Patent Application
20170359485
The present invention relates to image processing for reproducing the material appearance of images.
The need for image processing that reproduces the material appearance of images by controlling the gloss in addition to colors has been increasing. PTL 1 describes a technology for reproducing specular reflection light from an object to be reproduced within the dynamic range of the display device to excellently reproduce the gloss of the object using computer graphic techniques.
PTL 1: Japanese Patent Laid-Open No. 2010-246049
However, according to PTL 1, there still remains a mismatch between the range of the material appearance further including a material appearance element other than the specular reflection light from the object to be reproduced and the range of the material appearance reproducible by a material appearance reproducing apparatus, such as a printer. Accordingly, if the material appearance of the object to be reproduced cannot be reproduced by the material appearance reproducing apparatus, a reproduced object corresponding to the full reproduction range of the material appearance reproducing apparatus cannot be obtained or the material appearance of the object to be reproduced is damaged. As a result, a user of the material appearance reproducing apparatus cannot obtain reproduction of a desired material appearance.
The present invention provides image processing for obtaining a reproduced object having a desired material appearance fully using the reproduction range of the material appearance reproducing apparatus.
According to an aspect of the present invention, an image processing apparatus includes an input unit configured to receive first material appearance data representing a material appearance of an image, a material appearance mapping unit configured to convert the first material appearance data into second material appearance data corresponding to a material appearance reproducible by a material appearance reproducing apparatus, and a conversion unit configured to convert the second material appearance data into control data for reproducing the material appearance of the image using the material appearance reproducing apparatus. The first material appearance data includes a gloss signal corresponding to a specular gloss and a gloss signal corresponding to an image clarity.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings.
A material appearance reproducing technique according to the present exemplary embodiment is described first. As used herein the term “reproduction of material appearance” refers to outputting a reproduced object having an appearance that is the same as that of the object to be reproduced. In addition, the term “material appearance” refers to a set of properties to be matched between the reproduced object and the object to be reproduced to have the same appearance when the two are comparatively observed. The material appearance has a plurality of elements such as color, gloss, internal scattering, and shape. If the material appearance can be quantitatively expressed using a value, a reproduced object having an appearance that is the same as that of the object to be reproduced can be obtained by outputting the reproduced object so that the value is the same for the reproduced object and the object to be reproduced. Hereinafter, the value is referred to as a “material appearance signal”. If the object to be reproduced is, for example, a printout that is flat and that has a sufficiently small surface roughness, a reproduced object having a shape that is substantially the same as that of the object to be reproduced can be obtained by printing an image on a flat medium of the same type as the printout. In such a case, the important elements of the material appearance are the color and the gloss. That is, the material appearance is formed from the two elements. Even in the other cases, the color and gloss are important elements of the material appearance.
As a color signal that is the numerical representation of color, the value defined in existing CIELAB can be used, for example. CIELAB mainly represents the characteristics regarding the brightness and chromaticity of diffuse reflection light. As used herein, the term “diffuse reflection light” refers to reflection light in a diffuse reflection direction which is defined as directions other than the specular direction and its vicinity. By printing the reproduced object so that the CIELAB value of the reproduced object is the same as that of the object to be reproduced, the appearance in terms of color in the diffuse reflection direction can be made to be substantially the same as that of the object to be reproduced.
As a gloss signal, which is a numerical representation of the gloss, the value of widely used specular gloss, the value of widely used degree of sharpness of reflected, or the value of widely used reflection haze can be employed, for example. The specular gloss represents the properties regarding the brightness of specular reflection light. The values obtained by dividing the degree of sharpness of reflected and the specular gloss by the reflection haze represent the properties regarding the sharpness of an illumination image produced by reflection at a surface of the object. Hereinafter, the properties regarding the sharpness of the illumination image is referred to as “image clarity”. As the image clarity becomes higher, the degree of sharpness of reflected becomes higher and, thus, the value obtained by dividing the specular gloss by the reflection haze becomes higher.
The image 2231 illustrated in
In step S203, the color signal is converted into a color signal corresponding to a color reproducible by the material appearance reproducing apparatus. The process in step S203 is referred to as “color mapping”. The color mapping is performed using an existing technique. For example, the color signal is converted into a color signal having a CIELAB color value reproducible by the material appearance reproducing apparatus and having a hue angle that is the same as that of the CIELAB obtained in step S102 and the smallest color difference ΔE. As the hue angle and the color difference ΔE, the value of a widely used ab hue angle and the value of widely used CIEDE2000 can be employed, respectively. Note that if the color signal obtained in step S102 is a color signal reproducible by the material appearance reproducing apparatus, the color signal is not converted and is directly output as a converted color signal. Thereafter, the processing proceeds to step S204.
