JPH11355593A - Image processor, image processing method and control method for the processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of quantization processing parts and the cost by qunatizing a multilevel image which is density corrected for every color component into levels of n>=3 and setting the output range of color component of a correcting means in accordance with the number of gray scales for every color component that can be expressed by an image forming device. SOLUTION: Based on gray scale expressing ability information of a printer 3 obtained by communication, CPU 11 sets the output range of table data of a gamma conversion processing part 26 to be 0 to 255 and that of only the gamma table of black k to be a half of it, being 0 to 127, to binarize the quantization value of k even in ternary error spreading processing concerning four colors CMYK. Consequently, quantizing processing of density data is error spreading processing of making CMY ternary or binary. By executing processing of varying the gray scale range of data to input to a quantizing processing part 27 like this, it is possible to execute quantizing processing of different number of gray scales for every color component to unnecessitate the preparation of many quantizing processing parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method, and a control method therefor. For example, at least one predetermined color among a plurality of color components is expressed in three or more gradations, and a plurality of color components are expressed. An image processing apparatus and method connected to a printer or the like in which the number of expressible gradations of each color component is not all equal, and
It relates to the control method.

[0002]

2. Description of the Related Art An image recording apparatus such as a color ink-jet printer converts multi-value density data of C (cyan), M (magenta), Y (yellow) and K (black) into binary data for each color component. The color image is formed by controlling the ejection and non-ejection of the four CMYK inks according to the binarization result.

Recently, not only CYMK four color inks,
An ink jet printer that prints at three or more values for each color by simultaneously using the four colors and the same color ink having the same density is provided. Such a printer can form a high-quality color image with higher gradation than a four-color ink printer. However, for example, of CMYK
For K, it is considered that the effect of improving image quality is small even if ink with low density is used.Therefore, for CMY, two types of dark and light inks are prepared to express ternary values, and for K, one type of ink is prepared. Even in a printer that uses more than four colors of ink, such as expressing a binary image, not all color components are necessarily expressed in multiple gradations.

[0004] Alternatively, there is a printer in which two or more types of print heads are replaceable. One of the print heads is equipped with one type of ink cartridge for each color,
When this print head is used, binary representation of each color is performed. In addition, for example, two types of ink cartridges of each color are mounted on another print head, and when this print head is used, the ternary representation of each color can be performed.

[0005]

However, the above technique has the following problems.

In the case of a printer in which the number of gradations that can be expressed by each color of CMYK or a printer in which the number of gradations that can be expressed by changing the print head changes, the quantization processing of the multi-value density data is performed for each color or However, it is necessary to change for each installed print head. For example, CM
In printers where Y is ternary and K is binary, CM
It is necessary to binarize for Y and binarize for K. Further, when a certain print head is mounted, binarization is required, and when another print head is mounted, ternarization is required. For this reason, a binarization processing unit and a ternarization processing unit are prepared, and these processing units are switched and used according to the processing timing or the attached print head. This increases the number of gates in the array, which increases costs.

An object of the present invention is to solve the above-described problem. At least one predetermined color among a plurality of color components is expressed in three or more gradations, and each of the plurality of color components can be expressed. It is an object of the present invention to provide an image processing apparatus and method which do not require preparing a plurality of quantization processing units in order to supply image data to a printer apparatus or the like in which all the gradation numbers are not equal, and to provide a control method therefor. And

[0008] Further, a printer device capable of selectively mounting at least one of at least two types of print heads and capable of changing the number of gradations that can be expressed by changing the print heads. Another object of the present invention is to provide an image processing apparatus and method that do not require preparing a plurality of quantization processing units to supply image data to the image processing apparatus, and a control method thereof.

[0009]

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

An image processing apparatus according to the present invention expresses at least three tones for at least one predetermined color among a plurality of color components, and all of the expressible number of gradations of each of the plurality of color components are equal. Not necessarily, an image processing apparatus connected to an image forming apparatus that forms a visible image on a recording medium, a correction unit that performs density correction of a multi-valued image composed of the plurality of color components for each color component, A quantizing means for quantizing the density-corrected multi-valued image into n (≧ 3) values, and an output range of the correcting means according to the number of gradations for each color component that can be expressed by the image forming apparatus. Setting means for setting each time.

