JPH10224608A - Image processing unit and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing unit and its method that applies processing to image data for two-color output or the like in a way by which a color of an original image is identified. SOLUTION: A 2-color processing section 303 generates 2-color image data K, R and hue angle data DEG from received RGB image data. A color patterning processing section 304 selects any of a plurality of pattern data stored in a memory 3043 based on a result of comparing phase area division information stored in the memory with the hue angle data DEG for each picture element and applies patterning processing to the 2-color image data K, R by using the selected pattern data.

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 more particularly to an image processing apparatus and method for generating two-color component image data or density image data based on input color image data. It is.

[0002]

2. Description of the Related Art There is an image processing apparatus which performs various types of image processing on input digital image data and converts the image data into image data for two-color output. There is also an image processing apparatus that converts input digital image data, for example, RGB luminance data into CMYK density data.

[0003]

However, the above technique has the following problems. In other words, if the input RGB image data is converted into image data for two-color output, the reproducibility of the tint will inevitably decrease.For example, a portion having a completely different tint in the input image will have a similar color in the output image. There is a problem that it becomes taste.

When converting RGB image data into CMYK image data, the dynamic range of CMYK density data that depends on the characteristics of an output device is usually smaller than the dynamic range of RGB luminance data that depends on the characteristics of an input device. As a result, similar to the case of conversion to image data for two-color output, a problem occurs in that the reproducibility of the tint is reduced and an image having a tint different from the input image is output, and the hue is close to the saturation. Is noticeable in different colors.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has an image processing apparatus capable of performing a process of enabling the color of an original image to be distinguished from image data for two-color output. And a method thereof.

[0006]

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

[0007] An image processing apparatus according to the present invention comprises: generating means for generating image data of two color components based on input color image data; and storage means for storing a plurality of pattern data and phase area division information. Selecting means for selecting pattern data from the storage means for each pixel based on a hue of the color image data and the division information; and image data of the two-color component using the pattern data selected by the selecting means. And a processing means for performing a patterning process.

Further, according to the image processing method of the present invention, two-color component image data is generated based on the input color image data, and the division information of the phase area stored in the storage means and the color image data The hue is compared for each pixel, and based on the comparison result, one of a plurality of pattern data stored in the storage unit is selected for each pixel, and the two-color component is selected using the selected pattern data. Is characterized by performing patterning processing on the image data.

[0009]

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 embodiments, an example in which the present invention is applied to a copying machine will be described. However, the present invention is not limited to this, and is applied to image processing of a facsimile apparatus or a printer that forms an image with two or more color components. Can be applied.

[0010]

First Embodiment [Overview of Apparatus] FIG. 1 is an overview of an image processing apparatus according to an embodiment of the present invention.

In FIG. 1, a document feeder 1 feeds placed documents one by one or two sheets continuously to a predetermined position on a document glass 2. Scanner unit 4 has lamp 3
When an original is supplied onto the original platen glass 2 by the original feeding device 1, the original is scanned in a predetermined direction by a driving unit (not shown). Light reflected from the document passes through a lens 8 via mirrors 5, 6, and 7, and forms an image on an image sensor unit 9 including an RGB color separation filter, a CCD line sensor, and the like. The image signal output from the image sensor unit 9 is sent to an image processing unit described later.

An exposure control unit 10 constituted by a laser scanner scans the photosensitive member 11 with a light beam modulated based on an image signal output from the control unit described later, and applies an electrostatic force to the surface of the photosensitive member 11. Form a latent image. The electrostatic latent image formed on the photoreceptor 11 is visualized by a developer (toner) of a predetermined color by the developing device 12 or 13 to become a toner image.

The fixed-size recording paper (recording medium) loaded and stored in the recording paper loading section 14 or 15 is fed by a feed roller 25.
Or to the registration roller 28 by the
After the timing for aligning the image tip with the image formed on 11 is taken, it is supplied to the transfer separation charger 16.
Thereafter, the recording paper is transferred to the photoconductor 11 by the transfer separation charger 16.
After the upper toner image is transferred, it is separated from the photoconductor 11,
The toner image is sent to the fixing unit 17 by the transport belt 27 and is fixed.

