The present invention relates to a color reproduction system, and more particularly to a color reproduction system that includes a liquid crystal display device and a primary device thereof.
Typically, devices such as display devices, printing devices, and imaging devices each have a different color gamut (also known as color reproduction range). Moreover, in color televisions, the color gamut utilized in input video signals is different for every television standard. For these reasons, conventionally the color gamut of the signal from the signal source is mapped to the color gamut of the display device. Furthermore, in a liquid crystal display device, for example, voltages are applied to the liquid crystal layer according to the color values included in the RGB signal resulting from the mapping process so that the colors displayed on the display unit represent the colors in the signal from the signal source as accurately as possible. This mapping process, which is performed so that the output colors are as faithful as possible to colors in the input data regardless of differences in the color gamuts involved, is known as color gamut conversion. RGB signals with the same RGB values may actually produce different colors on display devices with different color gamuts, and therefore this color gamut conversion process adjusts the values of the RGB signals accordingly.
WO 2011/061954 Pamphlet, for example, discloses one example of such a color gamut conversion process. WO 2011/061954 Pamphlet discloses a display device that includes an image processing device (which corresponds to the electronic device 91 in
However, different electronic device manufacturers employ different levels of technology. Moreover, some manufacturers develop different color specifications in pursuit of unique colors. Therefore, even the same liquid crystal display device may exhibit different display image coloring depending on the electronic devices that are connected thereto. In other words, even when the same data is displayed on the same liquid crystal display device, the colors or color tones of the resulting display image may be different due to the differences between these electronic devices. Furthermore, these electronic devices have to perform the color gamut conversion process using the display information from the liquid crystal display device, which increases the development burden on electronic device manufacturers.
Therefore, the present invention aims to provide a color reproduction system that prevents differences in display image coloring due to the primary device and can also be produced more easily than when using conventional technologies.
A first aspect of the present invention is a color reproduction system, including:
a primary device that performs a color gamut conversion process on input data so as to output image data; and a liquid crystal display device having a liquid crystal panel, the liquid crystal display device displaying on the liquid crystal panel a color image based on the image data output from the primary device,
wherein a color gamut of the liquid crystal panel includes a color gamut specified by a prescribed standard, and
wherein the primary device sends to the liquid crystal display device as the image data only an RGB signal compliant with the prescribed standard.
A second aspect of the present invention is the color reproduction system according to the first aspect, wherein the prescribed standard is an sRGB standard.
A third aspect of the present invention is the color reproduction system according to the first aspect, wherein the prescribed standard is an bg-sRGB standard.
A fourth aspect of the present invention is the color reproduction system according to the third aspect, wherein the color gamut of the liquid crystal panel includes a color gamut of the input data.
A fifth aspect of the present invention is the color reproduction system according to the third aspect, wherein when a minimum gradation value is 0 and a maximum gradation value is 1, the RGB signal sent from the primary device to the liquid crystal display device can include values that are negative or greater than 1.
A sixth aspect of the present invention is the color reproduction system according to the third aspect, wherein the image data sent from the primary device to the liquid crystal display device is 10-bit data.
A seventh aspect of the present invention is the color reproduction system according to the first aspect,
wherein the primary device includes an input data converter that generates the image data by performing, in accordance with a color gamut of the input data and the color gamut specified by the prescribed standard, a color gamut conversion process on the input data, and
wherein the liquid crystal display device includes an image data converter that generates display data for the liquid crystal panel by performing, in accordance with the color gamut specified by the prescribed standard and the color gamut of the liquid crystal panel, a color gamut conversion process on the image data sent from the primary device.
An eighth aspect of the present invention is the color reproduction system according to the first aspect,
wherein the primary device includes an input data converter that generates the image data by performing, in accordance with a color gamut of the input data and the color gamut specified by the prescribed standard, a color gamut conversion process on the input data, and
wherein the liquid crystal display device includes:
A ninth aspect of the present invention is the color reproduction system according to the first aspect,
wherein the primary device includes:
wherein the liquid crystal display device includes:
A tenth aspect of the present invention is the color reproduction system according to the first aspect,
An eleventh aspect of the present invention is the color reproduction system according to the first aspect, wherein the color gamut of the liquid crystal panel includes a color gamut of the input data.
