JP2004253979A - Image processor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processor and an image forming apparatus which suppress scattering of toner and have high color reproducibility. <P>SOLUTION: In the image processor, an edge area, a dot area, and the like are extracted by an area decision part 40, and an MTF (modulation transfer function) control signal setting attribute whether or not image processing should be performed every area is created. Also, in the area decision part 40, an inner edge neighborhood area is extracted. In a color correction part 30, printing data are created for every output color (CMYK). In doing that, with regard to the inner edge neighborhood area, correction to reduce an amount of each color component is performed. In an MTF correction part 50, correction processing along the MTF control signal (edge emphasizing, smoothing, or the like) are performed with the printing data (CMYK) where the color correction has been carried out. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing apparatus and an image forming apparatus that handle color image data. More specifically, the present invention relates to an image processing apparatus and an image forming apparatus capable of performing appropriate image processing according to an attribute of an image area.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, image processing such as edge enhancement processing has been performed to improve the reproduction quality of black characters and line drawings included in a color image. For example, in the image processing device described in Patent Literature 1, the following processing is performed. First, an edge region of a black character is extracted. Further, the extracted edge region is enlarged. Then, in the enlarged edge region, K color enhancement processing is performed. Further, for each of the CMY colors in the area, the overall density is replaced with the color having the lowest density. Thus, in the region near the edge of the black character, the color (CMY) component is suppressed, and the black (K) component is emphasized. This improves the reproducibility of black characters and line drawings.
[0003]
[Patent Document 1]
JP-A-2000-206756
[0004]
[Problems to be solved by the invention]
However, the conventional technique described above has the following problems. That is, in the conventional image processing apparatus, when the total amount of toner is large in the area inside the edge, the level difference between the area where the toner is overlapped (the character part) and the area where there is no toner (the background part) becomes large. For example, when an image is formed by the image processing apparatus described in Patent Literature 1, toner is stacked as shown in FIG. In this case, there is a large difference in the toner accumulation amount between the solid portion corresponding to the character portion and the outer edge portion corresponding to the background portion. Moreover, the solid portion and the outer edge portion are very close. For this reason, the K color toner that is lastly stacked easily scatters. On the other hand, if the total amount of the toner is reduced in order to suppress the scattering of the toner, a dilemma that color reproducibility is deteriorated as a whole will occur.
[0005]
The present invention has been made to solve the problems of the above-described conventional image processing apparatus. That is, it is an object of the present invention to provide an image processing apparatus and an image forming apparatus which suppress scattering of toner and have high color reproducibility.
[0006]
[Means for Solving the Problems]
An image processing apparatus designed to solve this problem is an image processing apparatus that handles color image data. The image processing apparatus includes an edge region of input image data from input image data and an edge region inside the edge and adjacent to the edge region. Area extracting means for extracting an area near the inner edge; first output image creating means for creating output image data for each output color based on the input image data; A second output image creating means for creating output image data for each output color so as to reduce the amount compared with the output image creating means, and a second output image creating means for the inner edge vicinity extracted by the area extracting means. Image data selecting means for selecting the output image data created in step (1) and selecting the output image data created by the first output image creating means for the other area And it has a. Further, an image forming apparatus according to the present invention includes the image processing apparatus according to the present invention.
[0007]
In the image forming apparatus of the present invention, the edge area and the area near the inner edge are extracted by the area extracting means. Output image data is created by a first output image creating unit that performs normal color conversion and a second output image creating unit that performs color conversion while suppressing color components to low density. Then, for the vicinity of the inner edge, the converted data of the second output image creating means is used. That is, the toner amount in the region near the inner edge is smaller than the toner amount in the region adjacent to the region near the inner edge. By arranging the region near the inner edge between the character portion and the background portion, the level difference of the toner between the regions is reduced. Therefore, scattering of toner is suppressed. The output image data of the first output image creating means is used for the character portion and the edge portion. Therefore, the total amount of toner is large, and the color reproducibility of the output image is high.