A recording medium in which one of at least two types of print heads can be selectively mounted and the number of gradations that can be expressed by changing the print heads can be changed. An image processing apparatus connected to an image forming apparatus that forms a visible image on a multi-valued image.
The image processing apparatus further includes a quantization unit that quantizes the value to n (≧ 3), and a setting unit that sets an output range of the correction unit according to a print head mounted on the image forming apparatus.

[0012] In the image processing method according to the present invention, at least one predetermined color out of a plurality of color components is expressed in three or more gradations, and the number of expressible gradations of each of the plurality of color components is all equal. An image processing method of an image processing apparatus connected to an image forming apparatus that forms a visible image on a recording medium, wherein the color is determined according to the number of gradations for each color component that can be expressed by the image forming apparatus. An output range is set for each component, and based on the set output range, the density correction of the multi-valued image composed of the plurality of color components is performed for each color component, and the density-corrected multi-valued image is n (≧ 3). It is characterized in that it is quantized to a value.

Further, a recording medium in which one of at least two types of print heads can be selectively mounted, and the number of gradations that can be expressed by changing the print heads can be changed. An image processing method of an image processing apparatus connected to an image forming apparatus that forms a visible image, wherein an output range is set according to a print head mounted on the image forming apparatus, and the output range is set to the set output range. The multi-valued image is subjected to density correction based on the multi-valued image, and the density-corrected multi-valued image is quantized into n (≧ 3) values.

According to a control method of an image processing apparatus according to the present invention, at least one predetermined color among a plurality of color components is expressed by three or more gradations, and the number of gradations that can be expressed by each of the plurality of color components is represented. Are not all equal,
Correction means for performing density correction for each color component of a multi-valued image composed of a plurality of color components for supplying image data to an image forming apparatus for forming a visible image on a recording medium, and density-corrected multi-valued A method of controlling an image processing apparatus having a quantization unit that quantizes an image to an n (≧ 3) value, wherein the output of the correction unit according to the number of gradations for each color component that can be expressed by the image forming apparatus. The range is set for each color component.

Further, a recording medium in which one of at least two types of print heads can be selectively mounted and the number of gradations that can be expressed by changing the print heads can be changed. Correction means for performing density correction of a multi-valued image for supplying image data to an image forming apparatus for forming a visible image on the multi-valued image;
A method for controlling an image processing apparatus having a quantization unit for quantizing to an n (≧ 3) value, wherein an output range of the correction unit is set according to a print head mounted on the image forming apparatus. And

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

In the following, an example in which the present invention is applied to a color copying machine will be described. However, in the present invention, the functions of a processing unit for performing density conversion (a gamma conversion processing unit in the embodiment) and a quantization processing unit are described. It is characterized by its operation, and is not limited to a color copying machine, an image processing unit such as a color printer and a color scanner, an image processing device such as an image processor, and an image processing program supplied to a computer device such as a personal computer. It is also possible to apply to software such as a printer driver.

[0018]

[First Embodiment] FIG. 2 is a block diagram showing a configuration example of an image processing apparatus to which the present invention is applied.

In FIG. 2, an image input unit (scanner) 1
Scans an original image (original) and outputs digital image data of 256 gradations for each of RGB (red, green and blue) colors. The image processing unit 2 generates CMYK n-value data to be output to the printer device 3 based on RGB image data input from the image input unit 1 in raster scanning order. Hereinafter, the function of the image processing unit 2 will be described in detail.

The CPU 11 controls the entire image processing apparatus 2 using the RAM 13 as a work memory in accordance with the control and image processing programs stored in the ROM 12. The ROM 12 also contains image processing data such as a gamma conversion processing table described later. Further, an image processing apparatus described later
Needless to say, each of the functional blocks 2 can be achieved by the CPU 11 executing an image processing program stored in the ROM 12, but in that case, it is desirable to provide a dedicated image memory.