A twelfth aspect of the present invention is a color reproduction method for a color reproduction system that includes a primary device that outputs image data in accordance with input data and a liquid crystal display device that includes a liquid crystal panel that has a color gamut including a color gamut specified by a prescribed standard and that displays a color image based on the image data output from the primary device, the color reproduction method including:
a generating step in which the image data is generated by performing a color gamut conversion process on the input data by the primary device; and
a sending step in which the image data is sent from the primary device to the liquid crystal display device,
wherein, in the sending step, only an RGB signal compliant with the prescribed standard is sent from the primary device to the liquid crystal display device as the image data.
A thirteenth aspect of the present invention is a color reproduction system, including:
a primary device that outputs image data obtained by performing a color gamut conversion process on input data; and a liquid crystal display device having a liquid crystal panel, the liquid crystal display device displaying on the liquid crystal panel a color image based on the image data output from the primary device,
wherein a plurality of operation modes are prepared so as to be selectable,
wherein a color gamut of the liquid crystal panel includes a color gamut specified by a prescribed standard, and
wherein, when a prescribed operation mode among the plurality of operation modes is selected, the primary device sends to the liquid crystal display device as the image data only an RGB signal compliant with the prescribed standard.
A fourteenth aspect of the present invention is a color reproduction method for a color reproduction system that includes a primary device that outputs image data in accordance with input data and a liquid crystal display device that includes a liquid crystal panel that has a color gamut including a color gamut specified by a prescribed standard and that displays a color image based on the image data output from the primary device, the color reproduction method including:
a generating step in which the image data is generated by performing a color gamut conversion process on the input data by the primary device; and
a sending step in which the image data is sent from the primary device to the liquid crystal display device,
wherein a plurality of operation modes are prepared so as to be selectable, and
wherein, when a prescribed operation mode among the plurality of operation modes is selected, in the sending step only an RGB signal compliant with the prescribed standard is sent from the primary device to the liquid crystal display device as the image data.
In the first aspect of the present invention, the color reproduction system is configured such that only an RGB signal compliant with the prescribed standard is sent from the primary device to the liquid crystal display device. Therefore, the primary device may implement any data conversion process for converting the input data to data that is compliant with the prescribed standard regardless of the color gamut of the liquid crystal panel. Moreover, the liquid crystal display device may implement any data conversion process appropriate for the color gamut of the liquid crystal panel. Therefore, the primary device can implement the necessary process without requiring any information from the liquid crystal display device, and the liquid crystal display device can implement the necessary process without requiring any information from the primary device. This makes it possible to design and manufacture the primary device and the liquid crystal display device completely independently of one another. This, in turn, reduces the burden associated with color reproduction on manufacturers. Moreover, the implementations of the processes can be defined in advance, thereby making it unnecessary to determine various parameters using an online process. This makes it possible to produce color reproduction systems more easily than when using conventional technologies and reduces the costs of producing color reproduction systems. Furthermore, the image data sent to the liquid crystal display device is based on a predefined standard that does not depend on the primary device connected thereto, thereby preventing variation in the colors represented by that image data. This prevents differences in display image coloring due to the primary device. Therefore, the first aspect of the present invention makes it possible to provide a color reproduction system that prevents differences in display image coloring due to the primary device and can also be produced more easily than when using conventional technologies.
In the second aspect of the present invention, sRGB image data is sent from the primary device to the liquid crystal display device. As a result, colors in the standard sRGB color space are displayed accurately on the liquid crystal panel of the liquid crystal display device.
In the third aspect of the present invention, bg-sRGB image data is sent from the primary device to the liquid crystal display device. This makes it possible to accurately display colors of a larger gamut than that of the standard sRGB color space.
In the fourth aspect of the present invention, the color gamut of the liquid crystal panel is larger than the color gamut of the input data, and bg-sRGB image data is sent from the primary device to the liquid crystal display device. As a result, all of the colors represented in the input data can be displayed accurately on the liquid crystal panel of the liquid crystal display device.
In the fifth aspect of the present invention, image data that includes RGB values that are negative or greater than 1 is sent from the primary device to the liquid crystal display device. As a result, image data that represents colors of a larger gamut than that of the standard sRGB color space are sent from the primary device to the liquid crystal display device. This makes it possible to reproduce a colors of a larger gamut than that of the standard sRGB color space on the liquid crystal panel (as long as those colors are not outside of the color gamut of the liquid crystal panel itself).
