JP2012085123A - Image processor and processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control coloring of the regular reflection light of a recording image.SOLUTION: An input unit 103 inputs image data, and special effect image data obtained by applying a special effect on the image data. An amount of CL ink determination unit 109 acquires a chromaticity corresponding to the image data from an amount of CL ink LUT storage unit 110 which stores the chromaticity of regular reflection light reproduced when the amount of colorless color material is differentiated on a recording medium. A color decomposition unit 107 performs color decomposition of the image data to the amount of color material data corresponding to the amount of a plurality of color materials for each pixel. The amount of CL ink determination unit 109 determines the amount of colorless color material data corresponding to the amount of colorless color material for each pixel by using the chromaticity corresponding to the image data and the special effect image data.

Description

  The present invention relates to image processing for generating data for recording an image using a colorless color material.

  In copiers and printers, a method of recording characters and images using pigment-based colorless and transparent color materials (hereinafter, clear color materials) in addition to cyan, magenta, yellow, black, and other color materials has been proposed. ing.

  The following are known to use clear color materials. For example, Patent Document 1 discloses a method of using a clear color material to make glossiness of a recorded image uniform, that is, a method of controlling the glossiness of an image by overlaying a clear color material on an image recorded on recording paper. Is disclosed.

  Patent Document 2 discloses a method for realizing a watermark such as forgery prevention using a clear color material. That is, additional information is recorded on an image using a clear color material having a high reflectance or a clear color material containing a component that is visualized by irradiation with ultraviolet rays or infrared rays.

  Patent Document 3 discloses a method of giving a special effect to an image using a clear color material. That is, characters and images are recorded using a clear color material having a high reflectance so that the characters and images stand out due to the difference in gloss.

  However, the inventions disclosed in these patent documents use the gloss of the clear color material to achieve uniform gloss, watermark, and special effects, but do not control the coloring of regular reflection light. The specularly reflected light is light that is reflected at an angle equal to the incident light, and is, for example, illumination light reflected in a recorded image. As a cause of coloring the specular reflection light, there are known the generation of a rainbow-like luster due to thin film interference and a phenomenon in which an illumination image reflected in a recorded image is colored (hereinafter referred to as bronze phenomenon).

  Thin film interference is caused by a phase difference in reflected light due to a path difference between light reflected from the surface of the color material and light reflected from the lower layer of the color material or the recording paper surface after entering the color material. It is a phenomenon. Thin film interference depends on the refractive index of the color material and the thickness of the color material, and the coloration changes depending on the thickness of the clear color material.

  The bronze phenomenon is a phenomenon in which regular reflection light is colored by the color material due to the wavelength dependence of the reflectance of the color material. For example, it is known that specularly reflected light colors magenta with a cyan color material and colors yellow with a magenta color material.

  That is, when a special effect is imparted to an image using a clear color material, an unintended recorded image may occur due to the influence of thin film interference or bronzing.

JP 2006-035688 Japanese Unexamined Patent Publication No. 6-62821 JP 2007-127790 JP

  An object of the present invention is to control coloring of specular reflection light of a recorded image.

  The present invention has the following configuration as one means for achieving the above object.

  The image processing according to the present invention is reproduced when image data and special effect image data obtained by applying a special effect to the image data are input, and the color material amount of the colorless color material on the recording medium is varied. A chromaticity corresponding to the image data is obtained from a table storing chromaticities of specular reflection light, and the image data is color-coded into color material amount data corresponding to the color material amounts of the plurality of colored color materials for each pixel. Dissociating and determining, for each pixel, colorless color material amount data corresponding to the color material amount of the colorless color material using chromaticity corresponding to the image data and the special effect image data. To do.

  According to the present invention, it is possible to control the coloring of the specularly reflected light of a recorded image, and for example, it is possible to record an image that provides the intended special effect.

