JP4818147B2 - Image processing apparatus, image processing method, and program - Google Patents

Description

  The present invention relates to a color processing apparatus that performs color processing for forming a monochrome image using an image forming apparatus, and a control method therefor.

  2. Related Art Inkjet printers (hereinafter referred to as “color printers”) that are capable of printing a color image and equipped with a plurality of inks are known. In recent years, there has been an increasing demand for printing monochrome images using such a color printer. Since monochrome images do not have hue information, smoother gradation reproducibility is required than color images.

  Further, when printing a monochrome image, there may be a phenomenon in which the color tone changes suddenly (hereinafter referred to as “color shift”) in a gradual gradation change. The sensitivity with which a human recognizes a color difference is very sensitive near an achromatic color, and a slight difference in color tone can be easily recognized. Therefore, a monochrome image viewer can recognize the color shift even with a slight color shift. Therefore, the color shift is a major factor that deteriorates the image quality of the monochrome image.

  In recent years, various techniques have been proposed for suppressing the occurrence of color shift when printing a monochrome image. For example, when printing a monochrome image, the amount of achromatic ink is dominantly increased in each combination of ink colors of each gradation, and the amount of chromatic color ink used for fine tone adjustment is reduced. There is a known method (see Patent Document 1). According to Patent Document 1, even if there are individual differences among color printers or changes in the amount of ink discharged from the printer head due to changes over time, changes in color tone can be suppressed. In addition, as shown in FIG. 1, the output value (density signal) of each ink from highlight (maximum luminance signal) to shadow (minimum luminance signal) is monotonously increased, thereby reducing the cause of color shift. is doing.

By the way, the color tone of a monochrome image has various color tones such as a cool black tone, a warm black tone, a pure black tone, and a sepia tone. Each color tone (cold black tone, warm black tone, pure black tone, sepia tone) has no clear definition, but various color tones (for example, cold black tone with strong bluish color and , Etc.). The preference of the color tone of the monochrome image varies depending on the person. Therefore, it is desired that a delicate color tone can be freely controlled in printing a monochrome image by a color printer. Recently, printer drivers for color printers are often provided with a function for adjusting the color tone of a monochrome image (see Patent Document 2).
JP 2005-238835 A JP 2002-331893 A

  However, since the technique of Patent Document 1 uses a small amount of chromatic color ink, it is difficult to express various color tones when printing a monochrome image. Moreover, with the technique of patent document 2, a color shift cannot be suppressed effectively.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for suppressing the occurrence of color shift while allowing a user to flexibly set the color tone of a monochrome image.

In order to solve the above-described problem, the first aspect of the present invention is an image processing for forming a monochrome image using an image forming apparatus including an achromatic color material and at least three chromatic color materials. an apparatus, comprising: a plurality of color patches formed on the recording medium by using the image forming apparatus, a color material of the achromatic, two colors and the color material of the color material of the chromatic color, a plurality of It was formed by a combination of, the colorimetric values obtained by measuring a plurality of color patches with a color of the surrounding gray line, a color value that indicates white, a storage unit that stores a color value indicating the black, the image forming Based on acquisition means for acquiring a chromaticity indicating a color tone of a monochrome image to be formed on the apparatus, a color value indicating the white color, a color value indicating the black color, and one or more color values indicating the chromaticity , determine the shown to line the relationship between brightness and chromaticity in the black and white tone image Determining means for, with the colorimetric values of the previous SL plurality of combinations each color patch stored in the storage unit, based on the determined line by the determination means, two colors used to form a monochrome tone image the chromatic color selection means for selecting a color material, color measurement before Symbol color patches formed with a color material of the chromatic color two colors selected and the achromatic color material by selecting means comprising a value based on the determined line by the determination means, a creation means for creating a table of the usage made to correspond the lightness of monochrome tone image achromatic and color material of the chromatic color, the An image processing apparatus is provided.

