JP2008067262A - Color separation parameter creation method, image processing method, image processing device, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a parameter with superior graininess for color separation from a C<SB>0</SB>M<SB>0</SB>Y<SB>0</SB>signal to a CMYK signal. <P>SOLUTION: The method comprises: a starting point setting step (step1-step4) for determining a starting point of a black ink signal on colorless line for every line and a starting point of a black ink signal on two or more hue lines from two or more different hue lines to a black color for every line; and a color separation parameter creation step (step5) for creating a color separation parameter based on the determined starting point are provided. As for the starting point setting step, the starting point is determined in consideration of graininess at the time of image generation of the color on the colorless line (step1, 2), and each starting point on two or more hue lines is determined (step3, 4) in consideration of the graininess at the time of image generation of the color of a hue region, to which each of two or more hue lines belongs. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a color separation process for separating a three-color image signal into four or more output color signals for forming a color image on a recording medium, and more particularly to a technique for creating a color separation parameter in the color separation process. . The present invention can be suitably applied to devices such as color facsimiles, color printers, color copiers, and software for color printers operating on a computer.

  In image processing apparatuses such as color printers and color copying machines, image output is often performed using four color materials of cyan (C), magenta (M), yellow (Y), and black (K). In this case, it is necessary for the image processing apparatus to perform color conversion on the input color image data into CMYK four-color output color signals.

  Input color image data is generally represented by RGB signals of red (R), green (G), and blue (B). Color conversion of RGB color signals to CMYK output color signals is performed as follows. Done.

As a first stage, a process of converting the RGB color signal into a C ₀ M ₀ Y ₀ signal not including the black signal is performed. This conversion can be performed by interpolation calculation using a color conversion table, linear masking calculation, or the like.

As a second stage, black generation processing for generating a black signal from the C ₀ M ₀ Y ₀ signal is performed, and an achromatic component (under color) corresponding to the generated black signal is removed from the C ₀ M ₀ Y ₀ signal. Under color removal processing is performed. By replacing the achromatic component of C ₀ M ₀ Y ₀ with a K color material, effects such as saving of the color material and improving the stability of the achromatic color can be obtained.

Here, the black generation process and the under color removal process are collectively referred to as “black process”. In the conventional black ink processing, for example, a minimum value min (C ₀ , M ₀ , Y ₀ ) is calculated as a lower color component from C ₀ M ₀ Y ₀ and processed based on the following equation. However, αK, α, and β are predetermined coefficients.
K = αK × {min (C ₀ , M ₀ , Y ₀ ) −β}
UCR = α × {min (C ₀ , M ₀ , Y ₀ ) −β}
C = C ₀ -UCR
M = M ₀ -UCR
Y ₌ Y 0 -UCR formula (1).

FIG. 6 shows a graph of CMYK values in the line of C ₀ = M ₀ = Y ₀ . β indicates a point at which black signal generation starts (black start point). In FIG. 6, 85 (min. C ₀ , M ₀ , Y ₀ ), which is one third of the maximum value 255 of C ₀ , M ₀ , Y ₀ , is set as the black start point. In general, dots of K color material are more noticeable than CMY. Therefore, when the black start point β is set on the highlight side, graininess may be noticeable in the output image, resulting in a rough image. Therefore, in order to prevent roughness, it is necessary to set a black start point so that black is not generated on the highlight side.

In addition, as a black ink processing method with a higher degree of freedom, there is a method capable of setting a black ink starting point for each hue region (see, for example, Patent Documents 1 and 2). In this method, for example, a point in the C ₀ M ₀ Y ₀ space is represented by a point W (0, 0, 0), a point Y (0, 0, 255), a point M (0, 255, 0), a point R ( 0, 255, 255), point C (255, 0, 0), point G (255, 0, 255), point B (255, 255, 0), and point K (255, 255, 255). However, WYMRCGBK represents white, yellow, magenta, red, cyan, green, blue, and black, respectively. Ink start points are individually set for a total of seven lines: an achromatic color line W-K and shadow lines C-K, M-K, Y-K, RK, G-K, and B-K for each hue.

  FIG. 7A shows the line setting. For an arbitrary input value, black generation and under color removal processing are performed by performing interpolation calculation from the set values of the black start points of these seven lines.

