
, along with a guidance message (text data), which reads, for example, “Measure CIE XYZ values using a measuring instrument,” on the display device
14
(step S
73
).
In this case, a grayscale image consisting only of red color, for example, is displayed on the display device
14
, and the user
116
measures color values for the red color display using a measuring instrument (not shown), as an example of the display calibration information collection unit
118
, in accordance with the guidance message (step S
74
).
The color displayed on the display device
14
is usually measured in terms of X value, Y value, and Z value on the CIE XYZ chromaticity diagram (see FIG.
53
). In addition to the CIE XYZ values, values used to describe colors include, RGB, xy, uv, and u′v′, but all of these values can be derived by linear conversion from the CIE XYZ values.
In this way, display calibration information as color calibration data is collected through the display calibration information collection unit
118
(step S
75
).
By measuring several representative colors, such as blue, green, white, gray, and black, in addition to red, and obtaining their XYZ values, calibration can be performed relating to the ICC profile Ip, etc. of the display device
14
.
According to the display calibration system
100
of this embodiment, if a measuring instrument is available, the user
116
can collect data (measurement data taken by using the measuring instrument) necessary for the color calibration of the display device
14
by having a calibration image based on the calibration data
108
displayed on the display device
14
via the network
104
.
In this way, the user
116
of every client
106
connected to the network
104
can perform calibration relating to the ICC profile Ip, etc. of the display device
14
at the client
106
based, for example, on the same calibration data
108
.
The calibration relating to the ICC profile Ip, etc. of the display device
14
can be performed without using a specialized measuring instrument.
In this case, as shown, for example, in
FIG. 31
, the dot pattern image
46
consisting of black pixels and non-black pixels (in this example, a checkerboard dot pattern image with a white/black ratio of 1:1) and the grayscale pattern image
42
consisting of a plurality of grayscale patches
44
(
44
a
to
44
i
) of varying tonal densities are presented for display, along with such guidance messages as “Compare the top and bottom images”, “Which bottom image appears closest to the density of the top image?”, and “You can easily tell if you look at the screen from a distance.”
As explained with reference to
FIG. 55
, the luminance B of the display device
14
exhibits a light-emission pattern that follows the gamma characteristic. With a gamma value of 1.0, the luminance of the white/black dot pattern image
46
would become equal to that of the grayscale patch
44
having the intermediate gray color ((R, G, B)=(127, 127, 127)) in the grayscale pattern image
42
. However, since the gamma value of a CRT display or the like is greater than 1.0, the luminance of the white/black dot pattern image
46
becomes equal to that of the grayscale patch
44
having a gray color lighter than the intermediate gray. Accordingly, the gamma characteristic of the display device
14
can be obtained by selecting, using the keyboard
16
, etc., the grayscale patch
44
that matches the luminance of the dot pattern image
46
. In other words, the user
116
has only to operate the client
106
to answer the question in accordance with the guidance and the images
42
and
46
displayed on the display device
14
; then, data relating to the ICC profile Ip of the display device
14
is collected by the display calibration information collection unit
118
of the client
106
.
If the display device
14
has a relatively high resolution, an artifact called moire may appear on the display due to the interference between the frequency of the white/black dot pattern image
46
and the drawing frequency. The occurrence of moire may impair the accuracy of the visual comparison work of the user
116
. To avoid this, the dot pattern image
46
is generated not on a dot-by-dot basis, but in blocks of two dots (for example, when contiguous two dots at the attention point are white dots, contiguous two dots horizontally and vertically adjacent to the white dots are displayed as black dots) or in blocks of three dots, while holding the white/black ratio at 1:1, in other words, in the so-called checkerboard pattern. Since this causes the dot frequency to shift from the drawing frequency, no interference occurs, and the measurement can be performed without the interference of moire.
While using larger dots can prevent the occurrence of moire, if the dot size becomes too large, it becomes difficult to perform a comparison with the grayscale patch
44
. Since the comparison with the grayscale patch
44
can be accomplished easier as the dot size of the dot pattern image
46
becomes smaller, it is desirable not to make the dot size larger than necessary. Therefore, by checking the resolution or drawing frequency of the display device
14
in advance and by specifying the appropriate dot size, the comparative measurement can be performed using the smallest possible dot size that does not induce the occurrence of moire.