The paper discharge roller 18 discharges the recording paper on which the image has been recorded to the tray 20. The flapper 21 disposed immediately before the paper discharge roller 18 switches the transport destination of the recording paper on which the image is recorded to the discharge port or the internal transport path 22, and is used in a multiplex or double-sided image forming process.

In the two-sided image forming process, after the recording paper has passed the paper discharge sensor 19, the paper discharge roller 18 is rotated in the reverse direction, the flapper 21 is raised upward, and the recording roll is transferred to the transport path 22.
And 23 to the intermediate tray 24. At the next image forming timing, the recording paper stored in the intermediate tray 24 is supplied to the above-described image forming unit, and an image is recorded on the back surface of the recording paper. In the multiplex image forming process,
Raise 21 upward and feed the recording paper that has passed
It is conveyed to the intermediate tray 24 via 22 and 23. At the next image forming timing, the recording paper stored in the intermediate tray 24 is supplied to the above-described image forming unit, and the image is multiplex-recorded on the surface of the recording paper.

[Control Unit] FIG. 2 is a block diagram showing each control unit of the image processing apparatus according to the present embodiment.
According to a control program stored in the OM 1026 in advance, each control unit described later is controlled. In addition, RAM1027
It is used as a work memory or the like when performing calculations and processing by the PU circuit unit 1025.

The automatic document feeder control unit 1021 controls operations such as feeding the originals placed on the automatic document feeder 1 one by one or two consecutively onto the platen glass 2.

The image reader control unit 1022 includes the above-described image sensor unit 9 and outputs an analog image signal photoelectrically converted by the image sensor unit 9. The image signal control unit 1023 performs image processing on the image signal output from the image sensor unit 9, that is, the output signal of the image reader control unit 1022. The printer control unit 1024 irradiates and scans the photosensitive member 11 with a light beam obtained by driving the exposure control unit 10 based on the video signal output from the image signal control unit 1023.

The operation unit 1028 is an operation panel provided with a keyboard and a touch panel for setting a mode necessary for image formation, a display such as an LCD for displaying an operation state and operation conditions of the apparatus, and the like.

[Image Signal Control Unit] FIG.
It is a block diagram which shows the example of a detailed structure of 023.

In FIG. 3, C for reading image information
The analog RGB image signal output from the CD 301 is converted into, for example, an 8-bit digital RGB signal by the A / D converter 302. The digital image data output from the A / D converter 302 is converted to black by the two-color processing unit 303 together with each of the RGB data.
It is converted to two-color data of (K) and red (R). The color patterning processing unit 304 performs patterning processing using two-color data. The patterning process is a process of replacing a certain part of the input image with pattern image data such as a lattice pattern or a geometric pattern. The two-color image data thus patterned is filtered by the image processing unit 305,
After various image processing such as image format processing such as gamma conversion, error diffusion or screen processing is performed, the image data is sent to the printer unit 306 to form a two-color image.

FIG. 4 is a diagram showing a detailed configuration example of the two-color processing section 303 and the color-pattern processing section 304.
The hue angle data calculation unit 3032
The K image data and the R image data (both density data) corresponding to the input RGB image data are generated for each pixel using the hue angle data DEG calculated by the following.
The hue angle data calculation unit 3032 calculates hue angle data DEG for specifying in which hue region the pixel exists based on the input RGB image data. Hue here is a word that expresses the difference between colors.Since a color is expressed by the vector sum of RGB, which is the three primary colors of color, as a reference axis, it is usually the coordinates for each of the RGB axes. In some cases, it may be represented by a color system expressing hue such as HIS, Lab, or XYZ.

