JP2002290748A - Color image processing apparatus, color image processing method, program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image processing apparatus capable of correcting reverse taking from only a one-sided image when scanning a color original. SOLUTION: The color image processing apparatus according to the present invention comprises color component binarizing means 40 for binarizing each color component for a digital color original image provided by digitally inputting one side of the original which is color printed on both sides thereof, and reverse taking correcting means 50 for generating an image having reserve taking components which are corrected only when all components of binarized pixels exceed a predetermined threshold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image processing apparatus, a color image processing method, a program for executing the functions of the color image processing apparatus, and a computer-readable recording medium on which the program is recorded. “Show-through” in which the image of the second side is mixed and input into the image of the first side in a printed document
Is to be removed.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing an example of an image due to show-through. With the spread of color image input devices such as color scanners, digital cameras, and digital color copiers,
Document images of books, magazines, catalogs, advertisements, newspapers, and the like are also commonly input in color. Since these documents are often printed on both sides of a sheet of paper, as shown in FIG. 2, a "show-through" occurs in which the image on the back side is transparent and is mixed in the image on the front side. .
Further, in the case of a color document, the background color is not uniform, and a pattern, a pattern, and a photograph are often mixed. For this reason, the problem of removing “show-through” from an input image by digital image processing has been regarded as important for improving the image quality but difficult to handle. As a show-through correction method in such digital image processing, a method has been proposed in which a two-sided image is input, a show-through part is detected by comparing two images, and the luminance and color of the detected part are corrected. ing. For example, JP-A-7-87295
Gazette, JP-A-8-265563, JP-A-9-2
No. 05544, Japanese Patent Application Laid-Open No. 9-233319, and US Pat. No. 5,832,137. In addition, a method has been proposed in which only the image of the first surface is used, the distribution of edges and brightness on the image is analyzed, and a portion having a weak edge strength and a portion having a high brightness are corrected. A method of correcting the high luminance portion, for example, Japanese Patent Application Laid-Open No. 2000-2294
In Japanese Unexamined Patent Application Publication No. H06-209, an edge is detected from an input image, show-through is removed by increasing the luminance of pixels other than the edge and the low luminance area, and a corrected image is output. In the same publication, an edge is detected from an input image, an image is divided into an edge and a low-luminance region, and the luminance is increased only in a region where the average luminance in the region is high in the divided regions. The image is removed and the corrected image is output. further,
Japanese Patent Application Laid-Open No. H11-41266 proposes a method of judging presence or absence of show-through from a difference between a luminance value at the maximum frequency and a maximum luminance value obtained from a histogram of a read image.

[0003]

However, when these inventions are applied to a color image, information such as hue and saturation (or saturation) is discarded from the color information.
Since the show-through correction processing is performed using only the luminance (brightness), the show-through correction processing is also performed for yellow characters on a white background, and the hue and saturation are different from each other, but the contrast is small. Since no edge is detected for an adjacent area, the show-through correction processing may cause loss such as blurring of character boundaries and boundaries between areas, and may rather degrade image quality. The present invention
In order to solve the above-described problem, when scanning a color document that is printed on both sides and has a show-through from the second side on the first side, inputting only an image on one side of the paper, the color A color image processing apparatus capable of correcting show-through of an image, a color image processing method, a program for executing functions of the color image processing apparatus, and a computer-readable recording medium storing the program. And

[0004]