In step S204, the gloss signal is converted into a gloss signal corresponding to the gloss reproducible by the material appearance reproducing apparatus. Thereafter, the processing proceeds to step S104. The process in step S204 is referred to as “gloss mapping”. In the gloss mapping according to the present exemplary embodiment, a gloss element of interest is changed in accordance with the spatial distribution of the material appearance signals obtained in step S102. For example, since for a granular area of the reproduced object that glitters, the degree of the specular gloss has a significant impact on the appearance, the reproducibility of the specular gloss is given more weight over the image clarity. Hereinafter, such an area is referred to as an “area having a large gloss change”. In contrast, for an area in which substantially uniform gloss is widely distributed or an area in which the gloss that gently changes is widely distributed, the degree of the image clarity has a significant impact on the appearance. Thus, the reproducibility of the image clarity is given more weight over the specular gloss. Hereinafter, such an area is referred to as an “area having a small gloss change”. In the gloss mapping according to the present exemplary embodiment, a determination signal used for determining whether an area to be processed is an area having a large gloss change or an area having a small gloss change is set on the basis of the spatial distribution of the material appearance signals. Note that the determination signal is described in more detail below. Thereafter, determination is made on the basis of the determination signal. For an area determined to be an area having a large gloss change, the reproducibility of the specular gloss is given more weight, and the gloss signal is converted. In contrast, for an area determined to be an area having a small gloss change, the reproducibility of the image clarity is given more weight, and the gloss signal is converted. The determination signal is set for each of the areas. The determination signal for an area of interest is set on the basis of the material appearance signal of the area of interest and the material appearance signals of areas of non-interest in the vicinity. Note that hereinafter, the area of interest is also referred to as a “pixel of interest”.
Subsequently, in step S302, one of conversion in which the reproducibility of the specular gloss is given more weight and conversion in which the reproducibility of the image clarity is given more weight is selected for each area on the basis of the input data. In this manner, the processing suitable for each area is performed and, thus, a reproduced object having an appearance that negligibly differs from that of the object to be reproduced indicated by the input data can be obtained. More specifically, it is determined whether the determination signal regarding the size of the block including the area of interest is lower than a predetermined threshold value. For example, the threshold value is set to 0.5. If the size of the block associated with the area of interest is smaller than the threshold value, it is determined that the area is an area of a large gloss change. Thereafter, the processing proceeds to step S303. Otherwise, it is determined that the area is an area of a small gloss change. Thereafter, the processing proceeds to step S305.
In step S303, the signal corresponding to the specular gloss is converted to obtain a converted signal. That is, the following signal is obtained: a signal corresponding to a specular gloss reproducible by the material appearance reproducing apparatus and having the smallest difference from the signal corresponding to the specular gloss obtained in step S102 while maintaining the color signal converted in step S203. Subsequently, in step S304, the signal corresponding to the image clarity is converted to obtain a converted signal. That is, the following signal is obtained: a signal corresponding to an image clarity reproducible by the material appearance reproducing apparatus and having the smallest difference from the signal corresponding to the image clarity obtained in step S102 while maintaining the color signal converted in step S203 and the signal corresponding to the specular gloss obtained in step S303.
In addition, in step S305, the signal corresponding to the image clarity is converted prior to converting the signal corresponding to the specular gloss to obtain a converted signal. That is, the following signal is obtained: a signal corresponding to an image clarity reproducible by the material appearance reproducing apparatus and having the smallest difference from the signal corresponding to the image clarity obtained in step S102 while maintaining the color signal converted in step S203. Subsequently, in step S306, the signal corresponding to the specular gloss is converted to obtain a converted signal. That is, the following signal is obtained: a signal corresponding to the specular gloss reproducible by the material appearance reproducing apparatus and having the smallest difference from the signal corresponding to the specular gloss obtained in step S102 while maintaining the color signal converted in step S203 and the signal corresponding to the image clarity obtained in step S305.
In step S406, it is determined whether an area is present to the upper left of the processing area. If an area is present, the processing proceeds to step S407. Otherwise, the processing proceeds to step S409. In step S407, it is determined whether the processing area is in the same block as the upper left neighboring area of the processing area. That is, the difference in gloss between the processing area and the upper left neighboring area is obtained, and it is determined whether the difference in gloss is less than the predetermined threshold value. The determination is made in the same manner as in step S404. If the difference in gloss is less than the threshold value, it is determined that the processing area is in the same block as the upper left neighboring area of the processing area. Thereafter, the processing proceeds to step S408. Otherwise, the processing proceeds to step S409. In step S408, the block number of the block corresponding to the processing area is set to the block number of the upper left neighboring block. Thereafter, the processing proceeds to step S417.
In step S409, it is determined whether an area is present on top of the processing area if an area is present on top of the processing area, the processing proceeds to step S410. Otherwise, the processing proceeds to step S412. In step S410, it is determined whether the processing area is in the same block as the area on top of the processing area. That is, the difference in gloss between the processing area and the area on top of the processing area is obtained, and it is determined whether the difference in gloss is less than the predetermined threshold value. The determination is made in the same manner as in step S404. If the difference in gloss is less than the threshold value, it is determined that the processing area is in the same block as the area on top of the processing area. Thereafter, the processing proceeds to step S411. Otherwise, the processing proceeds to step S412. In step S411, the block number of the block corresponding to the processing area is set to the block number of the block corresponding to the area on top of the processing area. Thereafter, the processing proceeds to step S417.
