JP4470349B2 - Image processing apparatus and image processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus that handles color images or monochrome images, and an image processing method thereof. More specifically, the present invention relates to an image processing apparatus having a function of determining whether it is color or monochrome, and an image processing method thereof.
[0002]
[Prior art]
Conventionally, in an image processing apparatus, color or monochrome is identified based on the presence of color pixels in the image data to be handled, and appropriate image processing is performed. By the way, recent color image forming apparatuses are provided with a function of adding a unique pattern (hereinafter referred to as a tracking pattern) to the output image when forming a color image. This is a function for leaving a clue for identifying the type and machine number of the used color image forming apparatus in the copied material when, for example, banknotes or securities are copied. Such tracking patterns are usually printed in inconspicuous colors such as yellow. Therefore, when the image data to be processed by the image processing apparatus includes a tracking pattern or a specific pattern similar thereto, what kind of color / monochrome determination is to be made becomes a problem. Japanese Unexamined Patent Publication No. 11-355589 is cited as a prior art that pays attention to such a case. In the technique of the publication, all image data including a tracking pattern is determined to be color image data, and image processing is performed as a color image.
[0003]
[Problems to be solved by the invention]
However, the conventional techniques described above have the following problems. That is, it is considered that image data that is monochrome other than the tracking pattern is normally recognized as monochrome by the user. However, it is processed as a color image due to the presence of the tracking pattern. For this reason, the image data that the user recognizes as a monochrome image is not processed as a monochrome image. That is, the process desired by the user is different from the actual process of the image processing apparatus.
[0004]
The present invention has been made to solve the above-described problems of the prior art. That is, an object of the present invention is to provide an image processing apparatus and an image processing method for appropriately determining color / monochrome for image data having a specific pattern and performing image processing desired by a user.
[0005]
[Means for Solving the Problems]
The image processing apparatus of the present invention, which has been made for the purpose of solving this problem, handles image data, and is a specific pattern detection that detects a tracking pattern that is unique to the apparatus that formed the image in the image data. Means for recognizing color pixels in the image data, and comparing the value obtained by subtracting the number of pixels of the tracking pattern from the number of color pixels in the image data with a predetermined threshold value, Determination means for determining whether the image is monochrome or monochrome.
[0006]
In this image processing apparatus, when the image data is handled, a specific pattern in the image data is detected by the specific pattern detecting means. In addition, color pixels in the image data are recognized by the color pixel recognition means. Then, based on the presence state of the color pixels in the image data that do not correspond to the specific pattern, the determination unit determines whether the image data is color or monochrome. As a result, for image data in which a specific pattern exists, the specific pattern is ignored, and whether it is color or monochrome is determined by a portion other than the specific pattern. Thereafter, appropriate processing is performed based on the determination result. Thus, image processing that matches the user's intention is performed.
[0007]
In the present invention, it is desirable that the determination means determine whether the image data is color or monochrome by comparing a value obtained by subtracting the number of pixels of the specific pattern from the number of color pixels in the image data with a predetermined threshold. In this way, when determining whether it is color or monochrome, the specific pattern is ignored. For this reason, automatic color selection processing irrespective of the presence or absence of a specific pattern can be performed.
[0008]
In the image processing method of the present invention, when processing image data , a tracking pattern , which is a pattern unique to the device that formed the image, is detected in the image data, color pixels in the image data are recognized, and the image data Whether the image data is color or monochrome is determined by comparing a value obtained by subtracting the number of pixels of the tracking pattern from the number of color pixels in the data with a predetermined threshold. By this method, even if a specific pattern exists, it is possible to determine whether it is color or monochrome according to need.
[0009]
Alternatively, the image processing method of the present invention, when processing image data, compares the value obtained by subtracting the number of pixels of a specific pattern from the number of color pixels in the image data with a predetermined threshold value to determine whether the image data is color. You may determine whether it is monochrome. By this method, it is possible to determine whether a specific pattern is ignored or not.
[0010]
In addition, a tracking pattern can be considered as the specific pattern in the present invention. Thereby, it is possible to appropriately determine whether the image data having the tracking pattern is color or monochrome.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an image processing apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of a digital full-color copying machine (hereinafter referred to as a copying machine of the present embodiment) according to an embodiment. The copying machine of this embodiment has a scanner 100, an image processing unit 200, a printer 300, a control unit 400, an operation unit 500, and a display unit 600.
