JPH08340447A - Image processor with through prevention function - Google Patents

Abstract

PURPOSE: To prevent through copying without erasing information of a document unnecessarily by positively providing a means which detects through copy information on the document and correcting the density of an image on the basis of the detected information. CONSTITUTION: A through copy area deciding means 9 decides a through copy area where a through copy is possibly present by utilizing the color image signal (g) of a color image signal rgb outputted by an image input means 1. Then a through copy level detecting means 10 detects a level in the through copy area. Further, a through copy level correction processing means 11 adds an offset value (δ) to the detected copy level to obtain a copy level correction value. Furthermore, a copy level correction value storage means 12 stores the through copy level correction value obtained by the copy level correction processing means 11. Then a density correction processing means 6 performs density correction processing on the basis of the through copy level correction value (ura+δ) outputted by the copy level correction value storage means 12.

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 such as a copying machine or a facsimile, and more particularly to an image processing apparatus for reproducing an image by removing the show-through existing in a document.

[0002]

2. Description of the Related Art In an image processing apparatus such as a copying machine, an original having information on both sides thereof, for example, a book original may be input. When such an original is input as an input image to the image processing apparatus, the image signal corresponding to the original includes not only the information of the target surface but also the meaningless information of the back surface. Show-through may occur on the. Therefore, it is necessary to accurately detect the show-through information of the document included in the image signal input from the image input device and remove the show-through information from the image signal. To deal with such a show-through problem, conventionally, in an image processing apparatus such as a copying machine or a facsimile, when a double-sided original is used as an input image, density control considering the show-through of the original is not performed. The copy density was controlled by an automatic density control mechanism.
For example, Japanese Patent Application Laid-Open No. 3-68270 describes an embodiment of this automatic density control mechanism. This Japanese Patent Laid-Open No.
In the automatic density control mechanism described in Japanese Patent Laid-Open No. -68270, the background level of a document is detected, the density of pixels in a predetermined density range is averaged, the average density value is used as an offset value, and the background level is added to the offset value. The background removal process is performed using the background reference density. Also,
Japanese Patent Laid-Open No. 4-346366 describes a show-through removal processing method using fuzzy inference. Japanese Patent Laid-Open No. Hei 4
In the show-through removal processing method disclosed in Japanese Patent Laid-Open No. 346366, fuzzy inference based on information such as paper thickness and density obtained from several sensors is executed, and automatic density adjustment by this fuzzy inference is performed to show the show-through of a document. Have been removed.

[0003]

However, since the automatic density control mechanism disclosed in Japanese Patent Laid-Open No. 3-68270 does not positively detect the information regarding the show-through, the show-through is surely erased. There is no such thing. Even if the show-through of the document is removed, the design, characters, etc. in the highlight area of the document may be removed together with the show-through. In the show-through removal processing method disclosed in Japanese Patent Laid-Open No. 4-346366, show-through removal is performed by obtaining information regarding show-through from paper thickness, density, etc. Did not,
In other words, since the show-through removal processing is not performed separately for the areas where show-through is a problem and the areas where show-through is not a problem, especially when using high-quality paper, the patterns of highlight areas and low-contrast areas Characters may be removed.

The present invention has been made in view of the above points, and it is possible to accurately detect the show-through information of the document from the image signal corresponding to the document and to show the show-through of the highlight area of the document. The objective is to eliminate show-through while maintaining high image quality in the problem area.

[0005]

In order to achieve the above-mentioned object, the invention according to claim 1 is an image input means for reading a document and converting it into an image signal, and a color conversion for converting the image signal into an image recording signal. In an image processing apparatus including a processing unit and an image output unit that outputs an output image based on the image recording signal, a show-through area in which a show-through exists in the document based on the image signal corresponding to the document is defined. A show-through area determining unit for determining, a show-through level detecting unit for detecting a show-through level within the show-through area determined by the show-through area determining unit, and a show-through by performing a predetermined correction on the show-through level. A show-through level correction processing means for setting a level correction value; and a density correction processing means for carrying out density correction of the image recording signal based on the show-through level correction value. Was show-through removal function image processing apparatus according to symptoms.

According to a second aspect of the present invention, in the image processing apparatus with the show-through removal function according to the first aspect, the show-through area is a non-character area.