The shading correction processor 2 of the image processor 2
1 performs shading correction according to the reading characteristics of the image input unit 1 on the input RGB image data. The filtering processing unit 22 performs filtering such as smoothing processing or edge enhancement on the image data input from the shading correction processing unit 21. The scaling unit 23 performs scaling on the image data input from the filtering unit 22. The brightness / density conversion processing unit 24 converts the RGB image data input from the scaling unit 23 into CMY image data. UCR /
The masking processing unit 25 extracts a K component from the image data input from the luminance / density conversion processing unit 24, and performs a masking operation to match the obtained CMYK image data with the color reproduction characteristics of the printer device 3.

The gamma conversion processing section 26 performs density conversion on the image data input from the UCR / masking processing section 25 in accordance with the color development characteristics of the recording paper. The gamma conversion processing unit 26
It is realized as a table having 8-bit output data corresponding to each gradation of YK, that is, 4 × 256 = 1024 types of input data.

The quantization processing unit 27 converts the image data input from the gamma conversion processing unit 26 into n values (n ≧ 2, a relatively small number). The processing performed by the quantization processing unit 27 may include any of known n-value error diffusion processing and n-value dither processing,
It can be used selectively. n-valued CMYK n
The value image data is 0, 1, ..., for each color component of each pixel.
has any value of n-1, and is dot-sequential (one pixel unit), that is, in the order of C1, M1, Y1, K1, C2, M2, Y2, K2, C3,. It is sent to the printer device 3.

The printer device 3 forms a visible image on a predetermined recording sheet based on the CMYK n-value image data input from the image processing unit 2 in raster scanning order and dot sequence. The printer device 3 is an inkjet printer that records an image on recording paper by ejecting ink from a print head, and nc, nm, ny, nk for each color component of CMYK.
Can be expressed. For example, from the image processing unit 2 to C
When 0, 1,..., Nc-1 are input as image data, a cyan pixel having a density corresponding to the value is formed. Note that the value 0
Represents no ink ejection, and the value nc-1 corresponds to the maximum density. The same applies to Y, M and K.

However, the printer 3 of this embodiment is
Not all colors have the same number of tones, ie "nc
= nm = ny = nk ”. For example, the CMY three colors include a dark color ink (dark ink) and a light color ink (light ink), and for example, can express three gradations of dark ink discharge, light ink discharge, and ink non-discharge. However, for the K color, there is only one kind of ink, so that only two gradations can be expressed. Thus, in the present embodiment, nc = nm =
An example of the printer device 3 with ny = 3 and nk = 2 and the image processing unit 2 with a quantization number n = 3 will be described, but the present invention is not limited to this.
The number of gradations that can be expressed for the four colors of MYK is not the same, that is, "n
The present invention can be applied to an image processing apparatus including a printer apparatus other than “c = nm = ny = nk”, or an image processing apparatus connected to such a printer apparatus.

Next, referring to FIG.
The detailed configuration and operation of the quantization processing unit 27 will be described.

In FIG. 3, gamma tables 26a, 26b, 26c and 26d correspond to CMYK, respectively.
It is realized as a memory such as a ROM or a RAM in which 8-bit output data corresponding to input data of 6 gradations is stored.
The 8-bit × 4 data output from the gamma tables 26a to 26d is selected by the selector 26e according to the timing. In other words, the UCR / masking processing unit 25 sends C,
Image data is input in the order of M, Y, K, C,..., And the selector 26e selects gamma tables 26a to 26d corresponding to the colors of the input image data. For example, if the input is the timing of C color, the output of the gamma table 26a is selected.

The quantization processing section 27 performs error diffusion ternary processing according to the error diffusion matrix shown in FIG. Adder 27
a is the quantization error value of the pixel one line before the pixel of interest supplied from the FIFO memory 27c, and the quantization error value of the pixel on the left side supplied from the error register 27d before quantization of the pixel of interest. Add to pixel value.