Since dot size is proportional to the resolution of the display device
14
, the block size may be varied in accordance with the resolution of the display device
14
. The resolutions of common displays for PCs, including the display device
14
of the computer
10
, include VGA (640×480), SVGA (800×600), XGA (1024×768), SXGA (1280×1024), etc.
A plurality of image data with different block sizes for different resolutions are stored as the calibration data
108
. In the profile creation apparatuses
21
,
22
, and
23
, the data are stored in the pattern image data holding unit
30
.
The user
116
can thus select the block size appropriate to the resolution of the display device
14
.
When the display device
14
is a CRT display, as described above, since the drawing frequency in the horizontal direction is higher than that in the vertical direction, the color luminance level may drop in the case of an image, such as the dot pattern image
46
, that is complex in the horizontal direction. In such cases, the stripe pattern image
50
schematically shown in
FIG. 32
, consisting only of low-frequency horizontal lines extremely low in frequency in the horizontal direction, is used instead of the white/black dot pattern image
46
. In the example of
FIG. 32
also, the white and black horizontal lines are identical in thickness (which means that the ratio between the black pixels and white pixels in the stripe pattern image
50
is 1:1).
On the other hand, when the display device
14
is a liquid crystal display device or the like, the luminance level seldom drops if a horizontally complex pattern image is displayed.
It is therefore preferable to select the image pattern according to the type of the display device
14
, such as the stripe pattern image
50
, when the display device
14
is a CRT display, and the checkerboard dot pattern image
46
in the case of a liquid crystal display device or the like.
As described above, in the display calibration system
100
shown in
FIGS. 28 and 29
, by responding to the question in the guidance message while viewing the images displayed on the display device
14
of the client
106
, the user
116
can collect information representing the characteristics of the display device
14
, on which the dot pattern image
46
and the pattern image
40
are displayed, without using a specialized measuring instrument. In this case, the calibration data used to obtain the information (calibration information) relating to the display device
14
need not be held at the client
106
, but has only to be held in the calibration data holding unit
110
at the server
102
, and the calibration of the display device
14
at every client
106
can be performed using the same calibration data
108
.
The display calibration system
100
shown in
FIGS. 28 and 29
has been described for the case where the calibration of the display device
14
at the client
106
is performed by connecting the server
102
and the client
106
via the network
104
, but the present invention is not limited to the system consisting of the server
102
and clients
106
connected via the network
104
; for example, the invention is also applicable to a system where personal computers, one as the first equipment and the other as the second equipment, are connected via the network
104
. This also applies to the embodiments hereinafter described.
FIGS. 33 and 34
show the configuration of yet another embodiment of the present invention.
FIG. 33
illustrates the conceptual configuration of a display calibration system
120
, and
FIG. 34
shows a specific example of the configuration of the display calibration system (designated by the same reference numeral
120
).
To avoid complication, in the display calibration systems hereinafter described, including the one shown in
FIGS. 33 and 34
, elements corresponding to those of the above-described display calibration system
100
are designated by the same reference numerals, and detailed descriptions of such elements will be omitted.
The display calibration system shown in
FIGS. 33
and
34
comprises a server
102
and one or more clients
106
connected to the server
102
via a network
104
.
The server
102
includes a calibration data holding unit
110
for holding therein calibration data
108
relating to the ICC profile Ip of the display device
14
provided at each client
106
, a profile holding unit
122
for holding as a reference profile the ICC profile Ip (see
FIGS. 51 and 52
) as a CMS framework for color appearance matching, a profile modification unit
124
for modifying the ICC profile Ip, and a transmitting unit
112
and receiving unit
126
for performing data transfers to and from the client
106
via the network. As earlier described, the ICC profile Ip is used, for example, in ICM 1.0 in the Windows environment and in ColorSync 2.0 in the Macintosh environment.
On the other hand, the client
106
includes a receiving unit
114
, a display control unit
31
, a display calibration information collection unit
118
, and a transmitting unit
128
for transmitting the data, collected by the display calibration information collection unit
118
and relating to the ICC profile Ip of the display device
14
, as display calibration information to the server
102
via the network
104
.
