JPH07123251A - Picture processor - Google Patents

Abstract

PURPOSE:To obtain a picture processor capable of processing a picture with high definition by discriminating a black letter through the application of fuzzy control. CONSTITUTION:An edge detection circuit 211 of a black letter discrimination section detects an edge in picture, a saturation discrimination circuit 212 discriminates the saturation, a fuzzy discrimination circuit 213 utilizing fuzzy control obtains a fuzzy inferred value based on the edge and saturation to vary a UCR quantity based on the inferred value. Thus, an original image is reproduced distinctly in letters in a white background and faithfully in black thin lines detected in the picture by applying weak UCR processing, thereby high picture quality is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus for determining black characters in a color image.

[0002]

2. Description of the Related Art In recent years, color image data obtained by digitally processing color image data and outputting it to a color printer to obtain a color image, and color image data obtained by color-separating and electrically reading color originals are obtained. The development of a color printing system such as a so-called digital color copying machine, in which a color image is copied by printing out a sheet on paper, is remarkable.

Further, with the widespread use of these, the demands on the print quality of color images are also increasing, and in particular, there is an increasing demand for black characters and black fine lines to be printed blacker and sharper. That is, when a black original is color-separated, yellow, magenta, cyan, and block signals are generated as signals for reproducing black. However, when printing is performed as it is based on the obtained signals, four colors are superimposed. Since the color is reproduced, a slight deviation between the colors causes a color blur on the black fine line, and the black does not look black or appears blurry, which significantly deteriorates the print quality.

On the other hand, by utilizing the characteristics of black characters and fine lines in an image, for example, a black character is detected by an edge component and a chromatic color or an achromatic color of the image, and a black color is formed depending on whether it is in the image or in the non-image. Etc. have been proposed.

[0005]

However, in the above-mentioned conventional example, too much faithful reproducibility is pursued, so that black isolated points in the image are also faithfully reproduced, fine lines in the image, and achromatic outline portions. Also, black characters are processed, and some documents are noticeable, which is a factor that hinders high image quality.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image processing apparatus capable of processing an image with high quality by applying black image determination by applying fuzzy control. .

[0007]

In order to achieve the above object, the image processing apparatus of the present invention has the following configuration. A plurality of determining means for determining the character and line drawing portions in the image and a control means for performing fuzzy control of the separation of the character and line drawing portions based on the determination result of each determining means.

Further preferably, the plurality of judging means are
An edge detection unit that detects the edge amount in the image and a saturation determination unit that determines the saturation. Also preferably, further
A designating unit is provided for designating whether or not the area is to separate the character and the line drawing.

[0009]

In this structure, the character and line drawing portions in the image are judged, and the operation of fuzzy controlling the separation of the character and line drawing portions based on the judgment result.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the color image processing apparatus in the embodiment. 10
Reference numeral 1 denotes a platen glass, which is an original 102 to be read.
Is placed. The original 102 is illuminated by an illumination 103, passes through mirrors 104, 105, 106, and an optical system 107.
The image is projected onto the CCD 108 by the. Where CC
D108 is composed of a CCD line sensor having three lines of R (red), B (blue), and G (green). Further, the motor 109 causes the mirror 104 and the illumination 10
The first mirror unit 110 including 3 is driven at the speed V, and the second mirror unit 111 including the mirrors 105 and 106 is driven at the speed 1/2 V to scan the entire surface of the original 102. An image processing circuit 112 is a part that processes the read image information as an electric signal and outputs it as a print signal.

