JP6503834B2 - Image processing apparatus, image processing method, image processing program - Google Patents

Description

  The present invention adds the color signals of additive red (R), green (G) and blue (B) to the subtractive cyan (C), magenta (M) and yellow (Y), and red (R) The present invention relates to an image processing apparatus, an image processing method, and an image processing program for converting a color signal for printing using green (G) or blue (B).

  In order to print a digital image consisting of RGB data on paper, it is necessary to convert the RGB data into CMYK data. A color space that can be represented by printing based on CMYK data using C, M, Y, and K inks is narrower than a color space that can represent an image composed of RGB data on a display. Therefore, a color that does not fit into the CMYK data color space in the RGB data color space is replaced with an approximate color in the CMYK data color space.

  In addition, multi-color printing is also used using inks of RGB colors for expanding the color gamut of the RGB secondary color part reproduced by overlapping CMY primary colors.

Unexamined-Japanese-Patent No. 2006-31376

  When an image composed of RGB data is converted to CMYK data and printed on a sheet, an operator may perform a retouching operation to modify colors so that the printed image is vivid. The retouching operation has to be performed by an operator who is rich in experience and knowledge, and takes a long time.

  In addition, when using CMYK and RGB ink for color gamut expansion, it is necessary to create data for RGB besides CMYK. Since printing uses halftone dots to reproduce tone, halftone technology is generally used in which CMYK halftone dots do not interfere. In the case of multicolor printing, in order to avoid the moiré phenomenon caused by dot overlap, screen angles are assigned to the complementary colors of R, G and B, but moiré can not be completely avoided.

  Therefore, in order to realize color gamut expansion by four-color printing without concern about moiré, it is necessary to express original data in CMY three colors and assign the remaining colors to RGB ink for color gamut expansion. In addition, in order to create data for that purpose, conversion into R or G or B data which is one color desired to be added to three colors containing K information in CMY is required. It is not preferable that the achromatic color changes and takes on a tint when converting RGB data into CMY data that can obtain a vivid printed image.

  In addition, with regard to a printed matter containing a large amount of K characters, it is also possible to convert it into CMYK data and R or G or B data which is one color desired to be added.

An object of the present invention is to be able to convert RGB data into R or G or B data which is one color desired to be added to CMY from which a vivid print image is obtained without changing achromatic color.
Furthermore, by storing the K information in each color of CMY, an image processing apparatus, an image processing method, and an image processing program for creating data capable of color gamut expansion printing by four-color printing can be provided. An object of the present invention is to provide an image processing apparatus, an image processing method, and an image processing program capable of creating data with five or more colors.

In order to solve the problems of the prior art described above, the present invention provides R, G and B values indicating the levels of additive red, green and blue color signals and L ^* a ^* b ^* color system L ^* , a ^*, with reference to the first color profile indicating the relationship between b ^* values, of the RGB data, chromatic R, G, corresponding to the B value L ^*, a ^*, the b ^* value A modified RGB that converts only the values of a ^* and b ^{* in} the direction to increase the saturation, and does not convert the L ^* , a ^* , and b ^* values corresponding to the achromatic R, G, and B values. Color conversion module that generates data, L ^* a ^* b ^* color system L ^* , a ^* , b ^* values and subtractive colors cyan, magenta, yellow, black (if necessary), one color to be added C, M, Y, K (if necessary) indicating the level of each color signal of red or green or blue, R or G which is one color to be added Refers to the second color profile indicating a correspondence relationship is B, each R in the concealment RGB data, G, corresponding to the B value L ^*, a ^*, b ^* most approximate to the value L ^*, Select a ^* and b ^* values from the second color profile, and add C, M, Y and K (if necessary) values corresponding to the selected L ^* , a ^* and b ^* values, and add 1 An image processing characterized by comprising a printing color converter for outputting R, G or B values which are colors as R or G or B data which is one color to be added to CMYK (if necessary) for printing Provide an apparatus.

In the above image processing apparatus, the values of a ^* and b ^* of L ^* , a ^* , b ^* values corresponding to R, G, B values of the hue of cyan in the first color profile are a1, b1. When the values of a ^* and b ^* converted by the color conversion module are a2 and b2, the color conversion module determines that a2 is (−0.0008 × a1 ³ + 0.0065 × a1 ² + 1.596 × a1 + .7609) from ^{(-0.0018 × a1 3 -0.0587 × a1} 2 + 0.509 × a1-0.8142) such that the first range of up to convert the a1 to a2, b2 is (-0.0004 × b1 ³ Convert b1 to b2 so that the second range is from + 0.0077 × b1 ² + 1.5267 × b1−1.7158) to (−0.0007 × b1 ³ −0.0224 × b1 ² + 0.9027 × b1 +0.2427) It is preferable to do.

In the above image processing apparatus, the values of a ^* and b ^* of L ^* , a ^* , b ^* values corresponding to R, G, B values of the hue of magenta in the first color profile are a1, b1. When the values of a ^* and b ^* converted by the color conversion module are a2 and b2, the color conversion module is configured such that a2 is (−0.0006 × a1 ³ + 0.0257 × a1 ² + 1.0074 × a1 is converted to a2 so as to be a first range from a1 + 1.9869) to (−0.0002 × a1 ³ + 0.0103 × a1 ² + 0.9148 × a1−0.6582), and b2 is (+ 0.5015 ×) ^{b1 4 -0.0698 × b1 3 -3.6577 ×} b1 2 -1.1779 × b1 + 1.1221) from ^{(+ 0.1862 × b1 4 -0.0994 ×} b1 3 -1.3049 × b1 2 + 0.8372 × b1 + 0.6918) to the second It is preferable to convert b1 to b2 to be in the range.

In the above image processing apparatus, values of a ^* and b ^* of L ^* , a ^* , b ^* values corresponding to R, G, B values of yellow hue in the first color profile are a1, b1. and then, when the values of the b ^* of a ^* converted by the color conversion module was a2, b2, the color conversion module, a2 is ^{(-0.0741 × a1 3 -0.2281 × a1} 2 + 1.5887 × a1 from ^{-0.0597) (-0.169 × a1 3 -1.2732} × a1 2 -1.6351 × a1-1.6855) such that the first range of up to convert the a1 to a2, b2 is (+ 0.0002 × b1 ³ - Converting b1 to b2 such that the second range is from 0.0557 × b1 ² + 3.8295 × b1-19.174) to (−0.0005 × b1 ³ + 0.0496 × b1 ² −0.1869 × b1 + 9.3544) Is preferred.