[0008]
Further, the image processing apparatus of the present invention has a specific color enhancing means for converting the image data so as to increase the density of the component of the specific color among the output colors and decrease the density of the remaining components of the output color. The area extracting means extracts an edge area of a specific color whose density is increased by the specific color enhancing means, and the specific color enhancing means targets the edge area of the specific color extracted by the area extracting means. And better. That is, the color to be emphasized differs for each color of the edge region. For example, when a black edge region is extracted, only the K color is emphasized. When a color edge region is extracted, each color of CMY is emphasized. Thus, characters and lines can be sharply reproduced according to various originals.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an image processing apparatus according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the image processing apparatus according to the present embodiment includes an image reading / taking unit 10, an IF selecting unit 20, a color correcting unit 30, an area determining unit 40, and an MTF correcting unit 50. Further, the image reading / photographing unit 10 includes a CCD 11, an image synthesizing unit 12, an AD converting unit 13, a shading correcting unit 14, a line-to-line correcting unit 15, a chromatic aberration correcting unit 16, a scaling unit 17, It has a color conversion unit 18 and a base adjustment unit 19. The image reading section 10 creates image data by reading an image of a document using the CCD 11, and creates Lab data by performing image processing on the image data. The IF selecting section 20 selects one of Lab data from the image reading / photographing section 10 and RGB data from the controller IF section 60 using an IF selecting signal. The color correction unit 30 creates print data (CMYK) by performing color correction processing on image data (Lab or RGB). The area determination unit 40 extracts an area such as an edge area or a halftone dot area. The MTF correction unit 50 performs correction processing such as edge enhancement processing and smoothing processing on print data.
[0010]
Next, the area determining unit 40 will be described in detail. As shown in FIG. 2, the area determining section 40 includes a color signal creating section 41, an edge signal creating section 42, a halftone area signal creating section 43, an MTF control signal creating section 44, and a NAND circuit 45. ing. The color signal creation unit 41 uses the black region signal (Lab or RGB) based on image data (Lab or RGB). BLACK) and a low brightness area signal (_V_LOW). Details of the color signal creation unit 41 will be described later. The edge signal generation unit 42 generates a halftone dot isolated point signal (W_AMI, K_AMI), a character edge area signal (_IN_EDG), a character edge area signal (_EDG), and an extended edge area signal (_DIL_EDG). To do. The details of the edge signal creation unit 42 will also be described later. The halftone area signal creating section 43 creates a halftone area signal (_AMI) based on an isolated point signal for halftone discrimination. The halftone area extraction signal is a signal indicating whether or not each pixel is a halftone area. The MTF control signal creation unit 44 creates an MTF control signal (CMPX, KMPX) based on a halftone dot area signal, a character edge area signal, a character edge area signal, and a black area signal. The details of the MTF control signal creation section 44 will also be described later.
[0011]
Next, the color signal creation unit 41 of the area determination unit 40 will be described. As shown in FIG. 3, the color signal creation section 41 has a saturation signal creation section 411, a threshold value table section 412 for black determination, and determination sections 413 and 414. The color signal creation section 41 creates a black area signal (_BLACK) and a low brightness area signal (_V_LOW). The black area signal is a signal indicating whether or not each pixel is a black area. The low brightness area signal is a signal indicating whether the brightness value of the target pixel is lower than a predetermined value for each pixel. The black area signal (_BLACK) is used by the determination unit 414 to determine whether or not the saturation signal (W) created by the saturation signal creation unit 411 is smaller than the threshold created by the threshold table for black determination 412. It is created by making a judgment. Note that a color area can be extracted by using a threshold table for color determination instead of the threshold table for black determination. The low brightness area signal (_V_LOW) is created by the determination unit 413 determining whether the brightness value of the pixel of interest is smaller than a threshold value.
