JPH08181873A - Image forming device - Google Patents

Abstract

PURPOSE: To improve the reproducibility of an original image by automatically changing a parameter in image processing for a normal copy and a generation copy. CONSTITUTION: A CCD unit 101 outputs the image signals of three primary colors of R(red), G(green) and B(blue), respectively. An A/D converter 104 outputs the image signal inputted corresponding to a reference voltage as multilevel image data. An image processing part 111 consists of a color correction/UCR part 201, a filter part 202, a gamma correction part 203, a dither processing part 204, a pattern attaching part 205, a video control part 206, an image separating part 207, a pattern recognition part 208, a control part 209 and memory 210. A recording part 122 receives the input of the image data of Y(yellow), M(magenta), C(cyan) and K(black), and records each of image data on copying paper.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for performing image processing on input image data.

[0002]

2. Description of the Related Art Conventionally, generation copying, that is, copying a copy as an original again, causes gradation skipping, deterioration of resolution, deterioration of graininess, and the like. In the case of a color original, the color reproducibility is lowered, and the reproducibility of the original image is lowered. In order to compensate for this reproducibility, the parameters of image processing are changed while evaluating the copy image. However, there is a problem that this work is very complicated.

On the other hand, with the improvement in image quality of color copying machines,
There is a growing need to prevent the copying of securities such as banknotes. For this reason, a specific pattern unique to each machine is set in the copying machine, and each time the specific pattern is copied, the specific pattern is added to the image data and recorded. By detecting a specific pattern, the copying machine that made the copy can be specified. That is, a specific pattern is always added to the copy made by the color copying machine. This technique is disclosed in
No. 244390.

[0004]

According to the first and second aspects of the present invention, the reproducibility of the original image is improved by automatically changing the image processing parameters between the normal copy and the generation copy. The purpose is to

An object of the present invention is to improve the reproducibility of an original image by automatically changing the image processing parameters depending on the type of image, the normal copy and the generation copy. To do.

[0006]

In order to solve the above-mentioned problems, the invention according to claims 1 and 2 performs image processing for input image data with characteristics according to set parameters. Means, a pattern recognition means for recognizing a predetermined pattern combined with the input image data, a normal copy parameter and a generation copy parameter are stored. For image data whose pattern is not recognized by the memory means and the pattern recognition means, normal copying parameters are read from the memory means and set in the image processing means. For image data whose pattern has been recognized by the pattern recognition means, parameters for generation copying are read from the storage means to perform the image processing. Set to means And a controlling means for controlling so as to perform image processing by Rukoto. Further, it is characterized by further comprising a pattern adding means for adding the predetermined pattern to the image data subjected to the image processing.

In order to solve the above-mentioned problems, an image processing means for performing image processing on input image data with characteristics according to set parameters and an input image data are provided. An image separating means for discriminating the image type of the image and separating the images, a pattern recognizing means for recognizing a predetermined pattern combined with the input image data, and the image separating means. It is characterized by further comprising: control means for controlling the image processing means by setting parameters corresponding to the separation result and the recognition result by the pattern recognition means in the image processing means.

[0008]

According to the present invention, the image processing means for performing the image processing on the input image data with the characteristic according to the set parameters, and the input image data. A pattern recognizing means for recognizing a synthesized predetermined pattern, a storage means for storing a normal copy parameter and a generation copy parameter, and the pattern.
Image data whose pattern has not been recognized by the image recognition means.
For the data, the normal copy parameters are read from the storage means and set in the image processing means for image processing, and the pattern recognition means recognizes the pattern. For the image data, the control means controls the generation copy parameters from the storage means and sets them in the image processing means so that the image processing is performed. The reproducibility of the original image can be improved by automatically changing the image processing parameters between the normal copy and the generation copy.

According to the third aspect of the present invention, the image processing means for performing the image processing on the input image data with the characteristics according to the set parameters, and the image of the input image data. An image separating means for discriminating the type and separating the images, a pattern recognizing means for recognizing a predetermined pattern combined with the input image data, a separation result by the image separating means and the pattern. Since the control means for controlling the image processing means by setting the parameter corresponding to the recognition result by the image recognition means in the image processing means, the image type, the normal copy and the generation
It is possible to improve the reproducibility of the original image by automatically changing the image processing parameters by using the copy command.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The overall construction of a digital copying machine according to the present invention will be described with reference to FIG.