Operation of the display calibration system
120
of
FIGS. 33 and 34
will be described briefly. In this system
120
, the profile modification unit
124
at the server
102
modifies the ICC profile Ip based on the ICC profile Ip held in the profile holding unit
122
at the server
102
and on the data supplied from the display calibration collection unit
118
. The modified ICC profile Ip is sent to the client
106
as an ICC profile Ip specific to the display device
14
on which the measurements were taken. By incorporating this ICC profile Ip into the display control unit
31
, the client
106
can match color appearance between images displayed on the display device
14
and images output on a different image input/output device, such as a printer, not shown.
Next, the operation of the display calibration system
120
of
FIGS. 33 and 34
will be described in further detail with reference to the flowchart diagrammatically shown in FIG.
35
.
First, the calibration data
108
held in the calibration data holding unit
110
at the server
102
is transmitted from the transmitting unit
112
to the display control unit
31
via the network
104
and via the receiving unit
114
at the client
106
(step S
81
).
Next, at the client
106
, the dot pattern image
46
and grayscale pattern image
42
, as pattern images based on the calibration data
108
, are displayed on the display device
14
along with a guidance message (question) (see FIG.
31
), and the user
116
responds to the question using the keyboard
16
, etc. while viewing the displayed images (step S
82
).
This response is collected as display calibration information by the display calibration information collection unit
118
, and the resulting display calibration information is transmitted from the transmitting unit
128
to the profile modification unit
124
via the network and via the receiving unit
126
at the server
102
(step S
83
).
Upon receiving the display calibration information, the server
102
activates a profile modification program and modifies the contents of the ICC profile Ip by calculating the gamma characteristic, etc. as previously described (step S
84
).
The modified ICC profile Ip is stored in the profile holding unit
122
by being associated with the display device
14
of the client
106
and, at the same time, is transmitted from the transmitting unit
112
via the network
104
to the receiving unit
114
at the client
106
for incorporation into the display control unit
31
(step S
85
).
In this way, in the display calibration system
120
shown in
FIGS. 33 and 34
, the ICC profile Ip of the display device
14
of the client
106
can be obtained at the client
106
, though neither data nor the modification program relating to the ICC profile Ip is held at the client
106
.
FIG. 36
shows the configuration of a display calibration system
130
according to a further embodiment of the present invention. The display calibration system
130
differs in configuration from the display calibration system
120
shown in
FIG. 34
in that the profile holding unit
122
for holding the ICC profile Ip is provided at the client
106
, not at the server
102
.
In the display calibration system
130
of
FIG. 36
, the ICC profile Ip held as a reference profile at the client
106
is sent to the server
109
along with the collected display calibration information. At the server
102
, the profile modification unit
124
modifies the ICC profile Ip, and the modified ICC profile Ip is sent back to the client
106
. The modified profile Ip as a new reference profile is not only incorporated into the display control unit
31
, but is also held in the profile holding unit
122
.
The display calibration system
130
of
FIG. 36
has the advantage that the server
102
need not to hold the ICC profile Ip corresponding to each client
106
, and yet the server
102
can update the ICC profile Ip previously generated for each specific client
106
and already used by that client
106
.
Though not shown here, in the display calibration system
130
, the profile holding unit
122
may also be provided at the server
102
, like the server
102
in the display calibration system
120
of FIG.
34
. In that case, if the ICC profile Ip held at the server
102
or the client
106
is corrupted unpredictably, the profile can be restored using the other ICC profile Ip.
In the display calibration systems
120
and
130
shown in
FIGS. 34 and 36
where data are transferred in both directions, the Internet, a collection of interconnected networks all using the same protocol and same addressing schema, is used as the network
104
.
In an example using the Internet, a World Wide Web (WWW) server (hereinafter also referred to as an http server) is used as the server
102
that sends data to the client
106
.
In that case, the calibration data
108
held in the calibration data holding unit
110
is written using a WWW programming language, such as HTML (hypertext markup language) or Java.
FIG. 37
shows the calibration data
108
in the form of an HTML source program for displaying an image consisting of the guidance message and the checkerboard dot pattern image
46
and grayscale pattern image
42
shown in FIG.