As shown in FIG. 5A, the hue in the present embodiment is represented by an angle that makes a red (R) rotation around the counterclockwise direction with zero degree. Therefore, blue (B) is 120 degrees and green (G) is 240 degrees. In addition, the luminance data decreases toward the center of the regular hexagon illustrated in FIG. 5A, and increases toward the outer periphery.
In the two-color processing, low-luminance image data located near the center of the regular hexagon becomes low-density image data, and high-luminance image data located near the outer periphery becomes high-density image data. The R data is output in the area shown in FIG. 5B, and the density increases toward the direction of the arrow and the outer periphery in the figure. Similarly, K data is output in the area shown in FIG. 5C, and its density increases in the direction of the arrow and in the outer periphery in the figure.

The color-patterning conversion unit (K) 3041 in the color-patterning processing unit 304 receives the K input from the density generation unit 3031.
The hue angle data calculation unit 3032 calculates the density data for each pixel.
Is replaced with a predetermined pattern image according to the hue angle data DEG supplied from. Similarly, the color patterning conversion unit (R) 3042 converts the R density data input from the density generation unit 3031 in advance for each pixel according to the hue angle data DEG supplied from the hue angle data calculation unit 3032. Replace with the determined pattern image. The hue angle data DEG
Is read from the memory 3043 for storing pattern data for each pixel. Further, in the color patterning processing units 3041 and 3042, prior to the above processing, the hue angle area is determined in advance, and the hue angle data DEG is used to determine in which area each pixel exists.

FIG. 6 shows a color patterning processing unit 3041 (or 304).
In the block diagram illustrating the detailed configuration example of 2), the pattern replacement unit 601 selects a pattern to be assigned to the pixel based on the hue angle data DEG for each pixel, and outputs pattern data according to the pattern. . More specifically, as shown in FIG. 7, for example, the pattern replacement unit 601 determines which hue angle area includes the pixel from the hue angle data DEG of each pixel based on information obtained by dividing the entire hue area into five areas. Is determined, and pattern data corresponding to the determination result is selected from the memory 3043. Note that the hue area division information is set in the hue angle map memory 602 in advance, as described later. The pattern data selected by the pattern replacement unit 601 is ANDed with the original K or R density data for each pixel in the AND gate 603. Such processing may be referred to as “patterning processing” or “shading processing”.

[Processing] FIG. 8 is a flowchart showing an example of a processing procedure according to the present embodiment, which is executed by the CPU circuit unit 1025 when a color patterning process is instructed by the operation unit 1208.

In step S801, whether or not the hue angle area is automatically set is selected. If "not automatically set" is selected, the hue angle area is set manually, and the operation unit 1208 is operated in step S802a. Hue area information is input. If “set automatically” is selected, the document on the platen glass 2 is scanned once in step S803a to obtain the hue and saturation distribution of the document, and the hue region is automatically determined from the distribution. Set. The hue area set in this way, that is, the hue area division information is stored in the hue map memory 605.

When the setting of the hue area is completed, copying is enabled. In step S804, the process waits for the copy button to be pressed. When the copy button is pressed, the original image is read. And the concentration data of R are calculated. In parallel with step S805, hue angle data for each pixel is generated in step S806, and in step S807, the calculated hue angle data and preset hue angle area data are compared for each pixel, and uniquely determined. Select the pattern data to be performed.

In step S808, the selected pattern data and the generated density data of K and R are shaded to complete the process.

FIG. 9 is a diagram showing an example of an image obtained by the above-described image processing. FIG. 9 (a) is an original image, FIG. 9 (b) is an image after two-color processing, and FIG. It is an image after a color patterning process. According to the present embodiment, as shown in FIG. 9, different patterns are assigned to a plurality of colors of the original image, which are difficult to discriminate only by the two-color processing, so that differences in the colors of the original image can be identified. Can be made possible. Although not clearly shown in the example of FIG. 9, an image obtained by shading a pattern corresponding to the density of the image after the two-color processing is obtained as the image after the color patterning processing.

As described above, according to the present embodiment, when forming an image in two colors of black and one other color, the output image is subjected to shading using a pattern corresponding to the difference in hue of the original image. Accordingly, it is possible to express a difference in hue in an original image that is difficult to distinguish only by changing the density of two colors.

