JP4100116B2 - Image processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus that processes an image read by a scanner or the like. More specifically, the present invention relates to an image processing apparatus that distinguishes and processes whether or not a read image has been copied and formed.
[0002]
[Prior art]
Conventionally, in a copying machine or the like, a document image is read and a copy image is formed by appropriately processing the image. In particular, in a color copier, various processes for improving image quality are performed along with conversion of a color space from an input system to an output system. For example, edge enhancement processing is performed for MTF correction, moire removal, halftone removal, or setting of various parameters for color reproduction. However, when the copied paper is further copied as a manuscript like a so-called generation copy, the character portion is blurred or blurred, and the color tone is deteriorated. For this reason, the user is prompted to input the distinction between the first copy and the generation copy, and various parameters are switched accordingly (see, for example, Patent Document 1).
[0003]
On the other hand, there is a type in which a mark is added to a copied image, and this mark is detected at the time of reading to detect that it is a copy original. Various parameters are automatically switched (see, for example, Patent Document 2). According to this, when a copy image is formed, a fine specific pattern is added with a color that is not noticeable, such as yellow. If the specific pattern is included in the image read from the document, it is determined that the copy is a generation copy, and various parameters are switched to form an image. Furthermore, the number of copy generations of the document can be determined by removing the detected mark and adding a new mark.
[0004]
[Patent Document 1]
JP-A-6-46261 [Patent Document 2]
JP-A-11-266366 (page 4-6, Fig. 1-3)
[0005]
[Problems to be solved by the invention]
However, removing the mark is not so easy. If the image is simply removed as in the image processing apparatus described in Patent Document 2, the original image may be damaged. Furthermore, when the image is blurred or distorted by copying, or in the case of a mark with an unexpected pattern, it is not easy to determine whether the mark is a mark. For these reasons, when it cannot be recognized that the copy is a generation copy, the parameter is not switched and the pattern is overprinted. For this reason, there has been a problem that image quality deterioration further proceeds.
In addition, since the above marks are generally added so as to be scattered over the entire paper surface, they are also added to the background portion. This causes a problem that when the image is compressed and stored, the compression rate is lowered and an extra memory capacity is required.
[0006]
The present invention has been made to solve the problems of the conventional image processing apparatus described above. That is, an object of the present invention is to provide an image processing apparatus capable of preventing the image quality of the generation copy from being lowered and reducing the memory capacity required for storage.
[0007]
[Means for Solving the Problems]
In order to solve this problem, the image processing apparatus of the present invention includes a reading unit that reads an image of a document and acquires image data, and a mark that indicates that the document in the image data acquired by the reading unit is a copy A generation copy discriminating unit that discriminates whether or not the document is a copy, and a constant color region extracting unit that extracts a constant color region having a constant color in the image data acquired by the reading unit; it sets a first image forming condition when the document has not been determined to be a copy, a condition setting unit for setting the second image forming condition when the original is determined to be a copy, document added but when it is determined that the copy, the color of the position of the mark detected in the predetermined color region, a color conversion unit that converts the color of a certain color region around the mark, the mark image data A mark adding unit that has an image forming unit for forming an image from the image data. Then, the image forming unit, when the document is not determined to be a copy is more to the first image forming conditions set by the condition setting unit, marked with is obtained by the reading unit mark addition unit adds by performing image formation from the image data, if the document is determined to be copied, and more to the second image forming condition set by the condition setting section, is acquired by the reading unit converted by the color conversion unit Then, image formation is performed from the image data with the mark added by the mark adding unit.
[0008]
That is, in the image processing apparatus of the present invention, whether or not the original is a copy is determined based on whether or not a mark is detected in the image data acquired by the reading unit. Since the image forming conditions are changed according to the result, further deterioration due to blurring or blurring of the image can be prevented. Furthermore, if the document is determined to be copied, the mark which is detected in a certain color region is converted to the color of a certain color region around it. Therefore, the mark is removed from the image data. From the image data from which this mark has been removed, an image is formed on the basis of the changed image formation conditions, and then a mark is added, so that an image is formed with reduced mark overlap and reduced image degradation. Is done.
[0009]
In the present invention, the constant color area extraction unit extracts a background area whose color is the background color, and the color conversion section converts the color at the position of the mark detected in the background area to the background color . It is desirable.
In this way, the mark in the base area is converted into the base color, so that the mark is removed. And, since the mark included in the image area other than the background is not forcibly removed, the image is not damaged.
[0010]
In the present invention, the mark adding unit may add a mark only to an area to be subjected to color conversion by the color converting unit.