The second of the present invention, the colorant of the achromatic, and at least three colors colorant chromatic, color materials of the achromatic, 2-color coloring materials of a coloring material of the chromatic If, formed by a plurality of combinations of the colorimetric values obtained by measuring a plurality of color patches with a color of the surrounding gray line, a color value that indicates white, a storage unit that stores a color value indicating the black the image forming apparatus an image processing method for forming a monochromatic tone image using comprising the steps of: acquiring the chromaticity indicating the color tone of black and white tone image to be formed on the image forming apparatus, a color that indicates the white value, a color value indicating the black, the determination step of, based on one or more color values indicating the chromaticity to determine the brightness and chromaticity shown to line the relationship in the black and white tone image, wherein measuring before Symbol plurality of combinations each color patch stored in the storage unit Values and, based on the line determined in said determining step, a selection step of selecting two-color the chromatic colorant that used to form a monochrome tone image, before Symbol 2 color selected in the selection step and colorimetric values of color patches formed with said achromatic colorant and the chromatic colorant, based on the determined line in said determining step, the lightness of monochrome tone image achromatic and to provide an image processing method characterized by and a creation step of creating a table that associates the amount of color material of the chromatic color.

The third aspect of the present invention provides a program for causing a computer to execute each step of the image processing method .

  Other features of the present invention will become more apparent from the accompanying drawings and the following description of the best mode for carrying out the invention.

  With the above configuration, according to the present invention, it is possible for the user to flexibly set the color tone of a monochrome image and to suppress the occurrence of color shift.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The individual embodiments described below will help to understand various concepts, such as the superordinate concept, intermediate concept and subordinate concept of the present invention.

  The technical scope of the present invention is determined by the claims, and is not limited by the following individual embodiments. In addition, not all combinations of features described in the embodiments are essential to the present invention.

  In the following embodiments, an ink jet printer will be described as an example of an image forming apparatus, and ink will be described as an example of a color material. However, the following embodiments can also be applied to image forming apparatuses (for example, laser printers) other than ink jet printers and color materials (for example, toner) other than ink.

  In each of the following embodiments, the ink jet printer includes black ink (hereinafter also referred to as “K ink”) as an achromatic color material. In addition, as chromatic color materials, cyan ink, magenta ink, and yellow ink (hereinafter also referred to as “C ink”, “M ink”, and “Y ink”) are provided. However, other ink (for example, red ink or light magenta ink) may be provided in addition to or instead of these inks.

[First Embodiment]
FIG. 2 is a block diagram showing a personal computer (PC) 201 which is an example of a color processing apparatus according to the present invention. The PC 201 includes a CPU 202, a memory 203, a hard disk drive (HDD) 204, an input unit 205, an interface 206, and a CRT 208.

  The CPU 202 executes a program stored in the HDD 204 to perform various processes related to various color processing and storage, which will be described later.

  The memory 203 is used as a work area when performing color processing and as a temporary storage area for image data.

  The input unit 205 is used by the user to input various commands to the PC 201 and includes, for example, a keyboard and a mouse.

  The CRT 208 displays an image to be printed, a menu screen for color processing, and the like.

  The program for executing color processing may be supplied to the PC 201 from an external device (not shown).

  The PC 201 is connected to the ink jet printer 207 via the interface 206. The CPU 202 converts the image data for the PC 201 into image data for the ink jet printer 207 and transmits the image data, thereby causing the image to be printed. That is, the PC 201 controls the ink jet printer 207.

  FIG. 3 is a flowchart showing the flow of image data conversion processing executed by the CPU 202. The processing of each step shown in FIG. 3 can be realized by the CPU 202 executing a program stored in the HDD 204. However, the processing of each step shown in FIG. 3 may be realized by dedicated hardware.

  In the conversion process of the present embodiment, image data (RGB data) represented by luminance signals of red (R), green (G), and blue (B) is converted into C, M, Y, K, LC (light cyan), And LM (light magenta).