FIG. 3 is a block diagram illustrating an example of the configuration of an image processing apparatus and an image recording apparatus according to an embodiment. The figure explaining an example of a dot arrangement pattern. FIG. 3 is a diagram schematically illustrating a recording head and a recording pattern. The figure explaining the relationship between image data and special effect image data. FIG. 6 is a diagram for explaining an example of a CL ink amount LUT. FIG. 3 is a block diagram illustrating a configuration example of a CL ink amount determination unit. The figure explaining the example of the relationship between the thickness of CL color material and the color of specular reflection light. FIG. 4 is a block diagram for explaining an example configuration of an image processing apparatus and an image recording apparatus according to a second embodiment. The figure explaining an example of a color separation LUT. FIG. 6 is a diagram for explaining an example of a CL ink amount LUT. The block diagram explaining the structural example of an output data determination part. FIG. 6 is a diagram for explaining the relationship between ink ejection order, CL ink amount, and color of regular reflection light.

  Hereinafter, image processing according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In the following, a method of determining the amount of a colorless and transparent color material (clear color material) for each pixel based on arbitrary color information and controlling the coloring of regular reflected light will be described.

[Device configuration]
A configuration example of the image processing apparatus and the image recording apparatus of the embodiment will be described with reference to the block diagram of FIG.

  The image processing apparatus 101 is connected to the image recording apparatus 102 via an interface such as a serial bus (for example, USB). The image processing apparatus 101 can be realized by, for example, a printer driver installed in a personal computer (PC). The image processing apparatus 101 may be incorporated in the image recording apparatus 102. In this case, each configuration of the image processing apparatus 101 described below is realized by the CPU of the PC executing the printer driver program or the CPU of the image recording apparatus 102 executing the program of the image processing apparatus. Is done.

  The image recording apparatus 102 is, for example, an inkjet system that uses ink containing each color material (colored color material) of cyan C, magenta M, yellow Y, and black K, and ink containing a clear color material. Alternatively, the image recording apparatus 102 is, for example, an electrophotographic printer that uses toners including C, M, Y, and K toners and a clear color material. Hereinafter, an ink including a pigment-based clear color material (colorless color material) is referred to as “CL ink”, and a toner including the clear color material is referred to as “CL toner”. In the following description, it is assumed that the image recording apparatus 102 is an ink jet printer.

  Image data input by the input unit 103 of the image processing apparatus 101 is stored in the image buffer 104. The special effect image data input by the input unit 103 is stored in the image buffer 105.

  The image processing unit 106 performs color processing including color matching for converting RGB values of image data into device RGB values of the image recording apparatus 102. The color matching is a process for matching colors when the image recording apparatus 102 reproduces a color conforming to the sRGB standard. For example, color matching includes processes such as giving priority to perceptual matching (perceptual), giving priority to colorimetric matching (colorimetric), and giving priority to vividness (saturation). The image processing unit 106 converts an input value (RGB value of the image data) into an output value (device RGB value of the image recording device 102) using a three-dimensional lookup table (3DLUT) representing the correspondence between colors and an interpolation operation. To do.

  The color separation unit 107 performs color separation processing based on the color separation LUT, which is a 3DLUT representing the correspondence between the RGB values and the ink amounts of cyan C, magenta M, yellow Y, and black K stored in the color separation LUT storage unit 108. I do. That is, the device RGB value output from the image processing unit 106 is color-separated into color material amount data (CMYK data) indicating the respective ink amounts (color material amounts) of C, M, Y, and K inks. The color separation LUT is created in consideration of the image quality such as the granularity and gradation of the recorded image.

  Although described in detail later, the CL ink amount determination unit 109 determines the ink amount of the CL ink using the LUT stored in the CL ink amount LUT storage unit 110, and is a colorless color indicating the CL ink amount (color material amount) Output material amount data (CL data). Note that the color separation LUT storage unit 108 and the CL ink amount LUT storage unit 110 are nonvolatile memories such as a ROM and a hard disk.