31
. When this source program is stored as the calibration data
108
at the server
102
as an http server, the user
116
can display an image based on the calibration data
108
shown in
FIG. 31
on a WWW browser such as Netscape Navigator or Internet Explorer by accessing the server
102
.
The server
102
as an http server takes as display calibration information the response that the user
116
sends by viewing the image displayed based on the calibration data
108
, and modifies the existing ICC profile Ip using the profile modification unit
124
.
In a system using the Internet, electronic mail (E-mail) is used as a method of sending the ICC profile Ip to the client
106
at the user
116
. In this case, the functions of two servers, an http server for the WWW and a mail server (hereinafter called the SMTP server) for transferring mail, must be incorporated in the server
102
. Of course, the http server and the SMTP server may be configured as different servers between which data are transferred.
In the display calibration system (designated by reference numeral
120
or
130
) using the Internet, when the client
106
accesses the server
102
as an http server by using a WWW browser, the server
102
sends the ICC profile Ip by electronic mail to the E-mail address of the client
106
. The client
106
extracts only the ICC profile Ip from the received electronic mail and incorporates (installs) it into the display control unit
31
, etc.
In the display calibration systems
120
and
130
shown in
FIGS. 34 and 36
, the ICC profile Ip is modified and generated at the server
102
, but the configuration is not limited to the above example. Rather, the system may be configured in other ways, such as the display calibration system
132
shown in
FIGS. 38 and 39
.
In this example, the server
102
sends the calibration data to the client
106
, along with the source ICC profile Ip and a profile generation program, thereby enabling the profile modification unit
124
at the client
106
to generate an ICC profile Ip. The profile generation program is written using, for example, Java which is a programming language suited to the Internet WWW environment. The generation program is held at the server
102
as a WWW server, and the generation program itself, using Java, is sent to the client
106
at the request of the client
106
, thus enabling the profile generation program to be run on the CPU (not shown) of the client
106
.
In the above configuration, the display calibration information data for operating the profile modification unit
124
which is implemented by the profile generation program need not be sent to the server
102
via the network
104
, eliminating the need to use the CPU of the server
102
for profile generation and thus alleviating the burden of the network
104
as well as the server
102
.
More specifically, as shown in the flowchart of
40
, in the display calibration system
132
shown in
FIGS. 38 and 39
, the ICC profile Ip, profile modification program, and calibration data
108
are sent from the server
102
to the client
106
(step S
91
), and the user
116
enters his response to the guidance message while viewing the image displayed based on the calibration data (step S
92
). Thereupon, the profile generation program is executed at the client
106
, and the profile modification unit
124
modifies the ICC profile Ip based on the result of the user's response (step S
93
).
As earlier noted, Java can be employed as a programming language. On the Internet, a distributed data environment is realized. Data is held at each server
102
, and data is transmitted at the request of the user
116
. Java, developed as a network communication programming language, permits a Java program held at the server
102
to be sent to the user
116
along with the data requested by the user
116
so that the program can be run on the client
106
, the computer at the user
116
.
The ICC profile Ip may be held at the client
106
. An example of such a display calibration system
134
is shown in the block diagram of FIG.
41
. In the example of
FIG. 41
, the server
102
sends the calibration data
108
to the client
106
along with the profile generation program, and the client
106
activates the profile modification unit
124
based on the profile generation program and modifies the ICC profile Ip based on the ICC profile Ip held in the profile holding unit
122
.
In ICM 1.0 for Windows 95 or Windows 98, ICC profiles Ip are stored in the predesignated system-related folder (C:\Windows\System\Color). This is the same for ColorSync 2.0 for Macintosh.
In view of this, in a display calibration system
136
according to a still further embodiment of the present invention shown in
FIG. 42
, an install unit
138
is provided by which the ICC profile Ip modified by the profile modification unit
124
at the client
106
is automatically installed in the predesignated system-related folder, saving the user
116
the trouble of installing it himself.
FIGS. 43 and 44
show the configuration of a still further embodiment of the present invention. The display calibration system
140
shown here is configured so that the user
116
, based on the calibration data
108
sent from the server
102
, can directly adjust the contrast, brightness, color temperature, convergence, monitor distortion, and other parameters that have significant effects on the display color of the display device
14
, such as a CRT display, provided at the client
106
.