According to a first aspect of the present invention, there is provided a color image processing apparatus comprising: a digital color original obtained by digitally inputting one side of an original color-printed on both sides; Color component binarization means for binarizing the value of each color component with respect to an image, and correcting show-through components only for pixels for which all components of the binarized pixels are equal to or greater than a threshold value And a show-through correction unit that generates a transformed image. Further, claim 2 of the present invention
The color image processing apparatus according to claim 1, wherein the color component binarizing means sets a window of a predetermined size around each pixel, and sets a window of a predetermined size for each color component of the pixel in the window. The threshold value is set based on the statistic. Further, the color image processing apparatus according to the third aspect of the present invention calculates the edge strength when detecting an edge in a digital color original image obtained by digitally inputting one side of an original color-printed on both sides. Edge detecting means for detecting an edge from the edge strength; color component binarizing means for binarizing the value of each color component only for pixels having a low edge strength; and the color component binarizing means. And a show-through correction unit that generates an image in which show-through components are corrected only for pixels in which all components of the pixels binarized in step (b) are equal to or greater than a threshold value. Further, the color image processing apparatus according to claim 4 of the present invention,
Color component binarization means for binarizing the value of each color component with respect to a digital color original image obtained by digitally inputting one side of an original color-printed on both sides, and the binarized color Edge detection means for calculating the edge strength only for pixels having a component value equal to or greater than the threshold value and detecting an edge from the edge strength, and only for pixels having a low edge strength calculated by the edge detection means. And a show-through correction unit that generates an image in which a reflection component is corrected.

According to a fifth aspect of the present invention, there is provided a color image processing apparatus for detecting an edge of a digital color original image obtained by digitally inputting one side of an original color-printed on both sides. Edge detecting means for calculating an intensity and detecting an edge from the edge strength; color component binarizing means for binarizing the value of each color component with respect to the input image; and the edge detecting means. Pixels with low calculated edge intensities, and show-through that generates an image in which the show-through component is corrected only for pixels in which all the components of the pixels binarized by the color component binarization unit are equal to or larger than a threshold value. Correction means. According to a sixth aspect of the present invention, in the color image processing apparatus according to the third, fourth or fifth aspect, the edge detecting means determines an edge intensity from each color component of an image for detecting an edge. It is characterized in that an edge is detected in consideration of a correlation between the edge intensities of the respective components. According to a seventh aspect of the present invention, in the color image processing apparatus according to the third, fourth or fifth aspect, the color component binarizing means includes a predetermined size around each pixel. A threshold value is set based on a statistic of each color component of a pixel in this window, and binarization is performed. The color image processing method according to claim 8 of the present invention provides a digital color original image obtained by digitally inputting one side of an original color-printed on both sides.
It is characterized in that the value of each color component is binarized and an image in which show-through components are corrected only for pixels in which all components of the binarized pixels are equal to or greater than a threshold is generated. Also,
According to a ninth aspect of the present invention, in the color image processing method according to the eighth aspect, a window of a predetermined size is set around each pixel, and statistics for each color component calculated in the window are set. The method is characterized in that the threshold is set based on the amount. Further, according to the color image processing method of the present invention, when an edge is detected in a digital color original image obtained by digitally inputting one side of an original color-printed on both sides, the edge intensity is calculated. Then, an edge is detected from the intensity, and the value of each color component is binarized only for a pixel having a low edge intensity, and only for a pixel in which all components of the binarized pixel are equal to or larger than a threshold value. An image in which show-through components are corrected is generated. A color image processing method according to claim 11 of the present invention binarizes the value of each color component with respect to a digital color original image obtained by digitally inputting one side of an original color-printed on both sides, Only for pixels where the value of each component of the binarized color is equal to or greater than the threshold, edge strength is calculated, an edge is detected from the edge strength, and a show-through component is detected only for pixels having a low edge strength. It is characterized by generating a corrected image.

