JP2002171421A - Image processing method and image processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the problem of a conventional image processing method conducting black generating processing on the basis of an effective color component that has narrowed a reproduction color space when delaying conversion timing to a K color in a black generating table to suppress occurrence of a granular sense. SOLUTION: In the generation of image data recorded on a recording medium by a CMYK recording agent, a received RGB image signal is converted into a CMY components (S1), a K component is extracted on the basis of the CMYK component (S2), and the K component is converted on the basis of the table where an increment of the K color is set to each CMY (S35).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing method and an image processing apparatus, for example, to an image processing method and an image processing apparatus for separating an image signal into a plurality of color components and performing image processing.

[0002]

2. Description of the Related Art Conventionally, in an image processing apparatus such as a printer that prints out an image on a recording medium, for example, each color component of red (R), green (G), and blue (B) inputted by a scanner or the like is used. The RGB data consisting of the CMs for printing cyan (C), magenta (M), yellow (Y) and black (K)
It was converted to YK data.

For example, in an ink-jet printer, CMYK for output is based on inputted RGB data.
When generating data, first, the RGB luminance data is
After the conversion into MY density data, the K component, which is an achromatic component, is extracted from the CMY data to newly generate CMY data, which is a chromatic component (hereinafter, a color component).

After color correction and density correction are performed on the color components, a black generation process based on the K component is performed. Then, by performing output correction processing based on the characteristics of the ink and the like, a CM used for actual image formation is provided.
Each signal value of YK is obtained.

[0005]

However, in the above-described conventional image processing for generating YMCK data, the final signal value of the K component is determined with reference to a predetermined black generation table. Therefore, the K component value is determined uniformly irrespective of the composition ratio of the color components, that is, the color.

For this reason, if the conversion timing to the K ink is delayed in the black generation table in order to suppress the graininess, the graininess is suppressed in the recorded image, but the complementary color ink is used more than necessary, so that the color is not changed. There is a problem that the color space becomes turbid and the saturation decreases, and the color space to be reproduced becomes narrow.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and expands a reproduction color space while suppressing graininess when an image is recorded on a recording medium using a plurality of recording materials including an achromatic color. An object of the present invention is to provide an image processing method and an image processing device.

[0008]

As one method for achieving the above object, the image processing method of the present invention comprises the following steps.

In other words, there is provided an image processing method for generating image data to be recorded on a recording medium by using a plurality of recording materials including an achromatic color, wherein an input image signal is converted into a plurality of chromatic colors corresponding to the recording material. A conversion step of converting an achromatic component based on the plurality of chromatic components; an achromatic color extraction step of extracting an achromatic component based on the plurality of chromatic components; An achromatic color conversion step of performing conversion based on a first table set for each.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings.

First Embodiment Outline of Color Conversion Processing In this embodiment, RGB image data is input and CMYK
This is performed in a printer that performs image recording using the recording agent.

Before describing the features of this embodiment,
First, a general color conversion process (RGB → CMYK) in an ink jet printer will be described with reference to the flowchart of FIG.

In step S1, the luminance for converting the R, G, B luminance data into C1, M1, Y1 density data is calculated.
The density conversion is performed based on the following equation (1).
In the expression (1), A is a predetermined constant.

C1 = A × log (−R) M1 = A × log (−G) (1) Y1 = A × log (−B) Next, in step S2, there is nothing from C1, M1, Y1 data. A black component K1 which is a coloring component is extracted to obtain a color component C2,
Achromatic color extraction for generating M2 and Y2 is performed based on equation (2) shown below. Here, as can be seen from equation (2), after the achromatic component K1 is extracted, the color components C2,
One of the values of M2 and Y2 becomes zero. K1 = min (C1, M1, Y1) C2 = C1−K1 M2 = M1−K1 (2) Y2 = Y1−K1 Next, in step S3, the color components C2, M2, Y2 are obtained.
The color components C3,
Color correction processing for obtaining M3 and Y3 is performed based on the following equation (3).