In the sixth aspect of the present invention, the color reproduction system is configured such that 10-bit data is sent from the primary device to the liquid crystal display device, thereby achieving the same effects as in the fifth aspect of the present invention.
In the seventh aspect of the present invention, the primary device may implement any color gamut conversion process for converting the input data to data that is compliant with the prescribed standard regardless of the color gamut of the liquid crystal panel. Moreover, the liquid crystal display device may implement any color gamut conversion process appropriate for the color gamut of the liquid crystal panel. Therefore, like the first aspect of the present invention, the seventh aspect of the present invention makes it possible to provide a color reproduction system that prevents differences in display image coloring due to the primary device and can also be produced more easily than when using conventional technologies.
In the eighth aspect of the present invention, after the image data converter of the liquid crystal display device generates the display data for the liquid crystal panel, a gamma correction process is applied performed on that display data. Therefore, even when the liquid crystal panel exhibits a non-linear relationship between the gradation values in the input signal (the display data) input thereto and the resulting display brightness, the colors represented in the input data input to the primary device can still be reproduced accurately on the liquid crystal panel.
In the ninth aspect of the present invention, the color reproduction system is configured such that gamma-corrected image data is sent from the primary device to the liquid crystal display device, thereby achieving the same effects as in the eighth aspect of the present invention.
In the tenth aspect of the present invention, gamma-corrected image data compliant with the prescribed standard is sent from the primary device to the liquid crystal display device, and in the liquid crystal display device, the image data that is compliant with the prescribed standard and was sent from the primary device is input as-is to the liquid crystal panel. Therefore, the tenth aspect of the present invention makes it possible to use a relatively simple configuration to prevent differences in display image coloring due to the primary device in cases in which a general-purpose display with a standard color gamut is used.
In the eleventh aspect of the present invention, colors represented within the color gamut of the prescribed standard in the input data are displayed accurately on the liquid crystal panel.
The twelfth aspect of the present invention makes it possible to provide a color reproduction method for a color reproduction system that achieves the same effects as in the first aspect of the present invention.
In the thirteenth aspect of the present invention, a plurality of operation modes are prepared in advance for the color reproduction system, and when a prescribed operation mode is selected, differences in display image coloring due to the primary device are prevented.
The fourteenth aspect of the present invention makes it possible to provide a color reproduction method for a color reproduction system that achieves the same effects as in thirteenth aspect of the present invention.
Next, embodiments of the present invention will be described with reference to the attached figures.
The input data converter 210 performs a color gamut conversion process on input data DIN that is input to the electronic device 20. The color gamut conversion process performed by the input data converter 210 produces image data DAT, which is then sent from the electronic device 20 to the liquid crystal display device 30. The image data converter 310 performs a color gamut conversion process on the image data DAT sent to the liquid crystal display device 30, and the data resulting from that color gamut conversion process is sent to the liquid crystal panel 320 as display data DOUT. The liquid crystal panel 320 uses the display data DOUT to display a color image for viewing. In the present embodiment, it is assumed that the liquid crystal panel 320 exhibits a linear relationship between the gradation values of the display data DOUT input thereto and the resulting display brightness.
In the present embodiment, it is assumed that the input data DIN that is input to the electronic device 20 is compliant with the Adobe RGB standard. Moreover, in this color reproduction system 11, the image data DAT sent from the electronic device 20 to the liquid crystal display device 30 is compliant with the sRGB standard. Therefore, the input data converter 210 of the electronic device 20 converts Adobe RGB data to sRGB data. Furthermore, the image data converter 310 of the liquid crystal display device 30 converts the sRGB data to data for the liquid crystal panel 320.
Next, the color gamut conversion process will be described in more detail. As described above, in the present embodiment, the input data converter 210 of the electronic device 20 and the image data converter 310 of the liquid crystal display device 30 both implement a color gamut conversion process. In the following description, components such as the input data converter 210 and the image data converter 310 that implement a color gamut conversion process will be referred to simply as “color gamut converters”.