The quantization determining section 27b quantizes the corrected value of the target pixel input from the adder 27a, and calculates a quantization error. Since the quantization error is diffused to two pixels, the quantization determination unit 27b removes the least significant bit of the calculated quantization error and reduces its value to half.

The FIFO memory 27c delays the quantization error value output from the quantization determination unit 27b by one line in order to add the quantization error value to a pixel one line later. However, since error data for four colors is stored for one pixel, the number of cells in the FIFO memory 27c is the number of pixels in one line × 4.

The error register 27d delays the quantization error value output from the quantization determination section 27b by one pixel in order to add the quantization error value to the pixel on the right of the target pixel. However, in order to store an error value for each color of CMYK, the register 27d has a configuration in which, for example, four 8-bit registers are arranged.

The processing algorithm in the quantization determination unit 27b is as follows, where X is a corrected pixel value obtained by adding a correction error to the pixel value of the target pixel, and ΔX is a quantization error. (1) If 192 ≦ X, the quantization value is 2, and the quantization error ΔX is X
-256 (2) If 64 ≦ X <192, the quantization value is 1, and the quantization error ΔX is X
-128 (3) If X <64, the quantization value is 0 and the quantization error ΔX is X

As described above, the printer device 3 forms a color image using dark ink and light ink for CMY and a single ink for K. Therefore,
If pixel values 0 to 2 are input for CMY, three-gradation image formation is performed by ejecting no ink for 0, ejecting light ink for 1, and ejecting dark ink for 2. . However, for K, there is only one type of ink, so pixel value 0
Even if ~ 2 is input, three-tone image formation cannot be performed.

Therefore, the CPU 11, for example,
By communicating with the CPU, information indicating the gradation expressing ability is obtained (step S1 in FIG. 5), and table data of the gamma tables 26a to 26d is set based on the obtained information (step S2). That is, for the comma tables 26a to 26c, a table having an output range of 0 to 255 shown in FIG.
Only the gamma table 26d has an output range of 0 to 127 shown in FIG. 1B.
Is set. The table shown in FIG. 1B is obtained by, for example, halving the output values of a table whose normal output range is 0 to 255. In this way, even if the ternary error diffusion processing is performed for the four CMYK colors, the quantization value of K becomes 0 or 1, and an appropriate output can be obtained for the printer device 3.

That is, the quantization processing of the density data according to the present embodiment is an error diffusion processing in which CMY is ternary and K is binary. However, the present invention is not limited to this, and can be similarly implemented as long as the number of gradations for each color of the printer device 3 is different. Alternatively, even if the quantization processing is not error diffusion, for example, dither processing can be applied. When the gradation number of each color of the printer device 3 is nc, nm, ny, and nk, and the quantization number is n, the range of data input to the quantization processing unit 27 is represented by the following equation for each color. What is necessary is just to process the gamma conversion processing part 26 so that it may become the value of g. gc = 256 x (nc-1) / (n-1)-1 gm = 256 x (nm-1) / (n-1)-1 gy = 256 x (ny-1) / (n-1)- 1 gk = 256 × (nk-1) / (n-1)-1

In the above description, the example of changing the number of input gradations to the quantization processing unit 27 by changing the gamma table for each color has been described. However, the present invention is not limited to this.
As a result, some means for obtaining the same compression of the data range as described above may be provided, for example, means for shifting the data of K right by one bit in the above example.

As described above, by performing the process of changing the gradation range of the data input to the quantization processing unit for each color component, quantization with a different number of gradations for each color component is performed by one type of quantization method. Processing can be performed.

In the above description, an example in which an ink jet printer is used as the printer device 3 has been described. However, the present invention is not limited to this, and a case where a laser beam printer that forms an image using a plurality of toners of the same color and different densities is used. Are also included in the present invention. In addition to the case where the printer device 3 forms a color image using four colors of CMYK, in a printer device that forms a color image using three colors of CMY, image formation is performed in three gradations for CM and two gradations for Y. In this case, the present invention can be applied.