According to a third aspect of the present invention, in the image processing apparatus with the show-through removal function according to the second aspect, the non-character region is a region where a predetermined number or more of non-character pixels are continuous, and the show-through removal function is provided. Image processing device.

According to a fourth aspect of the present invention, in the image processing apparatus with the show-through removal function according to the first aspect, the show-through area is a non-pattern area.

According to a fifth aspect of the present invention, in the image processing apparatus with the show-through removal function according to the fourth aspect, the non-pattern area is an area in which a predetermined number or more of non-picture pixels are continuous, and the show-through removal function is provided. Image processing device.

According to a sixth aspect of the present invention, in the image processing apparatus with the show-through removal function according to the first aspect, the show-through area is an image in which the show-through removal function is an area in which pixels having a predetermined density or less are continuous. The processing device.

According to a seventh aspect of the present invention, in the image processing apparatus with the show-through removal function according to the first aspect, the show-through area is an area in which pixels having a predetermined saturation or less are continuous, and the show-through removal function is provided. The image processing device is used.

According to an eighth aspect of the invention, in the image processing apparatus with the show-through removal function according to the first aspect, the show-through area is an image processing apparatus with the show-through removal function, which is an area designated by a user.

[0013]

According to the first aspect of the present invention, the show-through area determining means determines the show-through area where the show-through area exists in the original, and the show-through level detecting means determines the show-through area determining means. Detect the show-through level inside. further,
The show-through level correction processing means obtains a show-through level correction value obtained by adding a predetermined offset value to the show-through level. By performing the density correction based on the show-through level correction value, the show-through in the show-through area is removed.

According to a second aspect of the invention, in the first aspect of the invention, the show-through of the non-character area is removed.

According to a third aspect of the present invention, in the first aspect of the present invention, the show-through of a non-character area in which a predetermined number or more of non-character pixels are consecutive is removed.

According to a fourth aspect of the invention, in the invention according to the first aspect, the show-through of the non-pattern area is removed.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the show-through of a non-picture region in which a predetermined number or more of non-picture pixels are continuous is removed.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the show-through is removed in a region where pixels having a predetermined density or less are continuous.

According to a seventh aspect of the invention, in the first aspect of the invention, the show-through is removed in the area where the pixels having a predetermined saturation or less are continuous.

According to the invention of claim 8, in the invention of claim 1, the show-through in the area designated by the user is removed.

[0021]

EXAMPLES Examples of the present invention will be described below.
The invention according to claim 1 will be described based on the embodiment of FIG. FIG. 1 is a functional block diagram of a frame-sequential color image processing apparatus showing a schematic configuration of the present invention. First,
The outline of each component shown in FIG. 1 will be described. The image input means 1 reads an original document and outputs a force error image signal rgb which is substantially linear with respect to the reflectance corresponding to the original document. log
The conversion means 2 converts the color image signal rgb into a density linear force error image density signal RGB by logarithmic conversion. The color correction processing means 3 considers the characteristics of the image input means 1 and the image output means 8, converts the color image density signal RGB into a complementary color image recording signal YMC which is a complementary color to these, and performs color correction. A linear approximation so-called masking method, a tetrahedral interpolation method, a triangular interpolation method, etc. have been proposed as a color correction method performed by the color conversion processing means 3, and color correction is performed using these methods. The black plate processing means 4 generates a black plate signal K from the color image recording signal YMC by the black plate processing shown in FIG. In the black plate processing of the black plate processing means 4, black that is output in the high chroma region or the highlight region (that is, a region having a low density) is taken into consideration in consideration of a region such as a high chroma region or a highlight region where black is not desired to be used. The plate signal K is set to zero. With such settings, the black plate signal K becomes zero up to the level of the threshold value (Th_α).