[0015]

(Equation 1)

Next, in step S4, C3, M3, Y
C4, M4, Y4, and K2 are obtained by performing independent density correction for each of the colors 3 and K1. In general, correction based on each value of density and contrast arbitrarily set by the user is performed by a printer driver or the like.

Next, in step S5, black generation processing based on the value of K2 is performed based on the following equation (4). Equation (4) shows the signal value of each color obtained by the black generation processing, and Kk, Kc, Km, and Ky are functions indicating each color component value (value for expressing black) based on K2. It is. FIG. 2A shows an example of a black generation table using the function. In the figure, the horizontal axis indicates the value of K2 (white to black), and the vertical axis indicates the signal value (0 to 255) of each generated color component. According to the figure, each CMYK value (Kk
It can be seen that [K2], Kc [K2], Km [K2], Ky [K2]) are uniquely determined by the value of K2. K3 = Kk [K2] C5 = C4 + Kc [K2] M5 = M4 + Km [K2] (4) Y5 = Y4 + Ky [K2] Then, in step S6, a predetermined output based on the characteristics of the ink and the like. By performing the correction process, C6, M6, Y6, and K4 used for actual image formation are obtained.

Here, FIG. 2B shows a black generation result (conversion result by the above equation (4)) from yellow to black (Yellow → Black) in the above-mentioned general image processing. Similarly, FIG. 2C shows a black generation result from blue to black (Blue → Black). According to these figures, it can be seen that the signal values of the K component corresponding to the K ink exhibit similar conversion characteristics in both figures.

As described above, in the general black generation processing, the signal value of the K component is generated based on the black generation table as shown in FIG. 2A, so that the signal value depends on the value of a chromatic color such as Yellow or Blue. Instead, it is determined uniformly based on the value of the achromatic color value K2.

For this reason, for example, in order to suppress graininess,
When the start timing of conversion to K ink is delayed in the black generation table, that is, when the rising position of the K component in FIG. 2A is shifted to the black side, the granularity is suppressed in the print result after the conversion, but the complementary color is more than necessary. Since the ink is used, the color becomes muddy, the saturation is reduced, and there is a problem that the color space to be reproduced is narrowed.

Therefore, it is desirable to make the K ink conversion start timing and the K ink amount after the conversion start variable for each color.

Further, color inks (Y component in FIG. 2B,
Similarly, the C and M components in FIG.
As long as the ink absorption capacity of the recording medium permits, the color space to be reproduced increases as the color ink amount increases. Therefore, it is desirable that the color components of the black generation table are also variable.

The color conversion processing in the present embodiment Therefore, the present embodiment is characterized in that the color space is enlarged simultaneously with the black generation processing.

First, FIG. 3 shows a flowchart of the color conversion processing in the present embodiment.

The processing shown in FIG. 3 is executed by, for example, a printer driver installed in a host computer. Specifically, the printer driver
A program for realizing the processing is stored in a hard disk, and the program is realized by the CPU executing the program under basic software (OS) while using the RAM as a work area.

In FIG. 3, the same processes as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

Black Generation and Color Space Expansion Processing In step S35, black generation and color space expansion processing, which are features of the present embodiment, are performed. Hereinafter, step S3
5 will be described in detail.
By the notation “z”, Z (C / M /
Y) A color component, for example, a C color component when expressing K color by “Kc”.

In the black generation processing of this embodiment, the following six tables i) and ii) are prepared in advance.
A method for creating these tables will be described later.

I) K color ink increase table K ink amount (ColKx) to be added for each line of C → Black, M → Black, Y → Black in the color space
K ink amount (Kk) in a predetermined black generation table
Tables showing the inclinations (Figs. 5A and 5B) from the data ・ PlusKc [0 ～ 255], PlusKm [0 ～ 255], PlusKy [0 ～ 25
5] The predetermined black generation table can be set arbitrarily by the user as well as the general black generation table shown in FIG. 2A.

Ii) Increasing tables for color inks Three tables showing the magnification (FIGS. 7A and 7B) of the amount of color ink to be added in each line of C → Black, M → Black and Y → Black in the color space.