In step S412, it is determined whether area is present the upper right of processing area. If an area is present, the processing proceeds to step S413. Otherwise, the processing proceeds to step S415. In step S413, it is determined whether the processing area is in the same block as the upper right neighboring area of the processing area. That is, the difference in gloss between the processing area and the upper right neighboring area is obtained, and it is determined whether the difference in gloss is less than the predetermined threshold value. The determination is made in the same manner as in step S404. If the difference in gloss is less than the threshold value, it is determined that the processing area is in the same block as the upper right neighboring area of the processing area. Thereafter, the processing proceeds to step S414. Otherwise, the processing proceeds to step S415. In step S414, the block number of the block corresponding to the processing area is set to the block number of the upper right neighboring area. Thereafter, the processing proceeds to step S417.
In step S415, the largest block number is updated by incrementing the largest block number by one. Thereafter, the updated largest block number is set for the block corresponding to the processing area. In step S417, it is determined whether the processing area is the last area 1202. If the processing area is the last area 1202, the first half processing is completed, and the processing proceeds to the second half processing. Otherwise, the processing returns to step S402. Note that the first half of the block building process is not limited to the above-described procedure. For example, another labeling process may be employed.
The configuration of the print head is described below.
The material appearance data input unit 1101 receives image data in the form of a material appearance signal. The material appearance signal is formed from a color signal and a gloss signal. Each of the pixels of the image data has elements of gloss signals (Gg, Sg) in addition to widely used color signals (R, G, B). The gloss signal Gg is a signal corresponding to the specular gloss. The gloss signal Sg is a signal corresponding to the image clarity. Each of the material appearance signals (R, G, B, Gg, Sg) that constitute the image data is an 8-bit digital signal. However, the format of the input image data is not limited thereto. For example, two types of image data, that is, image data formed from a color signal and image data formed from a gloss signal, may be input to the material appearance data input unit 1101.
The material appearance signal acquiring unit 1102 converts the material appearance signals that constitute the image received by the material appearance data input unit 1101 into color signals (L, a, b) based on CIELAB, a gloss signal (g) corresponding to the specular gloss, and a gloss signal (s) corresponding to the image clarity. It is desirable that the material appearance signals (L, a, b, g, s) output from the material appearance signal acquiring unit 1102 be signals that are based on the measurement values and that do not depend on the apparatus. The conversion from the color signals (R, G, B) into the color signals (L, a, b) is performed using a standard conversion technique, such as sRGB. Alternatively, the conversion may be performed by referring to a color table stored in an input material appearance table storage unit 1108 and using a widely used three-dimensional lookup table technique. The color table contains the relationship between the color signals (R, G, B) and the color signals (L, a, b). The conversion from the gloss signal (Gg) corresponding to the specular gloss into the gloss signal (g) and the conversion from the gloss signal (Sg) corresponding to the image clarity into the gloss signal (s) are performed by referring to a gloss table stored in the input material appearance table storage unit 1108 and using a widely used lookup table technique. The gloss table contains the correspondence between a gloss signal (Gg) and a gloss signal (g) and the correspondence between a gloss signal (Sg) and a gloss signal (s). Preferably, the color table and the gloss table are provided for each of the type of image data and each of the material appearance acquiring apparatuses that generate input image data in advance and are selected in accordance with the image data received by the material appearance data input unit 1101. Alternatively, the color table and the gloss table may be selected in accordance with a user instruction.
The material appearance mapping unit 1103 converts the material appearance signals (L, a, b, g, s) obtained by the material appearance signal acquiring unit 1102 into material appearance signals (L′, a′, b′, g′, s′) each corresponding to the material appearance reproducible by the image printing apparatus 800 through the above-described color mapping and gloss mapping.
The device signal conversion A unit 1104 converts the material appearance signals (L′, a′, b′, g′, s′) into a control signal including color material amount signals (C, M, Y, K), gloss control agent amount signals (A, B), and a pass control signal (P) of the image printing apparatus 800. The conversion is performed by referring to a device properties table stored in a device properties table storage unit 1109 and using a widely used n-dimensional lookup table technique.
The device signal conversion B unit 1105 performs a halftone process on the control signals (C, M, Y, K, A, B) converted by the device signal conversion A unit 1104 and converts the control signals (C, M, Y, K, A, B) into binary signals (C′, M′, Y′, K′, A′, B′), respectively, each indicating whether a dot is printed or not. Each of the binary signals (C′, M′, Y′, K′, A′, B′) indicates the dot print position. For example, a dot is printed at a position having a signal value of “1” and is not printed at a position having a signal value of “0”. To perform the halftone process, a widely used error diffusion technique or systematic dither technique.
The device signal conversion C unit 1106 performs a pass separation process on the basis of the control signal (P) related to the number of passes and the control signals (C′, M′, Y′, K′, A′, B′) related to the dot patterns of the color materials and the gloss control material. In the pass separation process, the logical OR of a pass mask and the control signals (C, M′, Y′, K′, A′, B′) is calculated, and control signals (C″, M″, Y″, K″, A″, B″) related to the dot pattern printed in each pass are generated. According to the first exemplary embodiment, the material appearance reproducing system has 16 sets of pass mask (for 1-pass printing to 16-pass printing). One of the sets of pass mask is selected in accordance with the value P and is used. For example, if the value of P is 2 indicating 2-pass printing, the cyan dot pattern for the first pass is generated by the logical OR of the pass mask for a first pass of the 2-pass printing pass mask set and the control signal C′ indicating the cyan dot print positions.