First, a method for converting tristimulus values in the RGB color system to tristimulus values in the XYZ color system will be described. When using the RGB color system, the actual representation of colors is dependent on the color space or device used. In contrast, the XYZ color system provides a method of color representation that is not dependent on the color space or device used. In other words, although RGB values do not necessarily represent colors accurately, XYZ values uniquely define every color.
Here, it is assumed that the three primaries R, G, and B can take values in the range of greater than or equal to 0 and less than or equal to 1. Moreover, let the chromaticity coordinates of the R stimulus value be xR, yR, and zR; let the chromaticity coordinates of the G stimulus value be xG, yG, and zG; and let the chromaticity coordinates of the B stimulus value be xB, yB, and zB. In this case, the xR, yR, and zR chromaticity coordinates for all RGB tristimulus values for which R≠0 and G=0 and B=0, for example, are constant, while the XYZ values in the XYZ color system change according to the R value. This also applies to the xG, yG, and zG chromaticity coordinates as well as to the xB, yB, and zB chromaticity coordinates. Below, let the XYZ values in the XYZ color system be XR, YR, and ZR.
When just the R stimulus value of the three primaries is set to the maximum value (that is, when R=1, G=0, and B=0), the xyz chromaticity coordinates are given by equation (1). Note that here, SR=XR+YR+ZR.
Furthermore, when R≠0 and G=0 and B=0, the XYZ values for any value of R are given by equation (2).
<#2>
X=RX
R
;Y=RY
R
;Z=RZ
R (2)
When just the G stimulus value of the three primaries is set to the maximum value (that is, when R=0, G=1, and B=0), the xyz chromaticity coordinates are given by equation (3). Note that here, SG=XG+YG+ZG.
Furthermore, when R=0 and G≠0 and B=0, the XYZ values for any value of G are given by equation (4).
<#4>
X=GX
G
;Y=GY
G
;Z=GZ
G (4)
When just the B stimulus value of the three primaries is set to the maximum value (that is, when R=0, G=0, and B=1), the xyz chromaticity coordinates are given by equation (5). Note that here, SB=XB+YB+ZB.
Furthermore, when R=0 and G=0 and B≠0, the XYZ values for any value of B are given by equation (6).
<#6>
X=BX
B
;Y=BY
B
;Z=BZ
B (6)
When the three primaries R, G, and B all have non-zero values, the XYZ values in the XYZ color system are the sums of each individual stimulus value. Therefore, combining equations (2), (4), and (6) above yields equation (7).
In matrix notation, equation (7) becomes equation (8).
Equation (8) thus defines the method for converting tristimulus values in the RGB color system to tristimulus values in the XYZ color system.
In the following matrix equations, the subscript “I” as indicated by the arrow 76 in
The right side of equation (9) is equal to the right side of equation (10), thereby yielding equation (11).
Letting the quantity indicated by the reference character 78 in equation (11) be T, equation (11) becomes equation (12).
This quantity T can also be represented as shown in equation (13). Below, this quantity T will be referred to as a “conversion coefficient.”
Therefore, as illustrated in
The electronic device 20 includes the input data converter 210, which functions as the color gamut converter 400 described above. In the present embodiment, the input data DIN that is input to the electronic device 20 is compliant with the Adobe RGB standard. Moreover, in the present embodiment, the image data DAT sent from the electronic device 20 to the liquid crystal display device 30 is compliant with the sRGB standard. Therefore, the input signal that is input to the input data converter 210 is Adobe RGB data, and the output signal that is output from the input data converter 210 is sRGB data.
From equations (9) to (13) above, the conversion coefficient TAdobe→sRGB for when the input signal is Adobe RGB data and the output signal is sRGB data is given by equation (14).
Therefore, as illustrated in
The liquid crystal display device 30 includes the image data converter 310, which functions as the color gamut converter 400 described above. In the present embodiment, the image data DAT input on the image data converter 310 is compliant with the sRGB standard. Furthermore, the image data converter 310 performs a color gamut conversion process on the sRGB image data DAT in order to generate display data DOUT for the liquid crystal panel 320. In other words, the input signal that is input to the image data converter 310 is sRGB data, and the output signal that is output from the image data converter 310 is data that is formatted appropriately for the color gamut of the liquid crystal panel 320.