[0039]

Second Embodiment As described above, there is an ink jet printer that can change the number of output gradations by replacing a print head. For example, when print head A is installed, three gradations of dark ink ejection, light ink ejection, and ink non-ejection are performed for each color component of CMYK, and when print head B is installed, ink ejection and ejection for each CMYK color are performed. In some cases, two gradations of non-discharge can be expressed. In such a case, in the image processing apparatus shown in FIG. 2, if the contents of the gamma tables 26a to 26d can be rewritten by a CPU (not shown) or the like, the same as in the first embodiment regardless of which print head is mounted, Then, the quantization processing can be performed by one quantization processing unit 27.

When the number of gradations that can be printed by the print head A is C,
Assuming that nca and M are nma, Y is nya and K is nka, and the number of gradations that can be printed by the print head B is C for ncb, M for nmb, and Y for ny
Let b and K be nkb. However, not all of these gradation numbers have the same value, and the gradation number n of the data that can be output by the quantization processing unit 27 is not smaller than the values of all eight gradation numbers. Shall be. When the cartridge A is mounted, the gamma conversion processing unit 26 performs processing so that the range of data input to the quantization processing unit 27 is from 0 to the value of g shown in the following equation for each color. I just need. Note that the following equation is for the case where the input range is 256, but if the input range is represented by f, for example, “256” in the following equation may be replaced with f. gc = 256 x (nca-1) / (n-1)-1 gm = 256 x (nma-1) / (n-1)-1 gy = 256 x (nya-1) / (n-1)- 1 gk = 256 × (nka-1) / (n-1)-1

When the cartridge B is mounted, the gamma conversion processing unit sets the range of data input to the quantization processing unit 27 from 0 to the value of g shown in the following equation for all colors. You can process it at 26. gc = 256 x (ncb-1) / (n-1)-1 gm = 256 x (nmb-1) / (n-1)-1 gy = 256 x (nyb-1) / (n-1)- 1 gk = 256 × (nkb-1) / (n-1)-1

As described above, as processing corresponding to steps S1 and S2 in FIG. 5, the CPU 11 determines the type of the printer head mounted on the printer device 3 and rewrites the gamma table according to the print head. For example, when the print head A is mounted, the gradation number of the data of each color of CMYK output from the quantization processing unit 27 is nca, nm, respectively.
a, nya, and nka, and ncb, nmb, nyb, and nkb when the print head B is mounted.In each case, without changing the quantization processing unit 27 itself, it is appropriate for the printer device 3. A quantization process can be performed.

Further, a ROM or EPROM for storing data for allowing the printer head to select an optimal gamma table or gamma table data itself is provided.
The CPU 11 that has read the data may set the gamma table of the gamma conversion processing unit 26.

In this embodiment, the printer 3
Need not be a color printer, and can be applied to a printer that can print only one color or two colors as long as the number of print gradations changes by replacing the print head.

According to the above-described embodiment, a color image forming apparatus in which the number of recordable gradations is not the same for all the color components, or an image formation in which the number of recordable gradations changes depending on the printhead to be mounted. In the image processing apparatus including the apparatus or connected to such an image forming apparatus, the image forming apparatus according to the number of gradations that can be expressed for each color, or by the print head mounted on the image forming apparatus By changing the output range of the density conversion processing unit for each color according to the number of expressed gradations, the number of gradations of the image data output from the quantization processing unit can be changed according to the state of the image forming apparatus or the image forming apparatus. Can be controlled to an optimum value.

[0046]

[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 storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU or MPU) of the system or apparatus.
Needless to say, this can also be achieved by the PU) 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. When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also the OS running on the computer based on the instructions of the program code.
It goes without saying that an (operating system) performs a part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, based on an instruction of the program code, It goes without saying that 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.

[0049]

As described above, according to the present invention, three or more gradations are expressed for at least one predetermined color among a plurality of color components, and the number of gradations that can be expressed for each of the plurality of color components It is possible to provide an image processing apparatus and method that does not require preparing a plurality of quantization processing units in order to supply image data to a printer device or the like in which not all are equal, and a control method thereof.