  The method for determining the black start point on each line is generally determined in consideration of graininess and roughness as in the case of the simple black processing method described above. In Patent Document 1, an image that changes from a primary color and a secondary color to black is output and determined experimentally while checking the image quality. Patent Document 2 states that “in the output image caused by K ink dots at the start of K ink input, pay attention to the graininess in the output image, and this graininess cannot be visually discriminated. The maximum complementary color ink amount (maximum gray component ink amount) is defined in advance ”. That is, conventionally, the black start point is determined in consideration of the graininess when the color on the line is output as an image.

  Also, in printers using dark and light color materials of the same color, highlights are reproduced using only light color materials, and dark colors are used in shadows, so it is necessary to determine the starting point of dark color materials. Come out. Patent Document 3 describes a method of setting the start point of a dark color material in a plurality of control lines.

JP 2001-353888 A Japanese Patent No. 3658286 JP 2002-33927 A JP 2002-33930 A

  However, since the method for setting the black start point described above only considers the graininess on the control line and cannot take into account the graininess between the lines, Graininess may be deteriorated. This will be described below.

  It is assumed that the black start point and the black generation amount are set on the seven control lines in FIG. The black generation amount for an arbitrary input value is obtained by performing an interpolation operation using the black generation amounts on the seven lines.

FIG. 8 shows a triangle WCK in the C ₀ M ₀ Y ₀ space. It is assumed that the black start point and the black generation amount are set in the KK and CK lines that are control lines. The black generation amount for an arbitrary point on the triangle WCK is obtained by interpolation from the black generation amounts on the two lines. Here, the black generation amount between the line and determined by linear interpolation of the C ₀ axial position of the black start points between lines is as shown in the curve in FIG. Assuming that an intermediate point between the point W and the point C is a point Ch, the black start point on the Ch-K line depends on the black start point setting of the two lines of the W-K line and the CK line. That is, the graininess on the Ch-K line depends on the black start point setting of the W-K line and the C-K line. Conventionally, however, the black start point is set so that the graininess on each line does not deteriorate. Therefore, even if it is guaranteed that the graininess on the CK line and the KK line is good, there is no guarantee that the graininess is necessarily good in the area between the control lines such as the Ch-K line. There is no problem. This problem is the same when the start point of the dark color material is determined in the system using the dark color material.

  The present invention has been made in view of the above problems, and its main object is to determine the black start point of each control line in consideration of the granularity of not only the control line but also the entire color space, and the black processing parameters. In addition, even when using dark color materials with similar colors, considering the graininess of the entire color space, not just the control lines, the starting point of the dark color material for each control line It is to provide a method for determining color separation parameters.

The invention according to claim 1 is a method for creating a color separation parameter in color separation processing for separating an input color signal composed of three color components into four or more output color signals including a black signal,
In the space of the input color signal, the start point of the black signal on the achromatic color line and the start point of the black signal on the plurality of hue lines from a plurality of colors having different hues are determined for each line. A starting point setting step,
A color separation parameter creation step for creating the color separation parameter based on the start point determined in the start point setting step,
The starting point determination step includes
A first step of determining the starting point on the achromatic color line in consideration of graininess when the color on the achromatic color line is output;
A second step of respectively determining the start points on the plurality of hue lines in consideration of graininess when the colors of the hue regions to which the plurality of hue lines belong are output;
A color separation parameter creation method characterized by comprising:

According to a second aspect of the present invention, an input color signal composed of three color components is separated into four or more output color signals including dark color signals and light color signals indicating color materials having the same color and different densities. A method for creating color separation parameters in processing,
In the space of the input color signal, the start point of the dark color signal on an achromatic color line and the start point of the dark color signal on a plurality of hue lines from a plurality of colors having different hues to black, A starting point setting step determined for each line;
A color separation parameter creation step for creating the color separation parameter based on the start point determined in the start point setting step,
The starting point determination step includes
A first step of determining the starting point on the achromatic color line in consideration of graininess when the color on the achromatic color line is output;
A second step of determining the start points on the plurality of hue lines in consideration of graininess when the colors of the hue regions to which the plurality of hue lines belong are output as images. This is a color separation parameter creation method.

  According to a third aspect of the present invention, in the color separation parameter creation method according to the first or second aspect of the present invention, the hue line from the plurality of colors having different hues to black has a primary color and a secondary color to black. It is characterized by including a line.

  According to a fourth aspect of the present invention, in the color separation parameter creating method according to the third aspect of the invention, the second step is performed when an image of a color of a planar region sandwiched between the hue line and the achromatic color line is output. The starting point is determined in consideration of graininess.