From equations (9) to (13) above, the conversion coefficient TsRGB→LCD for when the input signal is sRGB data and the output signal is data that is formatted appropriately for the color gamut of the liquid crystal panel 320 is given by equation (15).
Therefore, as illustrated in
Next, some specific examples of the color gamut conversion process will be described. In the following matrix equations, the subscript “Adobe” is used to indicate Adobe RGB data, the subscript “sRGB” is used to indicate sRGB data, and the subscript “LCD” is used to indicate data for the liquid crystal panel 320.
First, assume that the input data DIN that is input to the electronic device 20 is given by equation (16) (below, this data will be referred to simply as “target data”).
In this case, the input data converter 210 performs the color gamut conversion process using the conversion coefficient TAdobe→sRGB on the input data DIN in order to generate the image data DAT that includes the target data given by equation (17).
Furthermore, the image data converter 310 performs the color gamut conversion process using the conversion coefficient TsRGB→LED on the image data DAT in order to generate the display data DOUT that includes the target data given by equation (18).
Finally, the liquid crystal panel 320 displays an image using the display data DOUT generated by the image data converter 310.
Next, assume that the input data DIN that is input to the electronic device 20 is given by equation (19) (below, this data will be referred to simply as “target data”).
In this case, the input data converter 210 performs the color gamut conversion process using the conversion coefficient TAdobe→sRGB on the input data DIN in order to generate the image data DAT that includes the target data given by equation (20).
Furthermore, the image data converter 310 performs the color gamut conversion process using the conversion coefficient TsRGB→LCD on the image data DAT in order to generate the display data DOUT that includes the target data given by equation (21).
Finally, the liquid crystal panel 320 displays an image using the display data DOUT generated by the image data converter 310.
The gamut of the sRGB color space is smaller than the gamut of the Adobe RGB color space. Therefore, as shown above in equations (17) and (20), the data resulting from the color gamut conversion process implemented by the input data converter 210 of the electronic device 20 includes values that are greater than 1 as well as negative values. Similarly, the color gamut of the liquid crystal panel 320 of the present embodiment is larger than the gamut of the Adobe RGB color space. Therefore, as shown above in equations (18) and (21), the data resulting from the color gamut conversion process implemented by the image data converter 310 of the liquid crystal display device 30 only includes values that are greater than or equal to 0 and less than or equal to 1.
Moreover, as described above, the chromaticity coordinates of the white point of the liquid crystal panel 320 of the present embodiment match the chromaticity coordinates of the white points of the sRGB color space and the Adobe RGB color space. However, even if the chromaticity coordinates of the white point of the liquid crystal panel 320 are different than the chromaticity coordinates of the white point of the sRGB color space, a process for converting the chromaticity coordinates of the white point of the sRGB color space to the chromaticity coordinates of the white point of the liquid crystal panel 320 may simply be performed prior to the color gamut conversion process implemented by the image data converter 310.
In the color reproduction system 11 of the present embodiment that includes the liquid crystal display device 30 and a primary device thereof (the electronic device 20), sRGB is set in advance as the standard for data sent from the electronic device 20 to the liquid crystal display device 30. Therefore, the electronic device 20 may implement the color gamut conversion process for converting the input data DIN to sRGB data regardless of the color gamut of the liquid crystal panel 320. In this way, the electronic device 20 may generate data compliant with any predefined standard. Moreover, the liquid crystal display device 30 may implement any color gamut conversion process appropriate for the color gamut of the liquid crystal panel 320. Therefore, the electronic device 20 can implement the necessary process without requiring any information from the liquid crystal display device 30, and the liquid crystal display device 30 can implement the necessary process without requiring any information from the electronic device 20. This makes it possible to design and manufacture the electronic device 20 and the liquid crystal display device 30 completely independently of one another. This, in turn, reduces the burden associated with color reproduction on manufacturers. Moreover, the implementations of the processes can be defined in advance, thereby making it unnecessary to determine various parameters using an online process. This makes it possible to produce color reproduction systems more easily than when using conventional technologies and reduces the costs of producing of color reproduction systems. Furthermore, the data sent to the liquid crystal display device 30 is based on a predefined standard that does not depend on the electronic device 20 connected thereto, thereby preventing variation in the colors represented by that data. This prevents differences in display image coloring due to the primary device (the electronic device 20). Therefore, the present embodiment makes it possible to provide a color reproduction system that prevents differences in display image coloring due to the primary device and can also be produced more easily than when using conventional technologies.