  The gradation correction unit 111 receives CMYK data and CL data, and uses a one-dimensional LUT to perform gradation correction (gamma conversion) on the CMYK data according to the gradation characteristics of the image recording device 102, and to record an image on the CL data. Corrections that match the ejection characteristics of the apparatus 102 are performed. That is, the one-dimensional LUT for gradation correction linearly corrects the gradation characteristics of the image recording apparatus 102 for CMYK data. Further, the one-dimensional LUT for CL data linearly corrects the ejection amount of the CL ink of the image recording apparatus 102 for the CL data.

  The halftone processing unit 112 performs halftone processing on the CMYK data and CL data output from the gradation correction unit 111 by an error diffusion method or dither processing, and converts the data into an index value of several bits for each color material. For example, when the dot arrangement pattern is composed of 3 bits, the 8-bit ink amount is quantized into a 3-bit index value.

  The output buffer 113 buffers C′M′Y′K ′ data and CL ′ data output from the halftone processing unit 112. The C′M′Y′K ′ data and the CL ′ data are transmitted from the image processing apparatus 101 to the image recording apparatus 102 via the output unit 114 of the image processing apparatus 101 and the input unit 115 of the image recording apparatus 102 that constitute the interface. Forwarded to

  The dot arrangement unit 116 of the image recording apparatus 102 converts the input C′M′Y′K ′ data and CL ′ data into dot arrangement. That is, the index value is converted into data indicating the dot arrangement based on the dot arrangement pattern indicating the correspondence between the index value and the dot arrangement. Note that a dot is the minimum unit that can be recorded by ink ejected from each nozzle of the recording head 119. The dot arrangement pattern is a pattern that defines whether each nozzle ejects ink.

  An example of the dot arrangement pattern will be described with reference to FIG. The dot arrangement pattern is composed of, for example, a binary level indicating that one pixel in the image data is divided into 4 × 2 cells in the XY direction and whether or not dots corresponding to each cell are recorded. Each level shown on the left in FIG. 2 corresponds to an index value output from the halftone processing unit 112, and each 4 × 2 cell shown on the right in FIG. 2 corresponds to a dot. A cell to which a circle (●) is added indicates a cell for recording a dot, and the number of cells for recording a dot increases as the level increases. Further, (4n) to (4n + 3) shown in the upper part of FIG. 2 indicate pixel positions in the Y direction, and the dot arrangement is changed according to the pixel position even at the same level. In consideration of the scanning direction of the recording head 119, such a dot arrangement pattern distributes the number of ejections to the nozzle corresponding to the upper stage of the dot arrangement pattern and the nozzle corresponding to the lower stage, and has various characteristics peculiar to the image recording apparatus 102. Has the effect of dispersing noise.

  The mask processing unit 117 converts the dot arrangement output from the dot arrangement unit 116 into ejection data that matches the scanning method of the recording head 119. For example, when multi-pass printing is performed, ejection data for each scan for completing dot arrangement is generated by a plurality of scans of the print head 119.

  FIG. 3 schematically shows a recording head and a recording pattern. The recording head 701 has 16 nozzles for the sake of simplicity. As shown in FIG. 3, the nozzles are divided into first to fourth nozzle groups, and each nozzle group includes four nozzles. The black cells of the mask pattern 702 correspond to the dots recorded by each nozzle, and the patterns recorded by each nozzle group are complementary to each other. For example, when a solid image is formed in an area corresponding to 4 × 4 cells, four dots are recorded by the first to fourth nozzle groups in the first recording scan 703 to the fourth recording scan 706, respectively. Thus, an image of an area corresponding to 4 × 4 cells is formed. In other words, when the patterns recorded by each nozzle group are overlapped, the recording of the area corresponding to 4 × 4 cells is completed.