The output unit 1107 ejects each of the color materials and each of the gloss control agents on the basis of the dot pattern data generated by the device signal conversion C unit 1106. In this manner, an image representing a material appearance reproduced object is formed on a recording medium.
In the above-described material appearance reproducing procedure, the processes in steps S101 to S103 are performed by the material appearance data input unit 1101, the material appearance signal acquiring unit 1102, and the material appearance mapping unit 1103, respectively. In addition, the process in step S104 is performed by the device signal conversion A unit 1104, the device signal conversion B unit 1105, and the device signal conversion C unit 1106. Furthermore the process in step S105 is performed by the output unit 1107.
As described above, according to the first exemplary embodiment, the material appearance reproducing system performs the material appearance mapping to convert the input data into the material appearance data corresponding to the material appearance reproducible by the material appearance reproducing apparatus. In the material appearance mapping, the color signal and the gloss signal are converted so that the colors, the specular gloss, and the image clarity indicated by the input data are mapped to a combination of the colors, the specular gloss, and the image clarity reproducible by the material appearance reproducing apparatus. In this manner, even when the combination of the colors, the specular gloss, and the image clarity indicated by the input data is not reproducible by the material appearance reproducing apparatus, the reproduced object can be output by the material appearance reproducing apparatus.
In addition, in the material appearance mapping performed by the material appearance reproducing system according to the first exemplary embodiment, unlike an area having a small change in gloss, the reproducibility of the specular gloss is given more weight in an area having a large change in gloss. That is, when a specular gloss error is defined as a difference between the specular gloss indicated by the input data and the specular gloss of a reproduced object, the gloss signal is converted as follows. That is, the gloss signal is converted so that the specular gloss error in an area having a relatively large change in gloss is lower than the specular gloss error in an area having a relatively small change in gloss. In this manner, for example, a granular area that glitters can be excellently reproduced.
In addition, in the material appearance mapping performed by the material appearance reproducing system according to the first exemplary embodiment, unlike an area having a large change in gloss, the reproducibility of the image clarity is given more weight in an area having a small change in gloss. That is, when an image clarity error is defined as a difference between the image clarity indicated by the input data and the image clarity of a reproduced object, the gloss signal is converted as follows. That is, the gloss signal is converted so that the image clarity error in an area having a relatively small change in gloss is lower than the image clarity error in an area having a relatively large change in gloss. In this manner, for example, an area in which the substantially uniform gloss is widely distributed and an area in which gently changing gloss is widely distributed can be excellently reproduced.
In addition, according to the first exemplary embodiment, the material appearance reproducing system converts the input material appearance data into a signal value that is reproducible by the material appearance reproducing apparatus in a space having at least axes of the specular gloss and the image clarity. In this manner, for example, two types of gloss having the same specular gloss and different image clarifies can be recognized as different types of gloss and, thus, the appearance of the object to be reproduced indicated by the input data can be made to be the same as the appearance of the reproduced object.
According to the material appearance reproducing system of the first exemplary embodiment, the size of a block to which areas belong is used as a determination signal, and one of the process in which the reproducibility of the image clarity is given more weight and the process in which the reproducibility of the specular gloss is given more weight is selected. In first modification, another index is used as the determination signal. The first modification is described below.
As described above, according to the material appearance reproducing system of the first modification, a gloss distribution is generated by applying a lowpass filter to the spatial distribution of the material appearance signals, and the difference between the gloss signals for the area of interest before and after application of the lowpass filter is used as the determination signal. A large determination signal indicates that the area of interest has a large gloss change, and a small determination signal indicates that the area of interest has a small gloss change. In this manner, the material appearance reproducing apparatus can distinguish between an area having a large gloss change and an area having a small gloss change. Since fast Fourier transform (FFT) that can provide high-speed calculation can be employed in the lowpass process, the process can be performed at high speed.
In general, to distinguish between an area having a large gloss change and an area having a small gloss change, the value regarding the amplitude or the cycle of a gloss change can be used. As used herein, the term “amplitude” refers to a value related to a difference between gloss signals. A large amplitude of a gloss change indicates that a difference between the gloss signal of the area of interest and the gloss signal of an area in the vicinity of the area of interest is large. As used herein, the term “cycle” refers to a value related to spatial breadth or the size of an area. A long cycle of a gloss change indicates that a region having a level of the gloss signal that is substantially the same as the level of the gloss signal of the area of interest is widely distributed so as to be adjacent to the area of interest. If the determination signal indicates a value related to the amplitude of a gloss change, a larger determination signal indicates a larger gloss change. In contrast, if the determination signal indicates a value related to the cycle of a gloss change, a larger determination signal indicates a smaller gloss change. According to the first exemplary embodiment, the determination signal is a value related to the cycle of a gloss change. In contrast, according to the first modification, the determination signal is a value related to the amplitude of the gloss change. Note that the amplitude and the cycle of the gloss change can be acquired from the spatial distribution of the material appearance signals.