  According to a fifth aspect of the present invention, in the color separation parameter creating method according to the third aspect of the invention, the second step is a step of outputting a color on a hue plane including a hue line and an achromatic color line as an image. The start point is set in consideration of the characteristics.

  According to a sixth aspect of the present invention, in the color separation parameter creation method according to the fourth or fifth aspect of the present invention, in the start point determination step, a plurality of different start point settings are made for a color image to be considered for graininess. And outputting the image and evaluating the graininess.

According to the seventh aspect of the present invention, an input color signal composed of three color components is separated into a black signal or an output color signal of four or more colors including a dark color signal indicating a color material having the same system color and different density and a light color signal. An image processing method including a color separation processing step for performing color separation processing.
The color separation processing step performs the color separation processing using the color separation parameter created by the color separation parameter creation method according to any one of claims 1 to 6. It is a processing method.

  The invention according to claim 8 is a computer-readable recording medium in which a program for causing a computer to execute the start point setting step and the color separation parameter creation step of the color separation parameter creation method according to the invention of claim 1 is recorded. is there.

  The invention according to claim 9 is a computer-readable recording medium in which a program for causing a computer to execute the start point setting step and the color separation parameter creation step of the color separation parameter creation method according to claim 2 is recorded. is there.

  According to the tenth aspect of the present invention, an input color signal composed of three color components is separated into a black signal or an output color signal of four or more colors including a dark color signal indicating a different color material of the same color and a light color signal and a light color signal. A program for causing a computer to execute a color separation process performed using the color separation parameter created by the color separation parameter creation method according to any one of claims 1 to 6 is recorded. The computer-readable recording medium.

According to the eleventh aspect of the present invention, an input color signal composed of three color components is separated into a black signal or an output color signal of four or more colors including a dark color signal indicating a different color material of the same color and a light color signal and a light color signal. An image processing apparatus including color separation processing means for performing color separation processing.
7. The image processing apparatus according to claim 1, wherein the color separation processing unit performs the color separation processing using a color separation parameter created by the color separation parameter creation method according to any one of claims 1 to 6. is there.

  In the color separation parameter creation method according to the first aspect of the present invention, when setting the starting point of the black signal of the hue line, not only the hue line but also the granularity when the color of the hue region is output as an image is obtained. By setting the start point in consideration, it is possible to set the start point of the black signal with better granularity.

  In the color separation parameter creation method according to the second aspect of the present invention, when setting the starting point of the dark line color signal of the hue line, not only the hue line but also the granularity when the color of the hue region is output as an image By setting the start point in consideration of the above, it is possible to set the start point of a dark color signal with better granularity.

  In the color separation parameter creation method according to the invention described in claim 3, the start point is appropriately made different for each hue by using a line from the primary color and the secondary color to black as a line for setting the start point. Can do.

  In the color separation parameter creating method according to the fourth aspect of the invention, when setting the starting point of the hue line, in addition to the image on the hue line, an intermediate line set between the hue line and the achromatic color line By taking into account the graininess when an image is output as an image, it is possible to set a starting point in which the graininess does not deteriorate in the region between the hue line and the achromatic line.

  In the color separation parameter creating method according to the invention described in claim 5, when setting the starting point of the hue line, the graininess when the color of the planar region sandwiched between the hue line and the achromatic line is output as an image. By taking into consideration, it is possible to set the starting point without causing the graininess to deteriorate in the region between the hue line and the achromatic line.

  In the color separation parameter creation method according to the invention of claim 6, when setting the starting point of the hue line, for the color to be considered, by actually outputting and evaluating the image by setting a plurality of starting points, It is possible to more reliably evaluate the granularity and set the starting point.

  In the image processing method or apparatus according to the seventh or eleventh aspect of the invention, the color processing is performed using the color separation parameter created by the color separation parameter creation method according to any one of the first to sixth aspects. By performing the separation process, color separation with good graininess can be performed.

  According to the recording medium of the eighth, ninth, or tenth aspect of the present invention, the program recorded on the recording medium is read by a computer and executed, thereby creating a color separation parameter or color separation processing that does not deteriorate the granularity. be able to.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Example 1]
In the present embodiment, the contents of image processing will be described using a color printer as an example. The color printer receives RGB signals created by a PC (personal computer) application, etc., converts them into CMYK signals, and outputs them. Generally, the processing flow is as shown in FIG.