Also, a printer device capable of selectively mounting one of at least two types of print heads and changing the number of gradations that can be expressed by changing the print heads. It is possible to provide an image processing apparatus and method that do not need to prepare a plurality of quantization processing units to supply image data to the image processing apparatus, and a control method thereof.

[Brief description of the drawings]

FIG. 1A is a diagram showing a characteristic example of a gamma table set in a gamma conversion processing unit according to an embodiment of the present invention;

FIG. 1B is a diagram showing an example of characteristics of a gamma table set in a gamma conversion processing unit according to one embodiment of the present invention;

FIG. 2 is a block diagram illustrating a configuration example of an image processing apparatus according to an embodiment of the present invention;

FIG. 3 is a block diagram showing a detailed configuration example of a gamma conversion processing unit and a quantization processing unit shown in FIG. 2;

FIG. 4 is a diagram showing an example of an error diffusion matrix of an n-valued error diffusion process executed by the quantization processing unit shown in FIG. 3;

FIG. 5 is a flowchart illustrating an example of a gamma table setting process executed by the CPU illustrated in FIG. 2;

Claims (15)

[Claims] 1. A recording medium in which at least three gradations are expressed for at least one predetermined color among a plurality of color components and the number of expressible gradations of each of the plurality of color components is not all equal. An image processing apparatus connected to an image forming apparatus that forms a visible image, comprising: a correction unit configured to perform density correction of a multi-valued image including a plurality of color components for each color component; and a density-corrected multi-valued image. And a setting unit that sets the output range of the correction unit for each color component according to the number of gradations for each color component that can be expressed by the image forming apparatus. An image processing apparatus comprising: 2. An image processing apparatus which expresses at least three tones for at least one predetermined color among a plurality of color components, and wherein the number of expressible tones of each of the plurality of color components is not all equal. Correction means for performing density correction of the multi-valued image composed of the plurality of color components for each color component; quantizing means for quantizing the density-corrected multi-valued image to n (≧ 3) values; Setting means for setting an output range of the correction means for each color component according to the number of gradations for each expressible color component. 3. The image processing apparatus according to claim 1, wherein an output range of the correction unit is compressed according to the number of gradations for each expressible color component. 4. The method according to claim 1, wherein the number of gradations for each expressible color component is m.
If (≦ n), the output range of each color component of the correction means is from 0 to g = f × (m−1) / (n−1) −1, where f is represented by the input range. 3. The image processing device according to claim 1, wherein: 5. A recording medium in which one of at least two types of print heads can be selectively mounted, and the number of gradations that can be expressed by changing the print heads can be changed. An image processing apparatus connected to an image forming apparatus that forms a visible image on a multi-valued image, comprising: a correcting unit that performs density correction of a multi-valued image; and a quantizing the density-corrected multi-valued image to n (≧ 3) values. An image processing apparatus comprising: a quantization unit configured to set an output range of the correction unit according to a print head mounted on the image forming apparatus. 6. An image processing apparatus in which one of at least two types of print heads can be selectively mounted, and the number of gradations that can be expressed by changing the print heads can be changed. Correction means for performing density correction of the multi-valued image, quantization means for quantizing the density-corrected multi-valued image to n (≧ 3) values, and the correction means according to a print head to be mounted. Setting means for setting an output range of the image processing apparatus. 7. If the number of gradations that can be expressed by the attached printer head is m (≦ n), the output range of the correction means is 0 to g = f × (m−1) / (n−1). 7. The image processing apparatus according to claim 5, wherein f is represented by an input range. 8. A recording medium in which at least three gradations are expressed for at least one predetermined color component among a plurality of color components, and the number of reproducible gradations of each of the plurality of color components is not always equal. An image processing method for an image processing apparatus connected to an image forming apparatus that forms a visible image, wherein an output range for each color component is set according to the number of gradations for each color component that can be expressed by the image forming apparatus. Then, based on the set output range, the density correction of the multi-valued image composed of the plurality of color components is performed for each color component, and the density-corrected multi-valued image is quantized into n (≧ 3) values. Characteristic image processing method. 