JP2007129427A - Image forming apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processor or an image processing method for creating a copy in which legibleness is not damaged significantly by taking account of hue when a pattern image is attached to a copy or a printed matter. <P>SOLUTION: In the image processor, histogram about the level of each pixel of input image data is created for every color component, a pattern color is determined as the complementary color of a tone indicated by the histogram by analyzing each histogram thus created, pattern image data of a color thus determined is created, and then the pattern image data thus created is composed as input image data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus for synthesizing and outputting a copy-suppressed copy-forgery-inhibited pattern on a document for the purpose of suppressing illegal forgery and information leakage due to copying of an important document, or for the purpose of clarifying whether an original or a copy has been made. And an image forming method.

  Conventionally, receipts, securities, certificates, forms, resident's cards, and the like are printed on specially-printed paper called anti-counterfeit paper. The purpose of printing on such paper is to make it possible to clearly distinguish whether the copied material is copied from the original or not, or to prohibit or deter copying. Has been made. This anti-counterfeit paper is a paper that is difficult to be seen by humans in the original, but has a pattern in which characters such as “forbidden copying” appear when copying using a copying machine or the like. This pattern is basically provided for the purpose of preventing the original from being easily copied by copying. This has the effect of inhibiting the act of copying the original and forging the original, and has the effect of discouraging such use from the person who makes the copy. Furthermore, it is clear that such items are printed on anti-counterfeit paper, and when copied, it becomes clear that they have been copied. It is.

  However, such anti-counterfeit paper has a problem that it is more expensive than ordinary paper. Further, only characters set at the time of production of the anti-counterfeit paper can be raised, and the use of the paper is limited.

  On the other hand, as various contents are digitized, contents such as forms and resident's cards are also digitized. However, digitization of these forms and resident's forms is still in a transitional period, and content created using a computer can be output and used on paper (for example, the aforementioned anti-counterfeit paper) using a printer or the like. Many.

  In response to such a situation, attention has been paid to a technique for generating anti-counterfeit paper, which has been conventionally prepared in advance by plate making or the like, using a computer and a printer (Patent Document 1). This is a technique for generating image data called a tint block in addition to content data when printing and outputting content created using a computer, and outputting these data in an overlapping manner. The background pattern is sometimes called a copy check pattern. The copy-forgery-inhibited pattern image appears as a simple pattern or background image to the human eye in the original (printed matter output by the printer), but when copied, predetermined characters and images are visualized. And this printed original can give the same check effect as the forgery prevention paper. This is possible due to a dramatic improvement in printer performance.

  When a copy-forgery-inhibited pattern image created using a computer is output over the content data, it can of course be output using normal printing paper, etc., so it is less expensive than using pre-created anti-counterfeit paper. There are advantages in terms of In addition, when printing out content data, a tint block image can be printed out at the same time, so it is possible to freely determine the characters to be visualized when copying the original as well as the color of the tint block image. Become. Another advantage is that the output date and time, information specific to the printing apparatus, and the like can be used as the tint block image.

  Now, as described above, the copy-forgery-inhibited pattern image has an effect of suppressing the use of the copied material (as the original document) when the original is copied, such as when a predetermined character that was difficult to recognize before copying becomes obvious. Is realized.

  In order to achieve this effect, the generated copy-forgery-inhibited pattern image basically includes an area in which the same image as the original remains in the copy and an image existing in the original in the copy disappears or the above remaining area. It is composed of two areas that are thinner than the image. The copy-forgery-inhibited pattern image composed of the two areas is preferably set to have the same density in the (average) density in the two areas in a state where it is printed out. In other words, the printed copy-forgery-inhibited pattern image needs to be configured so that it is difficult for humans to visually recognize that characters to be visualized on a copy are hidden. An image area that is hidden in the printed output of the copy-forgery-inhibited pattern image but appears to be visually recognizable by humans in a copy of the printed output is called a “latent image (or latent image)”. In addition, an image area having a lower density than the density of a latent image that disappears with a copy or is visualized with the copy is referred to as a “background (or background image)” for convenience. The copy-forgery-inhibited pattern image basically consists of the latent image and the background image. In some cases, the latent image is called a foreground as a term on the user interface.

  The latent image is configured so that dots are concentrated in a predetermined area. On the other hand, the background portion is configured such that dots are dispersed within a predetermined area. By configuring so that the average density of dots in this region is substantially the same, it is possible to make it difficult to distinguish the latent image portion from the background portion in the printed output of the tint block image.

  Also, a technique called “camouflage” that makes it difficult to distinguish a hidden character or image (latent image) from a forgery-inhibited tint block is well known. 9 and 10 are diagrams showing dot states in these two image areas. FIG. 9 is an enlarged view of the latent image portion and the background portion of the background pattern, and shows a case where a camouflage pattern is added.

  The camouflage has a different density from the latent image part and background part, and a finer pattern part than the latent image part is placed on the entire forgery-inhibited tint block image including the latent image part and the background part (additional) To do). At first glance, this method emphasizes the contrast between the camouflage and the latent image portion or the background portion rather than the contrast between the latent image portion and the background portion, so that the camouflage pattern stands out, and the latent image or latent image This has the effect of making the outline of the image more inconspicuous. In addition, compared to a counterfeit pattern having no camouflage pattern, the counterfeit pattern having a camouflage pattern has an effect of giving a decorative impression to the printed matter. In the camouflage pattern, it is desirable that dots in the camouflage pattern disappear as much as possible after copying so that the latent image can be easily distinguished after copying. In the simplest implementation, camouflage can be achieved by not hitting dots at locations corresponding to the camouflage pattern. Needless to say, a dot is hit around the portion where the dot is not hit, and the dots have different ways of hitting in the case of the latent image portion and the background portion.

  FIG. 10 is a diagram showing a dot configuration of a latent image portion and a background portion of a tint block without a camouflage pattern. As shown in FIGS. 9 and 10, basically, a background pattern is formed by a background portion in which dots are dispersed in a predetermined area and a latent image portion in which dots are concentrated (as large dots). An image is constructed. Each dot in these two areas can be generated by different halftone dot processing or different dither processing. For example, when a tint block image is generated using halftone processing, the latent image portion performs halftone processing with a low number of lines. In addition, it is preferable that the background portion performs halftone dot processing with a high number of lines. Furthermore, when a copy-forgery-inhibited pattern image is generated using dither processing, the latent image portion performs dither processing using a dot-concentrated dither matrix. Further, it is preferable that the background portion performs dither processing using a dot dispersion type dither matrix.

  In general, a reading unit and an image forming unit of a copying machine have a limit level of input resolution for reading minute dots on a document, and a limit level of reproduction capability depending on output resolution for reproducing minute dots. . For example, a dot having a main scanning width of a scanner of a copying machine and a size corresponding to one sampling width of the sub-scan inevitably causes a deviation in main scanning and a sub-scanning sampling with respect to the dot. Then, it becomes four pixels arranged in the top and bottom and the left and right of the 1/4 level. In this case, it is rare to detect as one pixel at one level. On the other hand, in the case of a dot larger than this, for example, double vertically and horizontally, even if the above-described deviation is taken into consideration, one pixel is always at a level of 1. This means that in order to read the printing resolution faithfully, it is necessary to read at a resolution about 10 times the printing resolution.

  If the dots in the background portion of the copy-forgery-inhibited pattern image are formed smaller than the limit level of dots that can be reproduced by a copying machine and the dots in the latent image portion are formed larger than the limit level, the dots in the latent image portion on the copy Can be reproduced, and small dots in the background are not reproduced. By utilizing these characteristics, the latent image becomes apparent on a copy of the copy-forgery-inhibited pattern image. Hereinafter, an image that appears on a copy is referred to as a visible image. Even if the background part is reproduced to some extent by copying, if the average density of the latent image part on the copy is different from the average density of the background part and the boundary is clearly recognizable, the dot It is possible to obtain the same effect as when no is reproduced.

  FIG. 11A shows an example of the original, and FIG. 11B shows an example in which FIG. 11A is copied, showing that the latent image is visualized. This figure conceptually shows that a region where dots are concentrated is reproduced (visualized) in a copy, and a region where dots are dispersed is not reproduced in a copy.

  Note that copy-forgery-inhibited pattern printing is not limited to the above-described configuration, and it is sufficient that a character string or the like can be reproduced on a copy at a recognizable level. That is, even if a character string or the like is designated as the background portion and is shown in a state like a white character at the time of copying, the purpose of the tint block printing is achieved.

  As an example of the invention when such copy-forgery-inhibited pattern printing is applied to a copying machine, the applicant filed an invention by a combination with the ACS (auto color selection; color / monochrome discrimination for each page) function of the copying machine. ing. One of the inventions is when the copy-forgery-inhibited pattern image to be added to the original content to be copied is color, and when the determination result by ACS is the determination of monochrome content, the copy-forgery-inhibited pattern image generated as monochrome data is displayed. Append. This avoids charging by color image output (Patent Document 2).

  Another invention (Patent Document 2) of the present applicant is provided with means for determining the color density of the original content, and the difference between the color density of the tint block image and the determination result by the color determination means is small. , Correcting the density of the original content. In this correction, the readability is improved by adding a density difference from the added tint block image data.

JP 2001-197297 A JP 2005-115873 A JP 2005-193648 A

  However, in the tint block image addition method described in the background art, many technical methods related to tint block image formation are disclosed, and no improvement method for the tint of the tint block image and the original content is disclosed. In the above-described inventions (Patent Document 2 and Patent Document 3) by the present applicant, the density of the original content is corrected by detecting the difference between the color of the original content and the color of the tint block image. It has been disclosed to improve legibility over time. However, since no correction is performed on the color of the entire original content and the color of the tint block image, the fundamental solution has not been achieved in terms of legibility.

  In particular, if there are multiple documents to be copied by the user and the color of some of the documents is very close to the color and density of the copy-forgery-inhibited pattern image to be added, only the density correction will affect the effect of adding the copy-forgery-inhibited pattern image. It cannot be removed. As a result, there is a possibility that the readability of the original content is remarkably impaired in a plurality of copies in the copy original.

  Therefore, the present invention provides an image processing apparatus or image that generates a copy in which the legibility of the original content is not significantly impaired by considering the color when adding a copy-forgery-inhibited pattern image to a copy or printed matter. An object is to provide a processing method.

  Therefore, the invention according to claim 1 is an image processing apparatus, which generates a histogram for the level of each pixel of the input image data for each color component, and is generated by the generation unit. A tint block color determining unit that analyzes each histogram to determine a tint block color, a tint block generating unit that generates tint block image data of the optimal tint block color determined by the tint block color determining unit, and a tint block generated by the tint block generating unit And synthesizing means for synthesizing the image data with the input image data.

  The invention according to claim 2 is the image processing apparatus according to claim 1, wherein the histogram generation means is a character / thin line determination means for determining character / thin line for each pixel of input image data. Chromatic color determination means for determining whether the pixel is a chromatic color pixel or an achromatic color pixel, and significant information detection means for detecting significant information using the determination output of these determination means, the histogram includes the significant information detection Only significant information obtained by the means is generated.

  The invention according to claim 3 is the image processing apparatus according to claim 2, wherein the histogram generation means further determines whether or not the information is significant information for each pixel of the input image data. The histogram is generated only for significant information.

  According to a fourth aspect of the present invention, there is provided the image processing apparatus according to the first aspect, wherein the copy-forgery-inhibited pattern color determining means complements a color tendency indicated by a result of analyzing each histogram generated by the generating means. Is determined as the tint block color.

  The invention according to claim 5 is the image processing apparatus according to claim 1, wherein the tint block color determining means analyzes that each histogram generated by the generating means does not show a specific color tendency. In this case, the default color or the color designated in advance is determined as the tint block color.

  The invention according to claim 6 is the image processing apparatus according to claim 1, wherein when the number of pages of the input image data is plural, the histogram generation means and the tint block color determination means respectively A tint block color storing unit that stores the tint block color determined by the tint block color determining unit for each page, and among the tint block colors stored in the storage unit, the tint block color designated by the user Alternatively, calculate the number of pages of a background pattern color different from the default background color of the device, and if the calculated number is a predetermined number or the ratio of the calculated number to the total number of pages is less than a predetermined value, the default color or specified in advance If the calculated number is set as the tint block color and the calculated number is equal to or larger than the predetermined number or the ratio of the calculated number to the total number of pages, it is determined for each page. Setting color as background pattern color, further wherein the tint block generating means and setting means is characterized in that to produce the tint block image data of the tint block color set by said setting means.

  The invention according to claim 7 is the image processing apparatus according to claim 1, wherein the tint block generation unit uses the tint block color determined by the tint block color determining unit, or a default color or In response to a user input as to whether to use a predesignated color as a tint block color, it further includes an operation mode selection unit that controls selection of a tint block color used by the tint block generation unit, and the operation mode determines the tint block color If it is indicated that the optimum tint block color determined by the means is used, the tint block generation unit generates the tint block image data of the optimum tint block color determined by the tint block color determining unit. The generation means uses a default color or a color designated in advance as the tint block color.

  The invention according to claim 8 is an image processing method, wherein a histogram for the level of each pixel of the input image data is generated for each color component, and the generated background color is analyzed by analyzing each histogram. , Determining generation of copy-forgery-inhibited pattern color image data, and combining the generated copy-forgery-inhibited pattern image data with input image data.

  The invention according to claim 9 is the image processing method according to claim 8, wherein generating the histogram includes determining character / thin line for each pixel of input image data, chromatic color It is characterized by determining whether it is a pixel or an achromatic color pixel, and detecting significant information using these determination results, and the histogram is generated only for the detected significant information.

  The invention according to claim 10 is the image processing method according to claim 8, wherein the generation of the histogram determines whether or not it is significant information for each pixel of the input image data. The histogram is generated only for significant information.

  The invention according to claim 11 is the image processing method according to claim 8, wherein the determination of the tint block color includes a complementary color of a color tendency indicated by a result of analyzing each generated histogram. It is determined as a color.

  The invention according to claim 12 is the image processing method according to claim 8, wherein the determination of the tint block color is based on an analysis that each generated histogram does not show a specific color tendency. The default color or the color designated in advance is determined as the tint block color.

  The invention according to claim 13 is the image processing method according to claim 8, wherein the number of pages of the input image data is counted, and when the counted number of pages is plural, for each page, The generation of the histogram and the background pattern color are determined, the determined background pattern color is stored, and among the stored background patterns, the number of pages of the background pattern color different from the background pattern color designated by the user or the default background pattern color of the device When the calculated number is a predetermined number or the ratio of the calculated number to the total number of pages is less than a predetermined value, a default color or a predesignated color is set as the tint block color, and the calculated When the number is equal to or larger than a predetermined number or a ratio of the calculated number to the total number of pages, further comprising setting a color determined for each page as a tint block color; Generating a serial copy-forgery-inhibited pattern image data, and generates a background pattern image data of the set background pattern color.

  The invention according to claim 14 is the image processing method according to claim 8, wherein when the copy-forgery-inhibited pattern image data is generated, the determined copy-forgery-inhibited pattern color is used, or a default color or a predetermined color is set in advance. Receiving the user input as to whether to use the designated color as the copy-forgery-inhibited pattern color, further determining an operation mode for controlling selection of the copy-forgery-inhibited pattern color according to the received user input, and generating the copy-forgery-inhibited pattern image data Generates a copy-forgery-inhibited pattern image data of the determined copy-forgery-inhibited pattern color when the operation mode indicates that the decided copy-forgery-inhibited pattern color is used. It is characterized by creating image data.

  According to the present invention, a histogram for generating a histogram for each pixel level in the original content is generated for each color component, and the color information of the document is determined by analyzing the generated frequency distribution. Based on this determination result, a tint block color that maximizes the legibility of the original content, for example, a color that is complementary to the color information of the determination result is automatically selected, and this color is applied to the tint block job. Thus, it is possible to print the background pattern in a manner that improves the legibility, without impairing the legibility by adding the background pattern image. In addition, since the histogram for each pixel level or pixel level group of significant information is generated by referring to the character thin line determination result and chromatic color determination result, the color relationship between the true original content and the tint block color is selected appropriately It becomes possible to do. In addition, when the tint block color determination result from the histogram is different from the default tint block color of the device or the tint block color set by the user, the selected tint block color is disclosed to the user once. After this disclosure, it is possible to print with the tint block color switched (with the selected tint block color) after obtaining the user's consent, so that the tint block can be added to the original content more appropriately. . Further, particularly in a copying operation for adding a plurality of copy-forgery-inhibited pattern images, there may be a case where the copy-forgery-inhibited pattern color switching result is a predetermined number or a predetermined ratio or less. In this case, by switching the copy-forgery-inhibited pattern color by using the default copy-forgery-inhibited pattern color of the apparatus or the copy-forgery-inhibited pattern color specified by the user without adding the copy-forgery-inhibited pattern color, The output image appearance is maintained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the embodiment described below, an area to be visualized on a copy obtained by copying a printed output having a copy-forgery-inhibited pattern image is referred to as a latent image portion. An area that disappears on the copy or has a lower density than the density of the latent image portion on the copy is referred to as a background portion.

  The following description is based on the case where the present invention is applied to a copying apparatus, and other cases will be described in a form supplementing this description. This copying apparatus inputs text information and image information as a latent image portion via a user interface (hereinafter referred to as UI) to generate a copy. On this copy, the text information and image information, that is, the copy-forgery-inhibited pattern image as the background portion, is reproduced so as to improve the legibility of the true content of the copy.

  However, the background pattern image in the present invention is not limited to this. For example, text information or image information is set as a background portion, and an area around the background portion is set as a latent image portion, so that text information and image information are expressed as white on a copy. It may be a form.

  Further, the present invention is not defined by the type of tint block image, its generation process, color, shape, size, or the like.

  The following description explains an embodiment in which the present invention is mounted on a so-called copying machine including a scanner and a printing apparatus. In the following description, a description will be given assuming a single function copying machine for copying original content possessed by a user. However, it goes without saying that combinations of image forming apparatuses such as copiers, printing apparatuses, scanners, and MFPs (Multi Function Products) are also targeted. Further, it goes without saying that these devices are also applicable to a system in which the present invention is applied to a system in which these devices are connected to a plurality of computers via a network such as a LAN or WAN. Those skilled in the art will appreciate that the present invention can be implemented, for example, in a system that includes a computer and a printing device, or even in a system that includes a scanner.

Copier Configuration FIG. 1 is a block diagram showing a configuration of a copier according to an embodiment of the present invention. In the figure, reference numeral 1000 denotes a copying machine to which the present invention is applied. Reference numeral 10 denotes a CPU that performs overall control of the copying machine 1000, and reference numeral 11 denotes a RAM that functions as a main memory, a work area, and the like of the CPU 10, and is used as an output information expansion area and an environment data storage area. Reference numeral 12 denotes various ROMs configured in the copying machine, and includes, for example, a font ROM, a program ROM, and a data ROM. Reference numeral 13 denotes a main bus to which the CPU 10 is connected. Data control with various processing units is possible via the main bus 13. Reference numeral 14 denotes a reading unit, which includes, for example, a reading device such as a CCD or CIS and an A / D conversion unit that converts an analog signal output from the reading device into a digital signal used inside the copying machine. Reference numeral 15 denotes a reading unit i / f, which controls various device control signals configured in the reading unit 14 and controls reception of read data output from the reading unit 14. Reference numeral 16 denotes a reading processing unit, which performs image processing on the read data input from the reading unit i / f15. Reference numeral 17 denotes a recording processing unit. Image data obtained by combining recording image processing necessary for recording the image data processed by the reading processing unit 16 and a tint block image data generated by the tint block processing unit to be described later. Generate. Reference numeral 18 denotes a recording unit i / f, which controls data output from the recording processing unit 17. Reference numeral 19 denotes a recording unit that outputs image data controlled by the recording unit i / f 18. In this embodiment, the recording unit 19 is an electrophotographic engine. Therefore, the print data including the copy-forgery-inhibited pattern image is finally recorded on a medium such as paper by toner dots. Of course, the printing method in the present invention is not limited to such an electrophotographic method. For example, the present invention can be applied to any type of printing apparatus that performs printing by forming dots such as an ink-jet method.

  Reference numeral 20 denotes a tint block processing unit which controls the tint block image pattern and the tint block image color set via the UI of the copying machine. Reference numeral 21 denotes a memory, which is composed of a main memory of a copying machine or an external connection memory such as an HD. Reference numeral 22 denotes a memory controller for controlling the memory 21, and reference numeral 23 denotes an operation unit of the copying machine. The main configuration of the present invention will be described with reference to another drawing.

  FIG. 2 is a diagram showing an internal configuration of the reading processing unit 16 in FIG. In the figure, reference numeral 1601 denotes a shading correction processing unit that performs variation correction for each pixel in the main scanning direction using white offset and black offset values for input read image data. Reference numeral 1602 denotes a character determination unit that performs character / thin line determination in pixel units of input image data using output image data of the shading correction processing unit 1601. Reference numeral 1603 denotes a sub-scanning MTF correction processing unit that performs MTF correction in the sub-scanning direction of input image data. Reference numeral 1604 denotes a color space conversion unit that converts input image data into a color space required by the in-device processing unit. Reference numeral 1605 denotes a main scanning MTF correction unit that performs MTF correction in the main scanning direction. Reference numeral 1606 denotes a filter processing unit that performs filtering by switching edge enhancement filter coefficients in units of pixels based on the determination result of the character determination unit 1602. Reference numeral 1607 denotes a resolution conversion unit that converts input image data into the resolution of output image data. Reference numeral 1608 denotes a masking processing unit that performs masking processing on the output image data. Reference numeral 1609 denotes a chromatic color determination unit that determines whether a pixel is a chromatic color pixel or an achromatic color pixel for input image data. Reference numeral 1610 denotes a histogram generation unit that generates each color histogram of only significant information of the original content using the character determination unit 1602, the chromatic color determination unit 1609, and the input pixel data. Here, the significant information refers to, for example, only characters and symbol parts in the original content. Reference numeral 1611 denotes a copy-forgery-inhibited pattern color selection unit that determines the color of significant information for each page of the original content based on the histogram result by the histogram generation unit 1610 and selects the copy-forgery-inhibited pattern image color according to the determination. The details of the histogram generation unit 1610 and the tint block color selection unit 1611 which are the main requirements of the present invention will be described with reference to another drawing.

  FIG. 3 is a diagram illustrating an example of determination by the character determination unit 1602 and determination result by the chromatic color determination unit 1609 for input image data. As shown in the figure, the input image 300 is composed of text characters 301 and a background portion 302 thereof. In this description, when the text character 300 is, for example, blue (the input level varies) and the background portion 302 is white, the determination results of the character determination unit 1602 and the chromatic color determination unit 1709 are 303 and 304, respectively. Become. In this description, in order to make the outline of the invention itself more appropriate, both the determination result 303 and the determination result 304 are described as cases where there is no erroneous determination. The histogram generation unit 1610 creates a histogram using the determination result 303, the determination result 304, and the input pixel data. In creating a histogram, the determination by the character determination unit 1602 is a character ('1' portion in the determination result 303), and the determination by the chromatic color determination unit 1709 is chromatic color ('1' portion in the determination result 304). Use only certain pixels. That is, only significant information is used. If the histogram in this case is shown for each color (red, green, and blue), only blue pixels exist as in 305 (a) to (c). The background pattern color selection unit 1611 refers to the result of the histogram generation unit 1610 to determine a background pattern color when adding a background pattern to the input image data. That is, the tint block color is determined with reference to the results of 305 (a) to (c), which are the results of the histogram generation unit 1610. The color that best represents the original content is selected based on the histogram result, for example, a complementary color.

  That is, in the case of the results 305 (a) to (c), the content is only blue, and therefore, yellow, which is a complementary color of blue, is selected as the tint block color.

  Note that the color of the background pattern is a complementary color, which is an example of the present invention, and not all. That is, it goes without saying that any color that can improve the legibility of the original content corresponds to the present invention.

  In the example of FIG. 3, the case of blue text characters on a white background has been described, but the content actually copied by the copying machine has various colors. In this case, as a matter of course, even if the results of the character determination unit 1602 and the chromatic color determination unit 1609 are followed, the histogram results represent various distributions for each color. Furthermore, the determination by the character determination unit 1602 and the chromatic color determination unit 1609 is not 100%, and there is an erroneous determination part. Next, a method for determining a histogram result including such elements will be described. Consider a case where the histogram generated from the character determination result and chromatic color determination result for one page of the content to be copied has the shape shown in FIG. That is, when the histogram is not composed of only specific color components as in FIG. 3 described above, the tint block color selection unit 1611 generates an element for obtaining the tendency of each color. For example, the input levels are grouped into a plurality of levels, and the total number for each group is obtained. When the total number for each group is the same for each color, or when the total number of colors for each group varies, the background pattern color selection unit 1611 determines that the color distribution of the original content is diverse, and the specific background pattern Don't choose a color. That is, it is assumed that the copy-forgery-inhibited pattern color that best represents the original content cannot be specified from the color distribution, and copy printing is performed using the copy-forgery-inhibited pattern color set by the operation unit 23 or the default copy-forgery-inhibited pattern color of the apparatus. To do. In this way, referring to the histogram result generated by the histogram generation unit 1610, the copy-forgery-inhibited pattern color selection unit 1611 selects the copy-forgery-inhibited pattern color determined from the histogram only when the histogram result of a certain color is significantly different from the histogram result of another color. To do. For example, as shown in FIG. 5, when the color component G shows a numerical value higher than each of the other R and B, it is determined that the overall color tendency is G, and the resulting complementary color of G Is selected as the tint block color. Conversely, if only the color component G is smaller than the others, the overall color tendency is magenta, and its complementary cyan is selected as the tint block color.

Next, how the copying operation is executed using the selected tint block color will be described.
In the copying machine to which the present invention is applied, the operation unit 23 can designate a tint block color automatic selection mode and a mode other than the automatic selection mode, in other words, a non-automatic selection mode. The automatic selection mode is a mode in which a background pattern is printed using the background pattern color selected by the background pattern color selection unit 1611, that is, using the automatically determined background pattern color. The non-automatic selection mode is a mode in which the tint block color switching is not automatically determined, but is left (specified) to the user.

  FIG. 6 is a diagram showing a copying operation flow when the content to be copied is one original. When a copying operation start instruction is given by the user, the copying machine to which the present invention is applied starts its operation (step S601). When the copy operation mode does not involve copy-forgery-inhibited pattern image printing, reading of the image data of the content is started by the reading unit 14 and the reading unit i / f 15 (steps S602 and S603). The read image data is subjected to image processing by the reading processing unit 16 (step S604). The image data processed by the reading processing unit 16 is subjected to necessary image processing by the recording processing unit 17 and transferred to the recording unit 19 by the recording unit i / f 18. The recording unit 19 sequentially prints input image data (step S605). In step S602, when the copy operation involves copy-forgery-inhibited pattern image printing, the content image data is read by the reading unit 14 and the reading unit i / f15, and read image processing is performed by the reading processing unit 16 (steps S606 and S607). . In the processing by the reading processing unit 16, a character determination result and a chromatic color determination result for each pixel of the input image data are also generated. Using the determination result and input pixel data, the histogram generation unit 1710 generates a histogram for each color of only pixels that are significant information (step S608). In the histogram generation, the pixel levels of significant information may be grouped together for each plurality of levels and measured for each group, or may be measured for each level. In either case, the background pattern color selection unit 1611 automatically selects a background pattern color that can improve the legibility of the original content based on the obtained histogram result of each color (step S609). When the automatic copy mode is set by the user at the start of the content copying operation, the tint block color selected by the tint block color selection unit 1611 is used without using the preset tint block color or the default tint block color of the apparatus. To print the background pattern. Since the tint block color by the tint block color selection unit 1711 enhances the legibility of the original content, a tint block image using a color optimum for the content is added (step S611). In step S610, when the user selects the background pattern color, that is, the non-automatic selection mode, the CPU 10 displays the background pattern color selected by the background pattern color selection unit 1611 on the display unit configured in the operation unit 23. To do. When the user accepts the addition of the tint block image data of the color displayed on the display unit by pressing the OK button configured on the operation unit 23, the image data read by the reading processing unit 16 and the tint block color selection unit 1611 Is synthesized with the copy-forgery-inhibited pattern image composed of the color selected by the above. This is processed by the recording processing unit 17. The image data processed by the recording processing unit 17 is transferred and output to the recording unit 19 by the recording unit i / f (steps S613 and S611). In step S613, if the user does not accept the tint block color displayed on the display unit of the operation unit 23, the tint block image using the color specified by the user at the start of the copying operation or the default color of the apparatus is used. The copying operation is then performed (step S614).

  Next, an operation flow when there are a plurality of contents to be copied will be described. FIG. 7 is a diagram showing an operation flow at the time of a multiple sheet copying operation. When the copying operation of a plurality of contents is started by the user, the copying machine to which the present invention is applied starts the copying operation (step S701). When the copy operation mode does not involve copy-forgery-inhibited pattern image printing, reading of image data of content is started by the reading unit 14 and the reading unit i / f 15 (steps S702 and S703). The read image data is subjected to image processing by the reading processing unit 16 (step S704). The image data processed by the reading processing unit 16 is subjected to necessary image processing by the recording processing unit 17 and transferred to the recording unit 19 by the recording unit i / f 18. The recording unit 19 sequentially prints input image data (steps S705 and S706). In step S702, when the copy operation involves copy-forgery-inhibited pattern image printing, the content image data is sequentially read by the reading unit 14 and the reading unit i / f15, and read image processing is performed by the reading processing unit 16 (steps S707 and S708). ). In the processing by the reading processing unit 16, a character determination result and a chromatic color determination result for each pixel of the input image data are also generated. Using the determination result and input pixel data, the histogram generation unit 1610 generates a histogram for each color of only pixels that are significant information (step S709).

  The background pattern color selection unit 1611 selects the optimum background pattern color for each page of content based on the histogram generated by the histogram generation unit 1610, as in the case of copying one copy of background pattern (step S710). After selecting the tint block color, the selected tint block color is stored in the memory 21 in a format corresponding to the content page data (step S711).

  The processing from step S707 to step S711 is repeatedly executed by the reading unit 14 until reading of all the contents is completed (step S712). That is, the reading process is repeated until the tint block color selection of all contents is confirmed. When the user selects the copy-forgery-inhibited pattern color automatic selection mode (step S713), the copying machine to which the present invention is applied has a copy-forgery-inhibited pattern color that is different from the copy-forgery-inhibited pattern color specified by the user in advance or the default copy-forgery-inhibited pattern color of the apparatus. Count the number of selected contents. When the measurement result is equal to or less than a predetermined number or a predetermined ratio of the total number of contents / pages, the recording processing unit 17 converts all the original / background pattern image data using the background pattern color designated by the user or the default background pattern color of the device to Add to content. All contents are printed out by the recording unit i / f 18 and the recording unit 19 (step S714, step S715, step S716). In step S714, when the measurement result exceeds a predetermined number or a predetermined ratio in all the contents, the recording processing unit 17 generates a background pattern image of a color selected by the background pattern color selection unit 1611. The generated copy-forgery-inhibited pattern image is added to the corresponding content, and the recorded image processing is performed (steps S717 and S718).

  In the description of step S714, the threshold value for selecting the copy-forgery-inhibited pattern color specified by the user or the default copy-forgery-inhibited pattern color of the apparatus is set to a predetermined number or less or a predetermined ratio or less, but the apparatus of the present invention is not limited to the specification. That is, a threshold value related to tint block color switching may be set via the operation unit 23. In either case, if there are multiple contents to be copied with the copy-forgery-inhibited pattern, and the decipherability of the content is impaired due to the addition of the copy-forgery-inhibited pattern image with a limited number of them, the copy-forgery-inhibited pattern color is switched in accordance with the appearance of the copy content Control to not. More specifically, for example, even if one of 10 pieces of content is better when the set tint block color is changed, all the content is configured with the same color in consideration of the overall ratio. The copy-forgery-inhibited pattern image data is added.

  If the copy-forgery-inhibited pattern operation mode is set to non-automatic selection in step S713, the page information of the read content and the copy-forgery-inhibited pattern color switching information are displayed on the display unit of the operation unit 23 (step S719). ). When the user approves the tint block color switching, for example, by pressing an OK button configured on the operation unit 23, the recorded image processing is performed by combining the tint block image with the tint block color corresponding to the content. Is output by. If the user does not approve the copy-forgery-inhibited pattern color display information displayed on the operation unit 23, the recording processing unit 17 stores all the contents of the copy-forgery-inhibited pattern image data using the copy-forgery-inhibited pattern color preset by the user or the default copy-forgery-inhibited pattern color of the device. The process is applied to (step S720). The image data processed by the recording processing unit 17 is output and printed via the recording unit i / f 18 and the recording unit 19.

  In the above description, the histogram generation unit is the content page, but the present invention is not limited to the unit. That is, as shown in FIG. 8, the histogram generation unit is a rectangular unit composed of a predetermined number of pixels in the main scanning direction and a predetermined number of pixels in the sub scanning direction, and the tint block color is switched for each input image data of each rectangle. It is good also as a structure. In this case as well, it goes without saying that the tint block color automatic selection mode and the non-automatic selection mode can be designated by the operation unit 23. In other words, a mode in which the copy-forgery-inhibited pattern color is automatically switched for each rectangle, and a copy-forgery-inhibited pattern color selection result for each rectangle is displayed on the operation unit 23. The color may be switched. Further, when the background pattern color selection result for each rectangular area in one page is the same result with a predetermined number of rectangles or the number of rectangles set by the user using the operation unit 23, the background pattern color of the corresponding page is selected. You may make it comprise uniformly with a tint block color.

(1 of other embodiments)
In the above description, whether the user selects the automatic selection mode or the non-automatic selection mode for setting the tint block color? However, in addition to these modes, a mode in which the user designates or does not designate the tint block color may be used. That is, when the user does not specify the tint block color, for example, the operation can be performed assuming that the automatic selection mode is set in FIG. In this case, in step 614 of FIG. 6, printing is performed with the default tint block color. Also in FIG. 7, it can be operated assuming that the automatic selection mode is set. In this case, in step 715 of FIG. 7, printing is performed with the default tint block color.

  When the user designates the tint block color, for example, in FIG. 6, the process proceeds from step 609 to step 614, and in step 614, the tint block color is printed in the user designated color. In FIG. 7, the process proceeds from step 712 to step S715, and in step 715, printing is performed with the user-designated tint block color.

(2 of other embodiments)
In the above description, the color tendency is determined only for significant information including characters and symbols, and the tint block color is determined. However, the present invention is not limited to this. For example, the significant information may be defined on the assumption that all the image information (for example, characters, symbols, lines, graphic images, and photographic images) included in the document image is included in the significant information. In that case, the tint block image color corresponding to the hue (histogram information) of the document image is determined. Further, it is possible to determine the color tendency of the printing paper itself by the method described above, and to set the complementary color of the determined color as the tint block color. In this method, for example, in the case of a paper having a yellow tendency, a tint block color is printed in blue which is a complementary color thereof. By doing so, the tint block effect is enhanced in the output product in which the original and the tint block image are combined and output. That is, the latent image portion appearing on the copy becomes more conspicuous. This is because the latent image portion (characters such as confidental) appearing on the copy is blue and the other areas are complementary colors, so the difference is easily visible to the human eye.

  There are two synthesis methods in all the examples including this example. The first synthesizing method is a method in which a darker luminance value in two images is used as a luminance value of an image after synthesis. That is, when the R luminance value of the predetermined pixel in the first image is 100 and the R luminance value of the predetermined pixel in the second image is 150, the darker value 100 is This is a method of determining the luminance value. Of course, the above is also performed for the G luminance value and the B luminance value.

  The second synthesis method is a method of preferentially synthesizing one image. In other words, when there is a luminance value in the first image to be prioritized, no matter what luminance value exists in the second image, the luminance value is always used as a synthesized luminance value. . This is not performed for each RGB unlike the first combining method. Note that the first image to be prioritized may be a document image or a tint block image.

1 is a block diagram showing a configuration of a copying machine according to an embodiment of the present invention. It is a block diagram which shows the structure of the tint block color selection part in this invention. It is a figure which shows an example of the histogram generation method in a histogram generation part. It is a figure which shows an example of the histogram which the histogram production | generation part produced | generated. It is a figure explaining the selection method by a tint block color selection part. FIG. 10 is a diagram illustrating an operation flow when there is one copy original. FIG. 10 is a diagram illustrating an operation flow when there are a plurality of copy originals. It is a figure which shows the structure at the time of dividing a histogram generation into the rectangular unit of a page. It is an enlarged view of a latent image portion and a background portion of a background pattern. It is a figure which shows the dot structure of the latent image part of a tint block, and a background part. It is a figure showing the display of the actual image in a tint block.