Please refer to FIG. First, the color converter 1 converts the input RGB signal into a C ₀ M ₀ Y ₀ signal depending on the printer. Next, the black processing means 2 converts the C ₀ M ₀ Y ₀ signal into a CMYK signal. The converted CMYK signals are sequentially processed by the gamma converting unit 3, the total amount regulating unit 4, and the halftone processing unit 5, and finally output to a medium such as paper by the printer engine. The gamma conversion means 3 performs processing for adjusting gray balance, gradation, etc. by one-dimensional table conversion. The total amount regulating means 4 performs processing for keeping the total amount of CMYK color materials within the total amount that can be output by the printer engine. The halftone processing means 5 converts CMYK values having multi-level gradations into an area modulation format using a small number of gradations that can be reproduced by the printer engine.

  The present invention provides a method for setting parameters used in the black processing means 2. As the black processing means 2, for example, the methods described in Patent Documents 1 and 2 can be used. In these methods, the black ink processing parameters are created based on the black ink starting points set in a plurality of control lines including the achromatic color line. However, any black ink processing using the black ink processing parameters created in such a procedure is used. The means can be used as the black processing means 2.

Here, the output CMYK values on 17 × 17 × 17 grid points obtained by dividing the C ₀ M ₀ Y ₀ space into 16 are used as black processing parameters, and the black processing means 2 performs an interpolation operation using the black processing parameters. As a result, the output CMYK value is calculated.

  In addition, as a method of creating black ink (color separation) parameters, an achromatic color line and a line from the primary and secondary color points to the black point (hereinafter referred to as hue shadow lines) are set as seven control lines. First, an output CMYK value on the control line is determined based on the black start point set in the line. The line setting is as shown in FIG. The output CMYK value on the line can be obtained using the equation (1). However, the black start point is set for each line, and αK and α are appropriately determined according to the black start point so that CMYK at the common end point K of each line takes the same value.

Next, the output CMYK values on 17 × 17 × 17 lattice points are obtained by performing an interpolation operation based on the output CMYK values on the control line. As this method, for example, the method described in Patent Document 4 can be used. In this method, as shown in FIG. 7B, the C ₀ M ₀ Y ₀ space is divided into six tetrahedrons having W-K lines as common sides, and according to the tetrahedron to which the lattice points belong. Thus, control lines used for interpolation are made different. Since each of the six tetrahedrons includes three control lines as shown in FIG. 7B, an output CMYK value at an arbitrary grid point is obtained by performing an interpolation operation using CMYK on the three lines. Can be sought.

  Hereinafter, a method for appropriately setting the black ink starting point using a plurality of control lines, which is a feature of the present invention, will be described. FIG. 1 shows a flowchart of color separation parameter creation processing. Steps 1 to 4 are procedures for setting the black start point, and step 5 is a step of creating color separation parameters that do not deteriorate the graininess based on the black start point setting determined in steps 1 to 4.

First, in order to determine the black start point on the achromatic color line, an image of the achromatic color line with the black start point set is output (step 1). FIG. 3 shows an example of image data. An image set with C ₀ M ₀ Y ₀ value is converted into CMYK with a setting with a black start point and output. As described above, the output CMYK value on the control line can be obtained using the equation (1). For example, the black start point is converted into CMYK with settings set in nine stages such as β = 0, 16, 32, 48, 64, 80, 96, 112, 128, and output.

  Next, in consideration of the granularity of the output image, the black start point of the achromatic line is determined (step 2). Since the output images have different black start points, generally, the smaller the black start point value, the more often the graininess deteriorates due to the black ink. Therefore, the graininess is not deteriorated and a good one is selected. However, if the value of the ink starting point increases to some extent, the difference in graininess may not be felt.In that case, in consideration of the merits that are inherently made by adding ink, that is, the saving of color material usage, etc. The one with the smallest black starting point value is selected as long as the graininess does not deteriorate.

  Next, in order to determine the ink start point for each hue shadow line, the image of the hue shadow line and the image of the intermediate line between the hue shadow line and the achromatic color line are output with the black ink start point set. (Step 3). FIG. 4 shows image data output to determine the black start point of the C hue shadow line (C-K line). This image data is converted into CMYK with the black start point set in nine stages such as β = 0, 16, 32, 48, 64, 80, 96, 112, 128 and output.

  Next, in consideration of the granularity of the output image of the hue shadow line and the intermediate line, the black start point in each hue shadow line is determined (step 4). The determination method is that the hue shadow line and the intermediate line must be free of graininess due to black ink, and the one with the smallest ink start point value within the range where graininess does not deteriorate. The method of selection can be taken.