According to a color image processing method of the present invention, an edge is detected when an edge is detected in a digital color original image obtained by digitally inputting one side of an original color-printed on both sides. Calculate the intensity, detect edges from the edge intensity, binarize the value of each color component for the input image, the edge intensity is low, and all of the binarized pixels It is characterized in that an image in which the show-through component is corrected is generated only for pixels whose components are equal to or larger than a threshold value. Claim 13 of the present invention
Calculating an edge intensity from each component of a color of an image for detecting an edge, and calculating a correlation between edge intensities of the respective components in the color image processing method according to claim 10, 11 or 12; Is detected in consideration of the edge. Claim 14 of the present invention is claim 1
0, the color image processing method according to claim 11 or 12, wherein a window of a predetermined size is set around each pixel, and a statistic for each color component calculated in the window is set. It is characterized in that the threshold value is set based on the threshold value and binarized. Further, claim 1 of the present invention
A fifth program causes a computer to function as the color image processing device according to any one of claims 1 to 7. A computer-readable recording medium storing the program according to claim 16 of the present invention causes a computer to function as the color image processing apparatus according to any one of claims 1 to 7.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of an embodiment of the present invention will be described below in detail with reference to the drawings. Embodiment 1 FIG. 1 is a functional block diagram showing an embodiment (Embodiment 1) in which the present invention is applied to a color image processing apparatus (for example, a color digital copying machine). Example 1
Is composed of a color image input means 10, a preprocessing means 20, a color component binarization means 40, a show-through correction means 50 and an image output means 60. Color image input means 10
Input an original from a color image input device (for example, a digital color copier, a scanner, a camera, etc.), perform A / D conversion processing, and temporarily store the original in a memory or the like. Further, image data may be received from application software of a digital camera or a color document image analysis / recognition system, or input from a file in which image data is already stored. The pre-processing means 20 performs pre-processing such as smoothing the input image data to remove noise, regulating the total amount, and adjusting the density by engine gamma. The image output unit 60 performs dither / error diffusion processing, performs halftone processing such as performing data conversion so as to conform to the characteristics of the output device, performs layout processing to generate output data, and generates image data. For example,
Display device, printer, storage device, etc.). Conventional techniques are used for the color image input means 10, the preprocessing means 20, and the image output means 60.

The color component binarizing means 40 converts the color components (R (Red), G (Green), B
(Blue)), a binary image representing the result of classifying the input image data into ON pixels corresponding to characters, lines, dots, and picture parts on the surface and OFF pixels other than the pixels from the input image data. Output. In this binarization process, for each pixel (i, j), first, for a value R (i, j) of the R component, a character, a line, and a point satisfy a condition R (i, j) <Tr (i, j). Compare with j), turn on if condition is met
When the condition is not satisfied, binarization is performed by classifying the pixel as an OFF pixel. Where Tr (i,
j) is a threshold value. For example, Wx centered on the pixel (i, j)
Tr (i, j) = a · μr based on the average μr (i, j) and standard deviation σr (i, j) of the R component signal within the window of W (W is a window size parameter specified in advance). It is determined by (i, j) + b · σr (i, j). Where a and b are parameters specified in advance, and b is a parameter specified in advance as c.
It may be determined as b = c · μr (i, j). The picture part has a condition comparison μr (i, j) between μr (i, j) and a fixed threshold τr (which is a fixed threshold parameter for the R component specified in advance).
j) Detected by <τr. The processing for the R component is similarly performed for the G and B components. Under the above conditions, the fixed threshold for the G component is τg, and the fixed threshold for the B component is τb. That is, the pixel (i, j) has six conditions R (i, j) <Tr (i, j), μr (i, j) <τr, G (i, j) <Tg (i, j), μg
Classify an ON pixel if any of (i, j) <τg, B (i, j) <Tb (i, j), μb (i, j) <τb is satisfied, and classify an OFF pixel otherwise I do. In the above description, R,
Although the processing is performed in the order of G and B, the effect is the same even if the order is changed as appropriate. As a result of the color component binarization processing, the input image data is classified into ON pixels corresponding to characters, lines, dots, picture portions, and the like, and OFF pixels other than the ON pixels. For example, as a result of performing the above-described color component binarization processing on a show-through color image as shown in FIG. 2, pixels classified as ON pixels are shown in FIG. 3 as black. The show-through correction unit 50 performs show-through correction processing on an area classified as an OFF pixel among the areas in which the input image data is classified into the ON pixels and the OFF pixels by the color component binarization unit 40. Here, the show-through correction processing uses, for example, the technique of Japanese Patent Application No. 11-354412 filed by the present applicant. When show-through correction processing is performed on the OFF pixel area in the above-described binarization processing, an image in which show-through has been corrected as shown in FIG. 4 is obtained.