In the image processing apparatus described above, the first red hue in the color profile R, G, L corresponding to the B value ^*, a ^*, b ^* values of a ^* values and b ^* of the values a1, b1 and then, when the values of the b ^* of a ^* converted by the color conversion module was a2, b2, the color conversion module, a2 is ^{(+ 0.0003 × a1 3 -0.0393 ×} a1 2 + 2.3151 × a1 + .2089 ^{from) (-0.0001 × a1 3 + 0.0078} × a1 2 + 0.9417 × a1 + 0.7953) such that the first range of up to convert the a1 to a2, b2 is (-0.0005 × b1 B1 is set to a ^second range of ³ + 0.0118 × b1 ² + 1.3315 × b1−0.2592) to (−0.0001 × b1 ³ + 0.0105 × b1 ² + 0.7565 × b1 + 1.5076). It is preferable to convert into

In the above image processing apparatus, the values of a ^* and b ^* of L ^* , a ^* and b ^* values corresponding to R, G and B values of the green hue in the first color profile are a1 and b1. and then, when the values of the b ^* of a ^* converted by the color conversion module was a2, b2, the color conversion module, a2 is ^{(-0.0007 × a1 3 -0.0337 × a1} 2 + 1.2237 × a1 A1 is converted to a2 such that the first range is from −0.6896) to (+ 0.00002 × a1 ³ + 0.0021 × a1 ² + 1.1512 × a1 + 0.5305), and b2 is (0.0154 × b1 ^{3) -0.574 × b1 2 + 8.8314 × b} -32.365) from ^{(0.0114 × b1 3 -0.4456 × b1} 2 + 6.6982 × b1-22.866) such that the second ranging, converting the b1 to b2 Is preferred.

In the above image processing apparatus, the values of a ^* and b ^* of L ^* , a ^* , b ^* values corresponding to R, G, B values of the blue hue in the first color profile are a1, b1. and then, when the values of the b ^* of a ^* converted by the color conversion module was a2, b2, the color conversion module, a2 is ^{(0.0021 × a1 3 -0.0877 × a1} 2 + 1.9804 × a1 + 0. from ^{0338) (-0.0005 × a1 3 -0.0022} × a1 2 + 1.0938 × a1 + 0.1172) such that the first range of up to convert the a1 to a2, b2 is (0.002 × b1 ³ +0.0492 × b1 ² + 1.6385 × b1-2.9658) from ^{(-0.0006 × b1 3 -0.0151 × b1} 2 + 1.0452 × b1-0.5404) such that the second range up to, it is preferable to convert the b1 to b2 .

Further, in order to solve the problems of the prior art described above, according to the present invention, R, G, B values indicating the levels of each color signal of additive red, green and blue and L ^* a ^* b ^* color system With reference to a first color profile indicating a correspondence relationship with L ^* , a ^* , b ^* values, it is determined whether each pixel data composed of RGB data is chromatic data or not. if the data of the pixel data is chromatic color, converting R, G, L ^* corresponding to the B value, a ^*, b ^* a ^* in the value, b ^* value only in a direction to raise the color saturation, the pixel If the data is achromatic data, L ^* , a ^* , b ^* values corresponding to R, G, B values are not converted, and retouched RGB data is generated as it is, and L ^* a ^* b ^* is generated ^. C, M, Y, which indicate the levels of L ^* , a ^* , b ^* values of the color system and the subtractive cyan, magenta, yellow, black color signals L ^* , a ^* , corresponding to respective R, G, B values in the retouched RGB data with reference to a second color profile indicating a correspondence relationship with R, G or B values that are one color to be added b ^* most approximate to the value L ^*, a ^*, and b ^* values selected from the second color profile, the L selected in the second color profile ^*, a ^*, corresponds to the b ^* values C , M, Y, output one color R or G or B that you want to add as C, R or G or B data that you want to add CMY for printing, or, if K is required, five or more colors And providing an image processing method characterized by outputting the data as
The present invention provides an image processing method characterized by

Furthermore, in order to solve the problems of the prior art described above, the present invention provides an R, G, B value and L ^* a ^* b ^* table indicating the levels of additive red, green and blue color signals on a computer. With reference to a first color profile indicating a correspondence relationship with L ^* , a ^* , b ^* values of the color system, it is determined whether each pixel data configured by RGB data is chromatic data or not And if the pixel data is chromatic data, only the values of a ^* and b ^* in the L ^* , a ^* and b ^* values corresponding to the R, G and B values are increased in the direction to increase the saturation. And converting the L ^* , a ^* and b ^* values corresponding to the R, G and B values without conversion and generating modified RGB data as the values without conversion if the pixel data is achromatic data. , L ^* a ^* b ^* color system L ^* , a ^* , b ^* values and subtractive colors cyan, magenta, yellow, black Referring to the second color profile showing the correspondence between C, M and Y indicating the level of each color signal of the rack and the R or G or B value which is one color desired to be added, the respective R in the modified RGB data , G, B values, and L ^* , a ^* , b ^* values closest to the L ^* , a ^* , b ^* values are selected from the second color profile, and the second color profile is selected. C, M, Y corresponding to the selected L ^* , a ^* , b ^* value, R or G which is one color to be added, C or M value to be added with CMY for printing, R or G or B which is one color The present invention provides an image processing program which is executed as a step of outputting as data, or outputting as data of five or more colors if K is required.

According to the image processing apparatus, the image processing method, and the image processing program of the present invention, R or G or B data which is one color desired to be added with CMY for obtaining a vivid print image of RGB data without changing achromatic color Can be converted to Using red, green or blue screen angles for the K screen angle also helps to prevent moiré.
Moire is avoided by using the screen angle of the complementary color of each color for R, G, B moiré measures when K is used.