  In S301, the RGB data is converted into C, M, Y, K, LC, and LM density signals. In this conversion process, a three-dimensional lookup table (3D-LUT) stored in the HDD 204 is used. That is, the CPU 202 refers to the 3D-LUT to obtain a density signal expressed by C, M, Y, K, LC, and LM corresponding to the input RGB signal value combination. However, the 3D-LUT holds only density signals corresponding to discrete RGB signal values. Therefore, in the present embodiment, a density signal is obtained by interpolation processing based on a plurality of held data for the RGB signals in the area that is not held. Any known technique can be used for the interpolation processing, for example, linear interpolation processing can be used.

  In step S302, the density signal obtained in step S301 is subjected to output γ correction. The output γ correction is to correct the density signal value so that the optical density of the image finally printed on the recording medium is linear with respect to the input density signal. Here, correction is performed using a one-dimensional lookup table (1D-LUT) prepared in the HDD 204 independently for each color.

  In S303, the density signal corrected in S302 is quantized, and binary data for each ink color is obtained. Any known technique can be used for the quantization processing. For example, an error diffusion method or a dither method can be used.

  The ink jet printer 207 forms an image on a recording medium according to the binary data obtained by the above processing.

  The conversion process described above may vary depending on the type of recording medium, the type of image to be printed, and the like. Therefore, for example, the 3D-LUT used in the conversion process of S301 and the 1D-LUT used in the output γ correction process of S302 are prepared for each type of recording medium, type of image to be printed, print quality, and the like. It is common to be done.

  FIG. 4 is a flowchart showing a flow of image printing processing executed by the PC 201. When the user instructs printing of an image via the input unit 205, the CPU 202 displays a menu screen 50 (see FIG. 5) for print setting on the CRT 208 (S1).

  FIG. 5 is a diagram illustrating an example of a menu screen 50 for print settings. Fields 51, 52, and 53 are areas for selecting a paper type, print quality, and color mode, respectively. The inkjet printer 207 can use a plurality of types of recording media (for example, glossy paper, plain paper, matte paper, etc.) as image printing destinations, and a plurality of recording methods are prepared for each recording medium. .

  In the present embodiment, the user sets the type of recording medium to be used in the field 51. In the field 52, print quality (for example, speed priority, image quality priority, etc.) is set. Also, in field 53, it is set whether to print the image as a "color image", as a "monochrome photo image" whose color tone can be set, or simply as a "monochrome image" with color information discarded. To do. A “monochrome photographic image” is not always settable for all recording media. Normally, “monochrome photo image” can be selected only when a recording medium suitable for monochrome photo printing is set in the field 51.

  Note that the fields 51, 52, and 53 are implemented as, for example, drop-down menus.

  When the color setting button 54 is pressed, a menu screen for performing detailed color tone settings is displayed on the CRT 208. The contents of this menu screen can change depending on the color mode, but only the menu screen 60 (see FIG. 6) for “monochrome photo image”, which is important in this embodiment, will be described.

  FIG. 6 is a diagram showing an example of a menu screen 60 for setting a color tone for a monochrome photographic image.

  The preview image 61 is an image for the user to check the currently set color tone. The user can select a desired color tone from the color tone preset colors (for example, pure black tone, warm black tone, cool black tone, and sepia tone) in the field 62. The field 62 is implemented as a drop-down menu, for example.

  Further, the user can set the color tone by directly inputting the values of a * and b * in the CIE L * a * b * color system in the fields 63 and 64.

  The set coordinate 65 displays the values of a * and b * set in the fields 63 and 64 as coordinates in the a * -b * plane. The user can also set the color tone by moving the pointer 66 of the set coordinates 65 using the input unit 205.

  Here, the field 62, the fields 63 and 64, and the pointer 66 of the set coordinates 65 are interlocked. When any one of them is changed, the other fields and pointers 66 are also changed to corresponding contents and positions. The

  Note that the range of values of a * and b * that can be set on the menu screen 60 is limited to the vicinity of an achromatic color (around the gray line). Specifically, for example, a * = − 10 to +10 and b * = − 10 to +10.