The scanner 100 includes a CCD unit 10
1. In order to read the entire surface of the image of the original 103 placed on the original table 102, the CCD unit 101 electrically performs main scanning while the original table 102 is provided.
Subscan by CCD unit 101, and image data
Output. The image processing unit 110 performs image processing on the image data input from the scanner 100 and outputs the image data. The printer 120 includes a paper feed unit 121, a recording unit 122, and a paper discharge unit 123. The copy paper fed from the paper feed unit 121 is
The image data input from the image processing unit 110 is recorded in the recording unit 1.
The recording is performed at 22, and the paper is ejected to the paper ejection unit 123. Operation unit 130
Can be displayed to the operator and an instruction can be input from the operator.

The control block of the digital copying machine according to the present invention will be described with reference to FIG.

The CCD unit 101 includes R (red),
The image signals of the three primary colors of G (green) and B (blue) are output. The A / D converter 104 outputs the image signal input according to the reference voltage as multi-level image data. The image processing unit 111 includes a color correction / UCR unit 20.
1, a filter unit 202, a gamma correction unit 203, a dither processing unit 204, a pattern addition unit 205, a video controller.
Rule unit 206, image separation unit 207, pattern recognition unit 20
8, a control unit 209, and a memory 210. Recording unit 12
Image data of Y (yellow), M (magenta), C (cyan), and K (black) is input to 2 and each of the image data is recorded on a copy sheet. Here, the image processing unit 1
11 will be further described. The color correction / UCR unit 201 is a CC
The R, G, and B image data input from the D unit 101 are converted into Y, M, and C image data that are complementary colors, and the Y, M, and C image data are also converted. Is converted into K data consisting of overlapping images and output as Y, M, C, and K image data. The filter unit 202 receives the input Y (hereinafter, connected by a bus line),
MTF correction is performed on each of the M, C, and K image data in accordance with the parameters instructed by the control unit 209. The gamma correction unit 203 performs gamma correction on the input Y, M, C, and K image data according to the parameters instructed by the control unit 209. The dither processing unit 204 performs dither processing on the input Y, M, C, and K image data according to the parameters instructed by the control unit 209. Pattern
The image adding unit 205, among the input Y, M, C, and K image data, only the Y image data, the image data of a specific pattern unique to this copying machine. Is added. The video control unit 206 converts the input Y, M, C, and K image data into a form (frequency, phase, etc.) suitable for recording by the recording unit 122. In addition, the image separation unit 207
The image type is discriminated from each of the R, G, and B image data input from the CCD unit 101, and the separation result is output to the control unit 209. The pattern recognition unit 208 uses R,
Y image data is extracted from each of the G and B image data, and Y is extracted.
Specific pattern of the copying machine recorded with the image data of
The presence / absence of image data of the image is recognized, and the recognition result is obtained by the control unit 2.
It outputs to 09. The control unit 209 has a pattern recognition unit 20.
The parameters are read from the memory 210 according to the recognition result input from the image recognition unit 8 and the parameters are read by the image separation unit 2
07, the parameter is read from the memory 210 according to the separation result input from the image separation unit 207,
The parameters are set in the color correction / UCR unit 201, the filter unit 202, the gamma correction unit 203, and the dither processing unit 204. These inputs and outputs are performed via bus lines. The memory 210 stores each parameter. Then, the operation unit 130 outputs the data instructed and input by the operation unit 130 to the control unit 209, and the control unit 20.
The data input from 9 is displayed on the operation unit 130.

The image separation unit 207 will be described in more detail with reference to FIG. The edge separation unit 301 receives the input R,
When there are many density level change points in an image composed of G and B image data, this image is detected as a temporary character image, and this temporary character image is detected longer than a predetermined threshold value. In addition, it is detected as a character image. The halftone dot separating unit 302 receives the input R, G, and B image data.
When the image data consisting of images has a predetermined periodicity that is greater than a predetermined level, this image is detected as a temporary halftone dot image, and this temporary halftone dot image exceeds the predetermined threshold value. When it is detected for a long time, it is detected as a halftone image. The color separation unit 303 detects the image as a temporary black image when the input image including the R, G, and B image data has image data other than black at a predetermined level or less. When the provisional black image is detected longer than a predetermined threshold value, it is detected as a black image.
The comprehensive determination unit 304 comprehensively determines, based on the detection results of the edge separation unit 301, the halftone dot separation unit 302, and the color separation unit 303,
It is determined that the image is a character image, a photographic image, or a halftone dot image, and is output as data of the separation result.