[0012]
Next, the edge signal creation unit 42 of the area determination unit 40 will be described. As shown in FIG. 4, the edge signal creation unit 42 includes a 5 * 5 matrix creation unit 421, a feature extraction filter 422, comparison units 423, 424, determination units 425, 426, 427, a NOR circuit 428, And an extended edge area detection unit 429. The edge signal creation unit 42 creates a character edge area signal (_EDG), an extended edge area signal (_DIL_EDG), an in-character edge area signal (_IN_EDG), and an isolated point signal for halftone discrimination (W_AMI, K_AMI). Is done. The halftone dot isolated point signal is a signal indicating whether or not each pixel is a halftone dot region of a white isolated point or a halftone dot region of a black isolated point. The in-character edge area signal is a signal indicating whether or not each pixel is an area inside an edge including an edge of a character or a line (hereinafter, referred to as an “inner edge area”; see FIG. 5B). The character edge area signal is a signal indicating whether or not a pixel is a peripheral area including an edge of a character or a line for each pixel (hereinafter, referred to as an “edge area”; see FIG. 5C). The extended edge area signal is a signal indicating whether or not each pixel is an area adjacent to the edge area (hereinafter, referred to as “extended edge area”; see FIG. 5D).
[0013]
Each area attribute signal is created by the 5 * 5 matrix creation unit 421 based on the image data expanded into a 5 × 5 matrix. More specifically, the character edge area signal (_EDG) includes a value created by the primary scanning primary differential filter (see FIG. 6) in the feature amount extraction filter 422 and a secondary scanning primary differential filter (see FIG. 7). , The value created by the + type secondary differential filter (see FIG. 8), and the value created by the × type secondary differential filter (see FIG. 9). You. The extended edge area signal (_DIL_EDG) is created by the extended edge area detection unit 429 based on the character edge area signal (_EDG). Specifically, in the extended edge area detection unit 429, the character edge area signal (_EDG) is developed into a 5 × 5 matrix by the 5 * 5 matrix creation unit 430 as shown in FIG. Then, if at least one of the 24 pixels excluding the pixel of interest is a character edge region, a process for forcibly setting the character edge region is performed. Thereby, an extended edge area corresponding to the periphery of the character edge area is extracted. The in-character edge area signal (_IN_EDG) is created by the determination unit 427 based on the value created by the outer / inner edge discrimination filter (see FIG. 11) in the feature amount extraction filter 422. The halftone dot isolated point signals (W_AMI, K_AMI) are created by an isolated point detection filter in the feature amount extraction filter 422. Specifically, a white isolated point signal (W_AMI) for extracting a white isolated point and a black isolated point signal (K_AMI) for extracting a black isolated point are created.
[0014]
Further, from the NAND circuit 45 of the area discriminating section 40, based on the inverted signal of the extended edge area signal (_DIL_EDG) and the inverted signal of the low brightness area signal (_V_LOW), an extended inner edge area selection signal (SEL) is output. (See FIG. 2). The extended inner edge area selection signal is a signal indicating whether or not each of the pixels is an area on the character portion side in the extended edge area (hereinafter, referred to as an “extended inner edge area”; see FIG. 5E). .
[0015]
Next, the MTF signal creation section 44 of the area determination section 40 will be described. The MTF signal creation unit 44 creates MTF control signals (CMPX, KMPX) based on the four area attribute signals (_AMI, _IN_EDG, _EDG, _BLACK). The MTF control signal is a signal in which the content of the image processing performed by the MTF correction unit 50 is selected for each area. As shown in FIG. 12, an area determination table and an MTF control signal table are set in the MTF signal creation section 44. The area determination table is for determining which image area the target pixel belongs to from the area attribute signal. The MTF control signal table is used to select the necessary image processing content for each image area. For example, in the case of an image in which the character color is "black" and the background is "white solid", each image such as an outer edge portion, an inner edge portion, and a solid portion is determined based on the area determination table (a) in FIG. The area is determined. Then, by applying the result of the determination to the MTF control signal table (a), an MTF control signal (CMPX, KMPX) is created.