  When each recording scan is completed, the recording paper is conveyed by the height of the nozzle group. Therefore, an image of the same area of the recording paper (area corresponding to the height of each nozzle group) is completed by four recording scans. By forming an image of the same area of the recording paper by a plurality of nozzle groups in a plurality of recording scans, there is an effect of reducing variations peculiar to nozzles, variations in conveyance accuracy of the recording medium, and the like.

  The dot placement unit 116 and the mask processing unit 117 are realized as dedicated hardware circuits controlled by the CPU of the image recording apparatus 102, but the CPU of the image recording apparatus 102 may perform these processes.

  The head drive circuit 118 controls ink ejection of the recording head 119 at an appropriate timing based on the ejection data output from the mask processing unit 117. The CL ink is ejected so that the clear color material is the uppermost layer of the recorded image.

[Image data and special effect image data]
The relationship between image data and special effect image data will be described with reference to FIG. 4A shows image data, and FIG. 4B shows special effect image data of the image data in FIG. 4A. The image data and special effect image data are composed of, for example, RGB data of 8 bits for each color conforming to the sRGB standard. The image data is, for example, image data taken by a digital camera, and the special effect image data is image data obtained by applying a special effect to the image data by an image processing program operating on a PC.

  The special effect image data represents an image when a recorded image is observed with specularly reflected light. That is, the image data represents an image perceived when the observer observes under observation conditions that do not include regular reflection light. On the other hand, the special effect image data represents an image perceived when the observer observes under observation conditions including specularly reflected light. For example, in the image data of FIG. 4 (a), the vehicle window 201 is represented by a single color, and in the special effect image data of FIG. 4 (b), the vehicle window 202 is colored with specular reflection (change in window color). Is expressed.

[Determination of CL ink amount]
The CL ink amount determination process is a process for determining the CL ink amount to be superimposed for each pixel so as to control the coloring of the regular reflection light based on the special effect image data. The CL ink amount determination unit 109 determines the CL ink amount using the error diffusion method based on the CL ink amount LUT stored in the CL ink amount LUT storage unit 110 and indicating the correspondence between the CL ink amount and the color of the specular reflection light. To do.

  An example of the CL ink amount LUT will be described with reference to FIG. The CL ink amount LUT stores the measurement result of the chromaticity of the regular reflection light of the patch in which the CL color material is superimposed on the patch printed for the RGB value. Specifically, a plurality of patches in which the CL ink amount is changed and the amount (thickness) of the CL color material is changed are printed for a set of RGB value patches. Then, the chromaticity of the regular reflection light of each patch is measured, and the chromaticity for the combination of the RGB value and the CL ink amount is defined as the CL ink amount LUT. Of course, the CL ink amount LUT is a table for each type of recording paper that also stores the measurement result in the case of paper white with an RGB value of (0, 0, 0). Note that any objective method may be used for measuring the chromaticity of the specularly reflected light, but it is preferable to match the subjectivity as much as possible. For example, light may be incident on the recorded image at an incident angle of 45 degrees, the spectral reflection luminance of reflected light having an outgoing angle of 45 degrees may be measured, and the chromaticity ab in the CIELab color system may be calculated from the spectral reflection luminance.

  The first to third rows of the CL ink amount LUT shown in FIG. 5 are the RGB values of the image data, the fourth row is the CL ink amount, and the fifth and sixth rows are the measured values of the chromaticity ab of the specular reflection light. . The CL ink amount LUT holds, for example, 9 × 9 × 9 × 9 = 6561 sets of data in which the RGB value and the CL ink amount (0 to 255) are divided into 32 units. The number of data held by the CL ink amount LUT is not limited to 6561 sets, and may be determined in consideration of the LUT data amount and the accuracy of the colored control. A record of RGB = (0, 0, 0) represents the characteristics of the recording paper. Accordingly, a CL ink amount LUT is prepared for each type of recording paper, or a CL ink amount LUT corresponding to a typical recording paper type (for example, “plain paper”, “matte paper”, “gloss paper”) is prepared.