  In this embodiment, the CIE L * a * b * color system is used for setting the color tone, but other color systems may be used.

  When the OK button 67 is pressed, the color tone setting is completed and the screen returns to the menu screen 50 in FIG. When the cancel button 68 is pressed, the color change (setting change) made on the menu screen 60 is discarded, and the screen returns to the menu screen 50 in FIG.

  Refer to FIG. 5 again. When the OK button 55 is pressed, the print setting is completed, and the image printing process proceeds to S2 in FIG. If the cancel button 56 is pressed, the image printing process is stopped.

  Refer to FIG. 4 again. In S <b> 2, the CPU 202 determines whether or not the color mode set in the field 53 is a monochrome photographic image. It is determined whether or not the set color mode is “monochrome photo image”. If “monochrome photo image”, the process proceeds to S6; otherwise, the process proceeds to S3.

  In S3, the CPU 202 determines whether or not the color mode set in the field 53 is monochrome. If the set color mode is “monochrome”, the process proceeds to S4; otherwise, the process proceeds to S5.

  In S4, the CPU 202 discards the color information from the image data to be printed. Specifically, the RGB luminance signals are converted into gray (R = G = B) luminance signals L. In the conversion, a conversion formula L = 0.3R + 0.6G + 0.1B is used. In other words, in S4, the CPU 202 extracts brightness data from the image data to be printed.

  In step S5, the CPU 202 executes image data conversion processing (conversion processing 1). When the process reaches S5 without going through S4, the conversion process 1 is the conversion process described with reference to FIG. On the other hand, when the process reaches S5 via S4, in the conversion process 1, the conversion process using only the data of the 3D-LUT gray line (R = G = B line) in S301 in FIG. 3 is performed.

  If it is determined in S2 that the color mode is “monochrome photographic image”, in S6, the CPU 202 extracts lightness data from the image data to be printed and discards the color information in S6.

  In step S7, the CPU 202 executes image data conversion processing (conversion processing 2). Details of the conversion process 2 will be described later.

  The image data subjected to the conversion processing in S5 and S7 is binary data relating to each ink color, and the CPU 202 transmits it to the inkjet printer 207 via the interface 206 in S8. The ink jet printer 207 prints an image using the received binary data.

  Before describing the details of the color conversion process 2 in S7, the color measurement values of the color patches stored in the HDD 204, which is an example of a storage unit, will be described. This colorimetric value is used in the color conversion process 2 to create a table used by the CPU 202 to convert the luminance signal of the image to be printed into the density signal of each ink.

  FIG. 7 is a flowchart showing a flow of processing for generating a colorimetric value of a color patch. The colorimetric value is generated using an information processing device (not shown), an ink jet printer 207, and a colorimeter (not shown). Note that the PC 201 in FIG. 2 may be used as the information processing apparatus. 7 is preferably performed on all types of recording media that can select “monochrome photo image” as the color mode on the menu screen 50 of FIG.

  In S71, for K ink, for example, a basic curve such that γ = 1.8 is created for the luminance information.

  In S72 to S74, a plurality of color patches having colors around the gray line are printed on the recording medium by using each of the combinations of the two color materials among the chromatic color materials together with the achromatic color material.

  First, in step S72, data (ink color data) relating to the amount of ink used for K ink, C ink, and M ink is created. Specifically, the values of C ink and M ink are set to a plurality of levels (for example, 7 for each of the basic curve values for K ink corresponding to the grid point positions of the 3D-LUT described in S301 of FIG. 3). Create ink color data changed in step). For example, when there are 16 3D-LUT grid points for each axis of RGB, C ink and M ink are changed in 7 steps with respect to the basic K ink at 14 points excluding the white point and black point. A color patch is printed using the ink color data. In this case, 14 × 7 × 7 = 686 color patches are printed.