FIG. 5 is a flow chart for explaining the color component binarization processing. The first pixel in the scan order of the input and preprocessed image data is
(i, j) (step S01). A binary image F (i, j) representing the result of classification into ON pixels corresponding to characters, lines, points, picture parts, and the like of this image data and other OFF pixels
Are initialized as OFF pixels (step S02). R
For the component, the average μr (i, j) and the standard deviation σr (i, i) of the R component signal in a W × W window centered on the pixel (i, j)
j) is calculated (step S03). For the R component, a binarization threshold Tr (i, j) at the pixel (i, j) is calculated (step S
04). Tr (i, j) is determined by Tr (i, j) = a · μr (i, j) + b · σr (i, j) using a and b as parameters specified in advance. It is determined whether the pixel value R (i, j) of the R component is smaller than the threshold value Tr (i, j) or the average μr (i, j) of the R component is smaller than the fixed threshold value τr (step S05). When the condition of step S05 is satisfied, step S12
And the binary image F (i, j) is set as an ON pixel. With respect to the G component, an average μg (i, j) and a standard deviation σg (i, j) of the G component signal in a W × W window centered on the pixel (i, j) are calculated (step S06). For the G component, the pixel
The binarization threshold Tg (i, j) at (i, j) is calculated (step S0
7). Tg (i, j) is determined by Tg (i, j) = a · μg (i, j) + b · σg (i, j) using a and b as parameters specified in advance. It is determined whether the pixel value G (i, j) of the G component is smaller than the threshold value Tg (i, j) or whether the average μg (i, j) of the G component is smaller than the fixed threshold value τg (step S08). When the condition of step S08 is satisfied, step S12
And the binary image F (i, j) is set as an ON pixel. For the B component, the average μb (i, j) and standard deviation σb (i, j) of the B component signal in a W × W window centered on the pixel (i, j) are calculated (step S09). For the B component, the pixel
A binarization threshold value Tb (i, j) at (i, j) is calculated (step S1).
0). Tb (i, j) is determined by Tb (i, j) = a · μb (i, j) + b · σb (i, j) using a and b as parameters specified in advance. It is compared whether the pixel value B (i, j) of the B component is smaller than the threshold value Tb (i, j) or whether the average μb (i, j) of the B component is smaller than the fixed threshold value τb (step S11). When the condition of step S11 is satisfied, step S12
And the binary image F (i, j) is set as an ON pixel. If processing has been performed for all pixels (step S13),
The binary image F obtained by the above processing is output, and the processing is terminated (step S14). If there is a pixel that has not been processed yet, the next pixel is set to (i, j) in the scanning order, the process returns to step S02, and the above process is executed (step S02).
15).

<Embodiment 2> In Embodiment 2, edge detection is performed on image data that has been subjected to preprocessing in the same manner as in Embodiment 1, and the image data is converted into ON pixels corresponding to characters, lines, and the like. It is classified into other OFF pixels, and further OFF
In the area classified into pixels, binarization is performed on each color component to extract characters, lines, dots, picture parts, and the like on the surface from the image data. In this binarization process, the pixel to be processed is set to OFF as a result of the edge detection.
The second embodiment is the same as the first embodiment except that only pixels classified into pixels are used. In the second embodiment, as a result of the binarization using the color components, the input image data is converted into characters, lines, dots,
Areas classified into ON pixels corresponding to picture parts and the like and OFF pixels other than the ON pixels are not classified into ON pixels in areas classified as OFF pixels, that is, neither in edge detection nor in color component binarization processing. The show-through correction process is performed on the pixel region that has been set to obtain an image whose show-through has been corrected.