[0032]

Second Embodiment Hereinafter, an image processing apparatus according to a second embodiment of the present invention will be described. In the second embodiment,
The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[Configuration] FIG. 10 is a diagram showing a detailed configuration example of the two-color processing unit 303 and the color pattern processing unit 304 in the second embodiment. FIG. 11 is a color pattern processing unit 3041 in the second embodiment. FIG. 39 is a block diagram showing a detailed configuration example of (or 3042).

The color patterning processing unit 304 of the second embodiment
A memory 3044 is provided in addition to the configuration of the first embodiment.
, Stores output density data, which will be described in detail later. The color patterning conversion unit 3041 (and 3042) in the second embodiment performs shading processing on the density data input from the density generation unit 3031 using the pattern data read from the memory 3043, as in the first embodiment. Unlike the first embodiment, the density replacement processing based on the output density data read from the memory 3044 is performed by the output density replacement unit 604 shown in FIG.
Do with.

As in the first embodiment, the hue area division information stored in the hue angle map memory 602, the pattern data stored in the memory 3043, and the output density data stored in the memory 3044 are , Can be arbitrarily set from the operation unit 1028. Therefore, the initial value of the hue angle region, an example of which is shown in FIG. 12A, can be arbitrarily changed as shown by the arrow in FIG. 12B, or can be further divided in the saturation direction as shown in FIG. 12C.

[Processing] FIG. 13 is a flowchart showing an example of the processing procedure of the second embodiment, which is slightly modified from the processing procedure of the first embodiment shown in FIG.

That is, when “not automatically set” is selected in step S801, output density data of each hue region is input from the operation unit 1208 in step S811. If “set automatically” is selected, only the hue angle region is set based on the hue distribution information obtained by scanning the document. Further, in step S812 corresponding to step S807 of the first embodiment, the calculated hue angle data is compared with the preset hue angle area data and output density data for each pixel, and uniquely determined. Select the pattern data to be used. Then, as in the first embodiment, in step S808, the selected pattern data and the generated K and R density data are shaded to complete this processing.

As described above, according to the present embodiment, when an image is formed in two colors of black and one other color, a shading process using a pattern corresponding to a difference in hue of an original image and a density replacement process Is applied to the output image, it is possible to express the hue difference in the original image, which is difficult to distinguish only by changing the density of the two colors, in more detail.

[0039]

Third Embodiment Hereinafter, an image processing apparatus according to a third embodiment of the present invention will be described. In the third embodiment,
The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[Configuration] FIG. 14 is a block diagram showing a detailed configuration example of an image signal control unit 1023 according to the third embodiment.
In this configuration, the dichroic processing section 303 in the configuration of the image signal control section 1023 shown in FIG.

In FIG. 14, the digital image data output from the A / D converter 302 is converted into a YMCK
Is converted into density image data. Color patterning processing unit 30
Step 4 performs a patterning process using the YMCK image data.

FIG. 15 is a diagram showing a detailed configuration example of the luminance / density conversion unit 307 and the color patterning processing unit 304. The density generation unit 3071 in the luminance / density conversion unit 307 is calculated by the hue angle data calculation unit 3072. Y corresponding to the input RGB image data for each pixel using the hue angle data DEG
Generates MCK image data (density data). The hue angle data calculation unit 3072 calculates hue angle data DEG for specifying in which hue area the pixel exists based on the input RGB image data. Also,
The saturation data calculation unit 3073 calculates the saturation data CHROMA of the input RGB image data. The saturation can be obtained as the absolute value of the vector sum of the RGB data of each pixel.For example, a conversion table is prepared as the saturation data calculation unit 3073, and the vector sum is input by inputting the RGB data to the conversion table. The absolute value (saturation data) may be output.