9. A recording medium in which one of at least two types of print heads can be selectively mounted, and the number of gradations that can be expressed by changing the print heads can be changed. An image processing method of an image processing apparatus connected to an image forming apparatus that forms a visible image on an image forming apparatus, comprising: setting an output range according to a print head mounted on the image forming apparatus; An image processing method, comprising: performing a density correction of a multi-valued image based on the multi-valued image; and quantizing the density-corrected multi-valued image into n (≧ 3) values. 10. A recording medium in which at least three gradations of at least one predetermined color among a plurality of color components are expressed and the number of expressible gradations of each of the plurality of color components is not all equal. A recording medium on which a program code of an image processing method of an image processing apparatus connected to an image forming apparatus that forms a visible image is recorded, wherein the program code corresponds to a gradation number for each color component that can be expressed by the image forming apparatus. A code for a setting step for setting an output range for each of the color components, and a code for a correction step for performing, for each color component, density correction of the multi-valued image composed of the plurality of color components based on the set output range. A code for a quantization step for quantizing the corrected multi-valued image to n (≧ 3) values. 11. A recording medium in which one of at least two types of print heads can be selectively mounted, and the number of gradations that can be expressed by changing the print heads can be changed. A recording medium on which a program code of an image processing method of an image processing apparatus connected to an image forming apparatus that forms a visible image is recorded, wherein an output range is set according to a print head mounted on the image forming apparatus. The code of the setting step to be set, the code of the correction step to correct the density of the multi-valued image based on the set output range, and the quantization to quantize the density-corrected multi-valued image to n (≧ 3) values And a step code. 12. A recording medium in which at least three gradations are expressed for at least one predetermined color among a plurality of color components, and the number of expressible gradations of each of the plurality of color components is not always equal. Correction means for performing density correction for each color component of a multi-valued image composed of the plurality of color components for supplying image data to an image forming apparatus for forming a visible image, and converting the density-corrected multi-valued image to n (≧ 3) A recording medium on which a program code of a control method of an image processing apparatus having a quantization unit for quantizing to a value is recorded, wherein the program code is represented by a gradation number for each color component that can be expressed by the image forming apparatus. A code for setting an output range of the correction means for each color component. 13. A recording medium in which one of at least two types of print heads can be selectively mounted, and the number of gradations that can be expressed by changing the print heads can be changed. Correction means for performing density correction of a multi-valued image for supplying image data to an image forming apparatus which forms a visible image on the image forming apparatus;
(≧ 3) A recording medium in which a program code of a control method of an image processing apparatus having a quantization unit for quantizing to a value is recorded, wherein the correction unit of the correction unit according to a print head mounted on the image forming apparatus. A recording medium comprising a code for setting an output range. 14. A recording medium in which at least three gradations of at least one predetermined color component among a plurality of color components are expressed and the number of reproducible gradations of the plurality of color components are not all equal. Correction means for performing density correction for each color component of a multi-valued image composed of the plurality of color components for supplying image data to an image forming apparatus for forming a visible image, and converting the density-corrected multi-valued image to n A method of controlling an image processing apparatus having a quantization unit that quantizes a value to (≧ 3), wherein the output range of the correction unit is changed according to the number of gradations for each color component that can be expressed by the image forming apparatus. A control method characterized by setting for each component. 15. A recording medium in which at least one of at least two types of print heads can be selectively mounted, and the number of gradations that can be expressed by changing the print heads can be changed. Correction means for performing density correction of a multi-valued image for supplying image data to an image forming apparatus which forms a visible image on the image forming apparatus;
(≧ 3) A method of controlling an image processing apparatus having a quantization unit for quantizing to a value, wherein an output range of the correction unit is set according to a print head mounted on the image forming apparatus. How to control.