The determination signal may be a combination of a value related to the amplitude of a gloss change and the cycle of the gloss change. If the results of determination of the two types are not the same, the result for the determination signal having a high priority may be selected, for example. The priority may be assigned in advance, or may be assigned in accordance with the type of object to be reproduced, the type of recording medium, or a user instruction.
The gloss signal corresponding to the specular gloss need not be limited to a value measured under the standard conditions, but may be a value measured under other conditions or a function of the value. For example, the direction of illumination in the measurement may be at 30 degrees. In addition, the angles of aperture of illumination and received light are not limited to those under the standard conditions. Furthermore, the signal corresponding to the specular gloss may contain color information in addition to the brightness information. For example, as a signal containing color information, a CIELAB value calculated using JIS Z8722 after measuring the amount of specular reflection light can he used. Thereafter, as the gloss signal corresponding to the specular gloss, three signals gL, ga, and gb are used instead of the signal g. In such a case, a signal corresponding to the specular gloss in the gloss mapping is converted in a three-dimensional color space. To convert the signal, an existing color matching technique can be used, as in the conversion of the color signal.
In addition, the gloss signal corresponding to the image clarity is not limited to a value measured under the standard conditions. A value measured under other conditions or a function of the value may be used. For example, an angle φ formed by a direction in which the amount of reflection light is half the amount of the specular reflection light in the vicinity of the specular direction and the specular direction is measured, and the inverse function of the angle φ may be used.
In addition, as the gloss signal corresponding to the image clarity, the measurement value of the surface regularities or a function of the measurement value may be used. An object to be reproduced having a smooth surface, that is, small surface regularities has a large image clarity. An object to be reproduced having large surface regularities has a small image clarity.
In addition, the gloss signal may contain an element related to the normal direction of each of the areas. For some objects to be reproduced, the normal direction may vary from area to area. In such a case, to obtain a reproduced object having an appearance that is the same as the appearance of the object to be reproduced, information regarding the normal direction is needed in addition to the specular gloss and the image clarity as the information held by each area. The normal direction can be reproduced by controlling the surface regularities. The surface regularities can be printed by using, for example, a UV inkjet printer or a 3D printer. In addition, if the gloss signal has the element related to the normal direction, an element related to the difference in the normal direction is set in the gloss signal in addition to the difference in the specular gloss and the difference in the image clarity in order to calculate the gloss difference from an area in the vicinity. That is, the gloss difference used in steps S404, S407, S410, and S413 illustrated in
The technique for evaluating the gloss difference is also only an example. Another evaluation technique can be employed. For example, the difference in the specular gloss and the difference in the image clarity may be independently obtained. A threshold value may be set for each of the differences. If one of the differences is greater than the threshold value, it can be determined that the gloss difference is large.
The above-described threshold value is only an example. The threshold value is not limited to the value described in the above-described exemplary embodiment. The threshold value may be determined on the basis of the type of recording medium, the type of object that constitutes the material appearance data, or a user instruction.
According to the present exemplary embodiment, a configuration in which input data is directly converted into the control signal for controlling the material appearance reproducing apparatus is described. Note that the same numbering will be used in describing the configuration of the present exemplary embodiment as was utilized above in describing the first exemplary embodiment, and description of the same configuration is not repeated.
The device signal conversion D unit 1601 converts material appearance signals (R, G, B, Gg, Sg) that constitute the image data received by the material appearance data input unit 1101 into a control signal including color material amount signals (C, M, Y, K), gloss control agent amount signals (A, B), and a pass control signal (P) of the image printing apparatus 800. The conversion is performed by referring to a material appearance reproduction table stored in a material appearance reproduction table storage unit 1602 and using a widely used n-dimensional lookup table technique.
A technique for verifying whether the control signals (C. M, Y, K, A, B, P) that are set in the material appearance reproduction table so as to correspond to material appearance signals (R, G, B, G, S) are suitable is described below.
The material appearance data 1901 is input to the material appearance reproducing system according to the present exemplary embodiment. The material appearance reproducing apparatus outputs the reproduced object. In this manner, the reproduced object can be obtained. Let Dout1 denote the value obtained by measuring the specular gloss of the reproduced object using a technique defined in JIS Z8741. In the same manner, the material appearance data 1902 is input to the material appearance reproducing system according to the present exemplary embodiment, and the material appearance reproducing apparatus outputs the reproduced object. In this manner, the reproduced object is obtained. Let Dout2 denote the measurement value of the specular gloss of the area corresponding to the area 1903 of the reproduced object. To remove the adverse effect of a variation of the material appearance reproducing apparatus, the average of the specular gloss values of a plurality of reproduced objects may be used for the values of Dout1 and Dout2.
If the material appearance reproduction table is appropriately set, the reproducibility of the specular gloss is given more weight in an area having a large gloss change than in an area having a small gloss change. Accordingly, the difference between the specular gloss indicated by the material appearance data and the specular gloss of the reproduced object is small. That is, if the absolute value of (Dorg-Dout2) is less than the absolute value of (Dorg-Dout1), it is determined that the material appearance reproduction table is appropriate. However, if the absolute value of (Dorg-Dout2) cannot be less than the absolute value of (Dorg-Dout1) in any setting of the parameters of the material appearance data 1901 and the material appearance data 1907, it is determined that the material appearance reproduction table is inappropriate.