In this way, the mark is added only to the portion where the color of the mark is converted into the surrounding color by the color conversion unit. That is, a new mark is attached only to the part from which the mark has been removed. Therefore, since the double strike of the mark does not occur, further deterioration of the image is prevented.
[0011]
The image processing apparatus of the present invention may include a compression / decompression unit that compresses and decompresses image data, and a memory unit that stores image data compressed by the compression / decompression unit .
In this case, if the document is not determined to be a copy, the memory unit stores the image data acquired by the reading unit and compressed by the compression / decompression unit, and if the document is determined to be a copy. The image data acquired by the reading unit, converted by the color conversion unit, and compressed by the compression / decompression unit is stored. The mark adding unit adds a mark to the image data read from the memory unit and decompressed by the compression / decompression unit.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described in detail with reference to the drawings. The image processing apparatus according to the present embodiment is mounted on a color copier to copy and form a read color document.
[0013]
As schematically shown in FIG. 1, the image processing apparatus of the present embodiment first has a CCD 11 for each color of RGB as an image input unit. The CCD 11 corresponds to a reading unit. Each CCD 11 is connected to an A / D converter 12 for digitally converting the detection result. Further, an SH correction unit 13 for performing shading correction, a lightness / color difference separation unit 14 for converting colors into lightness and color difference methods, a sharpness adjustment unit 15 for image sharpening, and an HVC adjustment unit 16 are sequentially connected. ing.
[0014]
Furthermore, a color space conversion unit 17 that converts the color space of the image into an L ^* a ^* b ^* color space, an isolated point density replacement unit 18, a compression / expansion unit 19 for compressing and storing data, and a data storage unit A memory unit 20 is connected. Furthermore, a color space conversion unit 21 that converts the L ^* a ^* b ^* color space into a YMCK color space for an image forming apparatus, an MTF correction processing unit 22 that performs edge enhancement of an image, and a screen processing unit 23, and a new mark A mark adding unit 24 to be added is provided. And it has the image formation part 25 for forming the produced image data on a paper. Here, the isolated point density replacement unit 18 corresponds to a color conversion unit.
[0015]
In addition, a mark detection unit 30 is connected to the SH correction unit 13 as a configuration for detecting a mark. The mark detection unit 30 includes an isolated point detection unit 31 that detects an isolated point, a specific saturation detection unit 32 that detects whether or not the pixel is a specific saturation region, and a specific hue that detects whether or not the pixel is a specific hue region. A detection unit 33, a peripheral density detection unit 34 for detecting the density around the detected isolated point, and a parameter setting unit 35 for changing various parameters are provided. Here, the isolated point detection unit 31 corresponds to a generation copy determination unit, and the parameter setting unit 35 corresponds to a condition setting unit. The detection result of the mark detection unit 30 is obtained from the sharpness adjustment unit 15, the HVC adjustment unit 16, the color space conversion unit 17, the isolated point density replacement unit 18, the color space conversion unit 21, the MTF correction processing unit 22, and the screen processing unit 23. Input to each part.
[0016]
With these configurations, the image data input from the CCD 11 is sequentially processed and formed and output by the image forming unit 25 as indicated by arrows in FIG. First, the RGB image data read by the CCD 11 is converted into digital data by the A / D converter 12, and unevenness of scanner light distribution and CCD sensitivity variation between pixels are corrected by the SH correction unit 13. Next, the corrected RGB image data is converted into Y, Cr, and Cb signals by matrix calculation or the like in the lightness / color difference separation unit 14. The corrected RGB image data is also input to the mark detection unit 30.
[0017]
Here, the operation of the mark detection unit 30 will be described with reference to FIG. In the mark detection unit 30, the input RGB image data is first input to the isolated point detection unit 31. Then, an isolated point is detected by filter processing (S101). Next, it is determined whether or not the detected isolated points are equal to or smaller than a predetermined size (S102), and whether or not they are equal to or larger than a predetermined number is determined (S103). If it is smaller than the predetermined size (S102: Yes) and more than the predetermined number (S103: Yes), it is determined as a mark and the isolated point signal is turned ON (S104). The isolated point detection unit 31 performs the processing from S101 to S104.
[0018]
That is, in the image processing apparatus according to the present embodiment, when there are a predetermined number or more of isolated points having a predetermined size or less, the isolated points are determined as marks. Here, if it is a condition that each isolated point has the same color and the same shape as a mark, this may be further added as a criterion. Alternatively, yellow, which is generally a conspicuous color, is used as a mark, and this point can also be added as a criterion.