More specifically, this example aims at achieving a certain degree of color appearance matching, not by using the ICC profile Ip, but by generalizing the settings of the display device
14
relating to the ICC profile Ip.
The operation of the display calibration system
140
will be described with reference to the flowchart of FIG.
45
. First, the server
102
sends the calibration data
108
to the client
106
(step S
101
).
The display control unit
31
presents the guidance and images (the dot pattern image
46
with a white/black ratio of 1:1 and the grayscale pattern image
42
(grayscale patches
44
a
to
44
i
)) based on the calibration data
108
for display on the display device
14
, the guidance containing messages “Compare the top and bottom images,” “Adjust the display contrast so that the third patch from right in the bottom grayscale image becomes closest in density to the top image,” and “You can easily tell if you look at the screen from a distance,” as shown in
FIG. 46
(step S
102
).
In accordance with the guidance, the user
116
sets the contrast adjusting control (button), etc. (not shown) so that the third grayscale patch
44
from right appears the same in density as the dot pattern image
46
(step S
103
).
When all clients
106
connected to the network
104
have thus calibrated the respective display displays
14
in accordance with the calibration data
108
sent from the server
102
, the color output of every display device
14
becomes substantially the same.
In the display calibration system
140
of
FIGS. 43 and 44
, since the ICC profile Ip is not used for the calibration of the display device
14
, a certain degree of color appearance matching can be achieved in MS-DOS, UNIX, and other OS environments that do not support the ICC profile Ip.
That is, the display calibration system
140
can be applied to any client
106
connected to the network
104
, regardless of the OS, since the display settings are adjusted using the control features provided in the display device
14
itself and without creating the so-called device profile.
When the display device
14
is, for example, a CRT display, the phosphors used therein deteriorate with time, degrading the crispness of displayed color. That is, the color that the display device
14
produces varies over time. Therefore, performing the calibration of the display device
14
(the adjustment of the ICC profile Ip or the adjustment of contrast, etc.) only once is not sufficient, but recalibration must be performed periodically to compensate for variations in the characteristics of the display device
14
over time.
FIGS. 47 and 48
show the configuration of a display calibration system
142
which permits the user to periodically update the profile of the display device
14
of the client
106
.
In the display calibration system
142
, the server
102
includes an internal clock
148
as a clock means, and date/time information generated by the internal clock
148
is supplied to a calibration data/time information holding unit
144
as well as to a notification unit
146
. The calibration date/time information holding unit
144
holds therein a management table
150
or a management table
152
such as shown in FIG.
49
. The management table
150
consists of a previous calibration date/time storing section
153
, a next calibration date/time storing section
154
for storing data indicating the date and time of the next calibration scheduled to be performed after the elapse of a predetermined period (predetermined time) from the date and time of the previous calibration, and a mail address storing section
155
for storing the mail address of the target client
106
; the management table
152
consists of a next calibration date/time storing section
154
and a mail address storing section
155
for storing the mail address of the target client
106
.
The operation of the display calibration system
142
of
FIGS. 47 and 48
will be described with reference to the flowchart shown in FIG.
50
.
The calibration date/time information holding unit
144
of the server
102
compares the next calibration date and time stored in the management table
150
or
152
with the present date and time supplied from the internal clock
148
(step S
111
).
When the predetermined period has elapsed from the previous calibration date and time and the next calibration date and time has become equal to the present date and time, the notification unit
146
refers to the mail address stored in the storing section
155
and notifies the client
106
of the arrival of time to calibrate the display (step S
112
).
When a request is returned from the client
106
in response to the notification, the server
102
transmits the calibration data
108
to the client
106
(step S
113
), stores the date and time of the transmission as new calibration date and time in the storing section
153
, and updates the contents of the storing section
154
by adding the predetermined period to the new calibration date and time and thus creating the next calibration date and time data (step S
114
). The user
116
performs the calibration using the image displayed based on the-calibration data
108
(step S
115
).
In this way, in the display calibration system
142
of
FIGS. 47 and 48
, data indicating the date and time of the ICC profile Ip generated at each client
106
is held at the server
102
and, when a predetermined period has elapsed, a notification is sent to the corresponding client
106
, urging it to perform the calibration of the display device
14
. The client
106
creates the ICC profile Ip in accordance with this notification, to eliminate the effects of display deterioration over time.