According to the above-described technique, a process in which the reproducibility of the image clarity is given more weight and a process in which the reproducibility of the specular gloss is given more weight are reliably switched in accordance with the spatial distribution of the material appearance signals so that the difference between the appearances becomes smaller.
As described above, the material appearance reproducing system according to the second exemplary embodiment refers to the material appearance reproduction table describing a correspondence between a discrete material appearance signal and the control signal for controlling the material appearance reproducing apparatus and performs the processes that are performed by the units of the first exemplary embodiment through only a single conversion process. That is, the processes performed by the material appearance signal acquiring unit 1102, the material appearance mapping unit 1103, and the device signal conversion A unit 1104 of the first exemplary embodiment are performed as a single conversion process.
When a user of the material appearance reproducing apparatus wants to adjust the material appearance of a reproduced object into desired material appearance, it is difficult to freely adjust the distribution of the material appearance signal. According to the present exemplary embodiment, the user adjusts an input image instead of the material appearance reproducing apparatus. In such a case, the user does not know which adjustment operation to perform on the input image to obtain desired material appearance. Accordingly, the user tends to repeatedly attempt the adjustment operation. According to the third exemplary embodiment, a configuration including a material appearance adjustment unit is provided. Note that the same numbering will be used in describing the configuration of the present exemplary embodiment as was utilized above in describing the first exemplary embodiment, and description of the same configuration is not repeated.
The color adjustment value is formed from a brightness adjustment value ΔL and color adjustment values Δa and Δb. The value ΔL corresponds to L* defined in CIELAB. To perform control so that the reproduced object is brighter, the value ΔL is set to a larger positive value. In contrast, to perform control so that the reproduced object is darker, the value ΔL is set to a smaller negative value. The value Δa corresponds to a* defined in CIELAB. To perform control so that the red components of the reproduced object increase, the value Δa is set to a larger positive value. In contrast, to perform control so that the green components of the reproduced object increase, the value Δa is set to a smaller negative value. Similarly, the value Δb corresponds to b* defined in CIELAB. To perform control so that the yellow components of the reproduced object increase, the value Δb is set to a larger positive value. In contrast, to perform control so that the blue components of the reproduced object increase, the value Δb is set to a smaller negative value. A user interface (hereinafter simply referred to as a “UI”) may include a slide bar to acquire the adjustment values. In addition, for example, a slide bar for controlling the brightness has the displayed text “DARK” on one end and the display text “BRIGHT” on the other end. Thus, the user can intuitively set the adjustment value.
The adjustment value of the gloss is formed from an adjustment value Δg of the specular gloss and an adjustment value Δs of the image clarity. To perform control so that the specular gloss increases, a larger positive value Δg is set. In contrast, to perform control so that the specular gloss decreases, a smaller negative value Δg is set. Similarly, to perform control so that the image clarity increases, a larger positive value Δs is set. In contrast, to perform control so that the image clarity decreases, a smaller negative value Δs is set. A UI for acquiring the adjustment values of the gloss displays the images of the illumination light source (hereinafter also referred to as “illumination images”, which represent the appearance of the images produced by reflection at a surface of an object. Thus, the user can intuitively set the adjustment values.
Subsequently, in step S2302, the material appearance signals obtained in step S102 is corrected using the adjustment values obtained in step S2301. That is, adjusted material appearance signals L_a, a_a, b_a, g_a, and s_a are calculated as follows:
L_a=L+ΔL (1),
a_a=a+Δa (2),
b_a=b+Δb (3)
g_a=g+Δg (4), and
s_a=s+Δs (5),
Subsequently, in step S2303, the material appearance signals adjusted in step S2302 are converted into the material appearance signals corresponding to the material appearance reproducible by the image printing apparatus 800 serving as the material appearance reproducing apparatus using the above-described color mapping and gloss mapping.
Subsequently, in step S104, the material appearance signals converted in step S2303 are converted into the control signal for controlling the material appearance reproducing apparatus. Finally, in step S105, a reproduced object is output by the material appearance reproducing apparatus on the basis of the control signal obtained in step S104.
As described above, according to the third exemplary embodiment, the material appearance reproducing system includes an adjustment unit that controls the image clarity in terms of the gloss. That is, the material appearance reproducing system includes an adjustment unit that controls the sharpness of the illumination image produced by reflection at a surface of an object to be reproduced. In this manner, for example, even when the image clarity of the output reproduced object differs from the desired image clarity, the gloss of the reproduced object can be adjusted to the desired gloss. In addition, according to the third exemplary embodiment, the material appearance reproducing system includes an adjustment unit that controls the specular gloss in terms of the gloss. That is, the material appearance reproducing system includes an adjustment unit that controls the brightness of the illumination image generated by reflection at a surface of the object to be reproduced. In this manner, even when the specular gloss of the output reproduced object differs from the desired specular gloss, the gloss of the reproduced object can he adjusted to the desired gloss. Furthermore, the material appearance reproducing system according to the third exemplary embodiment includes two gloss adjustment units in terms of gloss, one of which controls the image clarity while the other controls the specular gloss. Even when the specular gloss is adjusted, the reproducibility of the image clarity is not improved. In addition, even when the image clarity is adjusted, the reproducibility of the specular gloss is not improved. Accordingly, to adjust the gloss of the reproduced object to the desired gloss, it is desirable that the material appearance reproducing system include two gloss adjustment units, one of which controls the image clarity while the other controls the specular gloss.