The color patterning conversion section (Y) 3045 in the color patterning processing section 304 receives the Y inputted from the density generation section 3071.
The hue angle data calculator 3072 calculates the density data for each pixel.
Is replaced with a predetermined pattern image in accordance with the hue angle data DEG supplied from the printer and the saturation data CHROMA supplied from the saturation data calculator 3073. Similarly, the color patterning conversion units 3046 to 3048 respectively include a density generation unit 3071
The M, C, and K density data input from the hue angle data DE supplied from the hue angle data calculation unit 3032 for each pixel.
Replace with a predetermined pattern image according to G and the saturation data CHROMA supplied from the saturation data calculation unit 3073. Note that hue angle data DEG and saturation data CHROM
The pattern data corresponding to A is read from the memory 3043 storing the pattern data for each pixel. Further, in the color patterning processing units 3045 to 3048, prior to the above processing, a hue area is determined in advance, and hue angle data DEG and saturation data CHROMA are determined in order to determine in which area each pixel exists. Is used.

FIG. 16 shows a color patterning processing unit 3041 (or 30).
42) is a block diagram showing a detailed configuration example of the present embodiment. The pattern replacement unit 601 selects a pattern to be assigned to the pixel based on the hue angle data DEG and the saturation data CHROMA for each pixel, and selects a pattern according to the pattern. Outputs pattern data. More specifically, the pattern replacement section 601
As shown in, based on the information obtained by dividing the entire hue area into 15 areas, it is determined from the hue angle data DEG and saturation data CHROMA of each pixel which hue area the pixel is included in, and the determination result Pattern data corresponding to memory 30
Choose from 43. Note that the hue area division information is set in the hue map memory 605 in advance, as described later. The pattern data selected by the pattern replacement unit 601 is shaded by the AND gate 603 on the Y (M, C or K) image data.

[Processing] FIG. 18 is a flowchart showing an example of the processing procedure of the third embodiment. The processing is executed by the CPU circuit section 1025 when the color patterning processing is instructed by the operation section 1208.

In step S801, whether or not the hue angle area is automatically set is selected. If "not automatically set" is selected, the hue angle area is set manually, and the operation unit 1208 is operated in step S802. A hue angle boundary value is input. If “automatically set” is selected, the document on the document table glass 2 is scanned once in step S803 to obtain the hue distribution of the document, and the hue angle area is automatically set based on the distribution status. . The hue angle area set in this way, that is, the hue area division information is stored in the hue angle map memory 602.

When the setting of the hue angle area is completed, copying is enabled. In step S804, the process waits until the copy button is pressed. When the copy button is pressed, the original image is read. Calculate YMCK concentration data. In parallel with step S805a, step S80
6a generates hue angle data for each pixel, and step S806b generates saturation data for each pixel.
In, the calculated hue angle data and saturation data are compared with hue angle area data set in advance for each pixel, and pattern data uniquely determined is selected.

Then, in step S808a, the selected pattern data and the generated YMCK density data are shaded to complete this processing.

FIG. 19 is a diagram showing an example of an image obtained by the above-described image processing. FIG. 19A shows an original image, and FIG.
The image after the density conversion, and FIG. 3C is the image after the color patterning process. According to the present embodiment, as shown in FIG. 19, a plurality of colors (especially colors with close hues and different chromas) of an original image that are difficult to determine when the luminance / density conversion is performed are different. By assigning a pattern, it is possible to identify a difference in tint of the original image.

[0050]

[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.).

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 a CPU or M
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. Examples of the storage medium for supplying the program code include a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM,
CD-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize 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 the 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.

In each of the above-described embodiments, the image processing (shading processing) by the color patterning processing unit 304 can be prohibited by the operation from the operation unit 1028.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts. Each module shown will be stored in a storage medium. That is, the program codes of at least the modules of “two-color data generation”, “hue comparison”, “pattern data selection”, and “patterning processing” may be stored in the storage medium.

[0056]

As described above, according to the present invention,
It is possible to provide an image processing apparatus and a method for performing processing that enables the color of an original image to be identified in image data for two-color output or the like.