FIG. 6 is a functional block diagram showing another embodiment (Embodiment 2) in which the present invention is applied to a color image processing apparatus (for example, a color digital copying machine). Preprocessing means 20, edge detection means 30,
It comprises a color component binarization unit 40, show-through correction unit 50, and image output unit 60. The configuration of the second embodiment is a configuration in which the edge detection means 30 is added to the functional configuration of the first embodiment, and the same reference numerals are given to the same functions. Hereinafter, the added functions and the accompanying changes will be described. The edge detection means 30 is a color image input means 1
0, and receives as input the image data preprocessed by the preprocessing means 20, and outputs a binary image F representing the result of classification into ON pixels corresponding to edges of the color image and other OFF pixels. I do. The following method is used to detect edges from the color image data. (1) A method of taking the square root of the sum of squares of the edge strength calculated by a Sobel operator or the like for each color component. (2) Reference H.-C. Lee and DR Cok, "Detecting bounda
ries in a vector field, "IEEE Trans.Signal Processi
ng, vol. 39, no. 5, pp. 1181-1194, 1991. Vector method. Among these edge detection methods, it is known that the method (2) is more robust against noise than the method (1). Further, the edge detection method based on the vector method of (2) is characterized in that in the combination of the edge intensities calculated for each color component, the correlation between the components is considered instead of simply taking the square root of the sum of squares. It is.

Specifically, u (x, y), v (x,
When y) and w (x, y) are defined as three components of a color as shown in Expression 1, the edge intensity at the pixel (x, y) is given by Expression 2.

(Equation 1) The edge strength image generated by the Sobel operator for the image of FIG. 2 is as shown in FIG. In FIG. 7, the higher the edge strength, the darker the black. Next, threshold processing is performed on the edge strength obtained by the above calculation. This threshold value is automatically set by statistically analyzing the intensity distribution, or the threshold value is prepared in advance and set by the user according to the degree of show-through and the paper quality.
By performing this threshold processing, pixels whose edge strength is equal to or greater than the threshold
N, the others are OFF. Also, for the ON pixels of the binarized edge image after the threshold processing,
An expansion process is performed.

FIG. 8 shows a binarized edge obtained by performing threshold processing on the color edge intensity shown in FIG. The color component binarizing unit 40 examines the binary image F detected by the edge detecting unit 30, and performs a color component binarizing process only on the OFF pixel region. In the edge detection obtained as a result and in the color component binarization processing, the show-through correction processing is performed on the pixel area that is not classified as the ON pixel, so that the show-through shown in FIG. A corrected image is obtained.

<Modification of the Second Embodiment> In the second embodiment, the binary image detected by the edge detecting means 30 is examined, and the color component Had been treated. However, in this modified example, conversely, the color component binarization unit 40 performs the binarization processing of the color component, and here, the edge is detected by the edge detection unit 30 for the OFF pixel area. In the resulting color component binarization processing and also in edge detection, show-through correction processing was performed on pixel areas that were not classified as ON pixels, thereby correcting show-through similar to that in the second embodiment. An image is obtained. <Another Modification of the Second Embodiment> FIG. 9 is a functional configuration diagram showing another modification of the second embodiment. In the second embodiment and the modification described above, the edge detecting means 30 and the color component binarizing means 40
And the order of processing was serial. In this modification, the result of the preprocessing unit 20 is given to the edge detection unit 30 and the color component binarization unit 40 in parallel,
Using the color component binarization processing result for the input image and the edge strength for the input image, neither the color component binarization processing nor the edge detection is classified as an ON pixel. By performing the show-through correction processing on the pixel region that has been shown, an image in which show-through has been corrected in the same manner as in the second embodiment can be obtained.