  Although FIG. 5 shows the chromaticity ab of the regular reflection light with respect to the RGB value and the CL ink amount, for example, the saturation value S and the chroma value C of the regular reflection light may be used instead of the chromaticity.

A configuration example of the CL ink amount determination unit 109 will be described with reference to the block diagram of FIG. Target color setting unit 403 converts the sRGB values of the special effect image data input from the image buffer 105 into Lab values, and outputs the chromaticity ab conversion result as the target chromaticity a _t b _t.

Candidate color determining section 404 outputs the sRGB values of the image data input from the image buffer 104, from the target chromaticity a _t b _t inputted from the target color setting section 403, CL ink amount (CL data). Specifically, with reference to the CL ink amount LUT405, each CL ink amount and ab value with respect to the sRGB value of the image data are interpolated, and the ab value closest to the target chromaticity a _t b _t (ab value with the smallest color difference) CL data corresponding to) is output. Further, the difference between the target chromaticity a _t b _t and the ab value having the minimum color difference is fed back to the target color setting unit 403 as ΔaΔb.

  The target color setting unit 403 performs error diffusion processing using the difference ΔaΔb output from the candidate color determination unit 404 as an error. Since the error diffusion processing is well known, the details are omitted, but the ab value of the special effect image data in the subsequent pixel processing includes the ab value error-diffused from the previous pixel processing, and the vicinity of the previous line. An ab value or the like that is error-diffused from the pixel processing is added.

[Colored regular reflection light]
An example of the relationship between the thickness of the CL color material and the color of the specularly reflected light will be described with reference to FIG. Figure 7 shows the measurement of the color of specularly reflected light when the refractive index of the air layer is 1, the refractive index of the CL color material is 1.5, and the thickness of the CL color material is changed from 100 nm to 300 nm at 20 nm intervals. It is the graph which plotted the chromaticity. FIG. 7 shows that the chromaticity of the specularly reflected light changes when the path difference changes due to the change in the thickness of the CL color material. Note that the locus of chromaticity of specularly reflected light draws a circle on the ab plane indicates that the specularly reflected light has any color.

  In this embodiment, referring to the CL ink amount LUT 405, the CL ink amount is determined for each pixel based on the image data and the special effect image data, and the coloring of the regular reflection light is controlled. Thereby, the color of the image observed in the observation environment that does not include the regular reflection light and the color of the image observed in the observation environment that includes the regular reflection light can be controlled.

  For example, when the image shown in FIG. 4 is formed, the image (color) shown in FIG. 4 (a) is observed in the observation environment that does not include the specular reflected light without controlling the coloring of the specular reflected light. The However, in an observation environment including regular reflection light, an unintended image (color) is observed due to coloring of regular reflection light. If the coloring of specular reflection light is controlled, the image shown in FIG. 4 (a) is observed in an observation environment that does not include specular reflection light, and the image shown in FIG. 4 (b) is observed in an observation environment that includes specular reflection light. Observed. That is, it is possible to reproduce the texture of an object or substance such as the gloss of glass or metal in an observation environment including specularly reflected light.

  In the above description, the case where the clear color material is overcoated on the image in the colored control of the specular reflection light has been described. However, the clear color material may be overcoated on a recording medium on which no image is recorded. . In that case, the data value of the image data is 0.

  The image processing according to the second embodiment of the present invention will be described below. Note that the same reference numerals in the second embodiment denote the same parts as in the first embodiment, and a detailed description thereof will be omitted.

  In the first embodiment, the method of controlling the coloring of the regular reflection light by determining the CL ink amount for each pixel has been described. If the method of Example 1 is a combination of a dye-based CMYK color material and a pigment-based CL color material, the coloring of regular reflection light can be controlled appropriately. On the other hand, when a pigment-based color material is used, it is known that the recordable color gamut differs depending on the ink ejection order, in other words, the color material stacking order. For example, the observed color differs between when the C color material and the M color material are overlapped in the order of CM and when they are overlapped in the order of MC. Furthermore, it is known that due to the bronze phenomenon, the coloration of the specularly reflected light changes depending on the color material superimposed thereon. That is, when using a pigment-based CMYK color material, it is necessary to control not only the CL ink amount but also the ink ejection order in order to control the coloring of the regular reflection light in detail. As in the first embodiment, the CL ink is ejected so that the clear color material is the uppermost layer of the recorded image.

