JP5575002B2 - Image processing apparatus, image forming apparatus, and image processing method - Google Patents

Description

  The present invention relates to an image processing apparatus, an image forming apparatus, and an image processing method.

  In recent years, high-quality digital color copying machines that provide a faithful copy of an original image have been put into practical use. For this reason, there is a risk that banknotes and securities will be easily copied and forged. Forgery prevention means to cope with this, it is a function to determine whether or not the document set on the document table is prohibited from being copied and to stop the copying operation or to prevent normal copying Can be considered. However, storing all these features for manuscripts such as banknotes, securities, travelers' checks, checks, and official documents all over the world, and prohibiting copying based on pattern matching means that storage capacity, processing time, It is virtually impossible from the viewpoint of bill correspondence.

  Therefore, a certain copying machine writes a special code pattern (so-called tracking pattern) that is not normally visible on the copy itself without prohibiting the copy itself, and the manufacturer, model name, serial number of the machine used for the copy. Information such as number and copy date can be specified. For example, there is a technique for writing a tracking pattern as a yellow dot pattern in a predetermined block. In order to minimize the deterioration of the output image due to the addition of the tracking pattern, generally, a yellow color material is used for the addition of the tracking pattern.

  In addition, it is required to be able to extract the tracking pattern from the printed matter and analyze the tracking pattern by reading it with an image input device such as a scanner. Therefore, the pixel density data is modulated according to the input density data. Thus, a technique for adding a pattern has been proposed (see, for example, Patent Documents 1 and 2).

  In recent years, a technique called a region separation technique has become widespread (see, for example, Patent Document 3). The area separation technique is a technique for detecting areas such as black characters, color characters, photographs, and halftone dots from a document image. According to the region separation technique, optimum image processing can be performed according to the document image. For example, for a manuscript image mainly composed of black characters such as business documents, the black character region is detected by region separation technology, and even if the detected black character region is a color copy, the characters are reproduced by reproducing only with black toner. It can reproduce sharply and suppress unnecessary toner consumption.

Japanese Patent Application Laid-Open No. 07-154585 Japanese Patent Laid-Open No. 06-062217 JP 2005-39453 A

  In an image forming apparatus such as a color copying machine or a color multifunction peripheral, usually, when a user executes a color copying function regardless of the contents of a document, a tracking pattern is always added using the technique described above. In general, a manuscript whose copying is prohibited is a color manuscript. When such a manuscript is illegally copied, color copying is performed, and thus a tracking pattern is always added to an output image during color copying. This ensures that counterfeiting can be tracked.

  For this reason, in a color image forming apparatus, when color copying is executed, a tracking pattern is added even if all the originals are monochrome. For example, when a color original and a monochrome original are mixed, if a color copy is uniformly executed, a tracking pattern is also added to the monochrome original. Even if a color portion and a monochrome portion are mixed in the original, if a color copy is executed, a tracking pattern is also added to the monochrome portion.

  In addition, in an image forming apparatus that performs optimal image processing according to the content of an original by the above-described area division technique, an optimal image can be obtained without the user being particularly conscious, so that an optimal image can be obtained. It is conceivable that even black text-based originals are often copied by color copy. In this case, a tracking pattern is also added when copying a manuscript whose copy is mainly prohibited, such as a monochrome manuscript or a business document, and which is not prohibited from being copied. For this reason, a large amount of yellow toner is used for adding the tracking pattern. Therefore, when the user does not recognize the addition of the tracking pattern, the yellow toner is consumed without knowing the reason for the user.

  Although it is possible to separate the monochrome area and the color area using the ACS function (automatic color original discrimination function), in copying using the ACS function, the color area of the image is determined according to the original discrimination result. Since different image processing is performed in the monochrome area, the image data is temporarily stored in a page memory or the like, and there is a possibility that the copying and printing throughput may be reduced.

  The present invention has been made in view of the above problems, and an image processing apparatus that adds a code pattern having specific information to an image while suppressing toner consumption during printing without reducing throughput. An object is to obtain an image forming apparatus and an image processing method.

  In order to solve the above problems, the present invention is configured as follows.