The pattern recognition unit 208 will be described in more detail with reference to FIG. The extraction unit 401 uses the input R,
Color conversion is performed on each of the G and B image data and Y image data is output. The comparison unit 402 receives the input Y image data.
The pattern is compared with a predetermined level to recognize the pattern, and the comparison result is output. The cycle detection unit 403 detects whether the input comparison result exists in a cycle within a predetermined range, and outputs it as recognition result data.

Here, the wording in the embodiment described below will be defined. An "original document" is a document that has not been copied. The "first generation copy" is a copy of an original document as a document by a copying machine. "Second generation copy"
Means that the first generation copy is copied as an original by a copying machine. "Third generation copy" means second generation copy
Is copied as a manuscript with a copying machine. And
"Generation copy" is a general term for those copied after the first-generation copy and for the act of copying.

The characteristics of the parameters in each block of the image processing unit 110 will be described.

The characteristics of the UCR processing performed by the color correction / UCR unit 201 will be described with reference to FIG. Parameter A
Is for making the UCR conversion rate 100%, and the image data as shown in FIG. 5A is converted into Y, M and C images as shown in FIG. 5B. K is the lowest level of data
Image data level, and the K image data level is subtracted from the Y, M, and C image data levels. The parameter B is to make the UCR conversion rate 80%, and the image data as shown in FIG.
The data is as shown in FIG. 5 (c). The parameter C makes the conversion rate of the UCR 50%, and the image data as shown in FIG. 5A is shown in FIG. 5D.
As shown in.

The filtering process performed by the filter unit 202 will be described with reference to FIG. The filter processing in this embodiment is performed by a digital filter, and is performed by calculating image data to be filtered and each image data adjacent to the image data on the image. Specifically, the numbers in the center of each matrix in FIG. 6 are the coefficients of the image data to be filtered, and the numbers in the periphery of each matrix are the coefficients of the adjacent image data. The result obtained by multiplying the image data with the image data is added. As shown in FIG. 6A, the parameter D is for performing extremely strong MTF correction, and corrects the resolution of the copy image which is lower than the original image as a result of being read by the CCD. It is a thing. Parameter E is shown in FIG.
As shown in (b), strong MTF correction is performed, but weaker MTF correction than parameter D is performed. The parameter F is weak M as shown in FIG. 6 (c).
The TF correction is performed, and the MTF correction weaker than that of the parameter E is performed. The parameter G is shown in FIG.
As shown in (d), the MTF correction is extremely weak, and the MTF correction is even weaker than the parameter F. The parameter H is, as shown in FIG.
In order to make a sudden density change such as a halftone image a constant density,
It is a weak smoothing. The parameter I is shown in FIG.
As shown in (f), the smoothing is stronger than that of the parameter H.

The gamma correction performed by the gamma correction unit 203 will be described with reference to FIG. FIG. 7A shows the characteristics of the image density (ID) of the original document and the image density (OD) on the copy. The first-generation copy, the second-generation copy, and the third-generation copy are shown. As the value becomes negative, the slope of the characteristics rises (the image density level on the copy sharply changes from small to large at the medium density level of the original document's image density), and the medium density level that the original document had It is shown that the grayscale difference of the density at 1 is not on the copy. FIG. 7B shows the characteristics of the input image data (ID) and the output image data (OD). Parameter
The data J, as indicated by J, makes the contrast of the image extremely large, and has a very high inclination at the medium density level (the output image data at the medium density level of the input image data). The concentration level of extremely rapidly increases from small to large). Parameter K, as indicated by K, has a slope at an intermediate concentration level, but is laid down rather than parameter J. Parameter
As indicated by L, the data L has a slope at the medium density level (the density level of the output image data gradually changes from small to large at the medium density level of the input image data). It has the opposite characteristics to those of the first-generation copy, and makes the characteristics of the image density of the original document and the image density on the copy linear (linear function). Parameter M
Indicates that the slope at an intermediate concentration level was extremely laid down, and that it was laid down rather than the parameter L. In this gamma correction, the background removal process is also performed at the same time, and each parameter has a threshold value that sets all the low density (high lightness) portions of the original image to level 0. For parameters J and L, level 4 and below are level 0
Therefore, the threshold is set to level 4. For the parameters K and M, the threshold value is set to level 1 so that the level 1 or lower is set to level 0. In addition, in the color copy,
In general, the gamma correction characteristic of the K image density is higher than the gamma correction characteristic of each of the Y, M, and C image densities. Therefore, in the case of color copy
At the time of copying, as shown in FIG. 7C, Y,
A parameter that allows the gamma correction characteristics of the K image density to lie more than the gamma correction characteristics of the M and C image densities.
To be