FIG. 1 is a block diagram showing an image processing apparatus according to an embodiment. It is a figure for ^{demonstrating} a L ^* a ^* b ^* colorimetric system. FIG. 6 is a characteristic diagram showing characteristics of cyan in a standard state before the values of a ^* and b ^* are converted by the color conversion module 10 in FIG. 1. FIG. 6 is a characteristic diagram showing characteristics of a ^* and b ^{* of} cyan obtained by converting values of a ^* and b ^* by the color conversion module 10. FIG. 6 is a characteristic diagram showing characteristics of magenta in a standard state before the values of a ^* and b ^* are converted by the color conversion module 10. FIG. 6 is a characteristic diagram showing the characteristics of each of a ^* and b ^{* of} magenta obtained by converting the values of a ^* and b ^* by the color conversion module 10. FIG. 10 is a characteristic diagram showing yellow characteristics in a standard state before the values of a ^* and b ^* are converted by the color conversion module 10. FIG. 6 is a characteristic diagram showing respective characteristics of yellow a ^* and b ^{* obtained} by converting values of a ^* and b ^* by the color conversion module 10. FIG. 10 is a characteristic diagram showing characteristics of red in a standard state before the values of a ^* and b ^* are converted by the color conversion module 10. FIG. 6 is a characteristic diagram showing characteristics of a ^* and b ^{* of} red obtained by converting values of a ^* and b ^* by the color conversion module 10. FIG. 10 is a characteristic diagram showing characteristics of green in a standard state before the values of a ^* and b ^* are converted by the color conversion module 10. FIG. 7 is a characteristic diagram showing characteristics of a ^* and b ^{* of} green obtained by converting values of a ^* and b ^* by the color conversion module 10. FIG. 10 is a characteristic diagram showing characteristics of blue in a standard state before the values of a ^* and b ^* are converted by the color conversion module 10. FIG. 6 is a characteristic diagram showing characteristics of a ^* and b ^{* of} blue obtained by converting values of a ^* and b ^* by the color conversion module 10. FIG. 6 is a diagram showing an example of a color image used to verify the effect of the image processing device, the image processing method, and the image processing program according to an embodiment. It is a figure which shows the color reproduction range which added red to the color reproduction range also including the combination of cyan, magenta, and yellow. It is a figure which shows the color reproduction range which added green to the color reproduction range also including the combination of cyan, magenta, and yellow. It is a figure which shows the color reproduction range which added blue to the color reproduction range also including the combination of cyan, magenta, and yellow. It is a figure for comparing the original data before converting the values of a ^* and b ^* by the color conversion module 10 with the retouched data after the conversion. It is a figure for comparing the original data before converting the values of a ^* and b ^* of cyan by the color conversion module 10 with the retouched data after the conversion. FIG. 6 is a diagram for comparing original data before converting the values of a ^* and b ^* of magenta by the color conversion module 10 with modified data after conversion. It is a figure for comparing the original data before converting the values of yellow a ^* and b ^* by the color conversion module 10 with the converted data after conversion. FIG. 16 is a view contrasting gray values of a ^* and b ^{* in} the color image shown in FIG. 15 with comparative examples in which the values of a ^* and b ^* are converted. It is a figure for comparing the original data before converting the values of a ^* and b ^* of red by the color conversion module 10 with the corrected data after conversion. It is a figure for comparing the original data before converting the values of a ^* and b ^* of green by the color conversion module 10 with the retouched data after converting. It is a figure for comparing the original data before converting the values of a ^* and b ^* of blue by the color conversion module 10 with the corrected data after conversion. 5 is a flowchart showing an operation of the image processing apparatus of the embodiment, an image processing method of the embodiment, and a process executed by an image processing program of the embodiment. It is a block diagram showing an example of composition of a computer which runs an image processing program of one embodiment.

  Hereinafter, an image processing apparatus, an image processing method, and an image processing program according to an embodiment will be described with reference to the attached drawings.

  As shown in FIG. 1, the image processing apparatus according to one embodiment includes a color conversion module 10 and a printing color converter 20. In FIG. 1, RGB data and a correction amount adjustment signal are input to the color conversion module 10. RGB data is, for example, image data generated by a digital camera.

  Here, RGB data is associated with a color profile CP1 that describes a table for converting colors. For example, in Exif (Exchangeable image file format) information, it is possible to describe the name (such as sRGB described later) of a color profile used as the color profile CP1.

  Managing color so that color does not change as much as possible, such as display and printer, is called color management. Color management is performed by using the color profile CP1 and a color profile CP2 described later.

  As a color profile, it is common to use an ICC profile conforming to the International Color Consortium (ICC) format. The color profiles CP1 and CP2 are an example of an ICC profile.

  It is assumed that RGB data is represented by a color space standard called sRGB defined by the International Electrotechnical Commission (IEC) as an example. The color profile CP1 corresponds to sRGB. Instead of sRGB, Adobe RGB may be used. Adobe RGB is a color space standard proposed by Adobe Systems Incorporated.

As shown in FIG. 1, the color profile CP1 has R, G, B values indicating the levels of R, G, B color signals, and L ^* a ^* b ^* color system (CIE L ^* a ^* b ^* ) Shows the correspondence with L ^* , a ^* , and b ^* values. The L ^* a ^* b ^* color system is represented by a three-dimensional color space shown in FIG. 2 (a). FIG. 2 (b) is a cross-sectional view of FIG. 2 (a), showing the circle formed by the a ^* and b ^* axes.

L ^* represents lightness. + A ^* indicates red, -a ^* indicates green, + b ^* indicates yellow, and -b ^* indicates blue. As shown in FIG. 2 (b), the circumferential direction of the circle represents the hue. As the color space goes from the center to the outside, the saturation becomes higher and the color becomes brighter.

  The color profile CP1 can not hold all of the huge color points that make up the sRGB color space, so it is possible to extract color points evenly, for example, about 1500 points from the color space, and hold them in the color profile CP1. Just do it. Color data not held in the color profile CP1 is interpolated by calculation.

The color conversion module 10, of the color profile CP1 that is associated with the input RGB data, chromatic R, G, L corresponding to the B value ^*, a ^*, b ^* values of a ^*, b ^* Only the value of is converted by the following conversion formula. The color conversion module 10 does not convert the value of L ^* and does not change the lightness.

If the values of R, G, G and B are all the same, such as R, G, B values (0, 0, 0), (128, 128, 128), (255, 255, 255) The color determined by the values of R, G and B is achromatic. The color conversion module 10 does not convert the achromatic L ^* , a ^* , b ^* values from (0, 0, 0) to (255, 255, 255), and outputs the values as they are.

Here, a conversion equation suitable for obtaining a vivid print image, in which the color conversion module 10 converts the values of a ^* and b ^* of chromatic color will be described. As a representative, a conversion equation for converting the values of a ^* and b ^* of each hue of cyan, magenta, yellow, red, green and blue will be described.

<Cyan>
L ^* a ^* b ^* a constituting a hue of cyan color system ^*, b ^* has a relation of equation (1).
b ^* = 1.505a ^* + 6.6189 (1)

The values of a ^* and b ^* of the hue of cyan specified in the color profile CP1 are converted to original data a1 and b1, and the values of a ^* and b ^* when converted to vivid cyan are modified data a2 and b2. The modification data a2 and b2 are expressed by the equations (2) and (3). Formulas (2) and (3) are formulas with the largest modification amount.

a2 = −0.0008 × a1 ³ + 0.0065 × a1 ² + 1.596 × a1 + 0.7609 (2)
b2 = −0.0004 × b1 ³ + 0.0077 × b1 ² + 1.5267 × b1−1.7158 (3)

When the values of a ^* and b ^* are converted by the equations (2) and (3), if the degree of change is too large, the original data a1 and b1 are corrected by the equations (4) and (5), the modified data a2, It may be converted to b2. Expressions (4) and (5) are expressions with the least amount of modification.