<Embodiment as Program> FIG.
FIG. 2 is a schematic diagram of hardware constituting a color image processing apparatus using the present invention. In the present embodiment, first,
Each function shown in FIG. 1, FIG. 6, or FIG. 9 is programmed and stored in the ROM 7. Then, this ROM7
Each function of the present invention is executed by the CPU 5 reading and executing the program stored in the CPU 5. When each function is executed, a color image input from the image input device 1 such as a scanner or a digital camera is stored in the RAM 6, read out from the RAM 6, and a show-through correction image is generated as a result of a series of processing. Is output to an image output device 4 such as a printer or a color digital copying machine. Further, the progress of the process and the results of the process are presented to the user through the display device 2 such as a display, and when necessary, the user inputs parameters necessary for the process from the input device 3 such as a keyboard or a touch panel. . Intermediate data created during the execution of the processing is also stored in the RAM 6 and read, corrected, and written by the CPU 5 as necessary. In the above, the recording medium of the program is the ROM 7, but other recording media, for example, a semiconductor medium (for example, ROM, IC memory card, etc.), an optical medium (for example,
Any of a DVD-ROM, MO, MD, CD-R, etc.) and a magnetic medium (eg, magnetic tape, flexible disk, etc.) may be used. Each program for realizing the functions of the present invention may be distributed in the form of a medium, or each program may be stored in a storage device such as a magnetic disk, and may be downloaded or pushed over a wired or wireless communication network or broadcast wave. It is also possible to distribute by.

[0016]

As described above, according to the present invention, colorized characters, lines,
By extracting points, picture portions, and the like, and applying show-through correction processing only to pixels that are not extracted, show-through can be corrected while preventing image quality deterioration. Also,
By detecting the edge strength, the boundary between characters and lines and the portion where the background color changes are extracted, and show-through correction processing is applied only to the pixels that are not extracted, thereby correcting show-through while preventing image quality deterioration. be able to.

[Brief description of the drawings]

FIG. 1 is a functional configuration diagram of a color image processing apparatus using the present invention.

FIG. 2 is a diagram illustrating an example of a show-through color image.

FIG. 3 is a diagram showing a result of binarizing color components with respect to the color image of FIG. 2;

FIG. 4 is a diagram illustrating a result of performing show-through correction on an area determined to be an OFF area by binarization.

FIG. 5 is a flowchart showing a processing procedure of color component binarization according to the present invention.

FIG. 6 is another functional configuration diagram of a color image processing apparatus using the present invention.

FIG. 7 is a diagram illustrating an output example based on color edge intensity when an edge is detected.

8 is a diagram illustrating an output example when the color edge intensity in FIG. 7 is binarized.

FIG. 9 is a functional configuration diagram of another modification of FIG. 6;

FIG. 10 is a schematic diagram illustrating a hardware configuration of a color image processing apparatus using the present invention.

[Explanation of symbols]

1 image input device, 2 display device, 3 input device, 4
Image output equipment, 5 CPU, 6 RAM, 7 ROM,
Reference Signs List 10 color image input device, 20 preprocessing means, 30
Edge detection means, 40 color component binarization means, 50
Show-through correction means, 60 image output means

Claims (16)