[0012]
The scanner 100 reads a document and acquires R, G, and B three-color separation signals that are analog data. Further, these three color separation signals are converted into RGB digital signals and output to the image processing unit 200. The image processing unit 200 performs color correction or the like on the RGB digital signals input from the scanner 100 according to the selected document mode. Through this color correction, the RGB digital signal is separated into C, M, Y, and K color components and output to the printer 300. The printer 300 forms an image with four colors of CMYK, and prints out output data of the image processing unit 200.
[0013]
Note that the copying machine of this embodiment is a one-drum system, and when performing full-color copying, any one component of CMYK is sequentially output to the printer 300 for each reading of the scanner 100, and is read four times in total. Perform one printout. Further, the image processing unit 200 determines color / monochrome of the read document.
[0014]
The control unit 400 is constituted by a microcomputer or the like, and controls the operation of the entire copying machine according to a program stored in advance in a ROM or the like. The operation unit 500 is an input device for an operator to select a copy mode, set the number of copies, and the like, and includes various keys and a touch panel on the display unit 600. In this case, the copy mode includes setting of presence / absence of pre-scan. The display unit 600 is a display device that performs display of various setting states, setting instructions for an operator, and the like.
[0015]
FIG. 2 is a diagram illustrating the configuration of the operation unit 500 and the display unit 600. The operation unit 500 includes various keys 502 to 505. A key 502 is a numeric keypad for inputting numerical values such as the number of copies and a zoom ratio, a key 503 is a start key for instructing start of operation of the apparatus, a key 504 is a stop key for instructing stop of operation, and a key 505 is a mode. This is a mode reset key for returning to the initial setting. The display unit 600 is a color display device with a touch panel, and a touch panel 501 is superimposed on the display unit 600 so that a mode can be selected.
[0016]
FIG. 3 is a diagram showing a display screen of the display unit 600 (touch panel 501). The display unit 600 includes a message area that displays a message such as “Can copy” at the upper left of the screen, a copy number display area that displays the number of copies to be displayed at the upper right of the screen, and an area that displays the copy magnification at the lower right of the screen. . Furthermore, various settings can be made on the display unit 600. For example, a key for selecting a color mode (automatic color selection, monochrome, color), a document mode (automatic character / photo mode, character mode, print photo mode, photographic paper) Key for selecting photo mode and copy original mode), key for selecting paper size (automatic paper selection, A4 horizontal, A4 vertical, A3), key for selecting magnification (same size, paper specified scaling), etc. Yes.
[0017]
Next, the overall operation of the copying machine of this embodiment will be described with reference to the flowchart of FIG. Note that the copying machine of the present embodiment includes a mode for performing color / monochrome determination of a document in the image processing unit 200 during pre-scanning and a mode for performing main scanning characters. First, the control unit 400 determines whether or not the pre-scan mode is set (S101). If the pre-scan mode is not selected (S101: NO), the scanner 100 scans once and forms a K color image (S102). While the K color image is being formed, the image processing unit 200 determines the color / monochrome of the document based on the data obtained by scanning (S103), and outputs the result to the control unit 400. . The control unit 400 determines whether the document is a color document based on the determination result input from the image processing unit 200 (S104). If it is not color, that is, if it is determined to be monochrome (S104: NO), the process is terminated without forming the remaining CMY images, and the printer 300 outputs in monochrome. On the other hand, if it is determined to be color (S104: YES), the scanner 100 scans three times, the printer 300 performs CMY image formation (S105), and outputs in full color.
[0018]
On the other hand, if the pre-scan mode is selected in S101 (S101: YES), pre-scan is performed (S106). Thereafter, the image processing unit 200 determines color / monochrome based on the data obtained by the pre-scan (S107), and outputs the result to the control unit 400. Next, the control unit 400 determines whether the determination result input from the image processing unit 200 is color (S108). If the color is determined (S108: YES), the scanner 100 performs four scans, the printer 300 performs CMYK image formation (S109), and outputs in full color. On the other hand, if it is determined to be monochrome (S108: NO), the scanner 100 performs one scan, the printer 300 performs image formation for K only (S110), and outputs in monochrome.