^{a2 = -0.0018 × a1 3 -0.0587 ×} a1 2 + 0.509 × a1-0.8142 ... (4)
b2 = −0.0007 × b1 ³ −0.0224 × b 1 ² + 0.9027 × b1 + 0.2427 (5)

The color conversion module 10 converts the value of a ^* of cyan within the range from equation (2) to the equation (4) and the value of b ^{* from} cyan within the range from equation (3) to equation (5). Good. The color conversion module 10 converts the values of a ^* and b ^* of cyan according to the modification amount adjustment signal supplied by operating the operation unit (not shown).

Assuming that the horizontal axis is -a ^* and the vertical axis is -b ^* , in the standard state where the color conversion module 10 does not convert cyan, cyan changes as shown in FIG. FIG. 4A shows the relationship between the original data a1 and the modification data a2 according to the equations (2) and (4), where the horizontal axis is the original data a1 and the vertical axis is the modification data a2. The color conversion module 10 changes the value of a ^* of cyan between the solid-line curve represented by equation (2) and the dashed-line curve represented by equation (4).

FIG. 4B shows the relationship between the original data b1 and the modification data b2 according to the equations (3) and (5), where the horizontal axis is the original data b1 and the vertical axis is the modification data b2. The color conversion module 10 changes the value of b ^* of cyan between the solid-line curve represented by the equation (3) and the dashed-line curve represented by the equation (5).

<Magenta>
L ^* a ^* b ^* a constituting the hue of magenta color system ^*, b ^* has a relation of equation (6).
b ^* =-0.2114a ^* + 3.964 (6)

The values of a ^* and b ^* of the magenta hue specified in the color profile CP1 are converted to original data a1 and b1, and the values of a ^* and b ^* when converted to vivid magenta are modified data a2 and b2. The modified data a2 and b2 are expressed by the equations (7) and (8). Formulas (7) and (8) are formulas with the largest modification amount.

a2 = −0.0006 × a1 ³ + 0.0257 × a1 ² +1. 0074 × a1 + 1.9869 (7)
^{b2 = 0.5015 × b1 4 -0.0698 ×} b1 3 -3.6577 × b1 2 -1.1779 × b1 + 1.1221 ... (8)

When the values of a ^* and b ^* are converted by the equations (7) and (8), if the degree of change is too large, the original data a1 and b1 are corrected by the equations (9) and (10). It may be converted to b2. Expressions (9) and (10) are expressions with the least amount of modification.

a2 = −0.0002 × a1 ³ + 0.0103 × a1 ² + 0.9148 × a1−0.6582 (9)
b2 = 0.1862 × b1 ⁴ −0.0994 × b 1 ³ −1.3049 × b 1 ² + 0.8372 × b 1 + 0.6 918 (10)

The color conversion module 10 converts the value of a ^* of magenta in the range from equation (7) to the equation (9) and the value of b ^* in magenta from the equation (8) to the equation (10). Good. The color conversion module 10 converts the values of a ^* and b ^* of magenta according to the modification amount adjustment signal.

Assuming that the horizontal axis is −a ^* and the vertical axis is −b ^* , in the standard state where the color conversion module 10 does not convert magenta, magenta changes as shown in FIG. FIG. 6A shows the relationship between the original data a1 and the modification data a2 according to the equations (7) and (9), where the horizontal axis is the original data a1 and the vertical axis is the modification data a2. The color conversion module 10 changes the value of a ^* of magenta between the solid-line curve represented by equation (7) and the dashed-line curve represented by equation (9).

FIG. 6B shows the relationship between the original data b1 and the modification data b2 according to the equations (8) and (10), where the horizontal axis is the original data b1 and the vertical axis is the modification data b2. The color conversion module 10 changes the value of b ^* of magenta between the solid-line curve represented by equation (8) and the dashed-line curve represented by equation (10).

<Yello>
L ^* a ^* b ^* a constituting a hue of yellow color systems ^*, b ^* has a relation of formula (11).
b ^* = − 8.9895a ^* + 1.3763 (11)

The values of a ^* and b ^* of the yellow hue specified in the color profile CP1 are converted to original data a1 and b1, and the values of a ^* and b ^* when converted to a bright yellow are assumed to be modification data a2 and b2. The modification data a2 and b2 are expressed by the equations (12) and (13). Formulas (12) and (13) are formulas with the largest modification amount.

^{a2 = -0.0741 × a1 3 -0.2281 ×} a1 2 + 1.5887 × a1-0.0597 ... (12)
b2 = 0.0002 × b1 ³ −0.0557 × b 1 ² + 3.8295 × b 1-19.174 (13)

When the values of a ^* and b ^* are converted in the equations (12) and (13), if the degree of change is too large, the original data a1 and b1 are corrected by the equations (14) and (15), the modified data a2, It may be converted to b2. Expressions (14) and (15) are expressions with the least amount of modification.

^{a2 = -0.169 × a1 3 -1.2732 ×} a1 2 -1.6351 × a1-1.6855 ... (14)
b2 = −0.0005 × b1 ³ + 0.0496 × b1 ² −0.1869 × b1 + 9.3544 (15)

The color conversion module 10 converts the yellow a ^* value in the range from equation (12) to the equation (14) and the yellow b ^* value in the range from equation (13) to the equation (15). Good. The color conversion module 10 converts the yellow a ^* and b ^* values according to the modification amount adjustment signal.

When the horizontal axis is −a ^* and the vertical axis is −b ^* , the yellow changes as shown in FIG. 7 in the standard state in which the color conversion module 10 does not convert the yellow. FIG. 8A shows the relationship between the original data a1 and the modification data a2 according to the equations (12) and (14), where the horizontal axis is the original data a1 and the vertical axis is the modification data a2. The color conversion module 10 changes the value of yellow a ^* between the solid-line curve represented by equation (12) and the dashed-line curve represented by equation (14).

FIG. 8B shows the relationship between the original data b1 and the modification data b2 according to the equations (13) and (15), where the horizontal axis is the original data b1 and the vertical axis is the modification data b2. The color conversion module 10 changes the value of yellow b ^* between the solid-line curve represented by equation (13) and the dashed-line curve represented by equation (15).