Next, the under color removal processing means 5 performs under color removal processing from the color image recording signal YMC and the black plate signal K,
A color image recording signal Y1M1C1 and a black plate signal K1 are generated. The density correction processing unit 6 outputs the power image recording signal Y1M1C1 and the black plate signal K1 to a color image so as to reduce the density of the show-through area based on the show-through level correction value output from the show-through level correction value storage unit 12. Recording signal Y
2M2C2 and black plate signal K2. The halftone processing means 7 performs dither processing on the color image recording signal Y2M2C2 and black plate signal K2, and also performs density conversion processing so-called printer γ correction suitable for the characteristics of the image output means 8 and outputs it to the image output means 8. To do. The image output unit 8 outputs the color image recording signal Y3M processed by the halftone processing unit 7.
An output image is output based on 3C3 and the black plate signal K3. The show-through area determination unit 9 identifies the area where the show-through of the document exists. The show-through level detecting means 10 detects the show-through level of the show-through area determined by the show-through area determining means 9. Details of the show-through area determination unit 9 and the show-through level detection unit 10 will be described later. The show-through level correction processing unit 11 obtains a show-through level correction value by correcting the show-through level in consideration of the characteristics of the image processing apparatus, that is, by adding an offset value (δ) to the show-through level. The show-through level correction value storage unit 12 stores the show-through level correction value and outputs the show-through level correction value to the density correction processing unit 6 during density conversion of the main scan.

Next, the operation of the prescan performed prior to the main scan will be described. This prescan is processed as follows. First, image input means 1 such as a scanner
The original is read by and the color image signal rgb corresponding to the original is obtained. The show-through area determining unit 9 determines a show-through area in which a show-through may exist by using the color image signal g of the color image signal rgb output from the image input unit 1. At this time, the color image signal used for determining the show-through area may be the color image signal r or the color image signal b. Next, show-through level detecting means 1
At 0, the show-through level in the show-through area determined by the show-through area determination unit 9 is detected. Next, the show-through level correction processing means 11 adds the offset value (δ) to the show-through level detected by the show-through level detecting means 10 to obtain a show-through level correction value. Further, the show-through level correction value storage unit 12 stores the show-through level correction value obtained by the show-through level correction processing unit 11.

Next, the operation during the main scan will be described. First, as preprocessing for color correction, the Log conversion unit 2 performs logarithmic conversion, and the image input unit 1 such as a scanner.
The input force image signal rgb is converted into a force image signal density signal RGB. Next, in the color conversion processing means 3, the color image density signal RGB is converted into the color image recording signal Y.
The black plate processing means 4 performs color correction while converting to MC.
Then, using the color image recording signal YMC, the black plate signal K
Set. Then, the under color removal processing means 5 performs under color removal processing from the color image recording signal YMC and the black plate signal K to generate a color image recording signal Y1M1C1 and a black plate signal K1. The color image recording signal Y1M1C1 and the black plate signal K1 are processed by the density correction processing means 6 shown in FIG.
The density correction processing is performed based on the show-through level correction value (ura + δ) output from the show-through level correction value storage unit 12. That is, the density correction processing unit 6 converts the color image recording signal Y1M1C1 and the black plate signal K1 as follows. First, when the color image recording signal Y1M1C1 and the black plate signal K1 are less than the show-through level correction value (ura + δ) output from the show-through level correction value storage means 12, the color image recording signal Y1M1C1 and the black plate signal K1 are obtained.
Is converted to zero. Then, the color image recording signal Y1M1
C1 and the black signal K1 are the show-through level correction value (ura +
When existing between δ) and a certain value (Th_3), as represented by a straight line with a constant slope (slope 2 in FIG. 10),
The color image recording signal Y1M1C1 and the black plate signal K1 are converted into a color image recording signal Y2M2C2 and a black plate signal K2. Furthermore, when the color image recording signal Y1M1C1 and the black plate signal K1 are Th_3 or more, the inclination is 1, that is,
The color image recording signal Y1M1C1 and the black plate signal K1 are converted so that the color image recording signal Y1M1C1 and the black plate signal K1 may coincide with the power image recording signal Y2M2C2 and the black plate signal K2. In this way, the density correction processing means 6
Converts the color image recording signal Y1M1C1 and the black plate signal K1 into the power image recording signal Y2M2C2 and the black plate signal K2 so as to reduce the density of the show-through area. And
In the halftone processing means 7, the power image recording signal Y2M
The 2C2 and the black plate signal K2 are subjected to dither processing and density conversion processing suitable for the characteristics of the image output means 8, so-called printer γ correction, and converted into a color image recording signal Y3M3C3 and a black plate signal K3. Finally, the image output means 8 outputs the color image recording signal Y3M3 output from the halftone processing means 7.
An output image is obtained based on C3 and the black plate signal K3.