Reference numerals 113, 114, 115 and 116 denote semiconductor lasers, which are driven by output signals from the image processing circuit 112, and the laser light emitted by each semiconductor laser is a polygon mirror 117 for each print color.
118, 119 and 120 scan the photosensitive drums 125, 126, 127 and 128 for each print color to form a latent image. Reference numerals 121, 122, 123, and 124 denote developing units for developing latent images with black (Bk), yellow (Y), cyan (C), and magenta (M) toners, respectively. Paper cassettes 129, 130,
Either the 131 or the manual feed tray 132 is selected, and the fed paper passes through the registration roller 133 and the transfer belt 1.
It is adsorbed on 34 and conveyed. The photosensitive drums 128, 127, 126, 1 are synchronized in advance with the paper feed timing, and
At 25, the images of the respective colors are developed and transferred to the paper. Then, the paper on which the toner of each color is transferred is separated /
The sheet is conveyed, fixed, and discharged onto the sheet discharge tray 136.

<First Embodiment> FIG. 2 is a block diagram showing the arrangement of an image processing circuit according to the first embodiment. The document is scanned by the color image reading unit, and the reflected light from the document is read by the color reading CCD 201.
The light is separated and the light enters. The electrical signals corresponding to the R (red), G (green), and B (blue) color components of the color original are sample-held by the analog processing circuit 202 for each color, and black correction, white correction, color balance, and the like are performed. After undergoing the processing, it is digitized by the A / D converter 203, and the shading characteristic of the image reading unit is corrected by the shading correction circuit 204. Then, it is converted into an NTSC RGB signal by the input masking circuit 205,
The converted RGB signals are converted into L by the density conversion circuit 206 next.
It is converted into color data C (cyan), M (magenta), and Y (yellow) corresponding to the color material in accordance with the OG characteristics.
After that, it is input to the UCR circuit 207 and the value of Bk (black) is calculated by the following equation.

Bk = Min (C, M, Y) The calculated Bk data is subjected to UCR for each color data of C, M and Y. The UCR amount is determined by the reference data of the LUT (lookup table), and its characteristic is shown in FIG. The amount shown in FIG. 3 shows the characteristic that UCR is started when the input Bk amount is about 40% and UCR is performed up to 50%. In this way, the color-corrected color data is corrected by the gamma correction circuit 208 in accordance with each printing by the color printer unit, and the filter 209
The edges are emphasized and smoothed through and sent to the printer unit 210.

Next, detection of a black character / black line image will be described below. First, as described above, the color separation signals R, G, and B that have been subjected to the shading correction are output to the edge detection circuit 21.
Enter 1. The density signal obtained from the RGB signal is input to the edge detection circuit 211. FIG. 4 is a diagram showing a detailed configuration of the edge detection circuit 211 shown in FIG.
The input density signal is expanded into five lines by the FIFOs 401 to 404, and edge components in eight directions with respect to the target pixel are detected. Here, the MAX value (edge degree) of the edge amount in eight directions is taken.

FIG. 5 is a diagram showing a detailed structure of the saturation determination circuit 212 shown in FIG. The maximum value MAX (R, G, B) and the minimum value MIN (R, G,) are detected by the maximum value detection unit 501 and the minimum value detection unit 502 for the input RGB signal.
B) is detected respectively. Then, the difference ΔC is calculated by the subtractor 503, data conversion is performed by the next LUT 504 according to the characteristics as shown in FIG. 6, and the saturation signal Cr is generated (chromaticity). In FIG. 6, the closer ΔC is to “0”, the lower the saturation (closer to an achromatic color), and the larger ΔC is, that is, the stronger the degree of chromatic color is, the closer to “0”,
In a completely chromatic color, Cr = 0. The degree of change is shown to follow FIG.

Next, the fuzzy decision circuit 213 shown in FIG.
Will be described below with reference to the block diagram shown in FIG. First, the membership functions 701 and 702 generate three elements each from the 8-bit edge and chromaticity data obtained by the edge detection circuit 211 and the saturation determination circuit 212 described above. FIG. 8 shows this state. Here, E of (a) shown in FIG.
L, EM, and EH each have a small amount of edge, normal,
In addition, CL, CM, and CH in (b) indicate that the black amount is small, usually, and large. In this way, each of the membership functions 701 and 702 outputs three elements.