PlusC [0-255], PlusM [0-255], PlusY [0-255] Then, using these tables, C4, M4, Y4, and K2 subjected to density correction in step S4 for,
Black is generated by performing processing based on the following arithmetic expression.

First, PlusK, which is the amount of K ink to be added, is obtained.

PlusK = PlusKc [K2] × C4 + PlusKm [K
2] × M4 + PlusKy [K2] × Y4 As a result, the amount of K ink to be recorded is K3 = Kk [K2] + PlusK (5).

Then, the color ink amount is calculated as follows: C5 = PlusC [K2] × C4 + Kc [K2] −Kc [PlusK] M5 = PlusM [K2] × M4 + Km [K2] −Km [PlusK] (6) Y5 = It is determined by the formula PlusY [K2] × Y4 + Ky [K2] −Ky [PlusK].

In the equation (6), the third term on the right-hand side corresponds to the amount of the color ink which is offset by the increase in the K ink amount by PlusK and the increase in the density according to the equation (5).

As described above, according to the present embodiment, the black generation processing in step S35 is executed according to the equations (5) and (6).

In the present embodiment, the color generation processing for adjusting the K ink amount and the color ink amount to desired amounts can be performed by the above-described black generation processing. Must be created in advance. Hereinafter, a method of creating the table will be described in detail.

Method for Creating Table Hereinafter, a method for creating each of the above-described tables i) and ii) will be described in detail.

I) K color ink increase table (PlusKx [0
~ 255]) As described above, it is necessary to set a predetermined black generation table.

First, the amount of K ink in the White → Black line (gray line) in the color space is determined in advance.

Similarly, for each of the CMY colors,
(C / M / Y) → K ink amount in Black line is determined in advance. Specifically, the conversion start timing of each color to K ink (the rising point of the K ink in the black generation table) and the K ink amount after the start of the conversion are determined.

"Start timing of conversion to K ink"
It is determined by the granularity of the K ink in the CMY inks. From the viewpoint of expanding the color space and reducing the amount of ink consumption, it is preferable to start using the K ink earlier as long as the granularity allows.

Regarding the “amount of K ink after the start of conversion”,
Increasing the amount of K ink as much as possible can realize a wide color space and a reduction in ink consumption. However, if the amount of K ink sharply increases, there is a risk of occurrence of false contours. preferable. For example, one method is to refer to the rising curve of the K ink on the gray line.

FIG. 4 shows a flowchart of the table creation processing. First, in step S91, the type of table to be created is determined. In this example, a PlusKc table is first created. Then, after the variable i is initialized in step S92, Plus in step S93
A Kx table is created based on equation (7).

PlusKx [i] = (ColKx [i] −Kk [i]) / (255−i) (7) Equation (7) will be described in detail with reference to FIGS. 5A and 5B. . FIG. 5A shows a white → Black line and a Color → Black line in the color space, and ColKx [i] and Kk [i] in equation (7) are points B indicating K2 on each line in FIG. 5A, respectively. , A indicate the amount of K ink at point A (K2 in FIG. 5A corresponds to i in equation (7)). Therefore, it can be seen that equation (7) expresses the gradient (AB / AC) of the K ink amount (Point B) on the Color → Black line from the K ink amount (Point A) on the gray line. .

FIG. 5B shows the relationship between the ink amounts at the points A and B. The inclination in FIG. 5B, that is, the degree of increase in the K ink amount, corresponds to PlusKx [K2].

Then, in step S94, PlusKc
By obtaining [i] for the 255 gradations from white to black, the PlusKc [0 to 255] table is completed.

Then, at step S95, the above described
By performing the calculation according to the equation (7) for each of the other 255 gradations of the M and Y colors, PlusKm [0 to 255], Plu
Each table of sKy [0 to 255] is also obtained.

Ii) Color ink increase table (PlusX)
[0-255]) Hereinafter, a case where a PlusC table is created will be described as an example. However, it is needless to say that PlusM and PlusY can be obtained in the same procedure.