The image processing apparatus according to the present invention determines that the partial image has low saturation for each predetermined number of lines of color image data, and the color determination unit determines that the partial image is not low saturation. The pattern addition processing unit that adds a code pattern to the partial image and the number of times the partial image is determined to be low saturation by the color determination unit are counted, and the partial image is determined not to be low saturation by the color determination unit And a count unit that resets the count when it is performed. The color determination unit determines that the partial image has low saturation when the saturation of all the pixels constituting the partial image is less than a predetermined threshold. The pattern addition processing unit does not add the code pattern to the partial image when the count value by the counting unit is equal to or greater than a predetermined threshold value, and the partial image when the count value by the count unit is not equal to or greater than the predetermined threshold value. Add a code pattern to

As a result, image processing is sequentially performed in units of a predetermined number of lines and a code pattern is added after determining the high saturation portion (color portion) in units of the predetermined number of lines without reducing the throughput. A code pattern is added to the image while suppressing toner consumption during printing. In addition, since the code pattern is also added to a part of the low chroma portion where the code pattern is easily detected from the printed material, the code pattern is easily detected from the printed material.

The image processing apparatus according to the present invention, in addition to the image processing equipment described above may be as follows. In this case, the threshold value is a predetermined value that is equal to or greater than the number of lines of the code pattern.

  Thereby, at least one code pattern can be added.

  The image processing apparatus according to the present invention may be as follows in addition to any of the image processing apparatuses described above. In this case, the threshold value is a predetermined value that is twice or more the number of lines of the code pattern.

  Thereby, even when the start position (position in the sub-scanning direction) of the code pattern is fixed, at least one code pattern can be added.

  The image processing apparatus according to the present invention may be as follows in addition to any of the image processing apparatuses described above. In this case, the color determination unit determines whether the partial image has low saturation for each line of the color image data.

  An image forming apparatus according to the present invention includes any of the image processing apparatuses described above.

The image processing method according to the present invention includes a color determination step for determining whether or not a partial image has low saturation for each predetermined number of lines of color image data, and a partial image that has been determined not to have low saturation. Counts the number of times that the partial image is determined to be low-saturated in the pattern addition step for adding the code pattern and the color determination step, and counts if the partial image is determined not to be low-saturation in the color determination step And a counting step for resetting . In the color determination step, if the saturation of all the pixels constituting the partial image is less than a predetermined threshold, it is determined that the partial image has low saturation. In the pattern addition step, if the count value is equal to or greater than a predetermined threshold, the code pattern is not added to the partial image. If the count value is not equal to or greater than the predetermined threshold, the code pattern is added to the partial image. To do.

  As a result, image processing is sequentially performed in units of a predetermined number of lines and a code pattern is added after determining the high saturation portion (color portion) in units of the predetermined number of lines without reducing the throughput. A code pattern is added to the image while suppressing toner consumption during printing.

  According to the present invention, a code pattern is added to an image while suppressing toner consumption during printing without reducing throughput.

FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of the tracking pattern addition processing unit in FIG. FIG. 3 is a flowchart for explaining the operation of the image processing apparatus shown in FIG. FIG. 4 is a flowchart for explaining the tracking pattern addition determination (step S2) processing in FIG. FIG. 5 is a diagram showing a specific example of tracking pattern addition by the image processing apparatus shown in FIG. FIG. 6 is a diagram showing another specific example of tracking pattern addition by the image processing apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention. This image processing apparatus is built in an image forming apparatus such as a copying machine or a multifunction machine, and is used to add a tracking pattern for specifying the origin of a counterfeit. The tracking pattern is an example of a code pattern.

  The image processing apparatus illustrated in FIG. 1 includes an image data reading unit 1, a color determination unit 2, a count unit 3, and a tracking pattern addition processing unit 4. The image data reading unit 1, the color determination unit 2, the count unit 3, and the tracking pattern addition processing unit 4 are, for example, a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. This is realized by executing the program with In this case, color image data for one page is stored in the RAM, and the image data reading unit 1 reads the color image data from the RAM in order by a predetermined number of lines (in this embodiment, one line at a time).

  The color determination unit 2 determines whether or not a partial image of a predetermined number of lines (in this embodiment, one line) read by the image data reading unit 1 has low saturation.

  In this embodiment, the color determination unit 2 determines that the partial image has low saturation when the saturation of all the pixels constituting the partial image is less than a predetermined threshold.