Though not shown here, a configuration that permits the user to periodically adjust the contrast, etc. of the display device
14
can also be accomplished by replacing the display calibration information collection unit
118
at the client
106
by the display device
14
and by making provisions to send the calibration data from the display control unit
31
to the display device
14
(see FIG.
44
).
Electronic mail is preferably used as means for notifying the client
106
. Electronic mail is the most commonly used notification means on the Internet. The E-mail address of the user
116
is stored in advance as the mail address of the client
106
and, when a predetermined period has elapsed, a mail message urging the user to perform the recalibration of the display device is sent to the E-mail address. The E-mail address of the user
116
as the administrator of the display device is contained in the display calibration information and is fetched from the client
106
when the user performs an operation on the display calibration information collection unit
118
.
In this case also, the WWW is used to display the calibration data
108
, as explained with reference to FIG.
30
. The WWW realizes a multimedia display environment such as images, voice, characters, etc. WWW browsers are available for various platforms including Windows, Macintosh, and UNIX and, by writing the calibration data
108
with a WWW programming language such as HTML or Java, all the clients
106
connected to the Internet can be supported across different platforms.
An example of the calibration data
108
held at the server
102
will be briefly described here. The contents of the calibration data
108
are substantially the same as the contents of the data held in the pattern image data holding unit
30
and grayscale image data holding unit
32
in the profile creation apparatuses
21
,
22
, and
23
(
FIGS. 2
,
14
, and
15
), and the details will not be given here, but briefly, the server
102
is configured to send the best suited calibration data according to the type of the display device
14
provided at the client
106
.
According to the present invention, by displaying on a display device a pattern image consisting of a plurality of colors and a grayscale image consisting of a single color, there is achieved the effect that based on the displayed images, the input/output characteristic, i.e., the electro-optical conversion characteristic, of a so-called display such as a CRT display or a liquid crystal display can be measured and calculated in a simple manner at the user side.
Further, according to the present invention, a pattern image consisting of a plurality of colors and a grayscale image consisting of a single color are displayed on a display device and, based on the displayed images, the input/output characteristic of the display is obtained, and the profile of the display is created based on the thus obtained input/output characteristic. This achieves the effect that the profile relating to the color appearance of the display device can be created by the user without using a specialized measuring instrument.
Furthermore, according to the present invention, since the system is configured so that calibration data is sent from the first equipment to the second equipment via a network, adjustments relating to the display profile, etc. can be easily made by the user at the second equipment without the need to get specially prepared reference data.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims
- 1. A calibration method for a display device, comprising:a calibration data transmitting step for transmitting calibration data from first equipment to second equipment via a network, said calibration data being held at said first equipment and transmitted in relation to a reference profile held at said first or said second equipment and applicable to a display device provided at said second equipment; a calibration image displaying step for displaying a calibration image and guidance based on said calibration data on said display device at said second equipment; a display calibration information collecting step for collecting data relating to the profile of said display device when an operation is performed in accordance with said guidance; and a reference profile modifying and holding step for modifying said reference profile at said second equipment or at said first equipment based on said collected display calibration information, and for holding said modified reference profile as a new reference profile at said first or said second equipment.
- 2. A calibration method for a display device as claimed in claim 1, further comprising a profile incorporating step for automatically incorporating said new reference profile held at said first or said second equipment in said reference profile modifying and holding step into a profile created in compliance with an ICC profile in a color management system at said second equipment.
- 3. A calibration method for a display device, comprising:a calibration data transmitting step for transmitting calibration data from first equipment to second equipment via a network, said calibration data relating to a profile for a display device provided at said second equipment; a calibration image displaying step for displaying a calibration image and guidance based on said calibration data on said display device at said second equipment; and a display adjusting means re-set ting step for changing the setting of display adjusting means provided on said display device when said display adjusting means on said display device is operated in accordance with said guidance and, further comprising: a calibration data transmission data holding step for holding at said first equipment data indicating the month, day, and year that said calibration data relating to the profile of said display device provided at said second equipment was transmitted from said first equipment to said second equipment via said network in said calibration data transmitting step; and a calibration reminding notification transmitting step for transmitting a notification reminding said second equipment of the arrival of time to calibrate said display device, from said first equipment to said second equipment via said network when a predetermined period has elapsed from said calibration data transmission date.