The operations of the show-through area determining means 9 and the show-through level detecting means 10, which are the features of the present invention, will be described in detail below. First, the show-through area determination means 9
Will be described. The area where show-through is a problem for the human eye is the area where the information from the back is reflected in the area where there is no information from the front over a large area on the white background. Conversely, when considering a general manuscript, even if there is a show-through in a certain picture or character, it does not matter so much. Based on such visual characteristics, the following areas are conceivable as areas where show-through is a problem. Therefore, there are the following features as a feature amount for detecting an area where the show-through is a problem. An area in which non-character pixels, non-picture pixels, or pixels having a density or saturation below a certain threshold level are continuous in a predetermined number or more in the main scanning direction, or an area designated by the user. By the way, in the present invention, the pattern character area determination circuit of Japanese Patent Application No. 6-55605 is used as a method for separating the non-character area from the character area and the non-picture area from the picture area.

The invention according to claims 2 and 3 is shown in FIG.
A description will be given based on the embodiment of. FIG. 3 illustrates a show-through area determination circuit using the character area determination circuit 13. The character area determination circuit 13 determines whether the pixel of interest is a character area by using the color image signal g of the color image signal rgb corresponding to the original by the image area separation technique, and outputs the result. When the pixel of interest is determined to be a character, the character area determination circuit 13 reads the preceding 7-pixel data in the 8-pixel buffer, that is, the area near the character area (at this time, the parallel data of 7 pixels is serialized. As a region determination result, an on signal is output when the target pixel is not a character pixel, and an off signal is output when the target pixel is a character pixel. Counting circuit 14
Is when the main scanning position is zero, and when the character area determination circuit 1
It will be reset when the signal from 3 turns off,
The force counter is added as long as the on signal continues. Further, if the counter value at the pixel of interest is equal to or greater than a predetermined threshold value (Th_2) and the signal from the counting circuit 14 is on, the determination circuit 15 indicates a region in which show-through may exist. The on signal is output.

The invention according to claims 4 and 5 is shown in FIG.
A description will be given based on the embodiment of. FIG. 4 shows a show-through area determination circuit using the pattern area determination circuit 16. The image area determination circuit 16 uses the image area separation technique to determine whether the pixel of interest is the image area or the non-image area using the color image signal g corresponding to the document, and outputs the result. When the pixel of interest is determined to be a pattern, the picture area determination circuit 16 reads the preceding 7 pixel data in the 8 pixel buffer, that is, the area near the picture area (at this time, the parallel data of 7 pixels is serialized. As a region determination result, an on signal is output if the pixel of interest is not a picture pixel, and an off signal is output if the pixel of interest is a picture pixel. The counting circuit 17 is reset when the main scanning position is zero and when the signal from the pattern area determination circuit 16 is turned off, but the force counter is added as long as the on signal continues. Further, the determination circuit 18
Indicates that the counter value at the pixel of interest has a predetermined threshold value (Th_
2) Above, and the signal from the counting circuit 17 is on
If so, it represents the area where the show-through may exist.
Output n signal.

The inventions described in claims 6 and 7 will be described based on the embodiments of FIGS. 5 and 6, respectively. FIGS. 5 and 6 show a show-through area determination circuit using the density determination circuit 19 and the saturation determination circuit 22, respectively. Concentration determination circuit 1
9 or the processing of the show-through area determination circuit using the saturation determination circuit 22 is similar to the processing of the show-through area determination circuit using the character area determination circuit 13 or the picture area determination circuit 16 described above, and image area separation is performed. By the technique, it is determined whether the pixel of interest is an area having a predetermined density or less or an area having a predetermined saturation or less using the color image signal rgb corresponding to the document, and the result is output. However, in the saturation determination circuit 22, max
The determination is made based on the values of (r-g, g-b, b-r).
By using max (r−g, g−b, b−r), the detection accuracy of the show-through area is improved as compared with the determination using only the color image signal g. For example, it is possible to exclude a high saturation pixel in which both the color image signal g and the color image signal b are low and the color image signal r is high from the show-through region candidates.