  In the second embodiment, an example will be described in which the ejection order of the ink other than the CL ink and the CL ink amount are determined for each pixel to control the coloring of the regular reflection light.

[Device configuration]
A configuration example of the image processing apparatus and the image recording apparatus according to the embodiment will be described with reference to the block diagram of FIG. As shown in FIG. 8, the configuration of the second embodiment includes an output data determination unit 904 instead of the CL ink amount determination unit 109 of the first embodiment. However, the operations of the image processing unit 106, the color separation unit 107, and the mask processing unit 117, and the configurations of the head driving circuit 118 and the recording head 119 are different from the first embodiment. On the other hand, the operations of the image buffers 104 and 105, the CL ink amount determination unit 109, the gradation correction unit 111, the halftone processing unit 112, the output buffer 113, and the dot arrangement unit 116 are the same as those in the first embodiment.

  The image processing unit 106 performs the processing described in the first embodiment, and outputs image data in a device-independent color space. As the device-independent color space, for example, a CIELab color system or a CIEXYZ color system may be used. For example, the RGB value of the image data may be converted into a CIEXYZ value using a conversion formula compliant with the sRGB standard, and the XYZ value may be converted into a CIELab value using a conversion formula defined by the CIE.

  Next, the color separation unit 107 outputs CMYK data obtained by color-separating Lab values output from the image processing unit 106 for each selectable ink ejection order. The color separation LUT storage unit 108 stores 3DLUTs including color separation results for each selectable ink ejection order. In the following, there will be described a case in which there are two selectable ink discharge orders, CMYK order (normal order) and KYMC order (reverse order), but other discharge orders are also possible.

  An example of the color separation LUT will be described with reference to FIG. The first to third columns are Lab values of the image data, the fourth to seventh columns are data (color separation results) indicating the ink amount of CMYK, and the eighth column is ejection order data. In the discharge order data, “0” indicates the normal order and “1” indicates the reverse order. That is, the color separation LUT has color separation results in the normal order and reverse order with respect to the same Lab value.

  Although details will be described later, the output data determination unit 904 outputs the CMYK to the gradation correction unit 111 based on the special effect image data, the CL ink amount LUT, and the CMYK data corresponding to the ink ejection order output by the color separation unit 107. Determine data and CL data.

  Subsequent processing is almost the same as in the first embodiment, and detailed description thereof is omitted. However, the second embodiment differs from the first embodiment in that the ink discharge order can be selected. Accordingly, any form may be used as long as the image recording apparatus 102 can select the ink discharge order. For example, it is only necessary to have a recording head in which the nozzle rows of the respective inks are arranged in the order of CMYK in the printing direction, and bi-directional printing is possible. Such a recording head can change the ink ejection order in the forward path and in the backward path. For example, when C ink and M ink are overlapped, the forward path can be overlapped in the order of CM, and the return path can be overlapped in the order of MC.

[Determination of output data]
The output data determination unit 904 determines CMYK data and CL data to be output to the gradation correction unit 111 based on the special effect image data, the CL ink amount LUT, and the CMYK data corresponding to the ejection order of the ink output by the color separation unit 107. To do. The CL ink amount LUT storage unit 110 stores the CL ink amount LUT indicating the chromaticity ab of the regular reflection light with respect to the ink ejection order, the CMYK data, and the CL ink amount.