- 4. A calibration apparatus for a display device, comprising a network for data transmission, first equipment which stores and manages data, and second equipment which uses functions of said first equipment, wherein:said first equipment includes calibration data holding means for holding therein calibration data relating to a profile for a display device provided at said second equipment, said second equipment includes said display device, display control means for controlling a display to be produced on said display device, and display calibration information collecting means; and said display control means, upon detecting the arrival of said calibration data transmitted from said first equipment to said second equipment via said network, displays a calibration image and guidance based on said calibration data on said display device at said second equipment and, when an operation is performed on said display device in accordance with said guidance, said display calibration information collecting means collects data relating to the profile of said display device based on said performed operation.
- 5. A calibration apparatus for a display device as claimed in claim 4, wherein:said first equipment further includes profile holding means for holding therein a reference profile for said display device provided at said second equipment, and a profile modifying means for modifying said reference profile; said second equipment transmits the data relating to the profile of said display device, collected by said display calibration information collecting means, as display calibration information to said profile modifying means at said first equipment via said network; and said profile modifying means modifies said reference profile based on said transmitted display calibration information, and said profile holding means holds said modified reference profile as a new reference profile.
- 6. A calibration apparatus for a display device as claimed in claim 4, wherein:said first equipment further includes profile modifying means for modifying the profile of said display device provided at said second equipment; said second equipment further includes profile holding means for holding therein a reference profile for said display device provided at said second equipment; and when transmitting the data relating to the profile of said display device, collected by said display calibration information collecting means as display calibration information, to said profile modifying means at said first equipment via said network, said second equipment also transmits said reference profile held in said profile holding means; said profile modifying means modifies said transmitted reference profile based on said transmitted display calibration information; and said first equipment transmits said modified reference profile to said second equipment, and said profile holding means holds said modified reference profile as a new reference profile.
- 7. A calibration apparatus for a display device as claimed in claim 6, further comprising profile incorporating means for automatically incorporating said new reference profile held in said profile holding means into a profile created in compliance with an ICC profile in a color management system at said second equipment.
- 8. A calibration apparatus for a display device, comprising:a network for data transmission; first equipment which stores and manages data; and second equipment which uses functions of said first equipment, wherein: said first equipment includes calibration data holding means for holding therein calibration data relating to a profile for a display device provided at said second equipment, said second equipment includes said display device, display control means for controlling a display to be produced on said display device and display adjusting means; and said display control means, upon detecting the arrival of said calibration data transmitted from said first equipment to said second equipment via said network, displays a calibration image and guidance based on said calibration data on said display device at said second equipment, and said display adjusting means is operated in accordance with said guidance.
- 9. A calibration apparatus for a display device, comprising:a network for data transmission first equipment which stores and manages data; and second equipment which uses functions of said first equipment, wherein: said first equipment includes calibration data holding means for holding therein calibration data relating to a profile for a display device provided at said second equipment, calibration data transmission data holding means for holding therein data indicating the month, day, and year that said calibration data was transmitted to said second equipment, and calibration reminding notification transmitting means for transmitting a notification reminding said second equipment of the arrival of time to calibrate said display device, from said first equipment to said second equipment via said network when a predetermined period has elapsed from said calibration data transmission date.
- 10. A calibration apparatus for a display device as claimed in claim 9, wherein:said first equipment further includes an electronic mail server for sending electronic mail, and an electronic mail address holding means for holding therein an electronic mail address of said second equipment; and said calibration reminding notification transmitting means transmits said calibration reminding notification to said electronic mail address via said electronic mail server.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-145787 |
May 1998 |
JP |
|
US Referenced Citations (5)
Foreign Referenced Citations (5)
Number |
Date |
Country |
0 597 797 |
May 1994 |
EP |
0 665 680 |
Aug 1995 |
EP |
0 785 672 |
Jul 1997 |
EP |
0828329 |
Nov 1998 |
EP |
9608811 |
Mar 1996 |
WO |