Next, FIG. 7 shows a show-through area determining circuit using the picture character area determining circuit 25. The picture character area determination circuit 25 determines whether the pixel of interest is the picture area or the character area by using the color image signal g corresponding to the original by the image area separation technique, and outputs the result. When it is determined that the pixel of interest is a pattern or a character, the picture character region determination circuit 25 reads the preceding 7-pixel data in the 8-pixel buffer, that is, the neighborhood region of the pattern region or the character region (at this time, 7 ON when the pixel of interest is neither a picture element pixel nor a character pixel as the area determination result
A signal is output, and an off signal is output when the pixel of interest is a picture element or a character pixel. Further, the density determination circuit 26 determines that the pixel level of interest has a predetermined threshold value (Th_1).
An on signal is output when: Next, the AND circuit 27 takes the AND of the output signal from the picture character region determination circuit 25 and the output signal from the density determination circuit 26, and outputs the result to the counting circuit 28. The counting circuit 28 turns off the signal from the AND circuit 27 when the main scanning position is zero.
When it becomes, it is reset and the force counter is added as long as the on signal continues. If the counter value at the pixel of interest is equal to or greater than the predetermined threshold value (Th_2) and the signal from the counting circuit 28 is on, the determination circuit 29 indicates an on signal indicating an area where show-through may exist. Is output.
In this way, the pattern area determination circuit and the character area determination circuit may be integrated. Further, as shown in FIG. 8, in order to improve the determination accuracy of the area determination circuit, a character area determination circuit 30, a pattern area determination circuit 31, a density determination circuit 32, and a saturation determination circuit 33 are separately provided, and each of them is provided. The output signal of the circuit may be ANDed by the AND circuit 34. Moreover, you may combine several types of said circuits suitably.

By the way, the picture referred to in the picture character region determination circuit of Japanese Patent Application No. 6-55605 is a halftone picture. Since a picture composed of a silver salt photograph is also inputted to the color copying machine, a photographic picture area judging circuit (not shown) may be used instead of the picture area judging circuit.
Specifically, the circuit may be configured to determine the area in the mask as a picture area when all the pixels in a certain predetermined mask have an intermediate level.

Next, the invention according to claim 8 will be described. The show-through area determination circuit for determining the area where the show-through may exist is automatically performed by the machine. This may be performed manually. In other words, the image is read by pre-scanning and displayed on a CRT, edit board, etc., and the user specifies the area where the show-through exists, for example, with a rectangular area (using a mouse or a dedicated electronic pen),
This may be the show-through area.

Although the image area separation technique of Japanese Patent Application No. 6-55605 is used in the above-described embodiment, the present invention may be any technique for separating a non-character region from a character region, a non-image region from an image region, or the like. For example, any method of image area separation technology may be used.

Next, the show-through level detection circuit 10 will be described. Here, the lowest density level (min (max (max (R, G, B)) of the maximum density (max (R, G, B)) of each pixel existing in the area in which the show-through may exist in the area determination circuit is used. R0, G0, B0), ...
max (Rn, Gn, Bn))) is detected. However,
Try to avoid spike noise as much as possible. Figure 9
A model of processing in the show-through level detection circuit 10 is shown in FIG. First, a max (R, G, B) signal of each pixel is generated, and when the target pixel is a region where there is a possibility of show-through, a plurality of pixels before the target pixel, for example, is the minimum max among 8 pixels. The (R, G, B) values are calculated and used as the show-through level (ura). Then, the minimum max (R, G, B) of the next eight pixels shifted by one pixel is compared with the previously obtained show-through level (ura), and the larger one is newly output as the show-through level. . That is, the show-through level is set to 0 before scanning, is rewritten each time a new show-through level is found, and the show-through level of the image is determined after the completion of the full-screen search.

The above is the method of detecting the show-through level during the pre-scan and then removing the background during the main scan. However, the show-through level is detected at the same time when the black plate signal K is generated during the first scan, and the show-through level is detected later. A method of performing show-through removal processing on the color image recording signal YMC is also possible. At this time, show-through removal processing is performed on the black plate signal K, for example, with an appropriately fixed threshold value. Alternatively, the method of not performing the show-through removal processing on the black plate signal K may be used.

[0035]

As described above, in the show-through removal processing performed by the conventional automatic density adjusting function, the show-through disappears or does not disappear depending on the offset amount added to the background level. According to the invention of claim 1,
Since it has a means for actively detecting the show-through information of the original, and performs the density correction processing of the image based on the detected information,
It is possible to remove the show-through without erasing the information on the document more than necessary. Further, since the show-through can be removed as described above and the information in other areas, especially the highlight area is not removed more than necessary, the show-through area such as the highlight area of the document becomes a problem. Can be maintained at high image quality.