[0019]
On the other hand, a region having a specific hue / saturation is detected from the RGB image data input to the mark detection unit 30. For this purpose, RGB data is first converted into hue / saturation data (S105). Then, the saturation data is input to the specific saturation detection unit 32 and the hue data is input to the specific hue detection unit 33. The specific saturation detection unit 32 detects a region where the saturation is a specific value (S106). Then, the saturation of the surrounding area is compared with the saturation reference to determine whether the saturation is within a predetermined range from the specific saturation (S107). If the saturation is within the predetermined range (S107: Yes), the saturation detection signal is turned ON (S108). The specific saturation detection unit 32 performs the processing from S106 to S108.
[0020]
Further, the specific hue detection unit 33 detects an area where the hue is a specific value (S109). Then, the hue of the peripheral area is compared with the hue reference to determine whether the hue is within a predetermined range from the specific hue (S110). If the hue is within the predetermined range (S110: Yes), the hue detection signal is turned on (S111). The specific hue detection unit 33 performs the processing from S109 to S111.
[0021]
That is, a small area having a specific hue / saturation is extracted from the entire image area. If white is set as the specific hue / saturation, a white background portion where no image is formed is extracted. Alternatively, if a portion with little variation in hue and saturation is extracted regardless of the color, a ground color portion or a solid region is extracted. When detecting the hue / saturation, the isolated point detected by the isolated point detection unit 31 may be removed.
[0022]
When the processing in the isolated point detection unit 31, the specific saturation detection unit 32, and the specific hue detection unit 33 is completed, the three detection signals are examined to determine whether all are ON (S112). That is, if all are ON, there is a small area where the hue / saturation is within a predetermined range, and a mark is detected therein. This mark can be a target of removal processing. On the other hand, if there is a mark that is not ON (S112: No), it means that no mark to be processed has been detected, and the process is terminated. This is because processing an isolated point included in an image portion other than a plain region such as a white background as a mark may damage the image.
[0023]
If all the three detection signals are ON (S112: Yes), the mark is the target of the removal process, and its peripheral density is detected (S113). That is, it is determined whether or not the density of the surrounding 7 × 7 pixels is within a predetermined range centering on the pixel of interest (S114). This can be done by determining whether the difference between the maximum value and the minimum value of the density of these pixels is equal to or less than a predetermined value. Alternatively, density variation (dispersion value) can be calculated and used as a criterion for determination. When it is determined that the periphery of the isolated point is at a predetermined density level (S114: Yes), the average density around the isolated point is acquired (S115). The peripheral density detection unit 34 performs the processes from S113 to S115.
[0024]
Next, from the result of the isolated point detection unit 31, if the isolated point signal is ON, it is determined that the document includes a mark. That is, it can be seen that the manuscript has been copied. Therefore, in order to prevent the copy image quality from further deteriorating, the parameter setting unit 35 changes and sets various parameters used in each processing unit shown in FIG. All of these parameters may be changed, or only some of these parameters may be selected and changed. If the isolated point signal is OFF, these parameters are not changed, and default values are used. Hereinafter, an example of changing parameters in the parameter setting unit 35 will be described.
[0025]
(1) The parameter of the smoothing filter is changed from weak to strong and set in the MTF correction processing unit 22. This eliminates noise and moire.
(2) The color adjustment parameter is changed from low to high saturation and set in the HVC adjustment unit 16, the color space conversion unit 17, and the color space conversion unit 21. This compensates for the desaturation.
(3) The character edge enhancement parameter is changed from strong to weak and set in the MTF correction processing unit 22. This suppresses noise due to excessive edge enhancement.
(4) The screen parameter is set in the screen processing unit 23 as the number of low lines → high line number. This prevents deterioration of graininess due to interference with the same number of lines. Or you may make it change the angle of a screen from a normal angle.
Each parameter is set as described above, and the processing of the mark detection unit 30 is finished.
[0026]
With the parameters set, the description of the operation in FIG. 1 will be continued. The image data converted by the lightness / color difference separation unit 14 in FIG. 1 is then input to the sharpness adjustment unit 15. Then, the brightness data is subjected to filter processing, and image sharpness improvement processing and blurring processing are performed. Further, the HVC adjustment unit 16 multiplies the color difference data by a coefficient and performs hue saturation adjustment. Thereafter, the color space conversion unit 17 converts the color space into the CIE-L ^* a ^* b ^* color space.
[0027]
Next, the isolated point density replacement unit 18 performs density replacement processing for the mark to be processed according to the result of the mark detection unit 30. That is, in S112 in FIG. 2, if it is determined in S114 that the periphery of the mark determined to be within the region of the predetermined saturation and the predetermined hue is the predetermined density level in S114, the isolated point acquired in S115. Replace with the average density around. Thereby, for example, the mark in the white background is replaced with the color of the surrounding white background, so that the mark is removed.