In addition, according to the third exemplary embodiment, the material appearance reproducing system acquires the above-described adjustment information by using a UI that displays images having different sharpness levels. In general, the users are not aware that the gloss includes the image clarity element and that the image clarity is a property regarding the sharpness of an image produced by reflection at a surface of the object. Accordingly, the user gets in a situation where the user cannot figure out which adjustment produces desired gloss and, thus, the user repeatedly performs the adjustment operation. By displaying images having different sharpness levels in the UI used to acquire the adjustment values of the gloss, the user can intuitively recognize that the sharpness of the illumination image produced by reflection at a surface of the object to be produced can be adjusted. As a result, the user does not get in a situation where the user cannot figure out which adjustment causes which effect and, thus, the user can obtain a reproduced object of a desired material appearance without repeating the adjustment operation. In addition, the material appearance reproducing system according to the third exemplary embodiment obtains the above-described adjustment information using a UI that displays images having different brightness levels and images having different sharpness levels. It is not generally known that the gloss has two elements, that is, the specular gloss and the image clarity and that the specular gloss represents the property regarding the brightness of an image produced by reflection at a surface of the object and the image clarity represents the property regarding the sharpness of the image produced by reflection at a surface of the object. Accordingly, the user gets in a situation where the user cannot figure out which adjustment produces desired gloss and, thus, the user repeatedly performs the adjustment operation. By displaying the above-described images in the UI used to acquire the adjustment values of the gloss, the user can be intuitively aware that the two elements, that is, the brightness of the illumination image produced by reflection at s surface of the object to be reproduced and the sharpness of the illumination image produced by reflection at a surface of the object to be reproduced can be adjusted. As a result, the user does not get in a situation where the user cannot figure out which adjustment causes which effect and, thus, the user can obtain the reproduced object of a desired material appearance without repeating the adjustment operation.
A UI for acquiring the adjustment values of the gloss according to the present modification that, differs from the UI according to the third exemplary embodiment is described below.
In addition, if an output preview check box 2608 is checked, the image in the display area 2601 is changed to a CG image of the object to be reproduced corresponding to the input material appearance data input in step S101. At the same time, the image in the display area 2602 is changed to a CG image of the object to be reproduced that is corrected using the tentatively set adjustment value. The CG image is an image obtained by simulating the appearance of the object to be reproduced viewed in the specular direction of a predetermined illumination light source when the object is illuminated by the illumination light source under predetermined conditions.
More preferably, the images displayed in the display areas 2601 and 2602 when the output preview check box 2608 is checked are CU images of the object to be reproduced corresponding to the material appearance data after the material appearance mapping performed in step 52303. By employing such a configuration, the image corresponding to the material appearance of the reproduced object actually output after the material appearance mapping can be examined before being output.
Note that the illumination image in the gloss adjustment UI according to the third exemplary embodiment may be an image corresponding to the input material appearance data. Alternatively, the image may be an image corresponding to the material appearance data after the material appearance mapping.
As described above, according to the first modification, the material appearance reproducing system acquires the above-described adjustment information using a user interface displaying the images having the sharpness that varies in accordance with an instruction provided externally. When adjustment is made, the sharpness of the illumination image produced by reflection at a surface of the object changes and, thus, the user can intuitively figure out the adjusted sharpness of the illumination image. As a result, the reproduced object having a desired image clarity can be obtained without repeating the adjustment operation. In addition, according to the first modification, the material appearance reproducing system acquires the adjustment information using user interface displaying images each exhibiting the sharpness and brightness of the illumination image that vary in accordance with an instruction provided externally. If the adjustment is made, the sharpness and brightness of the illumination image produced by reflection at a surface of the object vary. Thus, the user can intuitively recognize that the two elements, that is, the sharpness and brightness of the illumination image can be adjusted. As a result, a reproduced object having a desired material appearance can be obtained without repeating the adjustment operation.
In addition, according to the first modification, the material appearance reproducing system acquires the above-described adjustment information using a user interface displaying the images that vary in accordance with an instruction provided externally and that correspond to the input material appearance data. Thus, the gloss can be adjusted using the image of the object to be reproduced indicated by the input data. In this manner, the reproduced object having a desired material appearance can be obtained.
In addition, according to the first modification, the material appearance reproducing system acquires the above-described adjustment information using a user interface displaying the images having a sharpness that varies in accordance with an instruction provided externally and that correspond to the material appearance data obtained after the material appearance mapping. Thus, the gloss can be adjusted using the image corresponding to the material appearance of the reproduced object actually output after the material appearance mapping. In this manner, the reproduced object having a desired material appearance can be obtained.