[0019]
Next, the image processing unit 200 will be described in detail. FIG. 5 is a block diagram illustrating an internal configuration of the image processing unit 200. The image processing unit 200 includes a density conversion unit 201, a filter 202, a color correction / UCR (background color removal processing) unit 203, a selector 204, a gradation correction unit 205, a gradation processing unit 206, and a tracking pattern. Each processing unit includes a detection unit 207, a color pixel detection unit 208, a comprehensive determination unit 209, and a CPU 210. Each processing unit is controlled by the CPU 210.
[0020]
Next, the operation of the image processing unit 200 will be described. First, the scanner 100 outputs R, G, and B digital signals to the density conversion unit 201, the tracking pattern unit 207, and the color pixel detection unit 208, respectively.
[0021]
The density converter 201 converts the input R, G, B digital signals (reflected light data) into density data R1, G1, B1. Each converted density data is output to the filter 202. The filter 202 performs image correction such as smoothing and edge enhancement from the target pixel of the density data R1, G1, and B1 and the surrounding pixels. The corrected signals R2, G2, and B2 are output to the color correction / UCR unit 203.
[0022]
The color correction / UCR unit 203 corrects the input signals R2, G2, and B2 in order to remove the turbidity component of the color separation filter and the turbidity component of ink of the scanner 100. This color correction is executed by the following equation, for example.
C0 = K11 × R2 + K12 × G2 + K13 × B2
M0 = K21 × R2 + K22 × G2 + K23 × B2
Y0 = K31 × R2 + K32 × G2 + K33 × B2
K11 to K33 are coefficients for performing correction. Next, in the background color removal process (UCR process), the C1, M1, and Y1 signals obtained by removing some or all of the black components of the color-corrected C0, M0, and Y0 signals and the black ink corresponding to the removal. The signal K1 is generated. Here, when the background color removal rate is α (0 ≦ α ≦ 1), C1, M1, Y1, and K1 are executed by, for example, the following equations.
K1 = α × min (C0, M0, Y0)
C1 = C0-K1
M1 = M0-K1
Y1 = Y0-K1
min (C0, M0, Y0) is the minimum value of C0, M0, Y0. The signals C1, M1, Y1, and K1 after the background removal processing are output to the selector 204.
[0023]
The selector 204 selects one of signals C 1, M 1, Y 1, and K 1 under the control of the CPU 210 and outputs the selected signal to the gradation correction unit 205. The tone correction unit 205 corrects the density of C1, M1, Y1, and K1 according to the characteristics of the printer 300. The corrected signals C2, M2, Y2, and K2 are output to the gradation processing unit 206. The gradation processing unit 206 performs gradation processing on C2, M2, Y2, and K2, and generates C, M, Y, and K signals. The C, M, Y, and K signals are output to the printer 300 as output signals of the image processing unit 200. The printer 300 forms a color image based on the C, M, Y, and K signals.
[0024]
The tracking pattern detection unit 207 detects a tracking pattern from the input RGB digital signal. When a tracking pattern is detected, the number of pixels is counted, and the result is output to the overall determination unit 209 as a tracking pattern count value. The tracking pattern is detected by the method described in JP-A-9-186901.
[0025]
The color pixel detection unit 208 detects a color pixel from the input RGB digital signal by analyzing a histogram, extracting a feature amount for each small region, or the like. From these detection results, the number of pixels in the color pixel area in the document is counted, and the result is output as a color pixel count value to the overall determination unit 209. The color pixel detection is performed by the method described in Japanese Patent Laid-Open No. 8-256271.
[0026]
As shown in the block diagram of FIG. 6, the overall determination unit 209 includes a calculation unit 2091, a determination unit 2092, and a threshold value generation unit 2093. The threshold generation unit 2093 generates a threshold used for color / monochrome determination. The calculation unit 2091 determines the color / monochrome of the document based on the tracking pattern count value input from the tracking pattern detection unit 207 and the color pixel count value input from the color pixel detection unit 208. More specifically, the tracking pattern count value is subtracted from the color pixel count value, and the result is compared with a threshold value for determination. For example, when the threshold is larger, it is determined as monochrome, and when the threshold is smaller, it is determined as color. The determination result is output to the CPU 210 as a comprehensive determination result.