[0028]
The image data from which the mark has been removed is compressed by the compression / decompression unit 19 and stored in the memory unit 20. The data stored in the memory unit 20 is processed according to an output editing instruction by the user such as rotation processing or Nin1 processing. Then, the compression / decompression unit 19 performs decompression processing again. Next, the color space conversion unit 21 converts the image forming unit 25 into a YMCK color space. The MTF correction processing unit 22 performs edge enhancement and smoothing processing, and the screen processing unit 23 performs screen processing. Finally, a mark is newly added to the entire image by the mark adding unit 24 and output by the image forming unit 25. If there is a mark to be processed, a new mark may be added only to the specific hue / saturation area.
[0029]
That is, when there are a predetermined number or more of isolated points in the image, the isolated points are determined to be marks. As a result, it is determined that the copy is a generation copy, and various parameters are changed and set, so that deterioration in image quality can be prevented. Furthermore, if the isolated point is in a specific hue / saturation region and the variation in the peripheral density is within a predetermined range, the isolated point is converted into the peripheral average density. The mark is removed. Thereby, the compression rate in the compression / decompression unit 19 can be improved, and the amount of use of the memory unit 20 can be reduced.
[0030]
Next, an example in which an image is processed by the image processing apparatus according to the present embodiment will be described with reference to FIGS. First, as shown in FIG. 3, it is assumed that the original document 40 which is not a copy has a color frame 42 and a character 43 printed therein within a sheet 41. First, a first generation copy 50 (see FIG. 4) is created using this document 40. In this case, since the mark is not included in the document 40, various parameter changes by the parameter setting unit 35 and density replacement by the isolated point density replacement unit 18 are not performed.
[0031]
In the first generation copy 50, as shown in FIG. 4, a mark 44 is formed on the entire sheet 41 by the mark adding unit 24. In FIG. 4, each mark 44 is shown large for ease of understanding, but it is a small mark that is not easily visible in practice. Furthermore, the character 43 is subjected to processing such as edge emphasis. However, the character 43 is still slightly blurred or blurred compared to the character 43 in the document 40 due to the influence of the surrounding color frame 42. This point is also highlighted in this figure.
[0032]
Next, the first generation copy 50 is used as a manuscript to make a copy. The first generation copy 50 is read by the CCD 11, and after A / D conversion and shading correction, the image data is sent to the mark detection unit 30. In the mark detection unit 30, first, the isolated point detection unit 31 detects each mark 44 that is an isolated point. Further, the specific saturation detection unit 32 and the specific hue detection unit 33 detect specific saturation and hue regions. Here, since white was adopted as the specific hue and saturation, a white background portion was detected. The white background portion here is a peripheral portion of the paper 41 excluding the color frame 42.
[0033]
Next, each of the marks 44 included in the white background portion is replaced with the surrounding average density by the isolated point density replacement unit 18. Thus, intermediate data 51 as shown in FIG. 5 is created, and this intermediate data 51 is compressed and stored in the memory unit 20. In the intermediate data 51, the marks 44 inside the color frame 42 are left as they are, but the marks 44 in the surrounding white background portion are removed. As a result, compared with the case where the image of the first generation copy 50 is compressed as it is, the compression rate in the compression / decompression unit 19 is improved, and the memory capacity for storing can be reduced.
[0034]
Further, since the various parameters are changed by the parameter setting unit 35 because the mark 44 is detected, the blurring or blurring of the character 43 is restored to some extent. Subsequently, this data is converted into the YMCK color space by the color space conversion unit 21, and edge enhancement or the like is performed by the MTF correction processing unit 22 and the screen processing unit 23. Further, each mark 44 is newly added to the entire sheet 41 by the mark adding unit 24. As a result, the second generation copy 52 formed by the image forming unit 25 has a white background portion with a single mark 44 and a double mark 44 in the color frame 42. As a result, a second generation copy 52 as shown in FIG. 6 is formed.
[0035]
Next, as another example, instead of adopting white as the specific hue / saturation in the specific saturation detection unit 32 and the specific hue detection unit 33, a portion with less variation in hue / saturation regardless of the color is selected. An example of extraction will be described. In this way, a ground color portion and a solid region are extracted in addition to the white background portion. When this method is applied to the above-described example of the first generation copy 50, the intermediate data 60 stored in the memory unit 20 is as shown in FIG. That is, not only the white background portion but also each mark 44 in the color frame 42 is removed. However, the mark 44 on the boundary line between the white background and the color frame 42 or on the boundary line between the color frame 42 and the character 43 is not removed. In this example, a second generation copy 61 as shown in FIG. 8 is formed in the image forming unit 25.