Color reproduction systems in which the color gamut conversion process can be switched between the color gamut conversion process implemented using the method described above in Embodiment 1 and a color gamut conversion process implemented using a conventional method are also possible. In other words, a plurality of selectable operation modes may be prepared in advance, and the electronic device 20 and the liquid crystal display device 30 may apply the color gamut conversion process implemented using the method described above in Embodiment 1 when a prescribed operation mode is selected. In this case, when the prescribed operation mode of the plurality of operation modes that are prepared in advance is selected, only sRGB data is sent from the electronic device 20 to the liquid crystal display device 30 as the image data DAT, and when another operation mode is selected, data compliant with a standard other than sRGB is sent from the electronic device 20 to the liquid crystal display device 30 as the image data DAT. Similarly, configurations in which the color gamut conversion process can be switched between color gamut conversion processes implemented using the methods described in the following embodiments and a color gamut conversion process implemented using a conventional method are also possible.
Next, the bg-sRGB color space will be described. The bg-sRGB standard was created as an amendment to the sRGB standard in order to be able to represent a larger gamut of colors than can be represented in the standard sRGB color space. In the sRGB color space, RGB values are represented as values greater than or equal to 0 and less than or equal to 1. In the bg-sRGB color space, however, RGB values can be represented as negative values and values greater than 1 in addition to the values greater than or equal to 0 and less than or equal to 1. Linear RGB values can be represented as values greater than or equal to −0.524 and less than or equal to 1.675. Non-linear RGB values can be represented as values greater than or equal to −0.751 and less than or equal to 1.253. Moreover, in the bg-sRGB color space, gradation values are represented using 10 or more bits. However, the present embodiment assumes use of 10-bit gradation values.
The input data converter 210 of the electronic device 20 performs a color gamut conversion process on the Adobe RGB input data DIN in order to generate 10-bit bg-sRGB image data DAT. Moreover, the image data converter 310 of the liquid crystal display device 30 performs a color gamut conversion process on the 10-bit image data DAT in order to generate display data DOUT for the liquid crystal panel 320.
The present embodiment makes it possible to achieve the following effects in addition to the effects achieved in Embodiment 1. In the present embodiment, the image data DAT sent from the electronic device 20 to the liquid crystal display device 30 is compliant with the bg-sRGB standard. This makes it possible for the image data DAT that is sent from the electronic device 20 to the liquid crystal display device 30 to include RGB values that are negative or greater than 1. As a result, data that represents colors of a larger gamut than that of the standard sRGB color space can be sent from the electronic device 20 to the liquid crystal display device 30. This makes it possible to reproduce a colors of a larger gamut than that of the standard sRGB color space on the liquid crystal panel 320 (as long as those colors are not outside of the color gamut of the liquid crystal panel 320 itself).
In Embodiments 1 and 2, it was assumed that the liquid crystal panel 320 exhibits a linear relationship between the gradation values of the input signal (the display data DOUT) input thereto and the resulting display brightness. However, in most cases the liquid crystal panel 320 will exhibit non-linear characteristics. Therefore, the present embodiment assumes use of a liquid crystal panel 320 that has non-linear characteristics.
As illustrated in
The present embodiment makes it possible to achieve the following effects in addition to the effects achieved in Embodiment 1. In the present embodiment, after the display data DOUT for the liquid crystal panel 320 is generated by the image data converter 310 of the liquid crystal display device 30, the gamma correction process is performed on that display data DOUT. Therefore, even when the liquid crystal panel 320 exhibits a non-linear relationship between the gradation values in the input signal (the display data DOUT) input thereto and the resulting display brightness, the colors represented in the input data DIN input to the electronic device 20 can still be reproduced accurately on the liquid crystal panel 320.
Typically, the input signal sent to a liquid crystal display device is a gamma-corrected signal. Therefore, in the present embodiment, gamma-corrected image data DAT is sent from an electronic device 20 to a liquid crystal display device 30. Moreover, like in Embodiment 3, in the present embodiment a liquid crystal panel 320 has non-linear characteristics.