[0027]
Next, the color / monochrome determination process performed by the CPU 210 will be described with reference to the flowchart of FIG. First, the mode setting by the color mode selection key of the operation unit 500 is confirmed (S201). When the automatic color mode has been selected (S201: automatic color selection), priority is given to the comprehensive determination result by the comprehensive determination unit 209 to determine color / monochrome (S202). If the color mode has been selected (S201: color), it is determined to be color regardless of the overall determination result (S204). If the monochrome mode is selected (S201: monochrome), it is determined as monochrome regardless of the comprehensive determination result (S203). When the color is determined (S204) or monochrome (S203), the color / monochrome determination process is terminated. In other words, when the automatic color mode is selected, a color / monochrome image is output according to the result of the comprehensive determination, and in any other case, an arbitrary image is output by the user.
[0028]
As described in detail above, in the image processing apparatus according to the present embodiment, the tracking pattern detection unit 207 detects the tracking pattern in the image data. The color pixel detection unit 208 recognizes color pixels in the image data. Then, based on the detected number of pixels of the tracking pattern and the recognized number of color pixels, the comprehensive determination unit 209 performs color / monochrome determination processing. Further, the determination unit 2092 compares the value obtained by subtracting the number of pixels of the tracking pattern from the number of color pixels in the image data by the calculation unit 2091 with the threshold generated from the threshold generation unit 2093, thereby determining whether the image data is color. Whether it is monochrome or not is determined. As a result, color / monochrome discrimination processing ignoring the tracking pattern is realized.
[0029]
Note that this embodiment is merely an example and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, although a digital color copying machine is used in this embodiment, a color image processing apparatus such as a color printer or a scanner may be used. Note that image data in the case of a printer is image data or an image file input from a personal computer or the like. In the case of a scanner, even a monochrome document with a tracking pattern is created as a monochrome image depending on the color / monochrome determination result.
[0030]
In this embodiment, color / monochrome discrimination is performed by subtracting after counting all areas in the image data. However, it is determined whether each pixel is a tracking pattern, and is ignored if it is a tracking pattern. Also good.
[0031]
In this embodiment, color pixels and tracking pattern pixels are counted for all areas in the image data. However, the image data may be divided into a plurality of blocks, and color / monochrome discrimination may be performed in units of blocks. .
[0032]
In the present embodiment, the specific pattern is a tracking pattern, but this is not a limitation. For example, when information on a copyrighted work is included in a document as a specific pattern, if it is detected, the copyright fee may be added to the copy fee.
[0033]
【The invention's effect】
As is apparent from the above description, according to the present invention, there is provided an image processing apparatus and an image processing method for appropriately determining color / monochrome for image data having a specific pattern and performing image processing desired by the user. ing.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a copying machine according to an embodiment.
FIG. 2 is a diagram illustrating a configuration of an operation unit and a display unit of the copier according to the embodiment.
FIG. 3 is a diagram showing a display screen of a display unit of the copying machine according to the embodiment.
FIG. 4 is a flowchart showing the operation of the copying machine according to the embodiment.
FIG. 5 is a block diagram showing an internal configuration of an image processing unit of the copying machine according to the embodiment.
FIG. 6 is a block diagram illustrating an internal configuration of a general determination unit of the copying machine according to the embodiment.
FIG. 7 is a flowchart showing an operation of color / monochrome determination.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Scanner 200 Image processing part 207 Tracking pattern detection part 208 Color pixel detection part 209 Comprehensive determination part 300 Printer

Claims (2)

In an image processing apparatus that handles image data,
A specific pattern detecting means for detecting a tracking pattern which is a pattern unique to the apparatus that formed the image in the image data;
Color pixel recognition means for recognizing color pixels in image data;
Image processing comprising: a determination unit that determines whether the image data is color or monochrome by comparing a value obtained by subtracting the number of pixels of the tracking pattern from the number of color pixels in the image data with a predetermined threshold value apparatus. In the image processing method of image data,
The tracking pattern that is unique to the device that formed the image in the image data is detected,
Recognize color pixels in image data,
An image processing method comprising: determining whether image data is color or monochrome by comparing a value obtained by subtracting the number of pixels of the tracking pattern from the number of color pixels in the image data with a predetermined threshold value.

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