[Brief description of the drawings]

FIG. 1 is an outline view of an image processing apparatus according to an embodiment of the present invention;

FIG. 2 is a block diagram showing each control unit of the image processing apparatus according to the embodiment;

FIG. 3 is a block diagram showing a detailed configuration example of an image signal control unit shown in FIG. 2;

FIG. 4 is a diagram showing a detailed configuration example of a two-color processing unit and a color pattern processing unit shown in FIG. 3;

FIG. 5A is a diagram illustrating a hue according to the embodiment;

FIG. 5B is a diagram illustrating a hue according to the embodiment;

FIG. 5C is a diagram illustrating a hue according to the embodiment;

FIG. 6 is a block diagram showing a detailed configuration example of a color patterning processing unit shown in FIG. 4;

FIG. 7 is a diagram showing an example of dividing a hue area;

FIG. 8 is a flowchart illustrating an example of a processing procedure according to the embodiment;

FIG. 9 is a view showing an example of an image obtained by the image processing shown in FIG. 8;

FIG. 10 is a diagram illustrating a detailed configuration example of a two-color processing unit and a color pattern processing unit according to the second embodiment.

FIG. 11 is a block diagram illustrating a detailed configuration example of a color patterning processing unit according to the second embodiment;

FIG. 12A is a diagram showing a state in which a hue area is divided.

FIG. 12B is a diagram showing a state in which a hue area is divided.

FIG. 12C is a diagram showing a state in which a hue area is divided.

FIG. 13 is a flowchart illustrating an example of a processing procedure according to the second embodiment;

FIG. 14 is a block diagram illustrating a detailed configuration example of an image signal control unit according to the third embodiment;

15 is a diagram showing a detailed configuration example of a luminance / density conversion unit and a color patterning processing unit shown in FIG. 14;

16 is a block diagram showing a detailed configuration example of a color patterning processing unit shown in FIG.

FIG. 17 is a diagram showing an example of dividing a hue area.

FIG. 18 is a flowchart illustrating an example of a processing procedure according to the third embodiment;

FIG. 19 is a view showing an example of an image obtained by the image processing shown in FIG. 18;

FIG. 20 is a diagram showing an example of a memory map of a storage medium storing a program code according to the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Yaguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasuhiro Takiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Naoto Ito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (11)

[Claims] A generating unit configured to generate image data of two color components based on input color image data; a storage unit configured to store a plurality of pattern data and division information of a phase region; and a hue of the color image data. Selecting means for selecting pattern data from the storage means for each pixel based on the division information; and processing for patterning the two-color component image data using the pattern data selected by the selecting means. And an image processing apparatus. 2. The apparatus according to claim 1, wherein the selection unit selects pattern data for each of the two color components, and the processing unit performs a patterning process for each of the two color components. Image processing device. 3. The image processing apparatus according to claim 2, wherein the patterning process performs an AND operation on the image data and the pattern data for each pixel. 4. The image processing apparatus according to claim 1, further comprising a setting unit for setting the pattern data and the division information in the storage unit. 5. The image processing apparatus according to claim 1, further comprising a determination unit configured to determine the division information from a hue distribution of an image represented by the input color image data.
An image processing device according to any one of the above. 6. The image processing apparatus according to claim 1, wherein the division information is hue angle information. 7. The image processing apparatus according to claim 6, wherein the division information further includes saturation information. 8. The image processing apparatus according to claim 1, wherein the two color components are black and one color other than black. 9. Conversion means for converting input color image data as luminance information into output color image data as density information; storage means for storing a plurality of pattern data and division information of a phase region; Selecting means for selecting pattern data from the storage means for each pixel based on the hue of the image data and the division information; and performing patterning processing on the output color image data using the pattern data selected by the selecting means. An image processing apparatus comprising: 10. Image data of a two-color component is generated based on input color image data, and division information of a phase region stored in a storage unit is compared with a hue of the color image data for each pixel. Based on the comparison result, one of a plurality of pattern data stored in the storage unit is selected for each pixel, and a patterning process is performed on the two-color component image data using the selected pattern data. An image processing method comprising: 11. A computer-readable memory storing a program code for image processing, comprising: a code for generating image data of two-color components based on input color image data; and a phase stored in a storage means. A code for a step of comparing the area division information and the hue of the color image data for each pixel, and, based on the comparison result, one of a plurality of pattern data stored in the storage unit for each pixel. A computer readable memory comprising: a code of a selecting step; and a code of performing a patterning process on the image data of the two color components using the selected pattern data.