FIG. 7A shows Cyan → Black in the color space.
Here is an example of a line. In this case, the color ink is the C ink, but the larger the amount of the ink, the larger the color space. However, if the ink amount is too large, the ink overflows beyond the ink capacity of the recording medium. Therefore, the target value of the ink amount is determined so as to use as much C ink as possible while considering the ink allowable amount and the total ink amount of the recording medium.

Target C [K2] indicated by a thick line in FIG. 7A
Indicates the target value determined in this way. In addition, 2
In the case of printing the next color, the ink ejection amount is further increased. Therefore, it is necessary to consider the secondary color printing when determining the primary color ink amount target value.

FIG. 6 shows a flowchart of the PlusC table creation processing. First, in step S11, Plus
Set to create C table, and step S
After the variable i is initialized in step S19, step S13
In, a PlusC table is created based on equation (8).

PlusX [i] = (TargetX [i] − ((255−i) + Kx [i])) / (255−i) (8) Regarding equation (8), FIGS. 7A and 7B This will be described in detail with reference to FIG. As shown in FIG. 7B, C in the present embodiment
The target value TargetC [K2] of the ink amount is the C ink amount obtained by the conventional black generation processing (the sum of Kc [K2] for K color expression and 255-K2 for C color expression at the K2 point). More than. A PlusC table is calculated based on the increment A. In the expression (8), that is, in order to obtain the target value TargetX [i] based on the increment A calculated in the numerator, the signal value (255-K2) for C color expression is multiplied by a certain number. Asking what you need.

Then, in step S14, PlusC
By calculating [i] for the 255 gradations from white to black, PlusC [0 to
255] The table is completed.

Then, at step S15, the above
By performing the calculation according to equation (8) for each of the other 255 gradations of the M and Y colors, PlusM [0 to 255] and PlusM
Each table of Y [0 to 255] is also obtained.

As described above, according to the present embodiment,
By the black generation and the color space enlarging process in step S5, the K ink amount and the color ink amount can be respectively set to desired ink amounts according to the ink allowable amount of the recording medium. That is, the start timing of conversion to K ink and the K ink amount after the start of conversion can be made variable for each color, and the ink amount of each color ink can also be changed according to the ink allowance of the recording medium. can do.

As a result, while maintaining the color continuity in the recorded image, the graininess can be suppressed, and the reproducible color space can be further widened.

Further, the ink consumption can be reduced.

<Second Embodiment> Hereinafter, a second embodiment according to the present invention will be described.
An embodiment will be described.

FIG. 8 shows a flowchart of the color conversion processing in the second embodiment. In FIG. 8, FIG.
The same processes as those described above are denoted by the same reference numerals, and description thereof is omitted.

According to FIG. 8, step S5 in FIG.
The color space expansion processing is realized in the color correction processing shown in step S63 without performing the black generation processing shown in FIG.

Hereinafter, the color correction processing and the color space enlarging processing in step S63 will be described in detail. As in the first embodiment described above, Z () when expressing black K by the following “Kz” notation is used. C / M / Y), for example, a C color component when expressing K color by “Kc”.

In the second embodiment, the following i) and
Prepare the six tables shown in ii). A method for creating these tables will be described later.

I) Ink increase table for K color C → Black, M → Black, Y → Black,
Six tables showing the slope of the K ink amount (ColKx) to be added from the K ink amount (Kk) in black generation in each line of R → Black, G → Black, B → Black. PlusKc [0 to 255] ], PlusKm [0 ～ 255], PlusKy [0 ～ 25
5] PlusKr [0-255], PlusKg [0-255], PlusKb [0-255] These tables are generated by the same method as the K color ink increase table in the first embodiment described above. Here, detailed description is omitted.

Ii) Color ink increase tables Three tables showing the magnification of the color ink amount to be added in each line of C → Black, M → Black, Y → Black in the color space.

PlusC [0-255], PlusM [0-255], PlusY [0-255] These tables are also the same as the above-described color ink increase table in the first embodiment, and therefore description thereof is omitted. I do.

Then, by using these tables, C2, M2, Y subjected to achromatic color extraction in step S2.
2, K1 is subjected to color correction processing based on the following equation.