<Red>
L ^* a ^* b ^* a constituting the hue of red color system ^*, b ^* has a relation of formula (16).
b * = 0.8462a * + 8.8306 (16)

The values of a ^* and b ^* of the red hue specified in the color profile CP1 are converted to original data a1 and b1, and the values of a ^* and b ^* when converted to bright red are modified data a2 and b2. The modified data a2 and b2 are expressed by the equations (17) and (18). Formulas (17) and (18) are formulas with the largest modification amount.

^{a2 = 0.0003 × a1 3 -0.0393 ×} a1 2 + 2.3151 × a1 + 0.2089 ... (17)
b2 = −0.0005 × b 1 ³ + 0.0118 × b 1 ² + 1.3315 × b 1−0.2592 (18)

When the values of a ^* and b ^* are converted by the equations (17) and (18), if the degree of change is too large, the original data a1 and b1 are corrected by the equations (19) and (20). It may be converted to b2. Expressions (17) and (18) are expressions with the least amount of modification.

a2 = −0.0001 × a1 ³ + 0.0078 × a1 ² + 0.9417 × a1 + 0.7953 (19)
b2 = −0.0001 × b1 ³ + 0.0105 × b1 ² + 0.7565 × b1 + 1.5076 (20)

The color conversion module 10 converts the red a ^* value in the range from Expression (17) to the Expression (19) and the red b ^* value in the range from Expression (18) to Expression (20). Good. The color conversion module 10 converts the red a ^* and b ^* values in accordance with the modification amount adjustment signal.

When the horizontal axis is −a ^* and the vertical axis is −b ^* , red changes as shown in FIG. 9 in a standard state in which the color conversion module 10 does not convert red. FIG. 10A shows the relationship between the original data a1 and the modification data a2 according to the equations (17) and (19), where the horizontal axis is the original data a1 and the vertical axis is the modification data a2. The color conversion module 10 changes the value of a ^* of red between the solid-line curve represented by equation (17) and the dashed-line curve represented by equation (19).

FIG. 10B shows the relationship between the original data b1 and the modification data b2 according to the equations (18) and (20), where the horizontal axis is the original data b1 and the vertical axis is the modification data b2. The color conversion module 10 changes the red b ^* value between the solid curve represented by equation (18) and the dashed curve represented by equation (20).

<Green>
L ^* a ^* b ^* a constituting the hue of the color system of Green ^*, b ^* has a relation of formula (21).
b * =-0.3884 * a + 5.8639 (21)

The values of a ^* and b ^* of the green hue specified by the color profile CP1 are converted to the original data a1 and b1, and the values of a ^* and b ^* when converted to a vivid green are modified data a2 and b2. The modification data a2 and b2 are expressed by equations (22) and (23). Formulas (22) and (23) are formulas with the largest modification amount.

a2 = −0.0007 × a1 ³ −0.0337 × a 1 ² + 1.2237 × a 1−0.6896 (22)
^{b2 = 0.0154 × b1 3 -0.574 ×} b1 2 + 8.8314 × b1-32.365 ... (23)

When the values of a ^* and b ^* are converted by the equations (22) and (23), if the degree of change is too large, the original data a1 and b1 are corrected by the equations (24) and (25), the modified data a2, It may be converted to b2. Expressions (24) and (25) are expressions with the least amount of modification.

a2 = 0.00002 x a1 ³ + 0.0021 x a1 ² + 1.1512 x a1 + 0.5305 (24)
^{b2 = 0.0114 × b1 3 -0.4456 ×} b1 2 + 6.6982 × b1-22.866 ... (25)

The color conversion module 10 converts the value of a ^* of green within the range from equation (22) to the equation (24) and the value of b ^* of green within the range from equation (23) to equation (25). Good. The color conversion module 10 converts the green a ^* and b ^* values in accordance with the modification amount adjustment signal.

Assuming that the horizontal axis is -a ^* and the vertical axis is -b ^* , the green changes as shown in FIG. 11 in the standard state where the color conversion module 10 does not convert green. FIG. 12A shows the relationship between the original data a1 and the modification data a2 according to the equations (22) and (24), where the horizontal axis is the original data a1 and the vertical axis is the modification data a2. The color conversion module 10 changes the value of a ^* of green between the solid-line curve represented by equation (22) and the dashed-line curve represented by equation (24).

FIG. 12B shows the relationship between the original data b1 and the modification data b2 according to the equations (23) and (25), where the horizontal axis is the original data b1 and the vertical axis is the modification data b2. The color conversion module 10 changes the value of green b ^* between the solid-line curve represented by equation (23) and the dashed-line curve represented by equation (25).

<Blue>
L ^* a ^* b ^* a constituting the hue of blue color system ^*, b ^* has a relation of formula (26).
b ^* = − 0.6989 × a ^* -6.0183 (26)

The values of a ^* and b ^* of the blue hue specified in the color profile CP1 are converted to original data a1 and b1, and values ^* of a ^* and b when converted to bright blue are modified data a2 and b2. The modification data a2 and b2 are expressed by the equations (27) and (28). Formulas (27) and (28) are formulas with the largest modification amount.

a2 = 0.0021 × a1 ³ −0.0877 × a 1 ² + 1.9804 × a1 + 0.0338 (27)
b2 = -0.002 x b1 ³ + 0.0492 x b1 ² + 1.6385 x b1-2.9658 (28)

When the values of a ^* and b ^* are converted by the equations (27) and (28), if the degree of change is too large, the original data a1 and b1 are corrected by the equations (29) and (30), the modified data a2, It may be converted to b2. Expressions (29) and (30) are expressions with the least amount of modification.

^{a2 = -0.0005 × a1 3 -0.0022 ×} a1 2 + 1.0938 × a1 + 0.1172 ... (29)
^{b2 = -0.0006 × b1 3 -0.0151 ×} b1 2 + 1.0452 × b1-0.5404 ... (30)

The color conversion module 10 converts the value of a ^* of blue in the range from equation (27) to the equation (29) and the value of b ^* in blue from the equation (28) to the equation (30) Good. The color conversion module 10 converts the blue a ^* and b ^* values in accordance with the modification amount adjustment signal.

When the horizontal axis is −a ^* and the vertical axis is −b ^* , blue changes as shown in FIG. 13 in the standard state in which the color conversion module 10 does not convert blue. FIG. 14A shows the relationship between the original data a1 and the modification data a2 according to the equations (27) and (28), where the horizontal axis is the original data a1 and the vertical axis is the modification data a2. The color conversion module 10 changes the value of a ^* of blue between the solid curve indicated by equation (27) and the dashed curve indicated by equation (29).