[Claims] 1. A color component binarizing means for binarizing the value of each color component with respect to a digital color original image obtained by digitally inputting one side of an original color-printed on both sides. A color image processing apparatus comprising: a show-through correction unit configured to generate an image in which a show-through component has been corrected only for a pixel in which all of the components of the valued pixels are equal to or greater than a threshold value. 2. The color image processing apparatus according to claim 1, wherein the color component binarizing means sets a window of a predetermined size around each pixel, and sets a window of a pixel in the window. A color image processing apparatus, wherein a threshold value is set based on a statistic for each color component. 3. A digital color original image obtained by digitally inputting one side of an original color-printed on both sides, calculating an edge strength when detecting an edge, and detecting the edge from the edge strength. Edge detecting means, color component binarizing means for binarizing the value of each color component only for pixels having a low edge intensity, and all components of pixels binarized by the color component binarizing means. A color image processing apparatus, comprising: a show-through correction unit configured to generate an image in which a show-through component is corrected only for a pixel having a threshold value or more. 4. A color component binarizing means for binarizing the value of each color component for a digital color original image obtained by digitally inputting one side of an original color-printed on both sides, Edge detection means for calculating an edge intensity only for pixels having a value of each component of the coded color equal to or greater than a threshold value and detecting an edge from the edge intensity, and a pixel having a low edge intensity calculated by the edge detection means A color image processing apparatus, comprising: a show-through correction unit that generates an image in which a show-through component is corrected only for the image. 5. An edge is calculated from a digital color original image obtained by digitally inputting one side of an original color-printed on both sides when the edge is detected, and the edge is detected from the edge intensity. Edge detection means, color component binarization means for binarizing the value of each color component with respect to the input image, and a pixel having a low edge intensity calculated by the edge detection means, and the color Color image processing, comprising: a show-through correction unit that generates an image in which a show-through component is corrected only for pixels in which all components of pixels binarized by the component binarization unit are equal to or greater than a threshold. apparatus. 6. The color image processing apparatus according to claim 3, wherein said edge detecting means calculates an edge intensity from each component of a color of an image from which an edge is detected. A color image processing apparatus for detecting an edge in consideration of a correlation between edge strengths of components. 7. The color image processing apparatus according to claim 3, wherein said color component binarizing means sets a window of a predetermined size around each pixel. A color image processing apparatus characterized in that a threshold value is set based on a statistic of each color component of a pixel in the window and binarized. 8. A digital color original image obtained by digitally inputting one side of a document color-printed on both sides into a digital color original image, binarizing the values of the respective color components, and converting all of the binarized pixels. A color image processing method comprising: generating an image in which a show-through component is corrected only for a pixel whose component is equal to or greater than a threshold. 9. The color image processing method according to claim 8, wherein a window of a predetermined size is set around each pixel, and based on a statistic for each color component calculated in the window. A color image processing method, wherein the threshold value is set by setting the threshold value. 10. A digital color original image obtained by digitally inputting one side of an original color-printed on both sides, edge detection is performed when edges are detected, and edges are detected from the strengths. .., Binarizing the value of each color component only for the pixel having the low edge intensity, and generating an image in which the show-through component is corrected only for a pixel in which all components of the binarized pixel are equal to or larger than a threshold value. A color image processing method comprising: 11. A digital color original image obtained by digitally inputting one side of an original color-printed on both sides into a digital color original image, binarizing the value of each color component, and converting each of the binarized color components Only for pixels whose value is equal to or greater than the threshold value, the edge strength is calculated, an edge is detected from the edge strength, and an image in which the show-through component is corrected only for the pixel having a low edge strength is generated. Color image processing method. 12. A digital color original image obtained by digitally inputting one side of an original color-printed on both sides, the edge intensity is calculated when the edge is detected, and the edge is detected from the edge intensity. Then, with respect to the input image, the values of the respective color components are binarized, and the edge intensity is low, and show-through is performed only for pixels in which all components of the binarized pixels are equal to or greater than a threshold value. A color image processing method characterized by generating an image with corrected components. 13. The color image processing method according to claim 10, wherein edge intensity is calculated from each color component of the image of which edge is to be detected, and the edge intensity is calculated for each component. A color image processing method, wherein an edge is detected in consideration of the correlation of 14. A color image processing method according to claim 10, wherein a window of a predetermined size is set around each pixel, and calculation is performed within the window. A color image processing method, wherein the threshold value is set based on a statistic for each color component and binarized. 15. A program for causing a computer to function as the color image processing device according to any one of claims 1 to 7. 16. A computer-readable recording medium storing a program for causing a computer to function as the color image processing apparatus according to claim 1. Description: