JP2011254325A - Image processing apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a color shift of figure patterns between a plurality of pages having the known figure patterns.SOLUTION: The image processing apparatus comprises: a figure determination part for determining whether each page has the figure pattern which satisfies an arrangement condition that is previously registered or is predetermined in input images of the plurality of the pages or not; a color measuring part for measuring color of the figure pattern when the page has the figure pattern; a color difference determination part for determining a level of difference between the color of the figure pattern which has been measured and a specified color which is previously stored; and a color correction part for correcting the color of the figure pattern to the specified color, when the difference between the color of the figure pattern and the specified color is determined to be small.

Description

  The present invention relates to an image processing apparatus that performs color correction and an image forming apparatus including the image processing apparatus.

  In recent years, color printing using a multifunction machine or a printer has been routinely performed in a general office. Since color printing has become easy, various types of documents such as presentations and meeting materials are being colorized. Color documents include full-color images such as color photographs, mixed colors such as color-coded graphs, and standard text colors (usually black) and other colors (for example, red or blue) And a mixture of.

  On the other hand, there is the following prior art regarding color correction of a color image printed on paper or displayed on a display. In Patent Document 1, a lip region is extracted from face images of three primary colors, the average values of hue, saturation, and lightness of representative color pixels of the extracted lip region are calculated, and a target lipstick to be repainted is calculated. A lipstick color conversion system that performs color correction in consideration of a difference from a color is described.

Japanese Patent No. 3723349

  When a multi-page document is printed, a slight color shift may occur between pages. For example, when printing a document having the same chromatic color logo mark on any page, the logo mark that should be printed in the same color may be printed in a slightly different color. As the number of pages increases, color misregistration easily occurs. A cause of color misregistration is a change in output characteristics of the image forming apparatus. Further, when copying a printed matter having such a color shift, the color shift often becomes more conspicuous as generation proceeds from child copy to grandchild copy.

  In particular, when the logo mark color is a symbol color of a company or organization, it is desirable that the logo mark color is reproduced correctly, and it is desirable that the color is uniformly reproduced in at least one document. When an image element such as a character string, line, or pattern having the same symbol color is attached to the logo mark, it is desirable that the image element is also color-reproduced uniformly between pages.

  In view of such circumstances, an object of the present invention is to realize an image processing function for reducing color misregistration of a graphic pattern between a plurality of pages having a known graphic pattern.

  An apparatus that achieves the above object is an image processing apparatus that corrects the color of an input image, and whether or not there is a graphic pattern that satisfies a pre-registered or predetermined arrangement condition in an input image of a plurality of pages. A graphic determination unit for determining each page, a color measurement unit for measuring the color of the graphic pattern when there is the graphic pattern, a measured color of the graphic pattern and a designated color stored in advance A color difference determination unit that determines the difference between the color pattern and a color correction unit that corrects the color of the graphic pattern to the specified color when it is determined that the difference between the color of the graphic pattern and the specified color is small; Is provided.

  According to the present invention, it is possible to reduce color misregistration of a graphic pattern between a plurality of pages having a known graphic pattern.

1 is a diagram illustrating an external appearance of a multifunction peripheral including an image processing apparatus. FIG. 2 is a diagram illustrating a hardware configuration of a multifunction machine. It is a figure which shows the function structure of an image processing apparatus. It is a figure which shows an example of the operation screen for designation | designated of the figure pattern made into correction | amendment object. It is a figure which shows an example of the operation screen for designation | designated of the correction range. It is a figure which shows the color range concerning determination of a color difference. It is a flowchart which shows operation | movement of an image processing apparatus. It is a flowchart of a color difference calculation subroutine. It is a flowchart of an area determination subroutine. It is a flowchart of a color correction subroutine. It is a flowchart of a color correction registration process. It is a figure which shows the other example of a function structure of an image processing apparatus. 10 is a flowchart illustrating another example of the operation of the image processing apparatus.

  A multifunction device 1 illustrated in FIG. 1 has a function as an image processing device that corrects the color of an image read from a document D or an image input from an external device. The multifunction device 1 which is a multifunction peripheral (MFP) has various uses such as copying, image input, network printing, facsimile communication, mail transmission / reception, and document storage. Among these uses, image processing apparatuses are involved in copying, image input, network printing, and facsimile communication.

  In the multifunction device 1, an ADF (Auto Document Feeder) 21 and an image scanner 22 are arranged above the electrophotographic printer 23. The ADF 21 includes a document table 211 and a collection table 212, and conveys the document D from the document table 211 to the collection table 212. The document D is a sheet-like recording medium (paper) on which information to be read is recorded. When a plurality of documents D are set (set) on the document table 211, the ADF 21 conveys the documents D one by one in order. During the conveyance by the ADF 21, the document D passes through the reading position. The image scanner 22 optically reads image information recorded on the document D passing through the reading position. This reading format is a sheet-through format in which the document D is moved with respect to the optical system.

  An operation panel 25 is disposed on the front side of the image scanner 22. The operation panel 25 includes a touch panel unit 25A that displays various operation screens and a key panel unit 25B on which various fixed keys including numeric keys are arranged. The user of the multifunction device 1 can cause the multifunction device 1 to execute a desired operation by direct operation using the operation panel 25 or access from an external device (for example, a personal computer) connected via the network 4. .

  A typical example of an operation in which the multifunction device 1 functions as an image forming apparatus is a copy operation. After the end of reading by the cooperation of the ADF 21 and the image scanner 22, or at the time of reading, a sheet of the size designated by the operation input is fed from the multistage paper stocker 24 to the printer 23. In the printer 23, the image read from the document D is printed on the paper in a color according to the color designation. The paper on which the image is printed is discharged to the paper discharge tray 232.

  As shown in FIG. 2, the multi function device 1 includes a control circuit 26, an image processing circuit 27, a storage 28, and an external connection interface 29 in addition to the above-described elements. The control circuit 26 includes a ROM 261 that stores a control program, a CPU (central processing unit) 262 that executes the control program, and a RAM 263 that is used as a work area for executing the program. The image processing circuit 27 is responsible for various image processing including correction of output data of the image scanner 22 and bitmap development at the time of printing. The storage 28 is a mass storage device such as a hard disk drive. The storage 28 is provided with a memory area (so-called box) for storing various document files as well as a memory area for storing data related to the control of the multifunction machine 1. The external connection interface 29 connects the multifunction machine 1 and the network 4 and enables LAN communication and facsimile communication. Of the hardware elements of the multifunction machine 1 shown in FIG. 2, the operation panel 25, the control circuit 26, the image processing circuit 27, and the storage 28 are directly related to the configuration of the image processing apparatus 2.

  When the image processing apparatus 2 prints an image, it corrects the color of the graphic pattern registered in advance as necessary. This color correction function, for example, when copying a multi-page paper document with a logo mark on each page, aligns the color of the logo mark on all pages of the duplicated document and improves the appearance of the printed material (duplication). Contribute to

  FIG. 3 shows a functional configuration of the image processing apparatus 2. The image processing apparatus 2 includes an input processing unit 201, a graphic determination unit 211, a color measurement unit 212, a color difference determination unit 213, a region determination unit 214, and a color correction unit 215 as functional elements related to the color correction described above. These functional elements are realized, for example, when the CPU 262 of the control circuit 26 executes an image processing control program. Each functional element can be realized by combining software and hardware of the image processing circuit 27.

  The input processing unit 201 receives an operation input for registering one or more desired graphic patterns by a user and an operation input for specifying a graphic pattern to be corrected when executing a print job. The input processing unit 201 records the shape and color of the graphic pattern that the user instructs to register using the operation panel 25 in the nonvolatile memory 281 as the registration data D10. The memory 281 is a part of the memory area of the storage 28.

  The graphic determination unit 211 determines, for each page, whether or not there is a pre-registered graphic pattern indicated by the registration data D10 in a plurality of pages of input images. As the input image, the image of the original D read by the image scanner 22, the image of the document input from the external device as the print target via the network 4, and the operation panel 25 or the external device previously stored in the storage 27 There is an image of a document designated as a print target by access from.

  When it is determined that there is a graphic pattern, the color measurement unit 212 measures the color of the graphic pattern.

  The color difference determination unit 213 determines the difference between the color of the graphic pattern measured by the color measurement unit 212 and the designated color stored in advance, which is the color indicated by the registration data D10. For example, assuming a document having a logo mark, the color of the logo mark may be intentionally different from the designated color when the document is created. For example, it is usually blue and the blue is the designated color, but in the distribution materials during the promotion period, it is red, or the blue logo mark and the logo mark of other colors are arranged side by side. A color change is possible. In this way, it is expected that the user will be confused if the logo mark intentionally changed to a color other than the designated color is corrected to the designated color and printed. The determination by the color difference determination unit 213 is a determination for estimating whether or not the difference between the color of the graphic pattern in the print target image and the specified color is due to intentional color change.

  When it is determined that there is a graphic pattern registered in advance and the difference between the color of the graphic pattern and the specified color is small, the area determination unit 214 determines the color of the graphic pattern near the graphic pattern. It is determined for each page whether there is an area including a predetermined number of pixels or more in the same color. Information such as company name and corporate philosophy may be incidentally written near the logo. When such information and the logo mark are the same color, it is desirable to print both colors in the designated color of the logo mark. The area determination unit 214 determines whether or not there is an area that is considered to accompany the graphic pattern.

  When it is determined that the difference between the color of the graphic pattern and the specified color is small, the color correction unit 215 corrects the color of the graphic pattern to the specified color. The color correction unit 215 corrects the color of the area determined by the area determination unit 214 to the designated color together with the color of the graphic pattern determined by the graphic determination unit 211.

  The operation screen Q1 shown in FIG. 4 is used for designating a graphic pattern to be corrected. In the image processing apparatus 2, the user can register a plurality of graphic patterns in advance, and can select one or a plurality of graphic patterns registered for each print job as a color correction target. In the example shown in the figure, selection keys 111, 112, and 113 corresponding to three graphic patterns are displayed, and one of the keys that is pressed is highlighted. When the user presses the OK key 110 in this state, the graphic pattern corresponding to the selection key 111 becomes the target of color correction. The graphic patterns corresponding to the other two selection keys 112 and 113 are not subject to color correction. By limiting the target of color correction, it is not necessary to check whether or not all of the registered graphic patterns are present in the image, thereby reducing the processing burden.

  The operation screen Q2 shown in FIG. 5 is used for designating a page range for color correction. In this example, the options are “in page”, “in job”, and “in related job”. “In-page” is a mode for correcting the color of a graphic pattern in one page to a designated color. “In-job” is a mode for correcting the color of a graphic pattern included in a document related to one print job to a designated color. “Within related job” is a mode in which the color of a graphic pattern included in all documents related to an unexecuted print job submitted by a user identified by a login ID is corrected to a designated color. On the operation screen Q2, selection keys 121, 122, 123 corresponding to these options are displayed.

  FIG. 6 shows a color range related to determination of the difference between the color of the graphic pattern and the designated color. The color range of the graphic pattern to be subjected to color correction is set by brightness, saturation, and hue. The setting can be performed individually for the registered graphic pattern. In this example, the range setting in the color space of the L * a * b * color system is shown, but the range may be set in the sRGB space or another color space.

  FIG. 7 is a flowchart showing the operation of the image processing apparatus 2. For example, the image processing apparatus 2 fetches an image from the image scanner 22 in page units (# 11), performs preprocessing such as binarization, noise component removal, and discontinuous line interpolation (# 12), and is designated as a target. Pattern matching is performed between the existing graphic pattern (hereinafter referred to as a specific graphic pattern) and the page image (# 13). The graphic determination unit 211 determines the presence or absence of a specific graphic pattern on the page of interest (# 14), and if there is a specific graphic pattern, the color measurement unit 212 measures the color of the pattern (# 15). If the measured color is within the set color range, the color difference determination unit 213 determines that the difference between the color of the specific figure pattern and the specified color is small (# 16), and the color correction unit 215 determines the correction amount. Is calculated (# 16). Subsequently, the region determination unit 214 extracts a region having the same color as the specific graphic pattern whose distance from the specific graphic pattern is equal to or less than a predetermined value (# 18, # 19). Then, the color correction unit 215 corrects the color of the area extracted by the specific graphic pattern and area determination unit 214 to a designated color (# 20). According to the color correction range setting, color correction is performed for a single page, a single job, or a plurality of jobs (# 21, # 22).

  FIG. 8 is a flowchart of the color difference calculation subroutine. The color difference calculation mode is switched according to the color correction range setting. If the setting is “in page”, the color difference from the specified color is calculated from only the specific figure pattern in one page (# 171, # 172). However, if there are a plurality of specific graphic patterns in one page, the average value of the differences between the specific graphic patterns and the specified color is used as the color difference. If the setting is “within job”, the average value of the difference between each specific figure pattern within one job and the designated color is set as the color difference (# 173, # 174). If the setting is “within related job”, the average value of the differences between the specific graphic patterns in the plurality of jobs and the designated color is set as the color difference (# 175, # 176).

  FIG. 9 is a flowchart of the area determination subroutine. The area determination unit 214 acquires the color (C1) of the specific graphic pattern from the color measurement unit 212 (# 191), and searches for a pixel having the same color as the color (C1) of the specific graphic pattern in the input image (# 192). . The area determination unit 214 checks whether or not the input image is a monochromatic original limited to a specific color gamut (# 193), and if the input image is a monochromatic original, determines whether the pixel corresponds to an area to be corrected. Do not perform the process to check. If the input image is not a monochromatic original, the area determination unit 214 obtains the number of connected pixels having the same color as the color (C1) of the specific graphic pattern (# 194), and if the input image is larger than the predetermined threshold Th0. (YES in # 195) Further, it is checked whether or not the connected pixel is located at the end or center of the input image (# 196). If YES in this check, the connected pixel is set as a region to be color corrected (# 197). Even if the number of connections is less than the threshold value Th0, if there is the same color pixel at the same position on another page and the position is the edge or center of the image (YES in # 198), the connection is made. The pixel is an area to be color corrected. In this example, the sizes of the end and the center are fixed values, but the range may be set by the user. An upper limit of the number of connections may be provided so that the entire image of one page is not subject to color correction. Furthermore, although the determination as to whether the original is a monochromatic document is performed at the upper level, an operation flow in which the determination at the final stage is made to invalidate the color region determination result may be adopted.

  FIG. 10 is a flowchart of the color correction subroutine. The color correction 215 reads the image (# 201), converts the color of the specific graphic pattern from the color in the RGB space to the color in the L * a * b * color space, and compares it with the designated color. A difference is obtained by comparison, the difference amount is added to the image data, and the result is converted to a color in the CMYK color space that is the output color space (# 203, # 204, # 205). Here, the RGB, Lab, and CMYK spaces are illustrated, but color correction may be performed by converting to other color spaces.

  FIG. 11 is a flowchart of the color correction registration process. In order to receive an operation input of a designated color, the input processing unit 201 reads an image having a predetermined graphic pattern from a predetermined memory and displays it on the display of the operation panel 25 (# 301, # 302). Then, the input processing unit 201 accepts a graphic pattern position input by the user (# 303). A known technique is applied to the display and instruction operation. For example, if the pointer device is a touch panel, the position range is specified by drawing a closed loop surrounding the area or pointing to the vertex of a polygon. If the graphic pattern to be registered is a gradation pattern (YES in # 304), the density Maxt value, Min value, and the number of points to be registered are received (# 305). If it is not a gradation pattern, an instruction for a point to be registered is received (# 307). The input processing unit 201 receives designation of brightness, saturation, and hue that determine the color range for color correction (# 306).

  FIG. 12 shows another example of the functional configuration of the image processing apparatus. This example is intended to perform color correction not only on graphic patterns registered by the user, but also on figures that are limited to a certain extent, such as “confidential” and “FAX completed”. It is an example. According to this example, it is possible to save the user from registering each stamp image as a graphic pattern in an environment where a large number of stamps are used to create various documents.

  In FIG. 12, the image processing apparatus 2b includes, as functional elements related to color correction, an input processing unit 201, a graphic determination unit 211b, a color measurement unit 212, a color difference determination unit 213, a history determination unit 216, a color correction unit 215, and data management. Part 221 is provided. These functional elements are realized, for example, when the CPU 262 of the control circuit 26 executes an image processing control program. Each functional element can be realized by combining software and hardware of the image processing circuit 27. The functions of the remaining components other than the graphic determination unit 211b, the history determination unit 216, and the data management unit 221 are the same as those of the image processing apparatus 2 described above.

  The graphic determination unit 211b determines, for each page, whether or not there is a graphic pattern that satisfies a predetermined arrangement condition or registered in advance in an input image of a plurality of pages. The arrangement condition of this example is “located at the end or center of the page or in the same region of a plurality of pages”.

  When it is determined that there is a graphic pattern that satisfies a predetermined arrangement condition, the data management unit 221 records history data D20 indicating the graphic pattern and a color when the graphic pattern is printed by the memory 281.

  If it is determined that there is a graphic pattern that satisfies a predetermined arrangement condition in the image input after the history data D20 is recorded, the history determination unit 216 determines whether the graphic pattern is in the history data D20. Determine whether or not.