[0016]
The MTF control signal table is composed of a table for CMY colors and a table for K colors. Then, an MTF control signal (CMPX) for CMY colors and an MTF control signal (KMPX) for K colors are created. The MTF control signal is 3-bit data. The lower 2 bits select the type of base processing, and the upper 1 bit selects whether or not edge enhancement processing is performed. Specifically, three types of processing, ie, smoothing processing, min processing, and through processing, can be selected as the base processing. “0” is set for smoothing processing, “1” is set for min processing, and “2” is set for through processing. Is done. In the edge enhancement processing, “0” is set when enhancement processing is performed, and “1” is set when enhancement processing is not performed. For example, in the case of an image area determined to be an inner edge portion in the area determination table (a), the value of the MTF control signal (CMPX) for CMY colors is “101”, K in the MTF control signal table (a). The value of the MTF control signal (KMPX) for use becomes “010”.
[0017]
Note that the area discrimination table (b) and the MTF control signal table (b) in FIG. 12 are examples of tables used in an image in which the character part is “black” and the background part is “halftone”. The area discrimination table (c) and the MTF control signal table (c) in FIG. 12 are examples of tables used for an image in which the character part is “color” and the background part is “white solid”. That is, several tables are set for each feature of the image.
[0018]
Next, the color correction unit 30 in FIG. 1 will be described in detail. The color correction section 30 includes a first color correction processing section 31, a second color correction processing section 32, and a selector 33, as shown in FIG. As shown in FIG. 14, the first color correction processing unit 31 has three-dimensional table units 311C, 311M, 311Y, 311K and eight-point interpolation units 312C, 312M, 312Y, 312K for each color. The second color correction processing unit 32 has the same configuration. Each three-dimensional table section divides the Lab color space evenly in the form of a cube, and arranges print data (CMYK) corresponding to Lab data at eight vertices (lattice points) of the cube (see FIG. 15). ). Each of the eight-point interpolation units calculates print data based on the eight vertices and the interpolation data when the input Lab data does not correspond to the vertices of the cube (see FIG. 16). The difference between the first color correction processing unit 31 and the second color correction processing unit 32 lies in the contents of the print data set in each three-dimensional table unit. That is, the print data at an arbitrary grid point of each three-dimensional table in the first color correction processing unit 31 is C1, M1, Y1, and K1, and the print data at the same position in each three-dimensional table in the second color correction processing unit 32 Assuming that the print data at the grid points are C2, M2, Y2, and K2, the following equation (1) is set.
(C1 + M1 + Y1 + K1)> (C2 + M2 + Y2 + K2) (1)
That is, the second color correction processing unit 32 creates print data having a lower color component density than the first color correction processing unit 31. The selector 33 in FIG. 13 includes the C1, M1, Y1, and K1 data created by the first color correction processor 31 and the C2, M2, Y2, and K2 data created by the second color correction processor 32. Is to select one of the print data in accordance with the extended inner edge area selection signal (SEL) created by the area determination unit 40.
[0019]
Next, the MTF correction unit 50 in FIG. 1 will be described in detail. The MTF correction unit 50 performs correction processing (MTF correction processing) such as edge enhancement processing and smoothing processing on the print data (CMYK) based on the MTF control signals (CMPX and KMPX). As shown in FIG. 17, the MTF correction unit 50 includes a 5 * 5 matrix unit 51, a character processing filter unit 52, selectors 53 and 55, an integrating unit 54, and an adding unit 56. The character processing filter unit 52 has an edge emphasis filter 521, a smoothing filter 522, and a min filter 523. The edge enhancement filter 521 outputs the maximum value of the data converted by each of the 0 degree, 90 degree, and ± 45 degree differential filters as an edge enhancement amount. The smoothing filter 522 performs a smoothing process and outputs the result. The min filter 523 calculates the minimum value in the 5 × 5 matrix (min processing) and outputs the result.