  In this way, by outputting the image of the intermediate line in addition to the control line, not only the graininess on the control line but also the graininess on the intermediate line can be taken into consideration, and parameter setting with better graininess can be made. It becomes possible.

  Here, the intermediate line is a line from the intermediate point between the primary and secondary color points and the white point to the black point. However, the intermediate line is not limited to this, and may be a line positioned between the hue shadow line and the achromatic color line. Any line may be used. It is also possible to define an intermediate line instead of a hue shadow line as a black start point control line.

  The “start point setting step” in the claims corresponds to steps 1 to 4, the “first step” corresponds to steps 1 and 2, and the “second step” corresponds to steps 3 and 4.

[Example 2]
In the first embodiment, the ink start point in the hue shadow line is determined by outputting and evaluating the images of the hue shadow line and the intermediate line.

  In Example 2 described here, an image used for evaluation of graininess is different from that in Example 1. Specifically, a gradation image of a planar area sandwiched between the hue shadow line and the achromatic color line is output. In this way, the black starting point can be determined in consideration of a wider range of graininess.

  FIG. 5A shows input data for creating an output image with a black start point, and FIG. 5B shows the image. In the patch image of FIG. 5 (b), a diagonal patch image from the upper right to the lower left is set as an achromatic color line. In addition, a gradation image of a planar area sandwiched between the R hue shadow line and the achromatic color line is arranged. Similarly, M and G and Y and B can be output as a set of images.

  As a method for determining the black ink starting point on the hue shadow line, the gradation image of the planar area sandwiched between the respective hue shadow lines and the achromatic color line is compared with those having different black ink starting point settings. 1 can be determined from the same evaluation viewpoint.

[Example 3]
In the first and second embodiments, the method for determining the black start points of a plurality of control lines necessary for creating the black processing parameters has been described. In the case of a printer or the like using a plurality of color materials having different densities for image output, the present invention can also be applied to a method for determining the start point of a dark color material signal.

For example, instead of the black processing means, there may be a color separation means for separating the C ₀ M ₀ Y ₀ signal into 6 colors of CMYKLcLm. That is, with respect to the cyan color material and the magenta color material, dark and light color materials are used, dark cyan is represented as C, light cyan is represented as Lc, dark magenta is represented as M, and light magenta is represented as Lm. In this case, in order to improve the graininess of cyan or magenta single color, the color reproduction is performed using only the light color material in the highlight, while the dark color is reproduced by adding the dark color material in the shadow. Therefore, it is necessary to set the start point of the dark color material signal in the region from the highlight to the shadow. For example, in Patent Document 3, dark color material start points are set on a plurality of control lines in a system using dark and light color materials. In this case as well, by outputting not only the image of the control line but also the image between the control lines, it is possible to set the starting point of the dark color material without deteriorating the graininess.

  That is, color separation parameters in color separation processing for separating an input color signal composed of three color components into four or more output color signals including a dark color signal and a light color signal indicating color materials having the same system color and different densities. When creating, in the space of the input color signal, the start point of the dark color signal on an achromatic color line, and the dark color signal on a plurality of hue lines from a plurality of colors having different hues to black Is determined for each line (start point setting step), and the color separation parameter is created based on the determined start point (color separation parameter creation step). In the start point determining step, the start point on the achromatic color line is determined in consideration of the graininess when the color on the achromatic color line is output (first step), The start points on the plurality of hue lines are determined in consideration of the graininess when the color of the hue region to which each hue line belongs is output (second step).

[Other embodiments]
The first to third embodiments are examples of the method for creating the black processing parameter or the color separation parameter. However, the black processing or color separation processing is performed using the black processing parameter or the color separation parameter created by such a method. An image processing method including a processing step for performing black ink processing, and an image processing apparatus provided with means for performing black ink processing or color separation processing using the black ink processing parameters or color separation parameters created by such a method are also included in the present invention. . One embodiment of such an image processing method or image processing apparatus can be configured as shown in FIG.

  Further, a program for causing a computer to execute the procedure of the method for creating the black processing parameter or the color separation parameter of the present invention described in connection with the first to third embodiments, and the color separation parameter created by such a procedure. Also included in the present invention is a program that causes a computer to execute a color separation process using. This program may operate independently, or may implement the procedure of the method of the present invention in cooperation with an operating system, a device driver, other application programs, or the like. Various recording (storage) media that can be read by a computer, such as a magnetic disk, a magnetic tape, an optical disk, a magneto-optical disk, a nonvolatile memory card, and a ROM, on which such a program is recorded are also included in the present invention.