FIG. 14B shows the relationship between the original data b1 and the modification data b2 according to the equations (28) and (30), where the horizontal axis is the original data b1 and the vertical axis is the modification data b2. The color conversion module 10 changes the value of b ^* of blue between the solid curve represented by equation (28) and the dashed curve represented by equation (30).

  The color of each hue other than cyan, magenta, yellow, red, green, and blue described above is converted by the conversion equation corresponding to each hue. By dividing the hues finely and setting a conversion equation for each hue, it is possible to convert to a vivid color in a state suitable for each hue. The number of divisions of hue (the number of conversion equations set) is arbitrary.

  Next, the effect when the chromatic color is converted as described above by the color conversion module 10 will be described. As shown in FIG. 15, the effect was verified with four step data of light, middle, shadow and solid for cyan, magenta, yellow, red, green, blue and gray respectively.

  Let C1, C2, C3 and C4 be light, middle, shadow and solid in cyan, respectively. Let M1, M2, M3 and M4 denote light, middle, shadow and solid in magenta, respectively. For yellow, light, middle, shadow, and solid are Y1, Y2, Y3 and Y4, respectively.

  Let light, middle, shadow and solid in red be R1, R2, R3 and R4, respectively. Let G1, G2, G3, and G4 be light, middle, shadow, and solid in green, respectively. Let B1, B2, B3 and B4 be light, middle, shadow and solid in blue, respectively.

  Let light, middle, shadow, and solid in gray be gr1, gr2, gr3, and gr4, respectively.

  In addition, the data of cyan, magenta, yellow, red, green, blue, and gray each have a slight amount of turbidity, for example, adding a slight amount of cyan to red to make the state similar to an actual photo document. Ingredients were added.

FIG. 16 shows data of light, middle, shadow and solid of cyan, magenta, yellow, red, green and blue in the color reproduction area 30 in the a ^* , b ^* plane before conversion by the color conversion module 10. And shows how it changes after conversion.

  In FIG. 16, ▲ indicates original data before conversion by the color conversion module 10, and ▪ indicates correction data after conversion by the color conversion module 10. The modified data shown in FIG. 16 is obtained by the color conversion module 10 converting data of cyan, magenta, yellow, red, green, and blue lights, middle, shadow, and solid using the above-described formula for the maximum amount of modification. It is data.

  Let C1 ', C2', C3 'and C4' be the correction data of C1, C2, C3 and C4. The modification data of M1, M2, M3 and M4 are M1 ', M2', M3 'and M4'. Let Y1 ', Y2', Y3 ', Y4' be the correction data of Y1, Y2, Y3, Y4. The modification data of R1, R2, R3 and R4 are R1 ', R2', R3 'and R4'. Let G1 ', G2', G3 ', G4' be the correction data of G1, G2, G3, G4. Let B1 ', B2', B3 'and B4' be the correction data of B1, B2, B3 and B4.

  The colors cyan, magenta, yellow, red, green and blue respectively become higher in saturation toward the outside in the color reproduction area 30 and become brighter. As can be seen by comparing the original data before conversion and the converted data after conversion, in the corrected data, the curve connecting the light to the solid is longer than that of the original data, and is converted to a vivid color .

The difference between the original data and the correction data is relatively small in the light data near the intersection of the a ^* axis and the b ^* axis, and the difference between the original data and the correction data is in the middle, shadow, and solid data. It has been converted relatively large.

  The relationship between the original data of cyan, magenta, and yellow and the correction data shown in FIG. 16 will be described again with reference to FIGS. 17 to 19 show only three points of light, middle and shadow. In FIGS. 17 to 19, the arrows indicate the directions in which the saturation increases.

  As shown in FIG. 17, C1 to C3 of cyan are corrected to C1 'to C3' in the direction in which the saturation becomes higher. As shown in FIG. 18, M1 to M3 of magenta are corrected to M1 'to M3' in the direction in which the saturation increases. As shown in FIG. 19, yellow Y1 to Y3 are corrected to Y1 'to Y3' in the direction in which the saturation becomes higher.

  The red, green and blue colors are not shown again, but they are corrected in the direction in which the saturation becomes higher, as with cyan, magenta and yellow.

On the other hand, gray light, middle, shadow and solid data are not converted by the color conversion module 10. Therefore, as indicated by ▲ in FIG. 20, gr1, gr2, gr3, and gr4 do not change in the a ^* and b ^* planes and remain as original data.

  In FIG. 20, as a comparative example, when the saturation of the color image shown in FIG. 15 is increased by Photoshop (registered trademark) which is image processing software provided by Adobe Systems, Inc., gray gr1 to gr4 are used. Shows how it changes. ● indicates the states of gray gr1 to gr4 which are comparative examples.

  In the comparative example, the hue of gray, which is originally achromatic, is shifted, giving it a tint. In the present embodiment, the gray hue does not shift and does not take on a tint.

Returning to FIG. 1, as described above, the modified RGB data in which only the a ^* and b ^* values of the chromatic color are converted by the color conversion module 10 is supplied to the printing color converter 20. The color conversion unit 20 for printing uses L ^* a ^* b ^* color system L ^* , a ^* , b ^* values and subtractive cyan, magenta, yellow, black, red or green which is one color to be added, or It has C, M, Y, K indicating the level of each color signal of blue, and a color profile CP2 indicating the correspondence with R, G or B values which are one color to be added. K may not be present.

The color conversion module 20 selects the L ^* , a ^* , b ^* values most approximate to the L ^* , a ^* , b ^* values in the retouched RGB data with reference to the color profile CP2 with reference to the color profile CP2. Do. Then, the printing color conversion unit 20 outputs C, M, Y, K corresponding to the selected L ^* , a ^* , b ^* values, and an R or G or B value which is one color to be added. K may not be present.

Since the achromatic L ^* , a ^* , b ^* values are supplied as they are to the printing color converter 20, the printing color converter 20 is the L that most approximates the achromatic L ^* , a ^* , b ^* values. ^*, a ^*, and select the b ^* value, the selected L ^*, a ^*, b ^* C corresponding to the value, M, Y, K, and outputs the R or G or B values is one color to be added . K may not be present.

  The printing color converter 20 converts all pixel data of the modified RGB data into C, M, Y, K values, and C, M, Y, K, R, G or B which is one color to be added. It is output as R or G or B data which is one color desired to be added to CMY for printing using ink. K may not be present.

In FIG. 1, (96, 0, 0) of L ^* , a ^* , b ^* values in color profile CP1 are (90, 0, -2) of L ^* , a ^* , b ^* values in color profile CP2. It is assumed that it is the closest. If the values of a ^* and b ^* are not converted by the color conversion module 10, (90, 0, -2) of the color profile CP2 is selected, and the C, M, Y and K values are (5, 3). , 3, 0) will be output. K may not be present.