Explanation of symbols

1000 Copying machine 10 CPU
11 RAM
12 ROM
13 System bus 14 Reading unit 15 Reading i / f
16 Reading processing unit 17 Recording processing unit 18 Recording unit 19 Recording unit 20 Background pattern processing unit 21 System memory 22 Memory controller 23 Operation unit 201 Shading correction processing unit 202 Character / thin line determination unit 203 Sub-scanning MTF correction processing unit 204 Color space Conversion unit 205 Main scanning MTF correction unit 206 Filter processing unit 207 Resolution conversion unit 208 Masking processing unit 209 Chromatic color determination unit 210 Histogram generation unit 211 Background pattern color selection unit 300 Input image 301 Text character 302 Background portion 303 Character thin line determination result 304 Existence Color judgment result

Claims (14)

Histogram generating means for generating a histogram for each pixel of the level of each pixel of the input image data;
A tint block color determining unit that analyzes each histogram generated by the generating unit and determines a tint block color;
A tint block generation unit for generating tint block image data of the optimal tint block color determined by the tint block color determination unit;
An image processing apparatus comprising: combining means for combining the copy-forgery-inhibited pattern image data generated by the copy-forgery-inhibited pattern generating means with input image data.   The histogram generation means includes character / thin line determination means for determining character / thin line for each pixel of the input image data, chromatic color determination means for determining whether the pixel is a chromatic color pixel or an achromatic color pixel, and determination by these determination means The image processing according to claim 1, further comprising significant information detection means for detecting significant information using an output, wherein the histogram is generated only for significant information obtained by the significant information detection means. apparatus.   The said histogram generation means is further provided with a means to determine whether it is significant information for every pixel of input image data, The said histogram is produced | generated only about significant information. Image processing device.   The image processing apparatus according to claim 1, wherein the tint block color determining unit determines a complementary color of a color tendency indicated by a result of analyzing each histogram generated by the generating unit as a tint block color.   The tint block color determining unit determines a default color or a predesignated color as a tint block color when analyzing that each histogram generated by the generating unit does not show a specific color tendency. Item 8. The image processing apparatus according to Item 1. When the number of pages of input image data is plural, each of the histogram generation means and the tint block color determination means is executed for each page,
A tint block color storing unit for storing the tint block color determined by the tint block color determining unit for each page;
Of the tint block colors stored in the storage unit, the number of pages of a tint block color different from the tint block color specified by the user or the default tint block color of the device is calculated, and the calculated number is a predetermined number or the total of the calculated numbers. When the ratio to the number of pages is less than a predetermined value, a default color or a predetermined color is set as the tint block color, and the calculated number is equal to the predetermined number or the ratio of the calculated number to the total number of pages And a setting means for setting the color determined for each page as the tint block color when it is large,
The image processing apparatus according to claim 1, wherein the tint block generation unit generates tint block color tint block image data set by the setting unit. The tint block generation unit receives a user input as to whether the tint block generation unit uses the tint block color determined by the tint block color determination unit, or uses a default color or a predetermined color as the tint block color. Further comprising an operation mode selection means for controlling selection of a tint block color used by
When the operation mode indicates that the optimum tint block color determined by the tint block color determining unit is used, the tint block generation unit generates tint block image data of the optimum tint block color determined by the tint block color determining unit. If not shown, the tint block generation means uses a default color or a predesignated color as the tint block color. Generating a histogram for each color component for each pixel level of the input image data;
Generate and analyze each histogram to determine the tint block color,
An image processing method comprising: generating copy-forgery-inhibited pattern image data of the determined copy-forgery-inhibited pattern color; and synthesizing the generated copy-forgery-inhibited pattern image data with input image data.   The generation of the histogram includes determining character / thin line for each pixel of input image data, determining whether the pixel is a chromatic pixel or an achromatic pixel, and detecting significant information using these determination results. The image processing method according to claim 8, wherein the histogram is generated only for detected significant information.   9. The image according to claim 8, wherein generating the histogram comprises determining whether or not the information is significant information for each pixel of the input image data, and the histogram is generated only for the significant information. Processing method.   The image processing method according to claim 8, wherein the determination of the tint block color includes determining a complementary color of a color tendency indicated by a result of analyzing each generated histogram as a tint block color.   9. The determination of the tint block color includes determining a default color or a predesignated color as a tint block color when analyzing that each of the generated histograms does not exhibit a specific color tendency. An image processing method described in 1. Counting the number of pages of input image data,
When the counted number of pages is plural, the generation of the histogram and the background pattern color are determined for each page, the determined background pattern color is stored, and the stored background pattern color is designated by the user. Calculate the number of pages of a tint block color or a tint block color different from the default tint block color of the device, and if the calculated number is a predetermined number or the ratio of the calculated number to the total number of pages is less than a predetermined value, the default color or Set a predesignated color as the tint block color, and if the calculated number is equal to or larger than the predetermined number or the ratio of the calculated number to the total number of pages, set the color determined for each page as the tint block color To further comprise
The image processing method according to claim 8, wherein generating the tint block image data generates tint block image data having a set tint pattern color. When generating the copy-forgery-inhibited pattern image data, accepting user input as to whether to use the determined copy-forgery-inhibited pattern color, or to use a default color or a pre-designated color as the copy-forgery-inhibited pattern color;
Further comprising determining an operation mode for controlling selection of a tint block color according to the received user input,
When the copy-forgery-inhibited pattern image data indicates that the determined copy-forgery-inhibited pattern color is used for the operation mode, the copy-forgery-inhibited pattern image data is generated. Alternatively, the copy-forgery-inhibited pattern image data of a color specified in advance is created.

Images