  Similarly, in S73, a color patch using K ink, Y ink, and M ink is printed, and in S74, a color patch using K ink, M ink, and C ink is printed.

  Here, the reason why only two colors of chromatic color ink are used for each color patch is to reduce the number of chromatic color inks that cause color shift. Even if only two chromatic inks are used, if any two of C, M, and Y are used, colors of all chromaticities can be expressed. Therefore, the color tone set on the menu screen 60 in FIG. It can be reproduced.

  The interval for changing the value of the chromatic color ink is arbitrary, and in the present embodiment, if the plurality of color patches to be printed can include a range of a * = − 10 to +10 and b * = − 10 to +10. Good.

  In step S75, each of the plurality of color patches is measured, and the result (L * a * b * value) is stored in the HDD 204 in association with the ink color data used for printing the corresponding color patch. When a device other than the PC 201 is used as the information processing device, for example, the colorimetric values are temporarily stored in the storage device of the information processing device and copied to the HDD 204 via a medium such as a CD-ROM or the Internet. Good.

  With the above processing, the PC 201 is provided with a storage unit (HDD 204) that stores colorimetric values acquired from a plurality of color patches having colors around the gray line.

  Next, the conversion process 2 of S7 will be described in detail with reference to FIG.

  In S81, the CPU 202 acquires color tone information including chromaticity set by the user on the menu screen 60 of FIG.

  In step S82, the CPU 202 acquires the colorimetric values described with reference to FIG.

In step S <b> 83, the CPU 202 determines a brightness line indicating a relationship between brightness and chromaticity in a monochrome image to be printed by the inkjet printer 207. There are various methods for determining the lightness line. For example, the chromaticity acquired in S81 may be associated with all the lightness values. However, this method cannot express perfect white (color with extremely high luminance) or black (color with extremely low luminance). Therefore, in the present embodiment, as an example, the color measurement values (L _w , a _w , b _w ) of paper white and the color measurement values (L _k , a _k , b _k ) of black are stored in the HDD 204 as an example. . Then, (L _k , a _k , b _k ), (L ₁ , a _t , b _t ), (L ₂ , a _t , b _t ), and (L _w , a _w , b _w ) The connecting line is the lightness line. In this embodiment, L ₁ <((L _k + L _w ) / 2) <L ₂ is set, but the present invention is not limited to this, and the number of points is not limited to four. It is preferable to interpolate between the colorimetric value of paper white, the colorimetric value of black, and the colorimetric value corresponding to the chromaticity designated by the user and one or more predetermined brightness values. Any known technique can be used for the interpolation method between the four points. For example, linear interpolation or spline interpolation can be used. FIG. 9 is a diagram illustrating an example of a brightness line determined by linear interpolation.

  In S84, the CPU 202 selects an ink combination that minimizes the color difference between the color that can be formed on the recording medium and the brightness line. Specifically, for example, among the colorimetric values acquired in S82, the color difference is calculated for points on the lightness line corresponding to each K ink value (14 points in the present embodiment). Then, for each combination of inks, the minimum color difference at each point is summed, and the combination that minimizes the total value is finally selected. In the present embodiment, it is assumed that a combination of C and Y is selected.

  In S85, the CPU 202 performs an interpolation process using the colorimetric values corresponding to the selected combination. As a result, colorimetric values corresponding to color patches formed by the ink and K ink corresponding to the selected combination and not included in the plurality of color patches described with reference to FIG. 7 are obtained. Generated. That is, in the present embodiment, only 7 × 7 = 49 colorimetric values are stored in the HDD 204 for a specific K ink value, but this number is increased by interpolation processing.

  In S86, for each of the 14 points described above, the CPU 202 is a colorimetric value corresponding to the combination selected in S84, and among the colorimetric values acquired in S82 and the colorimetric values generated in S85, Select the colorimetric value that minimizes the color difference. Then, a table indicating the relationship between the lightness corresponding to the 14 points described above and the ink color data corresponding to the selected colorimetric value (that is, the amount of each ink used) is created.