However, L ^* in the color profile CP1, a ^*, b ^* values of (96, 0, 0) is supplied to a ^*, b ^* values are converted print color converter 20 by the color conversion module 10 Therefore, the other L ^* , a ^* , b ^* values of the color profile CP2 are selected, and the other C, M, Y, K values are output. K may not be present.

In FIG. 1, (0, 0, 0) of the L ^* , a ^* , b ^* values in the color profile CP1 are the most to (10, 0, 3) of the L ^* , a ^* , b ^* values in the color profile CP2. (100, 0, 0) of the L ^* , a ^* , b ^* values in the color profile CP1 are similar to (94, 0, -1) of the L ^* , a ^* , b ^* values in the color profile CP2. Suppose it approximates.

Since the achromatic L ^* , a ^* and b ^* values are supplied as they are to the printing color conversion unit 20, the printing color conversion unit 20 outputs (10, 0, 3), (94, 0, 0) of the color profile CP2. Select -1) and output (100, 100, 100, 100) and (0, 0, 0, 0) as C, M, Y, K values. K may not be present.

  The operation of the image processing apparatus of this embodiment shown in FIG. 1 and the image processing method of one embodiment will be described using the flowchart shown in FIG.

  In step S11, the color conversion module 10 determines whether the pixel data of the input RGB data is chromatic. If the color conversion module 10 is a chromatic color (YES), the process proceeds to step S12, and if it is not a chromatic color (NO), the process proceeds to step S14.

The color conversion module 10, at step S12, L ^* color profile CP1 corresponding to R, G, B values of the pixel data, a ^*, of b ^* value, a ^*, only the conversion value of b ^* To generate the modified RGB data. The color conversion module 10 converts the values of a ^* and b ^* so as to increase the saturation. At this time, it is preferable to use the above-mentioned conversion formula.

In step S13, the printing color conversion unit 20 selects, from the color profile CP2, L ^* , a ^* , b ^* values most approximate to the L ^* , a ^* , b ^* values of the modified RGB data.

In step S14, the color conversion unit 20 for printing uses color profiles for L ^* , a ^* , b ^* values that most approximate the L ^* , a ^* , b ^* values corresponding to the R, G, B values of pixel data. Select from CP2.

In step S15, the printing color conversion unit 20 selects C, M, Y, K corresponding to the L ^* , a ^* , b ^* value selected in step S13 or S14, R or G which is one color to be added. Or output B value as R or G or B data which is one color to be added to CMYK. The processes of steps S11 to S15 are performed on all pixel data constituting the input RGB data. K may not be present.

  The image processing program (computer program) may cause the computer to execute the processing shown in FIG.

  In FIG. 22, the computer 50 has a CPU 51 and a storage unit 52. The storage unit 52 stores an image processing program. The storage unit 52 is a ROM, a hard disk drive, or the like. The image processing program may be recorded on a recording medium such as an optical disk, and the recording medium may be reproduced by a reproduction device of the recording medium to read out the image processing program.

  RGB data is input to the CPU 51. The CPU 51 executes the processing of each step shown in FIG. 21 by the image processing program to generate R or G or B data which is one color desired to be added to CMYK. The R, G or B data, which is one color desired to be added to CMYK, is supplied to the printing device 60. The printing device 60 prints C, M, Y, K, R, G, or B data, which is one color desired to be added, onto the paper, using C, M, Y, K, one color R, G, or B ink that is desired to be added. K may not be present.

  The computer 50 may be a microcomputer or a personal computer. An image processing program may be provided to the computer 50 via a network.

  The printing apparatus 60 may be a home or office printer such as an inkjet printer, or may be a business-use printing machine. The printing device 60 may be an offset printing machine that prints a newspaper.

  As described above, according to the image processing apparatus, the image processing method, and the image processing program of the present embodiment, it is one color desired to be added to CMYK data to obtain a vivid print image of RGB data without changing achromatic color. It can be converted to R or G or B data. K may not be present. According to the image processing apparatus, the image processing method, and the image processing program of the present embodiment, it is possible to easily obtain a vivid print image without any experience or knowledge.

  The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the present invention. Use of hardware and software in the image processing apparatus is optional. The color conversion module 10 and the printing color conversion unit 20 may be individually configured by an integrated circuit, or the entire color conversion module 10 and the printing color conversion unit 20 may be configured by an integrated circuit. .

10 color conversion module 20 color conversion unit for printing 50 computer 51 CPU
52 storage unit 60 printing device CP1, CP2 color profile

Claims (9)