[0036]
As another example, instead of adding each mark 44 to the entire sheet 41 in the mark adding unit 24, it is possible to add each mark 44 only to the area whose density has been replaced by the isolated point density replacing unit 18. It is. This eliminates the area where each mark 44 is added twice, and the second generation copy is almost the same as the first generation copy shown in FIG.
[0037]
As described in detail above, according to the image processing apparatus of the present embodiment, the mark detection unit 30 detects a mark. If the document is found to have been copied due to the presence of the mark, the parameter setting unit 35 changes various parameter values and sets them in each processing unit. As a result, it is possible to prevent deterioration in image quality. Further, each mark 44 on the white background is replaced with the peripheral average density in the isolated point density replacement unit 18. Therefore, the compression rate can be improved and the memory capacity required for storage can be reduced.
[0038]
Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, in the above embodiment, determination is made based on the density of 7 × 7 pixels around the target pixel in order to calculate the peripheral density of the isolated point to be processed, but this size is not limited to 7 × 7 pixels. Absent. Further, the peripheral density of the entire isolated point may be detected instead of one pixel as the target pixel.
For example, in the above embodiment, the mark color is inconspicuous yellow, but there is also an idea of using a conspicuous color. Alternatively, in the case of generation copy, a method of adding a mark having the same color as that of the mark detected by the isolated point detection unit 31 is also conceivable.
[0039]
【The invention's effect】
As is apparent from the above description, according to the present invention, there is provided an image processing apparatus capable of preventing the image quality of the generation copy from being lowered and reducing the memory capacity required for storage.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an image processing apparatus according to an embodiment.
FIG. 2 is a flowchart illustrating an operation of a mark detection unit.
FIG. 3 is an explanatory diagram illustrating an example of a document for copying.
FIG. 4 is an explanatory diagram illustrating an output example of a first generation copy.
FIG. 5 is an explanatory diagram illustrating an example of intermediate data stored in a memory using a first generation copy as a document;
FIG. 6 is an explanatory diagram illustrating an output example of a second generation copy.
FIG. 7 is an explanatory diagram showing another example of intermediate data stored in a memory using a first generation copy as a document;
FIG. 8 is an explanatory diagram illustrating another output example of the second generation copy.
[Explanation of symbols]
11 CCD (reading unit)
18 Isolated point density replacement part (color conversion part)
24 mark adding unit 25 image forming unit 31 isolated point detecting unit (generation copy discriminating unit)
35 Parameter setting section (condition setting section)

Claims (4)

A reading unit that reads an image of a document and obtains image data;
A generation copy discriminating unit that discriminates whether or not the manuscript is a copy by detecting a mark (hereinafter simply referred to as “mark”) indicating that the manuscript is a copy in the image data acquired by the reading unit. When,
A constant color region extracting unit for extracting a constant color region having a constant color in the image data acquired by the reading unit;
A first image forming condition is set when the original is not determined to be a copy, and a second image forming condition is set when the original is determined to be a copy. If it is determined that copy, color conversion for converting the color of the position of the mark detected in the predetermined color region in the image data acquired by the reading unit, the color of the constant color region around the mark Part,
A mark adding unit for adding a mark to image data;
An image forming unit that forms an image from image data;
The image forming unit includes:
If the document has not been determined to be a copy is more to the first image forming conditions set by the previous SL condition setting unit, the mark is added in the in the image data mark addition unit acquired by the reading unit Image formation from the captured image data,
If the document is determined to be copied, the mark more second image forming condition set in the previous SL condition setting unit, the converted image data is acquired the color conversion unit by the reading unit An image processing apparatus for performing image formation from image data to which a mark is added by an adding unit. The image processing apparatus according to claim 1,
The constant color area extraction unit extracts a background area whose color is a background color;
The image processing apparatus, wherein the color conversion unit converts a color at a mark position detected in a background area into a background color . In the image processing device according to claim 1 or 2 ,
The image processing apparatus according to claim 1, wherein the mark adding unit adds a mark only to a region subjected to color conversion by the color conversion unit. In the image processing device according to any one of claims 1 to 3,
A compression / decompression unit that compresses and decompresses image data;
A memory unit for storing image data compressed by the compression / decompression unit;
The memory unit is
If it is not determined that the document is a copy, the image data acquired by the reading unit and compressed by the compression / decompression unit is stored;
If it is determined that the document is a copy, the image data acquired by the reading unit, converted by the color conversion unit and compressed by the compression / decompression unit is stored;
The mark adding unit adds a mark to image data read from the memory unit and decompressed by the compression / decompression unit.

Images