The material appearance may be adjusted for a particular area instead of all the areas of input data, in such a case, the configuration of the above-described embodiments may additionally include a unit for specifying an adjustment area. In addition, the material appearance adjustment value acquiring unit 2501 may acquire the adjustment value for the specified adjustment area, and the material appearance correcting unit 2503 may correct the material appearance signal of only the specified adjustment area. Furthermore, the adjustment operation may be performed a plurality of times as needed. In such a case, a unit for acquiring information as to whether additional adjustment operation is performed is further provided. In addition, after the process performed by the material appearance correcting unit 2503 is completed, the information as to whether an additional adjustment operation is performed is acquired. If an additional adjustment operation is performed, the unit for specifying the adjustment area is re-activated to specify the adjustment area. In the second and subsequent adjustment operations, the material appearance correcting unit 2503 further corrects the result of previous correction. That is, instead of the input material appearance signals (L, a, b, g, s) in equations (1) to (5), the input material appearance signals (L-a, a_a, b_a, g_a, s_a) obtained in the previous correction are used. According to the modification, the material appearance of only a particular area can be adjusted, or different adjustments can be performed on different areas. In this manner, a reproduced object having a desired material appearance can be obtained.
In addition, the material appearance adjustment value acquiring unit 2501 may restrict acquirable adjustment information in accordance with the material appearance reproducible by the material appearance reproducing apparatus. For example, even when the slide bar 2603 allow an adjustment value Δg in the range of −10 <Δg <10 to be selected, the slider is inhibited to move to the right end of the slide bar if the specular gloss Δg reproducible by the material appearance reproducing apparatus <5. According to such a modification, the adjusted value is within the reproducible range at all times. Thus, a reproduced object having a desired material appearance can be obtained without repeating the adjustment operation.
In addition, as described in the first exemplary embodiment and some modifications, the signal corresponding to the specular gloss may contain the color information in addition to the brightness information. That is, the material appearance reproducing apparatus may control the color of the illumination image produced by reflection at a surface of the object in addition to the brightness of the illumination image. For example, instead of g, three signals gL, ga, and gb may be used as the gloss signal corresponding to the specular gloss. Note that gL, ga, and gb are signals corresponding to L*, a*, and b* of the CIELAB color space regarding the specular reflection light, respectively. In such a case, the material appearance adjustment value acquiring unit 2501 has a configuration to acquire the adjustment value of the chromaticity in addition to the adjustment value of the brightness as the adjustment value of the specular gloss. For example, by using the slide bar 2603 of the adjustment acquiring UI illustrated in 24, an adjustment value ΔgL regarding the brightness of the gloss is acquired instead of Δg. In addition, a UI for acquiring adjustment values Δga and Δgb regarding the chromaticity of the gloss is further provided. For example, the adjustment values of a red component and a green component of the specular reflection light are acquired by using the slide bar for acquiring the adjustment value Δga. In addition, the adjustment values of a yellow component and a blue component of the specular reflection light are acquired by using the slide bar for acquiring the adjustment value Δgb. Alternatively, in another example, a two-dimensional plane having axes of Δga and Δgb may be displayed in a UI. By acquiring any given position in the plane, a combination of Δga and AΔb may be acquired. In such a case, the material appearance correcting unit 2503 adds ΔgL, Δga, and Δgb to the material appearance signals gL, ga, and gb, respectively, to obtain adjusted material appearance signals. According to the present modification, the color of the specular reflection light can be also adjusted. Thus, the reproduced object having a desired material appearance can be obtained.
In addition, the images having different brightness levels or having different sharpness levels displayed in the UI for acquiring the material appearance adjustment values need not be the images of the illumination light source. That is, the images 2401 to 2408 illustrated in
The functional configuration of the material appearance reproducing system may be a configuration in which part or whole of the above-described configuration achieved using the host 700 is achieved by the image printing apparatus 800. In addition, while the above-described exemplary embodiments have been described with reference to six types of recording material (C, M, Y, K, A, and B), another type of recording material may be used. For example, a red recording material, a white recording material, or a gold recording material may be used. In addition, three or more types of gloss control agent may be used. While the above-described exemplary embodiments have been described with reference to a serial inkjet printer serving as the material appearance re-producing apparatus, a full-line inkjet printer, an electrophotographic printer, a sub-limation printer, or a silk printing may be used as the material appearance reproducing apparatus. Alternatively, a UV printer that prints a surface shape or a 3D printer that prints a 3D shape may be used. In addition to printers, the present technology may be applied to image display apparatuses, such as a display or a projector.
All the areas of the material appearance data need not be processed using the technique described in the above exemplary embodiments. A technique in which the technique of the above-described embodiment is not applied to some of the areas and a technique in which the technique of the above-described exemplary embodiment is applied to only some of the areas are encompassed within the scope and spirit of the present invention. For example, some of the areas of the material appearance data may be reproduced using a particular color material without performing the material appearance mapping.
In addition, the present invention can be achieved by supplying a program that provides at least one function of the above-described exemplary embodiment to a system or an apparatus via a network or a recording medium and reading out and executing the program using at least one processor of the system or the apparatus. Alternatively, the present invention can be achieved by a circuit (e.g., ASIC) that provides at least one function of the above-described exemplary embodiment.
According to the present invention, the image processing for obtaining a reproduced object having a desired material appearance using a reproducible range of the material appearance reproducing apparatus can be provided.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to he understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2014-254595, filed Dec. 16, 2014, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-254595 | Dec 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/006011 | 12/3/2015 | WO | 00 |