R1 = min (M2, Y2) G1 = min (C2, Y2) B1 = min (C2, M2) C2 '= C2-G1-B1 M2' = M2-R1-B1 Y2 '= Y2-R1- G1 Next, based on the obtained C2 ', M2', Y2 ', R1, G1, and B1, the K ink amount PlusK to be added is calculated by the following equation.

PlusK = PlusKc [K1] × C2 ′ + PlusKm [K
1] × M2 '+ PlusKY [K1] × Y2' + PlusKr [K1] × R1 +
PlusKg [K1] × G1 + PlusKb [K1] × B1 As a result, the actually recorded K ink amount K2 is obtained as K2 = Kk [K1] + PlusK.

The color ink amounts C3, M3, Y3 are obtained by the following equations.

C3 = Plus C [K1] × (Cc [C2 '] + Gc [G
1] + Bc [B1]) + Kc [K1] −Kc [PlusK] M3 = PlusM [K1] × (Mm [M2 ′] + Rm [R1] + Bm [B
1]) + Km [K1] −Km [PlusK] Y3 = PlusY [K1] × (Yy [Y2 ′] + Ry [R1] + Gy [G
1]) + Ky [K1] −Ky [PlusK] In the above equation, the third term on the right-hand side corresponds to the amount of color ink that is offset by the amount of K ink increased by PlusK and increased in density.

As described above, according to the second embodiment, in the above-described color correction forming process in step S63,
As in the first embodiment, it is also possible to perform a color space expansion process for adjusting the K ink amount and the color ink amount to desired amounts. As a result, while maintaining color continuity, graininess can be suppressed, a reproducible color space can be further widened, and ink consumption can be reduced.

Third Embodiment Hereinafter, a third embodiment according to the present invention will be described.
An embodiment will be described.

In the above-described first and second embodiments, an example has been described in which a K color ink increase table is created in which the amount of K ink to be added is expressed as a gradient from the amount of K ink on the gray line.

Therefore, the third embodiment is characterized by having a black generation table as shown in FIG. According to the black generation table shown in FIG. 9, by giving a negative value as the K ink amount of the gray line, the recording characteristics as shown in FIG. 10A can be obtained. According to FIG. 10A, printing is performed only with the color ink without using K ink in the hatched portion. In particular, in the portion C in the drawing, printing using the K ink is performed on the gray line, but it is preferable not to use the K ink in this portion.

FIG. 10B shows the relationship between the K ink amount (point A) on the gray line shown in FIG. 10A and the K ink amount (point B) on the Color → Black line. According to FIG.
It can be seen that the K ink amount is a negative value during AF.

As described above, according to the third embodiment, a color range in which no K ink is used can be set by giving the K ink amount a negative value in the black generation table. This makes it possible to further reduce the granularity in the recording result.

Although FIG. 9 shows an example in which the minus portion ST of the K ink amount is connected by a straight line, the shape connecting the ST is changed to change the shape within the triangle of White-Color-Black. It is possible to finely adjust the K ink amount. FIG. 11 shows an example in which ST is nonlinear. According to FIG. 11, it can be seen that the color range not using the K ink is separated by a curve.

[0079]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Further, an object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and to provide a computer (a computer) of the system or the apparatus. It is needless to say that the present invention can also be achieved by a CPU or MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Also,
When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also the operating system (OS) running on the computer based on the instructions of the program code.
It goes without saying that a case where the functions of the above-described embodiments are implemented by performing some or all of the actual processing, and the processing performs the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. Needless to say, the CPU included in the function expansion card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0082]

As described above, according to the present invention, when an image is recorded on a recording medium using a recording material of a plurality of colors including an achromatic color, the reproduction color space can be enlarged while suppressing graininess. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a general color conversion process in an inkjet printer.

FIG. 2A is a diagram illustrating an example of a general black generation table.

FIG. 2B is a diagram showing an example of a black generation result based on the black generation table of FIG. 2A.

FIG. 2C is a diagram showing an example of a black generation result based on the black generation table of FIG. 2A.

FIG. 3 is a flowchart illustrating a color conversion process according to the embodiment.