  An example of the CL ink amount LUT will be described with reference to FIG. The CL ink amount LUT stores the measurement result of the chromaticity of specular reflection light when the amount of CL ink to be printed over a patch printed for a certain CMYK value is changed. The first row is the ink ejection order, the second to fifth rows are CMYK data, the sixth row is CL data, and the seventh and eighth rows are measured values of chromaticity ab of specular reflection light.

A configuration example of the output data determination unit 904 will be described with reference to the block diagram of FIG. Target color setting unit 905 converts the sRGB values of the special effect image data input from the image buffer 105 into Lab values, and outputs the chromaticity ab conversion result as the target chromaticity a _t b _t.

  The output data determination unit 906 acquires from the CL ink amount LUT 907 the chromaticity ab of regular reflection light in each CL data for the ink ejection order and CMYK data input from the color separation unit 107. Specifically, the ab value in each CL data is interpolated with respect to the CMYK data with reference to the CL ink amount LUT907. For example, when the CL data is in increments of 32, 18 chromaticities ab are acquired for two ink ejection orders.

Then, the output data determination unit 906 determines a chromaticity ab acquired, the color difference of the target chromaticity a _t b _t inputted from the target color setting section 905 calculates the color difference is a minimum chromaticity ab. Then, CMYK data and CL data in the ink discharge order corresponding to the chromaticity ab having the smallest color difference are output.

The relationship between the ink ejection order, the CL ink amount, and the color of the specularly reflected light will be described with reference to FIG. FIG. 12 (a) shows the case where the ink discharge order is normal, and FIG. 12 (b) shows the case where the ink discharge order is reverse. For example, it is assumed that the point 1301 indicates the target chromaticity a _t b _t output from the target color setting unit 905. When the ink ejection order is normal, the CL ink amount having the smallest color difference from the target chromaticity is 96 and the color difference is 12. When the ink ejection order is reverse, the CL ink amount with the smallest color difference from the target chromaticity is 128 and the color difference is 7. In this case, the output data determination unit 906 outputs CMYK data and CL data = 128 in which the ink ejection order is smaller and the color difference is smaller.

  It should be noted that the coloring of specularly reflected light can be controlled within a range that can be achieved by additive color mixing by randomly mixing different amounts of CL ink at a certain ratio. Therefore, the determination may be made based on whether or not the target color is within the range.

  As described above, the coloring of the regular reflected light can be suitably controlled by determining the stacking order of the color materials other than clear and the amount of the clear color material for each pixel. For example, when reproducing specularly reflected light with the target chromaticity 1301 shown in FIGS. 12 (a) and 12 (b), select a reverse ink ejection order that has higher chromaticity reproduction accuracy than the normal ink ejection order. Can do. That is, it is possible to control the coloring of the specularly reflected light with higher accuracy by dynamically changing the order of ink ejection (the order of overlapping color materials other than clear).

  In the above description, the case where the ink ejection order is forward and reverse is described. However, even when there are three or more ejection orders, the same effect can be obtained by selecting the ejection order that minimizes the color difference. Can do.

[Modification]
In the first and second embodiments, an example in which one clear color material is used has been described. However, a plurality of clear color materials having different refractive indexes can be used. In that case, the chromaticity of the specular reflection light corresponding to each clear color material is recorded in the CL ink amount LUT, and the type of clear color material and the clear color material amount are determined so that the color difference from the target chromaticity is minimized. do it. For example, when there are two types of clear color materials, CL1 data indicating the ink amount of the first clear color material and CL2 data indicating the ink amount of the second clear color material may be determined.