Next, the inference value applied to the fuzzy rule is obtained by the MIN method 703 and the MAX method 704. The fuzzy rule advocated here is multi-valued processing when the amount of edges is large and the amount of black is large (that is, the background is closer to white and clear black). To do. When the amount of edges is small and the amount of black is small (that is, the background is dark and black is not clear), UC
It is regulated to reduce the amount of R. Then, a fuzzy inference value as shown in FIG. 9 is obtained from the three elements obtained from each of the membership functions 701 and 702 by the defuzzification (centroid method) 705 and output to the UCR processing 207 described above. However, UCR processing is performed.

As described above, according to the first embodiment, when a black character is determined, multivalued data is used, fuzzy control is applied, and the UCR amount is changed according to the fuzzy inference value. As a result, the characters in the white background are clearly defined, and the black thin lines detected in the image are weakly UC.
By applying R, the original can be reproduced faithfully,
It is possible to maintain high image quality.

<Second Embodiment> Next, as a second embodiment, the handling of the determination signal when the black character determination in the case of applying image compression is obtained by fuzzy inference will be described. Figure 1
0 is a block diagram showing the configuration of the image processing circuit according to the second embodiment. The same parts as those in the first embodiment shown in FIG. 2 are designated by the same reference numerals.

As shown in the figure, the image is compressed by the encoder unit 221 and is stored in the memory unit 222. 223
Decompress in the decoder part of. The other image formation is the same as in the first embodiment. Furthermore, in the black character determination unit,
It is necessary to thin out the data of the black character determination signal as the image is compressed. 11 is a diagram showing a thinning circuit added after the fuzzy judgment circuit of FIG. 7, and the fuzzy judgment circuit 224 shown in FIG. 10 includes the circuit of FIG. Here, padding is performed in a 4 × 4 block.

Further, in the first and second embodiments, a region is designated by a digitizer (not shown) or the like, and only the selected region is subjected to the fuzzy processing as in the above-mentioned embodiment. U for areas other than the area
It is also possible to maintain higher image quality without applying CR. The present invention may be applied to a system including a plurality of devices or an apparatus including a single device.

It goes without saying that the present invention can also be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0023]

As described above, according to the present invention,
It is possible to process images with high quality by applying fuzzy control to make black character determination.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a color image processing apparatus in an embodiment.

FIG. 2 is a block diagram showing a configuration of an image processing circuit in the first embodiment.

FIG. 3 is a diagram showing UCR characteristics.

4 is a diagram showing a detailed configuration of an edge detection circuit 211 shown in FIG.

5 is a diagram showing a detailed configuration of a saturation determination circuit 212 shown in FIG.

6 is a diagram showing characteristics of the LUT 504 shown in FIG.

7 is a block diagram showing a detailed configuration of a fuzzy determination circuit 213 shown in FIG.

FIG. 8 is a diagram for explaining elements of the membership function shown in FIG.

FIG. 9 is a diagram for explaining a fuzzy rule.

FIG. 10 is a block diagram showing a configuration of an image processing circuit according to a second embodiment.

11 is a diagram showing a part of the fuzzy decision circuit 224 shown in FIG. 10. FIG.

[Explanation of symbols]

 201 CCD 202 Analog processing 203 A / D converter 204 Shading correction 205 Input masking 206 Density conversion 207 UCR 208 Gamma (γ) correction 209 Edge enhancement 210 Printer section 211 Edge detection 212 Saturation determination 213 Fuzzy determination

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H04N 1/60 1/46 4226-5C H04N 1/40 D 4226-5C 1/46 Z

Claims (3)

[Claims] 1. A plurality of determining means for determining a character and a line drawing portion in an image, and a control means for fuzzy controlling the separation of the character and the line drawing portion based on the determination result of each determining means. Image processing device. 2. The image processing apparatus according to claim 1, wherein the plurality of determination units are an edge detection unit that detects an edge amount in an image and a saturation determination unit that determines saturation. 3. The image processing apparatus according to claim 1, further comprising a designating unit that designates whether or not the region is a region for separating a character and a line drawing.