[0020]
Next, the operation of the image processing apparatus according to the present embodiment will be described. In the image processing apparatus, the image data is sent to the color correction section 30 and the area determination section 40 via the IF selection section 20 (see FIG. 1). The image data may be Lab data read by the CCD 11 of the image reading unit 10 or RGB data sent from a scanner or the like via the controller IF 60. Hereinafter, a case where Lab data is used will be described.
[0021]
Next, the area determination unit 40 creates an MTF control signal (CMPX, KMPX) from the transmitted image data (see FIG. 2). Further, an extended inner edge area selection signal (SEL) is output. More specifically, a black area is extracted by the color signal creation unit 41. In addition, a low brightness area whose brightness is equal to or less than a predetermined value is extracted. The edge signal creating section 42 and the halftone dot area signal creating section 43 extract a halftone dot area, an inner edge area, an edge area, and an extended edge area. The MTF control signal generator 44 determines an image area based on the extracted result (FIG. 12: area determination table). Further, a correction process suitable for each image area is selected for each of the determined images (FIG. 12: MTF control signal table). Then, the selection result is output as an MTF control signal.
[0022]
On the other hand, the color correction unit 30 creates print data (CMYK) from the input image data (Lab) (see FIG. 13). Specifically, the first color correction processing unit 31 and the second color correction processing unit 32 create print data for each output color. Then, the selector 33 selects the print data (C2, M2, Y2, K2) converted by the second color correction processing unit 32 for the extended inner edge area based on the extended inner edge area selection signal (SEL). For the other areas, the print data (C1, M1, Y1, K1) converted by the first color correction processing section 31 is selected. As a result, for the extended inner edge area, print data having a low density of each color component is selected.
[0023]
Next, the MTF correction processing unit 50 performs a correction process on the print data created by the color correction unit 30 (see FIG. 17). Specifically, first, a 5 × 5 matrix creation unit 51 creates a 5 × 5 matrix. Thereafter, the character processing filter unit 52 creates edge enhancement data, data after smoothing processing, and data after min processing. Then, whether or not to perform the edge enhancement processing is selected based on the data of the upper 1 bit of the MTF control signal for C color (CMPX2 in FIG. 17). Further, one of the data after the smoothing processing, the data after the min processing, and the data of the through processing is based on the lower 2 bits data of the MTF control signal for the C color (CMPX1-0 in FIG. 17). Selected. That is, which correction process is performed for each color is selected by the MTF control signal. For example, in the case of an image area determined to be an inner edge portion in the area determination table (a) of FIG. 12, the base processing is “min processing” and the edge enhancement processing is “none” for each color of CMY. On the other hand, for the K color, the base processing is “through processing” and the edge enhancement processing is “present”. The corrected print data is sent to an image forming engine or the like via the printer IF 70.
[0024]
The image processing apparatus is provided in an electrophotographic color image forming apparatus. For example, it is provided in a tandem type full-color copying machine as shown in FIG. This color copier includes an image reader unit 1 and a printer unit 2. Further, the printer unit 2 forms an image on the recording paper S based on the image data created by the image reader unit 1. Specifically, the printer unit 2 includes a control unit 3 and image forming units 4K, 4C, 4M, and 4Y. This image processing apparatus corresponds to a part of the control unit 3. A toner image of each color is formed on the image forming units 4K, 4C, 4M, and 4Y by a control signal generated by the control unit 3. Then, the toner images are superimposed on the transfer belt 5 to form a color image.
[0025]
Next, the state of toner adhesion when a black character image (background is “solid white”) is printed by the image processing apparatus will be described. FIG. 19 is a diagram showing the state of adhesion of black characters and toner around the black characters. The horizontal axis in FIG. 19 indicates an image area, and the vertical axis indicates the amount of adhered toner. The maximum amount of toner is 255 for each color, and the maximum amount of toner adhesion is 255 × 4 colors = 1020. The state of each image area is as follows. The MTF correction is in accordance with the MTF control signal table (a) in FIG.