[Other Examples]
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

Claims (11)

Input means for inputting image data and special effect image data obtained by applying a special effect to the image data;
An acquisition means for acquiring chromaticity corresponding to the image data from a table storing chromaticity of specularly reflected light that is reproduced when the color material amount of the colorless color material on the recording medium is varied;
Color separation means for color-separating the image data into color material amount data corresponding to the color material amounts of the plurality of color materials for each pixel;
Determining means for determining, for each pixel, colorless color material amount data corresponding to the color material amount of the colorless color material using chromaticity corresponding to the image data and the special effect image data; A featured image processing apparatus.   The table further stores the chromaticity of the regular reflection light that is reproduced when the color material amount of the colorless color material on the patch recorded by a plurality of color materials is changed according to the image data. 2. The image processing apparatus according to claim 1, wherein   3. The image processing apparatus according to claim 1, wherein the table stores a correspondence relationship between the image data and the chromaticity.   The determining means calculates a target chromaticity from the special effect image data for each pixel, and determines the colorless color material amount data from the target chromaticity and a chromaticity corresponding to the image data. 4. The image processing device according to claim 1, wherein the image processing device is an image processing device.   The determining means determines the colorless color material amount data that minimizes the color difference between the target chromaticity and the chromaticity of the image data, and the chromaticity of the regular reflected light with respect to the determined colorless color material amount data and the 5. The image processing apparatus according to claim 4, wherein a difference in target chromaticity is error-diffused into the special effect image data. An image processing apparatus for generating data for recording an image using a plurality of colored color materials and colorless color materials,
The colorless color material is stacked with a plurality of thicknesses on the patch recorded according to the color material amount data indicating the color material amount of the plurality of color materials corresponding to the stacking order of the plurality of color materials. A memory for storing a table in which measured values of chromaticity of specularly reflected light in a plurality of patches are recorded;
Input means for inputting image data and special effect image data obtained by applying a special effect to the image data;
For each pixel, color separation means for color-separating the image data into the color material amount data corresponding to each of the overlapping orders;
For each pixel, using the table, the color material amount data corresponding to the overlap order and the special effect image data, the color material amount to be output from the color material amount data corresponding to the overlap order An image processing apparatus comprising: determining means for determining data and determining colorless color material amount data indicating a color material amount of the colorless color material.   The determining means calculates a target chromaticity from the special effect image data for each pixel, and outputs the output from color material amount data corresponding to the target chromaticity and the overlapping order with reference to the table. 7. The image processing apparatus according to claim 6, wherein power color material amount data and the colorless color material amount data are determined.   The determining means determines the color material amount data in the overlapping order and the colorless color material amount data that minimize the color difference between the target chromaticity and the chromaticity of the regular reflection light. Item 8. The image processing device according to Item 7. An image processing method of an image processing apparatus having input means, acquisition means, color separation means, and determination means,
The input means inputs image data and special effect image data obtained by applying a special effect to the image data,
The acquisition means acquires a chromaticity corresponding to the image data from a table that stores the chromaticity of specularly reflected light that is reproduced when the color material amount of the colorless color material on the recording medium is varied,
The color separation means color-separates the image data into color material amount data corresponding to the color material amounts of the plurality of colored color materials for each pixel,
The determining means determines, for each pixel, colorless color material amount data corresponding to the color material amount of the colorless color material using chromaticity corresponding to the image data and the special effect image data. A featured image processing method. A plurality of colorless color materials stacked in a plurality of thicknesses on a patch recorded according to color material amount data indicating the color material amounts of the plurality of colored color materials, corresponding to the overlapping order of the plurality of colored color materials. A memory for storing a table in which measured values of chromaticity of specularly reflected light in the patch are input, input means, color separation means, and determination means, and using the plurality of colored color materials and the colorless color material An image processing method of an image processing apparatus for generating data for recording an image, comprising:
The input means inputs image data and special effect image data obtained by applying a special effect to the image data,
The color separation means color-separates the image data into the color material amount data corresponding to the overlapping order for each pixel,
The determination means outputs, from the color material amount data corresponding to each of the overlap orders, using the table, the color material amount data corresponding to the overlap order and the special effect image data for each pixel. A color material amount data to be determined is determined, and colorless color material amount data indicating a color material amount of the colorless color material is determined.   9. A program that causes a computer to function as each unit of the image processing apparatus according to claim 1.