  For example, the saturation of a certain pixel is the difference between the maximum value and the minimum value of color coordinate values such as RGB and CMY of that pixel. For example, when the color image data is RGB data, assuming that the color coordinate value of a certain pixel is (R, G, B), the saturation is MAX (R, G, B) −MIN (R, G, B). When a pixel is colorless (monochrome), the saturation of the pixel is zero.

  The counting unit 3 counts the number of times the partial image is determined to have low saturation by the color determination unit 2, and resets the count when the color determination unit 2 determines that the partial image is not low saturation. . The count unit 3 generates on / off control data indicating the determination result. The value of the on / off control data is set to a predetermined first value (for example, 0) indicating that a tracking pattern is not added if the count value is equal to or greater than a predetermined threshold, and if not, a tracking pattern is added. It is set to a predetermined second value (for example, 1) indicating that this is to be performed.

  The tracking pattern addition processing unit 4 adds a tracking pattern to at least the partial image determined by the color determination unit 2 as not having low saturation. In this embodiment, the tracking pattern addition processing unit 4 applies the tracking pattern to the partial image when the count value by the counting unit 3 is equal to or larger than a predetermined threshold based on the value of the on / off control data by the counting unit 3. If the count value by the counting unit 3 is not equal to or greater than a predetermined threshold value, a tracking pattern is added to the partial image.

  For example, the above-described threshold value is set to a predetermined value equal to or greater than the number of lines of the tracking pattern (for example, the same as the number of lines of the tracking pattern). Alternatively, the threshold value is a predetermined value that is twice or more the number of lines of the tracking pattern (for example, the same value as twice the number of lines of the tracking pattern).

  FIG. 2 is a block diagram showing a configuration of the tracking pattern addition processing unit 4 in FIG. The tracking pattern addition processing unit 4 illustrated in FIG. 2 includes a density modulation unit 11, a tracking pattern generation unit 12, and a data selection unit 13.

  The density modulation unit 11 derives the density of the tracking pattern added to the image. This density may be a fixed value or, for example, in the same manner as described in Patent Documents 1 and 2, the pixels in a predetermined number of lines (one line in this embodiment) read by the image data reading unit 1 are used. You may make it derive | lead-out by a calculation etc. from a value.

  The tracking pattern generation unit 12 changes the pixel value of the tracking pattern added to the image data for the predetermined number of lines read (one line in this embodiment) (that is, the pixel value is changed by adding the tracking pattern). Information indicating the position of the pixel to be generated).

  For example, the tracking pattern generation unit 12 does not add the value 1 for the pixels to which the tracking pattern is added among the pixels of a predetermined number of lines (in this embodiment, for one line) as the dot pattern information. An array of binary data having the same number of pixels as a predetermined number of lines (one line in this embodiment) is generated with a value of 0 for the pixels.

  When the number of lines required to add one tracking pattern is plural (for example, 10 to 100 lines), for example, the processing target line among the plural lines constituting the tracking pattern according to the line number of the processing target line One line of the tracking pattern for is generated. Alternatively, the tracking pattern generation unit 12 monitors the value of the on / off control data, and the value of the on / off control data is changed from a value indicating that the tracking pattern is not added to a value indicating that the tracking pattern is added. The head line of the tracking pattern may be added to the line at the time of switching, and thereafter, the subsequent lines of the tracking pattern may be sequentially added as long as the value of the on / off control data does not change.

  The data selection unit 13 is a predetermined number of lines (one line in this embodiment) read by the image data reading unit 1 according to the on / off control data and the output value of the tracking pattern generation unit 12, And image data having a pixel value derived by the density modulator 11 is selected.

  When the ON / OFF control data indicates the addition of the tracking pattern for a certain number of lines (one line in this embodiment), the data selection unit 13 selects the predetermined number of lines (one line in this embodiment). For the pixel designated by the dot pattern information from the tracking pattern generation unit 12, the output value of the density modulation unit 11 is used. On the other hand, when the ON / OFF control data does not indicate the addition of the tracking pattern for a certain predetermined number of lines (one line in this embodiment), the data selection unit 13 selects the predetermined number of lines (in this embodiment). For one line, the read image data is selected and output.