  Subsequently, the CPU 202 performs the conversion process described with reference to FIG. 3 to generate binary data. However, the table used in S301 is not the 3D-LUT described with reference to FIG. 3, but the table created in S86. That is, the CPU 202 generates binary data (print data) used for monochrome image formation (printing) from the brightness data extracted in S6 of FIG. 4 using the table created in S86.

  If the table created by the processing shown in FIG. 8 is used, the PC 201 causes the inkjet printer 207 to print a monochrome image so that the color difference from the brightness line determined based on the color tone desired by the user is reduced. be able to. Therefore, occurrence of color shift is suppressed.

  Note that the interpolation processing in S85 contributes to reducing the color difference between the printed image and the brightness line, but is not essential.

  As described above, according to the present embodiment, the PC 201 includes a storage unit that stores colorimetric values of color patches corresponding to the recording medium to be used. In addition, when printing a monochrome photographic image, the user is allowed to set a color tone using chromaticity. Then, each time a monochrome photographic image is printed, a table for converting lightness into ink color data is created based on the colorimetric value and the chromaticity set by the user.

  Thereby, it becomes possible for the user to flexibly set the color tone of the monochrome image and to suppress the occurrence of color shift.

  Further, since the table is created when the monochrome photographic image is printed, the HDD 204 does not need to store a table corresponding to a large number of colors, and can reduce the data amount.

<Modification 1>
In this embodiment, in order to print a color patch, three color inks of C, M, and Y are used as chromatic ink (see FIG. 7), but the present invention is not limited to this. For example, instead of C and M, light cyan (LC) or light magenta (LM) may be used. In this case, since the LC ink and the LM ink have a density lower than that of the C ink and the M ink, there is an additional effect that the graininess of the C ink and the M ink in the highlight area of the printed image can be suppressed. .

<Modification 2>
In the present embodiment, only the K ink is used as the achromatic ink, but the present invention is not limited to this. For example, in addition to the K ink, the same effect can be obtained by using a gray (Gy) ink having a lower density than the K ink. In this case, in S71 of FIG. 7, for K ink and Gy ink, for example, a basic curve is generated such that γ = 1.8 in a combination as shown in FIG. By using not only the K ink but also the Gy ink, there is a further effect that the graininess of the K ink in the highlight area of the printed image can be suppressed. The same effect can be obtained even if two or more achromatic inks are added.

[Other Embodiments]
In the processing of the above-described embodiment, a storage medium in which a program code of software that embodies each function is recorded may be provided to the system or apparatus. The functions of the above-described embodiments can be realized by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying such a program code, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, or the like can be used. Alternatively, a CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like can be used.

  The functions of the above-described embodiments are not only realized by executing the program code read by the computer. In some cases, an OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. include.

  Furthermore, the program code read from the storage medium may be written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. After that, the CPU of the function expansion board or function expansion unit performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

It is a figure explaining background art. 1 is a block diagram showing a personal computer (PC) 201 which is an example of a color processing apparatus according to the present invention. 4 is a flowchart illustrating a flow of image data conversion processing executed by a CPU. 5 is a flowchart showing a flow of image printing processing executed by a PC 201. It is a figure which shows an example of the menu screen 50 for print setting. It is a figure which shows an example of the menu screen 60 for the color tone setting with respect to a monochrome photograph image. It is a flowchart which shows the flow of the process which produces | generates the colorimetric value of a color patch. It is a flowchart explaining in detail a part of the conversion process 2 of S7 of FIG. It is a figure which shows an example of the lightness line determined by linear interpolation. It is a figure which shows an example of the basic curve using black ink and gray ink.