According to the inventions of claims 2 and 3, in addition to the effect of the invention of claim 1, the character information of the original is not detected as the show-through information from the back side, and the show-through is accurately performed. The level can be detected.

According to the inventions of claims 4 and 5, in addition to the effect of the invention of claim 1, the image information of the original is not detected as the show-through information from the back side, and the show-through is accurately performed. The level can be detected.

According to the invention of claim 6, in addition to the effect of the invention of claim 1, the information of the high density area of the document is not detected as the show-through information from the back side, and the show-through is accurately performed. The level can be detected.

According to the invention of claim 7, in addition to the effect of the invention of claim 1, the high saturation level information of the original is not detected as the show-through information from the back side, and the show-through level is accurately determined. Can be detected.

According to the invention of claim 8, in addition to the effect of the invention of claim 1, since the user can specify the show-through area of the document, the show-through level of only the area where the user wants to remove the show-through can be set. It can be detected accurately.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a frame-sequential color image processing apparatus showing a schematic configuration of the present invention.

FIG. 2 is a diagram showing a black plate signal K generated by a black plate process.

FIG. 3 is a diagram showing a show-through area determination circuit using a character area determination circuit.

FIG. 4 is a diagram showing a show-through area determination circuit using a pattern area determination circuit.

FIG. 5 is a diagram illustrating a show-through area determination circuit using a density determination circuit.

FIG. 6 is a diagram illustrating a show-through area determination circuit using a saturation determination circuit.

FIG. 7 is a diagram showing a show-through area determination circuit using a picture character area determination circuit and a density determination circuit.

FIG. 8 is a diagram showing a show-through area determination circuit using a character area determination circuit, a pattern area determination circuit, a density determination circuit, and a saturation determination circuit.

FIG. 9 is a diagram illustrating a model of processing in a show-through level detection circuit.

FIG. 10 is a diagram illustrating a density correction process in a density correction processing unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 image input means 2 log conversion means 3 color conversion processing means 4 black plate processing means 5 undercolor removal processing means 6 density correction processing means 7 halftone processing means 8 image output means 9 show-through area determination means 10 show-through level detection means 11 show-through level correction processing means 12 show-through level correction value storage means 13, 30 character area determination circuit 14, 17, 20, 23, 28, 35 counting circuit 15, 18, 21, 24, 29, 36 determination circuit 16, 31 picture area judgment circuit 19, 26, 32 density judgment circuit 22, 33 saturation judgment circuit 25 picture character area judgment circuit 27, 34 AND circuit.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G06T 5/00 G06F 15/68 310J

Claims (8)

[Claims] 1. An image input means for reading a document and converting it into an image signal, a color conversion processing means for converting the image signal into an image recording signal, and an image output means for outputting an output image based on the image recording signal. In the image processing device provided,
A show-through area determining unit that determines a show-through area in the original based on the image signal corresponding to the original, and a show-through area in the show-through area determined by the show-through area determining unit. A show-through level detecting means for detecting a show-through level, a show-through level correction processing means for performing a predetermined correction on the show-through level and setting a show-through level correction value, and the image based on the show-through level correction value. An image processing apparatus with a show-through removal function, comprising: a density correction processing means for correcting the density of a recording signal. 2. The image processing apparatus with a show-through removal function according to claim 1, wherein the show-through area is a non-character area. 3. The image processing apparatus with a show-through removal function according to claim 2, wherein the non-character area is an area where a predetermined number or more of non-character pixels are continuous. Image processing device. 4. The image processing apparatus with a show-through removal function according to claim 1, wherein the show-through area is a non-picture area. 5. The image processing apparatus with a show-through removal function according to claim 4, wherein the non-picture area is an area in which a predetermined number or more of non-picture pixels are continuous. Image processing device. 6. The image processing apparatus with the show-through removal function according to claim 1, wherein the show-through area is an area in which pixels having a predetermined density or less are continuous. apparatus. 7. The image processing apparatus with the show-through removal function according to claim 1, wherein the show-through area is an area in which pixels having a predetermined saturation or less are continuous. Processing equipment. 8. The image processing apparatus with a show-through removal function according to claim 1, wherein the show-through area is an area designated by a user.