R, G, B values indicating the level of each color signal of additive red, green, and blue and a first relationship indicating the correspondence between L ^* a ^* b ^* L ^* , a ^* , b ^* values of the color system With reference to the color profile, among the RGB data, only the values of a ^* and b ^* in L ^* , a ^* and b ^* values corresponding to R, G and B values of chromatic color are converted in the direction to increase the saturation A color conversion module for generating modified RGB data with the L ^* , a ^* , b ^* values corresponding to the achromatic R, G, B values converted as they are without conversion;
L ^* a ^* b ^* C, M, Y, R or L indicating the level of L ^* , a ^* , b ^* values of color system and subtractive cyan, magenta, yellow, red or green or blue color signals An L that most approximates to L ^* , a ^* , b ^* values corresponding to respective R, G, B values in the modified RGB data with reference to a second color profile indicating a correspondence relationship with G or B values ^* , A ^* , b ^* values are selected from the second color profile, and C, M, Y, R or G or B values corresponding to the selected L ^* , a ^* , b ^* values are printed for printing A color converter for printing that outputs CMY and R or G or B data;
An image processing apparatus comprising: The values of a ^* and b ^* of L ^* , a ^* and b ^* values corresponding to R, G and B values of cyan hue in the first color profile are a1 and b1, respectively, and the color conversion module When the converted values of a ^* and b ^* are a2, b2,
The color conversion module
a2 is the first range from (−0.0008 × a 1 ³ + 0.0065 × a 1 ^{2 2} + 1.596 × a 1 +0.7 609) to (−0.0018 × a 1 ³ −0.0587 × a 1 ² +0.5 9 10 a 1−0.8142) So convert a1 to a2,
b2 is the second range of ^{(-0.0004 × b1 3 + 0.0077 ×} b1 2 + 1.5267 × b1-1.7158) from to ^{(-0.0007 × b1 3 -0.0224 × b1} 2 + 0.9027 × b1 + 0.2427) The image processing apparatus according to claim 1, wherein b1 is converted to b2. Let the values of a ^* and b ^* of L ^* , a ^* and b ^* values corresponding to R, G and B values of the magenta hue in the first color profile be a1 and b1, respectively, by the color conversion module When the converted values of a ^* and b ^* are a2, b2,
The color conversion module
and a first range from (−0.0006 × a1 ³ + 0.0257 × a1 ² + 1.0074 × a1 +1.9869) to (−0.0002 × a1 ³ + 0.0103 × a1 ² + 0.9148 × a1−0.6582) Convert a1 to a2 so that
b2 is ^{(+ 0.5015 × b1 4 -0.0698 ×} b1 3 -3.6577 × b1 2 -1.1779 × b1 + 1.1221) from ^{(+ 0.1862 × b1 4 -0.0994 ×} b1 3 -1.3049 × b1 2 + 0.8372 × b1 + 0. 2. The image processing apparatus according to claim 1, wherein b1 is converted to b2 so as to be a second range up to 6918). Let the values of a ^* and b ^* of L ^* , a ^* and b ^* values corresponding to R, G and B values of yellow hue in the first color profile be a1 and b1, respectively, by the color conversion module When the converted values of a ^* and b ^* are a2, b2,
The color conversion module
a2 is ^{(-0.0741 × a1 3 -0.2281 × a1} 2 + 1.5887 × a1-0.0597) from ^{(-0.169 × a1 3 -1.2732 × a1} 2 -1.6351 × a1-1.6855) such that the first range of up to , Convert a1 to a2,
b2 is ^{(+ 0.0002 × b1 3 -0.0557 ×} b1 2 + 3.8295 × b1-19.174) a second range of up to ^{(-0.0005 × b1 3 + 0.0496 ×} b1 2 -0.1869 × b1 + 9.3544) The image processing apparatus according to claim 1, wherein b1 is converted to b2. Let the values of a ^* and b ^* of L ^* , a ^* and b ^* values corresponding to R, G and B values of the red hue in the first color profile be a1 and b1, respectively, by the color conversion module When the converted values of a ^* and b ^* are a2, b2,
The color conversion module
a2 from ^{(+ 0.0003 × a1 3 -0.0393 ×} a1 2 + 2.3151 × a1 + 0.2089) and the first ranging ^{(-0.0001 × a1 3 + 0.0078 ×} a1 2 + 0.9417 × a1 + 0.7953) Convert a1 to a2 so that
b2 from ^{(-0.0005 × b1 3 + 0.0118 ×} b1 2 + 1.3315 × b1-0.2592) and second ranging ^{(-0.0001 × b1 3 + 0.0105 ×} b1 2 + 0.7565 × b1 + 1.5076) The image processing apparatus according to claim 1, wherein b1 is converted to b2 so as to be. Let the values of a ^* and b ^* of L ^* , a ^* and b ^* values corresponding to R, G and B values of the green hue in the first color profile be a1 and b1, respectively, by the color conversion module When the converted values of a ^* and b ^* are a2, b2,
The color conversion module
a2 from ^{(-0.0007 × a1 3 -0.0337 × a1} 2 + 1.2237 × a1-0.6896) and the first ranging ^{(+ 0.00002 × a1 3 + 0.0021} × a1 2 + 1.1512 × a1 + 0.5305) Convert a1 to a2 so that
b2 and a second range of up to ^{(+ 0.0154 × b1 3 -0.574 ×} b1 2 + 8.8314 × b1-32.365) from ^{(+ 0.0114 × b1 3 -0.4456 ×} b1 2 + 6.6982 × b1-22.866) The image processing apparatus according to claim 1, wherein b1 is converted to b2 so as to be. The values of a ^* and b ^* of L ^* , a ^* , b ^* values corresponding to R, G, B values of the blue hue in the first color profile are a1, b1, and the color conversion module When the converted values of a ^* and b ^* are a2, b2,
The color conversion module
a2 becomes ^{(+ 0.0021 × a1 3 -0.0877 ×} a1 2 + 1.9804 × a1 + 0.0338) a first range from to ^{(-0.0005 × a1 3 -0.0022 × a1} 2 + 1.0938 × a1 + 0.1172) So convert a1 to a2,
b2 is a ^second range from (−0.002 × b 1 ³ + 0.0492 × b 1 ^{2 2} + 1.6385 × b ¹⁻² + 9.658) to (−0.0006 × b 1 ³ −0.0151 × b 1 ² + 1.0452 × b 1−0.5404) The image processing apparatus according to claim 1, wherein b1 is converted to b2. R, G, B values indicating the level of each color signal of additive red, green, and blue and a first relationship indicating the correspondence between L ^* a ^* b ^* L ^* , a ^* , b ^* values of the color system Referring to the color profiles, chromatic R, G, corresponding to the B value L ^*, a ^*, b ^* in the value a ^*, and converts the value of b ^* only in a direction to raise the color saturation, achromatic The modified RGB data is generated without converting the L ^* , a ^* , b ^* values corresponding to the R, G, B values without conversion.
L ^* a ^* b ^* Color system L ^* , a ^* , b ^* and subtractive colors C, M, Y, R or C indicating the level of cyan, magenta, yellow, red or green or blue color signals An L that most approximates to L ^* , a ^* , b ^* values corresponding to respective R, G, B values in the modified RGB data with reference to a second color profile indicating a correspondence relationship with G or B values ^* , A ^* , b ^* values are selected from the second color profile,
Outputting the C, M, Y, R or G or B value corresponding to the selected L ^* , a ^* , b ^* value in the second color profile as CMY and R or G or B data for printing An image processing method characterized by On the computer
R, G, B values indicating the level of each color signal of additive red, green, and blue and a first relationship indicating the correspondence between L ^* a ^* b ^* L ^* , a ^* , b ^* values of the color system Referring to the color profiles, chromatic R, G, corresponding to the B value L ^*, a ^*, b ^* in the value a ^*, and converts the value of b ^* only in a direction to raise the color saturation, achromatic Generating the modified RGB data as the values without converting the L ^* , a ^* , b ^* values corresponding to the R, G, B values;
L ^* a ^* b ^* Color system L ^* , a ^* , b ^* and subtractive colors C, M, Y, R or C indicating the level of cyan, magenta, yellow, red or green or blue color signals An L that most approximates to L ^* , a ^* , b ^* values corresponding to respective R, G, B values in the modified RGB data with reference to a second color profile indicating a correspondence relationship with G or B values Selecting the ^* , a ^* , b ^* values from the second color profile;
Outputting the C, M, Y, R or G or B value corresponding to the selected L ^* , a ^* , b ^* value in the second color profile as CMY and R or G or B data for printing When,
An image processing program characterized by executing