  For example, the value of the on / off control data is 1 when the tracking pattern is added, 0 when the tracking pattern is not added, and the value of the dot pattern information is 1 for the pixel to which the tracking pattern is added. When the pixel to which the tracking pattern is not added is 0, the data selection unit 13 calculates the logical product of the value of the on / off control data and the value of the dot pattern information for each pixel, and the calculation result is 1. For example, the output value of the density modulation unit 11 is output. If the calculation result is 0, the value of the image data read by the image data reading unit 1 is output.

  Next, the operation of the image processing apparatus will be described.

  FIG. 3 is a flowchart for explaining the operation of the image processing apparatus shown in FIG.

  The image data reading unit 1 reads the color image data line by line from the top in order (step S1).

  Whether or not to add a tracking pattern to this line is determined by the color determination unit 2 and the count unit 3 (step S2).

  Here, details of the tracking pattern addition determination (step S2) will be described. FIG. 4 is a flowchart for explaining the tracking pattern addition determination (step S2) processing in FIG.

  In the tracking pattern addition determination, first, the color determination unit 2 determines whether or not the one-line partial image read by the image data reading unit 1 has low saturation (step S11), and the determination result is determined. Notify the count unit 3.

  When the color determination unit 2 determines that the partial image has low saturation based on the determination result, the count unit 3 increments the counter value by 1 (step S12), and the color determination unit 2 If it is determined that the partial image does not have low saturation, the counter value is reset to 0 (step S12). Note that the count unit 3 sets the initial value of the counter value to 0 when processing of one page of color image data is started.

  Then, the count unit 3 determines whether or not the current counter value is equal to or greater than a predetermined threshold value (step S14). If the current counter value is equal to or greater than the predetermined threshold value, the on / off control is performed. The data value is a value indicating that the tracking pattern is not added (step S15), and if the current counter value is not equal to or greater than the predetermined threshold value, the tracking pattern is added to the value of the on / off control data. (Step S16).

  When the determination of whether or not to add a tracking pattern is completed in this way, the tracking pattern addition processing unit 4 refers to the value of the on / off control data and determines whether or not to add the tracking pattern to the line. If it is determined (step S3) and it is determined that a tracking pattern is to be added, the tracking pattern is added to the line, and image data with the tracking pattern added is output (step S4). On the other hand, when it is determined that the tracking pattern is not added, the tracking pattern addition processing unit 4 outputs the image data of the line from the image data reading unit 1 as it is without adding the tracking pattern to the line.

  At this time, in the tracking pattern addition processing unit 4, for each line, the density modulation unit 11 derives the density of the tracking pattern added to the image, and the tracking pattern generation unit 12 generates dot pattern information of the tracking pattern. The data selector 13 adds a tracking pattern to the line designated by the on / off control data.

  Then, the image data reading unit 1 determines whether or not this line is the last line of the color image data of one page (step S5). If this line is not the last line, the process proceeds to step S1. Returning, the image data of the subsequent next line is read. The read image data for one line is processed in the same manner.

  In this way, the processing is sequentially performed up to the last line of the color image data of one page, and when the processing of the last line is completed, the processing for the color image data of one page is completed.

  Here, a specific example will be described.

  FIG. 5 is a diagram showing a specific example of tracking pattern addition by the image processing apparatus shown in FIG. FIG. 5A shows a page image. FIG. 5B is a diagram illustrating a location where a tracking pattern is added and a location where a tracking pattern is not added in the page image shown in FIG.

  The page image shown in FIG. 5A includes a color image 101 of securities. Parts other than the color image 101 are white.

  In the case of this page image, since the white (that is, low saturation) line is continuous from the top line near the top of the page, the counter value of the count unit 3 increases. Is less than the threshold value, a tracking pattern is added. When the counter value of the count unit 3 is equal to or greater than the threshold value, the tracking pattern is not added. While the white line continues, the counter value of the count unit 3 increases, the counter value of the count unit 3 continuously exceeds the threshold value, and no tracking pattern is added.

  Thereafter, when a line not having low saturation (that is, a color line) is detected in the line including the color image 101, the counter value is reset, and the addition of the tracking pattern is started. When the counter value is reset and the addition of the tracking pattern is started, the tracking pattern is continuously added unless the low saturation line continues beyond the above-described threshold value.

  Then, when the processing of the line including the color image 101 is almost completed and the same number of low-saturation lines as the above-described threshold continues, the counter value of the counting unit 3 becomes equal to or greater than the threshold, and the tracking pattern is not added.