It is a flowchart for demonstrating embodiment of this invention. 1 is a block diagram of an image processing apparatus to which the present invention can be applied. An example of the image data output for determining the black start point on the achromatic line is shown. The example of the image data output in order to determine the black start point on a C phase shadow line and the black start point on the intermediate line of a C phase shadow line and an achromatic line is shown. An example of an image and data for creating the image for graininess evaluation is shown. Indicates CMYK on the line C ₀ = M ₀ = Y ₀ . C ₀ M ₀ Y ₀ space, tetrahedral divided it is a diagram for explaining the control line. It is a figure for demonstrating the problem of the conventional black starting point setting method.

Explanation of symbols

1 color conversion means 2 black processing means (color separation processing means)
3 Gamma correction means 4 Total amount regulating means 5 Halftone processing means

Claims (11)

A method for creating a color separation parameter in color separation processing for separating an input color signal composed of three color components into four or more output color signals including a black signal,
In the space of the input color signal, the start point of the black signal on the achromatic color line and the start point of the black signal on the plurality of hue lines from a plurality of colors having different hues are determined for each line. A starting point setting step,
A color separation parameter creation step for creating the color separation parameter based on the start point determined in the start point setting step,
The starting point determination step includes
A first step of determining the starting point on the achromatic color line in consideration of graininess when the color on the achromatic color line is output;
A second step of respectively determining the start points on the plurality of hue lines in consideration of graininess when the colors of the hue regions to which the plurality of hue lines belong are output;
A method for creating a color separation parameter, comprising: Create color separation parameters in color separation processing for separating an input color signal composed of three color components into four or more output color signals including dark color signals and light color signals indicating color materials having the same color and different densities. A method,
In the space of the input color signal, the start point of the dark color signal on an achromatic color line and the start point of the dark color signal on a plurality of hue lines from a plurality of colors having different hues to black, A starting point setting step determined for each line;
A color separation parameter creation step for creating the color separation parameter based on the start point determined in the start point setting step,
The starting point determination step includes
A first step of determining the starting point on the achromatic color line in consideration of graininess when the color on the achromatic color line is output;
A second step of determining the start points on the plurality of hue lines in consideration of graininess when the colors of the hue regions to which the plurality of hue lines belong are output as images. Color separation parameter creation method.   The color separation parameter creation method according to claim 1, wherein the hue line from a plurality of colors having different hues to black includes a line from a primary color and a secondary color to black.   4. The color according to claim 3, wherein the second step determines the start point in consideration of graininess when a color of a planar region sandwiched between a hue line and an achromatic color line is output as an image. Decomposition parameter creation method.   4. The color separation according to claim 3, wherein the second step sets the start point in consideration of graininess when a color on a hue plane including a hue line and an achromatic color line is output. 5. Parameter creation method.   6. The color separation according to claim 4 or 5, wherein in the start point determination step, an image of a color to be considered for graininess is output by a plurality of different start point settings, and the graininess is evaluated. Parameter creation method. Color separation that performs color separation processing to separate an input color signal composed of three color components into a black signal or an output color signal of four or more colors including a light color signal and a dark color signal indicating a color material of the same color and different density An image processing method including processing steps,
The image processing method according to claim 1, wherein the color separation processing step performs the color separation processing using a color separation parameter created by the color separation parameter creation method according to claim 1.   A computer-readable recording medium in which a program for causing a computer to execute the start point setting step and the color separation parameter creation step of the color separation parameter creation method according to claim 1 is recorded.   A computer-readable recording medium in which a program for causing a computer to execute the start point setting step and the color separation parameter creation step of the color separation parameter creation method according to claim 2 is recorded.   A color separation process for separating an input color signal composed of three color components into a black signal or an output color signal of at least four colors including a light color signal and a dark color signal indicating a color material having a different density in the same system color. A computer-readable recording medium on which a program for causing a computer to execute a color separation processing step performed using the color separation parameter created by the color separation parameter creation method according to any one of 1 to 6 is recorded. Color separation that performs color separation processing to separate an input color signal composed of three color components into a black signal or an output color signal of four or more colors including a light color signal and a dark color signal indicating a color material of the same color and different density An image processing apparatus comprising processing means,
The image processing apparatus according to claim 1, wherein the color separation processing unit performs the color separation processing using a color separation parameter created by the color separation parameter creation method according to claim 1.

Images