Claims (9)

An image processing apparatus for forming a monochrome image using an image forming apparatus including an achromatic color material and at least three chromatic color materials,
A plurality of color patches formed on a recording medium using the image forming apparatus , wherein the achromatic color material and a combination of two color materials among the chromatic color materials are formed. A storage unit storing a colorimetric value obtained by measuring a plurality of color patches having a color around the gray line, a color value indicating white, and a color value indicating black ;
Obtaining means for obtaining the chromaticity indicating the color tone of black and white tone image to be formed on the image forming apparatus,
A color value indicating the white, the color values indicating the black, based on the one or more color values indicating the chromaticity to determine the brightness and chromaticity relationship indicates to line of in the monochrome tone image A determination means;
And colorimetric value before Symbol plurality of combinations each color patch stored in the storage unit, based on the determined line by the determining means, the two colors used to form a monochrome tone image of the chromatic selection means for selecting a color material,
And colorimetric values of color patches formed with a selected two colors wherein the chromatic colorant of said achromatic colorant by prior Symbol selection means, based on the determined line by said determining means and creation means for creating a table of the usage made to correspond the lightness of monochrome tone image achromatic and color material of the chromatic color,
An image processing apparatus comprising: Wherein the achromatic color material, based on the colorimetric values of color patches formed by using a color material of the chromatic color two colors selected by said selecting means, by interpolation color value of the interpolation color patches Further comprising interpolation means for generating,
The creation unit creates the table based on the color value of the interpolation color patch generated by the interpolation unit in addition to the colorimetric value of the color patch stored in the storage unit. An image processing apparatus according to 1.   The selecting means selects the two chromatic color materials included in the combination that minimizes the sum of the color differences between the colorimetric values of the plurality of color patches and the line from among the plurality of combinations. ,
  The creating means creates a table in which the brightness and the usage amount of the color material corresponding to the color patch having the color value that minimizes the color difference between the color value having the brightness in the line are created.
  The image processing apparatus according to claim 1. Wherein the storage unit, for each of a plurality of types of recording medium, and the colorimetric values, and color values indicating the white stores a color value representing the black,
The acquisition unit further acquires the type of the record medium that form a monochromatic-tone image,
Said determining means, said selecting means and said generating means, to any one of claims 1 to 3, characterized by using a pre-Symbol color value that corresponds to the recording medium of the type acquisition means has acquired The image processing apparatus described. Extraction means for extracting brightness data from image data;
The print data by the image forming apparatus is used to form a monochrome tone image, a generation unit configured to generate from the luminosity data by using the table,
The image processing apparatus according to claim 1, further comprising: The image processing apparatus according to claim 1, wherein the colorimetric value is a colorimetric value in a CIEL * a * b * color system. The image forming apparatus is an inkjet printer;
The achromatic color material includes black ink,
The image processing apparatus according to claim 1 , wherein the chromatic color materials of at least three colors include cyan ink, yellow ink, and magenta ink. And achromatic color material, and at least three color chromatic color colorant, wherein the colorant of the achromatic, two colors and the color material of the color material of the chromatic color was formed of a plurality of combinations of A monochrome adjustment using an image forming apparatus including a storage unit storing colorimetric values obtained by measuring a plurality of color patches having a color around a gray line, a color value indicating white, and a color value indicating black An image processing method for forming an image , comprising:
An acquisition step of acquiring chromaticity indicating the color tone of black and white tone image to be formed on the image forming apparatus,
A color value indicating the white, the color values indicating the black, based on the one or more color values indicating the chromaticity to determine the brightness and chromaticity relationship indicates to line of in the monochrome tone image A decision process;
And colorimetric value before Symbol plurality of combinations each color patch stored in the storage unit, the based on the determined line at decision step, the color of the two colors of the chromatic color used to form a monochrome tone image A selection process for selecting materials ;
And colorimetric values of color patches formed with a front Symbol 2 color the chromatic color material of which is selected in the selection step and the achromatic color material, based on the determined line in said determining step a creation step of creating a table of the usage made to correspond colorant brightness and the achromatic color and the chromatic color of monochrome tone image,
An image processing method comprising:   A program for causing a computer to execute each step of the image processing method according to claim 8.