  Thereafter, since the color is white until the last line of the page, the tracking pattern is not continuously added until the last line.

  FIG. 6 is a diagram showing another specific example of tracking pattern addition by the image processing apparatus shown in FIG.

  FIG. 6A shows a page image. FIG. 6B is a diagram showing a location where a tracking pattern is added and a location where a tracking pattern is not added in the page image shown in FIG.

  The page image shown in FIG. 6A includes a color photographic image 201 and a black character image 202. The other parts are white.

  In the case of this page image, a color photographic image 201 exists near the top of the page, and lines of non-saturation lines (that is, color lines) are continuous, so a tracking pattern is added. With respect to the range of the line including the color photographic image 201, a tracking pattern is continuously added unless the low-saturation line continues beyond the above-described threshold value.

  When the processing of the line including the color photographic image 201 is completed, the low saturation line (in this case, the monochrome line) of the character image 202 continues, and the counter value of the counting unit 3 increases. When the same number of low-saturation lines as the above threshold value continue, the counter value of the counting unit 3 becomes equal to or greater than the threshold value, and the tracking pattern is not added.

  Thereafter, since the character image 202 or the white monochrome line is used up to the final line of the page, the tracking pattern is not continuously added up to the final line.

  As described above, according to the above-described embodiment, the color determination unit 2 determines, for each line of color image data, whether or not the partial image by the line has low saturation, and the tracking pattern addition processing unit 4 adds a tracking pattern to the partial image determined by the color determination unit 2 as not having low saturation.

  As a result, image processing is sequentially performed in units of one line, and a tracking pattern is added after determining a high saturation portion (color portion) in units of a predetermined number of lines. There is no need to expand the data. Therefore, the code pattern is added to the image while suppressing toner consumption during printing without reducing the throughput.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

  For example, in the above embodiment, when the color determination unit 2 determines whether or not a partial image with a predetermined number of lines has low saturation, the continuous number of color pixels in the predetermined number of lines (for example, one line). If it is less than the threshold, it may be determined that the saturation is low, and if not, it is determined that the saturation is not low.

  In the above embodiment, the color image data is processed line by line, but may be processed by a predetermined number of lines of two or more lines.

  The present invention is applicable, for example, to adding a tracking pattern used for forgery determination.

2 color determination unit 3 count unit 4 tracking pattern addition processing unit (an example of pattern addition processing unit)

Claims (6)

A color determination unit that determines whether or not the partial image has low saturation for each predetermined number of lines of color image data;
A pattern addition processing unit that adds a code pattern to the partial image that is determined not to have low saturation by the color determination unit;
A count unit that counts the number of times the partial image is determined to have low saturation by the color determination unit, and resets the count when the color determination unit determines that the partial image is not low saturation; equipped with a,
The color determination unit determines that the partial image has low saturation when the saturation of all pixels constituting the partial image is less than a predetermined threshold;
The pattern addition processing unit does not add the code pattern to the partial image when the count value by the count unit is equal to or greater than a predetermined threshold, and when the count value by the count unit is not equal to or greater than the predetermined threshold, Adding the code pattern to the partial image;
An image processing apparatus. The threshold value, the image processing apparatus according to claim 1, characterized in that the predetermined value or more the number of lines of said code pattern. The threshold value, the image processing apparatus according to claim 1, characterized in that the predetermined value of more than 2 times the number of lines the code pattern. The color determining unit, an image according to any one of claims 1 to 3, the partial image for each line of the color image data and judging whether the low chroma Processing equipment. Image forming apparatus characterized by claim 1 including an image processing apparatus according to any one of claims 4. A color determination step for determining whether or not the partial image has low saturation for each predetermined number of lines of color image data;
A pattern addition step of adding a code pattern to the partial image determined not to have low saturation;
A count step of counting the number of times that the partial image is determined to have low saturation in the color determination step, and resetting the count when it is determined that the partial image is not low saturation in the color determination step; equipped with a,
In the color determination step, when the saturation of all the pixels constituting the partial image is less than a predetermined threshold, it is determined that the partial image has low saturation,
In the pattern addition step, when the count value is equal to or greater than a predetermined threshold, the code pattern is not added to the partial image, and when the count value is not equal to or greater than the predetermined threshold, the code pattern is added to the partial image. Adding,
An image processing method characterized by the above.

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