[0026]
(Outer edge)
Since the first color correction processing unit 31 is selected by the color correction unit 30, the total amount of CMYK is large. In addition, the MTF correction unit 50 selects the min process for both the CMY color and the K color. In the example of FIG. 19, since the outer edge portion is solid white, the toner amount of each color is 0 by the min process.
[0027]
(Inner edge)
Since the first color correction processing unit 31 is selected by the color correction unit 30, the total amount of CMYK is large. Further, the MTF correction unit 50 selects the min processing for the CMY color and the edge enhancement processing for the K color. In the example of FIG. 19, since the outer edge portion is solid white, the CMY color toner amount is 0 by the min process.
[0028]
(Near the inner edge)
Since the second color correction processing unit 32 is selected by the color correction unit 30, the total amount of CMYK is small. Further, since the vicinity of the inner edge is regarded as a solid portion by the MTF correction unit 50, through processing is selected for both CMY colors and K colors. In the example of FIG. 19, the toner amount of each color is small.
[0029]
(Solid)
Since the first color correction processing unit 31 is selected by the color correction unit 30, the total amount of CMYK is large. The MTF correction unit 50 selects through processing for both CMY colors and K colors. In the example of FIG. 19, the toner amount of each color is large.
[0030]
As described above in detail, in the present image processing apparatus, the area discriminating section 40 extracts the vicinity of the inner edge. Further, the area discrimination section 40 creates an MTF control signal in which the content of the MTF correction is selected for each area. The color correction section 30 has a first color correction processing section 31 for performing normal conversion and a second color correction processing section 32 for suppressing color components to a low density, and converts image data into print data. And The conversion data of the second color correction processing unit 32 is used for the vicinity of the inner edge. That is, the toner amount in the vicinity of the inner edge is smaller than the toner amount in the adjacent solid portion. Since the portion near the inner edge is located between the solid portion and the background portion, the level difference of the toner between the regions is reduced. Therefore, scattering of toner is suppressed. The conversion data of the first color correction processing unit 31 is used for a solid portion and an edge portion. That is, since the total amount of toner is large, the color reproducibility of the output image is high. Accordingly, an image processing apparatus that suppresses toner scattering and has high color reproducibility and an image forming apparatus including the image processing apparatus are realized.
[0031]
Further, in the present image processing apparatus, the MTF correction unit 50 performs a correction process (edge enhancement, smoothing, etc.) according to the characteristics of the image. Further, in order to select an appropriate correction content, an MTF control signal is created for each area and each color of the area in accordance with the MTF control signal table set in the MTF control signal creation section 44. As a result, it is possible to perform correction to emphasize the K color if the edge is a black edge and emphasize each color of CMY if the edge is a color edge. Therefore, the reproducibility of characters and lines formed by the image data after the MTF correction is high.
[0032]
Note that the present embodiment is merely an example, and does not limit the present invention in any way. Therefore, naturally, the present invention can be variously modified and modified without departing from the gist thereof. For example, although the color correction unit 30 is provided with the second color correction processing unit 32 for lowering the color density, the color correction unit 30 may be provided with a third color correction processing unit for increasing the color density. This makes it possible to reproduce characters and lines more sharply according to various originals.
[0033]
【The invention's effect】
As is apparent from the above description, according to the present invention, an image processing apparatus and an image forming apparatus which suppress scattering of toner and have high color reproducibility are provided.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an overall configuration of an image processing apparatus according to an embodiment.
FIG. 2 is a diagram illustrating a configuration of an area determining unit of the image processing apparatus.
FIG. 3 is a diagram illustrating a configuration of a color signal creation unit of an area determination unit.
FIG. 4 is a diagram illustrating a configuration of an edge signal creation unit of the area determination unit.