As illustrated in
Moreover, as illustrated in
Furthermore, as illustrated in
The gamma correction processor 220 of the electronic device 20 performs an sRGB gamma correction process. More specifically, as shown in equations (22) to (24), the linear RGB values (RsRGB, GsRGB, BsRGB) before gamma correction are converted to non-linear RGB values (R′sRGB, G′sRGB, B′sRGB) according to the respective magnitudes of the linear RGB values.
Next, the de-gamma correction processor 340 of the liquid crystal display device 30 performs an sRGB de-gamma correction process. More specifically, as shown in equations (25) to (27), the non-linear RGB values (R′sRGB, G′sRGB, B′sRGB) before de-gamma correction are converted to linear RGB values (RsRGB, GsRGB, BsRGB) according to the respective magnitudes of the non-linear RGB values.
Furthermore, like in Embodiment 2, the data sent from the electronic device 20 to the liquid crystal display device 30 may be compliant with the bg-sRGB standard. In this case, the following process is implemented.
First, in the electronic device 20, a gamma correction process is performed using equations (28) to (30).
Next, in the electronic device 20, a normalization process is performed using equation (31) to convert the gamma-corrected R′G′B′ values to integers. Note that in equation (31), int is a function that converts the quantity inside parentheses to an integer, WDC is a digital representation of the white point, and KDC is a digital representation of the black point.
When using a 10-bit bg-sRGB color space, equation (31) can be rewritten as equation (32).
Next, in the liquid crystal display device 30, equation (33) is used to convert the data sent from the electronic device 20 back to pre-normalization data. Note that equation (33) represents the inverse operation of equation (31).
When using a 10-bit bg-sRGB color space, equation (33) can be rewritten as equation (34).
Next, in the liquid crystal display device 30, a de-gamma correction process is performed using equations (35) to (37).
In the color reproduction system 15 of the present embodiment, gamma-corrected image data DAT is sent from the electronic device 20 to the liquid crystal display device 30. Therefore, as in Embodiment 3, even when the liquid crystal panel 320 exhibits a non-linear relationship between the gradation values in the input signal (the display data DOUT) input thereto and the resulting display brightness, the colors represented in the input data DIN input to the electronic device 20 can still be reproduced accurately on the liquid crystal panel 320. The present embodiment also achieves all of the same effects as Embodiment 1.
As in Embodiment 4, in the present embodiment a gamma correction process is performed on image data DAT generated by the input data converter 210, and then the gamma-corrected image data DAT is sent to the liquid crystal display device 30. As illustrated in
Typically, the gamma characteristics of general-purpose displays are designed such that γ=2.2. Therefore, the gamma correction processor 220 of the electronic device 20 implements a gamma correction process with γ=2.2. Doing this ensures compatibility of gamma characteristics between the electronic device 20 and the liquid crystal display device 30.
Moreover, general-purpose displays can only handle RGB values that are greater than or equal to 0 and less than or equal to 1. As a result, if image data DAT that includes RGB values that are negative or greater than 1 is input to the liquid crystal panel 320, the liquid crystal panel 320 will not be able to accurately reproduce the colors represented in the original input data DIN. Therefore, the configuration of the present embodiment may be applied to a system that does not strictly require accurate color reproduction.
In the present embodiment, gamma-corrected sRGB image data DAT is sent from the electronic device 20 to the liquid crystal display device 30, and in the liquid crystal display device 30, the sRGB image data DAT sent from the electronic device 20 is input as-is to the liquid crystal panel 320. Therefore, the present embodiment makes it possible to use a relatively simple configuration to prevent differences in display image coloring due to the primary device (the electronic device 20) in cases in which a general-purpose display with a standard color gamut is used.
The present invention is not limited to the embodiments described above, and various modifications may be made without departing from the spirit of the present invention. For example, in the embodiments described above, the data sent from the electronic device 20 to the liquid crystal display device 30 was sRGB data or bg-sRGB data. However, the present invention is not limited to these examples. The data sent from the electronic device 20 to the liquid crystal display device 30 may be compliant with any standard including standards other than sRGB and bg-sRGB as long as the standard is defined in advance.
Number | Date | Country | Kind |
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2013-233730 | Nov 2013 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2014/069301 | 7/22/2014 | WO | 00 |