  FIG. 13 is a flowchart showing the operation of the image processing apparatus 2b. The image processing apparatus 2b captures an image (# 101), and extracts a graphic corresponding to the arrangement condition (# 102). If the extracted graphic is present on a plurality of pages (YES in # 103) and the specific graphic pattern is specified as a correction target (YES in # 104), the difference between the color of the graphic and the specified color is obtained (# 105, # 106). If the difference from the designated color is within the predetermined range, the color of the figure is corrected to the designated color (# 107, # 108).

  On the other hand, if the graphic extracted from the page of interest is only on a single page or is not a registered graphic pattern even if it is on multiple pages (NO in # 103 or NO in # 104), a history determination unit 216 checks whether the figure exists in the history data D20 (# 109). If the figure exists in the history data D20 (YES in # 109), the color correction unit 215 corrects the color of the figure to the color at the time of past printing designated by the history data D20 (# 110).

  In the above embodiment, the operation of performing color correction when printing an image has been exemplified. However, a specific graphic pattern included in an image to be transmitted that is read by the image scanner 22 or input from an external device also during facsimile transmission. You may make it perform color correction with respect to.

1 MFP (image forming device)
2, 2b Image processing device 211 Graphic determination unit 212 Color measurement unit 213 Color difference determination unit 215 Color correction unit 214 Area determination unit 216 History determination unit 23 Printer (printing mechanism)
221 Data management D20 History data

Claims (6)

An image processing apparatus that performs color correction on an input image,
A graphic determination unit that determines, for each page, whether or not there is a graphic pattern that satisfies a pre-registered or predetermined arrangement condition in an input image of a plurality of pages;
When there is the graphic pattern, a color measuring unit that measures the color of the graphic pattern;
A color difference determination unit for determining the magnitude of the difference between the measured color of the graphic pattern and the specified color stored in advance;
An image processing apparatus comprising: a color correction unit that corrects the color of the graphic pattern to the specified color when it is determined that the difference between the color of the graphic pattern and the specified color is small. The image processing apparatus according to claim 1, wherein the graphic determination unit determines that there is a graphic pattern that satisfies the arrangement condition when there are graphic patterns having the same shape on two or more pages. When it is determined that there is a pre-registered graphic pattern and it is determined that the difference between the color of the graphic pattern and the specified color is small, a predetermined color is set in the vicinity of the graphic pattern in the same color as the color of the graphic pattern A region determination unit that determines for each page whether or not there is a region including more than the number of pixels,
3. The image according to claim 1, wherein the color correcting unit corrects the color of the region determined to be present by the region determining unit to the specified color together with the color of the graphic pattern determined to be present by the graphic determining unit. Processing equipment. A computer program executed by a computer included in an image processing apparatus that performs color correction of an input image,
When executed by the computer,
A graphic determination unit that determines, for each page, whether or not there is a graphic pattern that satisfies a pre-registered or predetermined arrangement condition in an input image of a plurality of pages;
When there is the graphic pattern, a color measuring unit that measures the color of the graphic pattern;
A color difference determination unit for determining the magnitude of the difference between the measured color of the graphic pattern and the specified color stored in advance;
A computer program that realizes a color correction unit that corrects the color of the graphic pattern to the specified color when it is determined that the difference between the color of the graphic pattern and the specified color is small. An image forming apparatus for printing an image on paper,
A graphic determination unit that determines, for each page, whether or not there is a graphic pattern that satisfies a pre-registered or predetermined arrangement condition in an input image of a plurality of pages;
When there is the graphic pattern, a color measuring unit that measures the color of the graphic pattern;
A color difference determination unit for determining the magnitude of the difference between the measured color of the graphic pattern and the specified color stored in advance;
A color correction unit that corrects the color of the graphic pattern to the specified color when it is determined that the difference between the color of the graphic pattern and the specified color is small;
An image forming apparatus comprising: a printing mechanism that prints an image in which the color of the graphic pattern is corrected. When it is determined that there is a graphic pattern that satisfies a predetermined arrangement condition, a data management unit that records history data indicating the graphic pattern and a color when the graphic pattern is printed;
History determination for determining whether or not the graphic pattern exists in the history data when it is determined that there is a graphic pattern that satisfies a predetermined arrangement condition in the image input after the history data is recorded And further comprising
The image forming apparatus according to claim 5, wherein the color correction unit corrects the color of the graphic pattern determined to be in the history data to a color when printed in the past indicated by the history data.

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