FIG. 4 is a flowchart illustrating a process of creating a K color ink increase table.

FIG. 5A is a diagram for explaining a method of creating a K color ink increase table.

FIG. 5B is a diagram for explaining a method of creating a K color ink increase table.

FIG. 6 is a flowchart illustrating a process of creating a color ink increase table.

FIG. 7A is a diagram for explaining a method of creating a color ink increase table.

FIG. 7B is a diagram for explaining a method of creating a color ink increase table.

FIG. 8 is a flowchart illustrating a color conversion process according to the second embodiment.

FIG. 9 is a diagram illustrating a black generation table according to the third embodiment.

FIG. 10A is a diagram showing recording characteristics obtained in a third embodiment.

FIG. 10B is a diagram showing recording characteristics obtained in a third embodiment.

FIG. 11 is a view showing a modification of the third embodiment.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Aki Yamada 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2C262 AA02 AA24 AA26 AB13 AC02 BA02 BA07 BA20 BC01 5B057 AA11 CA01 CA08 CA12 CB01 CB08 CB12 CE16 DB02 DB06 DB09 5C077 LL02 LL19 MP08 PP31 PP32 PP33 PP37 PP38 PQ08 PQ23 TT05 5C079 HB01 HB03 HB12 KA15 LA03 LB11 MA04 NA02

Claims (16)

[Claims] 1. An image processing method for generating image data to be recorded on a recording medium by using a plurality of colors of recording materials including an achromatic color, wherein an input image signal is converted into a plurality of chromatic colors corresponding to the recording material. A conversion step of converting into a component, an achromatic color extraction step of extracting an achromatic component based on the plurality of chromatic components, and an achromatic component extracted by the achromatic color extraction unit,
An achromatic color conversion step of converting the increment based on a first table set for each of the chromatic color components. 2. The image processing method according to claim 1, wherein in the achromatic color conversion step, the achromatic color component is converted based on a sum of increments determined for each of the chromatic color components. 3. The image processing method according to claim 1, wherein the first table indicates an inclination amount from an achromatic component value indicated in a predetermined black generation table. 4. The predetermined black generation table can arbitrarily set a conversion start timing to an achromatic color value and an achromatic color value at the start of the conversion for each chromatic color component. The image processing method described in the above. 5. The image processing method according to claim 3, wherein the black generation table has a negative value as an achromatic component value. 6. A chromatic color conversion step for converting the plurality of chromatic color components based on a second table in which respective increments are set. The image processing method described in the above. 7. In the chromatic color conversion step, the plurality of chromatic color components are converted based on the second table and the achromatic color component value extracted in the achromatic color extraction step. The image processing method according to claim 6. 8. The image processing method according to claim 6, wherein the second table indicates a magnification of a chromatic component value with respect to a predetermined target value. 9. The image processing method according to claim 1, wherein the recording agents of the plurality of colors are cyan, magenta, yellow, and black. 10. The image processing method according to claim 9, wherein the first table is provided for each of cyan, magenta, and yellow. 11. The image processing method according to claim 9, wherein the first table is provided for each of cyan, magenta, yellow and red, green, and blue. 12. An image processing apparatus for generating image data to be recorded on a recording medium by using a plurality of color recording materials including an achromatic color, wherein the input image signal is converted into a plurality of chromatic colors corresponding to the recording material. Conversion means for converting into a component, achromatic color extraction means for extracting an achromatic component based on the plurality of chromatic components, and a first table for setting an increment of the achromatic component for each of the chromatic components An image processing apparatus comprising: an achromatic color conversion unit configured to convert an achromatic component extracted by the achromatic color extraction unit based on the first table. 13. A chromatic color conversion means for performing conversion based on a second table for setting an increment for each of the plurality of chromatic color components. Image processing device. 14. An image forming apparatus for forming an image on a recording medium based on the achromatic color component converted by the achromatic color converting means and the chromatic color component converted by the chromatic color converting means. Claim 1.
3. The image processing device according to 3. 15. A program for realizing the image processing method according to claim 1 by being executed by a computer. 16. A recording medium on which the program according to claim 15 is recorded.