FIG. 5 is a diagram showing a specific example of each image area.
FIG. 6 is a diagram illustrating an example of a primary scanning primary differential filter of a feature amount extraction filter.
FIG. 7 is a diagram illustrating an example of a sub-scan primary differential filter of a feature amount extraction filter.
FIG. 8 is a diagram illustrating an example of a + type secondary differential filter of a feature amount extraction filter.
FIG. 9 is a diagram illustrating an example of an x-type secondary differential filter of a feature amount extraction filter.
FIG. 10 is a diagram illustrating a configuration of an extended edge area detection unit of the edge signal creation unit.
FIG. 11 is a diagram illustrating an example of an outer / inner edge discrimination filter of a feature amount extraction filter.
FIG. 12 is a diagram illustrating a configuration example of each table set in an MTF control signal creation unit of an area determination unit.
FIG. 13 is a diagram illustrating a configuration of a color correction unit of the image processing apparatus.
FIG. 14 is a diagram illustrating a configuration of a first color correction processing unit of the color correction unit.
FIG. 15 is a diagram illustrating an outline of processing of a three-dimensional table unit.
FIG. 16 is a diagram illustrating an outline of processing of an 8-point interpolation unit.
FIG. 17 is a diagram illustrating a configuration of an MTF correction unit of the image processing apparatus.
FIG. 18 is a conceptual diagram illustrating an overall configuration of an image forming apparatus according to an embodiment.
FIG. 19 is a diagram illustrating a toner attachment state (example) when a black character image is printed.
FIG. 20 is a diagram illustrating a toner adhesion state (conventional example) when a black character image is printed.
[Explanation of symbols]
30 color correction unit
31 First Color Correction Processing Unit (First Output Image Creation Means)
32 Second color correction processing unit (second output image creating means)
33 selector (image data selection means)
40 area determination unit (area extraction means)
50 MTF correction unit

Claims (4)

In an image processing device that handles color image data,
Region extracting means for extracting, from the input image data, an edge region of the input image data and an inner edge vicinity region inside the edge and adjacent to the edge region;
First output image creation means for creating output image data for each output color based on the input image data;
A second output image creating means for creating output image data for each output color so as to reduce the density of each color component based on the input image data as compared with the first output image creating means;
The output image data created by the second output image creating means is selected for the area near the inner edge extracted by the area extracting means, and the other areas are created by the first output image creating means. Image data selecting means for selecting the output image data. The image processing apparatus according to claim 1,
Specific color enhancing means for converting image data so as to increase the density of a specific color component of the output color and to reduce the density of the remaining output color component;
The area extracting means extracts an edge area of a specific color whose density is increased by the specific color emphasizing means,
The image processing apparatus according to claim 1, wherein the specific color emphasis unit targets an edge region of the specific color extracted by the region extraction unit. In an image forming apparatus that forms a color image by superimposing toner images,
Region extracting means for extracting, from the input image data, an edge region of the input image data and an inner edge vicinity region inside the edge and adjacent to the edge region;
First output image creation means for creating output image data for each output color based on the input image data;
A second output image creating means for creating output image data for each output color so as to reduce the density of each color component based on the input image data as compared with the first output image creating means;
The output image data created by the second output image creating means is selected for the area near the inner edge extracted by the area extracting means, and the other areas are created by the first output image creating means. Image data creating means for creating image data by selecting the output image data thus created,
An image forming apparatus comprising: a toner image forming unit that forms a toner image for each color based on the image data created by the image data creating unit. The image forming apparatus according to claim 3,
Specific color enhancing means for converting image data so as to increase the density of a specific color component of the output color and to reduce the density of the remaining output color component;
The area extracting means extracts an edge area of a specific color whose density is increased by the specific color emphasizing means,
The image forming apparatus according to claim 1, wherein the specific color emphasis unit targets an edge region of the specific color extracted by the region extraction unit.

Images