The dither processing performed by the dither processing section 204 will be described with reference to FIG. As shown in FIG. 8A, the parameter O is one in the main scanning direction and one in the sub scanning direction.
The dither processing is performed by using individual (1 × 1) image data. The parameter P is 2 as shown in FIG. 8 (b).
The dither processing is performed by the image data of × 2.
This makes it possible to express many gradations. Parameter
As shown in FIG. 8C, the data Q is for performing dither processing with 1 × 2 image data, and is capable of expressing many gradations while improving the resolution. .

FIG. 9 shows the relationship between the density distribution of the original image and the threshold value at the time of image separation. A general second-generation copy is an edge-emphasized copy of the edge-emphasized first-generation copy, so that the degree of edge emphasis is too large. In such a second-generation copy, a change point (edge) may also exist in the photographic image, so that the photographic image is separated as a character image or a halftone image. Therefore, during the generation copy, compared to the normal copy,
It is necessary to change the separation threshold so that the image is easily separated into a photographic image or a halftone image.

The parameters in the image separation unit 207 will be described. The parameter R is an edge detection unit 301.
A predetermined threshold value for detecting the continuity of the temporary character image in is set. The parameter S is for setting a predetermined threshold for detecting the continuity of the temporary halftone dot image in the halftone dot separating unit 302. Parameter T is
A predetermined threshold value for detecting the continuity of the temporary black image in the color separation unit 303 is set. Parameter U
Is for setting the threshold value in the edge detection unit 301 higher than that for the parameter R, and the provisional character image is a parameter.
The character image is not detected unless it is continuous for longer than R. Parameter V is parameter S
The threshold value in the halftone dot separating unit 302 is set higher than that in the halftone dot separating unit 302, and if the temporary halftone dot image is not continuous for a longer period than the parameter S, the halftone dot image is not detected. The parameter W has a color separation unit 30 more than the parameter T.
The threshold value in 3 is set to a high value so that the temporary black image is not detected as a black image unless it is continuous for a longer period than the parameter T.

The data in the memory 210 will be described with reference to FIG. The above-mentioned parameters A to W are all stored in the memory 210 as shown in FIG. 10A, and separately from this, as shown in FIG. And each item data of the table determined by the relationship between
It is stored as a table having data (01) to (26).

The operation unit 130 will be described with reference to FIG. The operation unit 130 includes a copy star key 1101,
Tenki 1102, Change Key 1103, Variable Key 110
4, +/- key -1105 and an operation display panel 1106 are provided. Copy Star Toki-1101 is a copy
Is a key for starting. Tenki 1102 is
This is a key for inputting numerical values such as specifying the number of copies. Change key 1103 is a generation copy mode.
It is a key to change the parameter when reading. A scaling key-1104 is a key for changing the copy magnification from 100%. +/- key -1205 is used to change +/- when changing the set numerical value. The operation display panel 1106 displays the set numerical value, mode and mode.
The key associated with the displayed key can be displayed and the displayed key can be selected.

The display and selection control of the operation display panel 1106 in the change mode will be described with reference to FIGS.
Check whether the change key 1103 is turned on (120
1). When turned on, the change flag is set to 1 (1
202). As shown in FIG. 13, each parameter is assigned to the item data (13) to (24) of the table (1203).
Item data (13) to (2) in which each parameter is assigned
4) and "OK" key are displayed on the operation display panel 1106, and each parameter can be changed by the numeric keypad-1102 or +/- key-1105 (1204). "OK"
It is confirmed whether the key is turned on (1205). When the "OK" key is turned on, each changed parameter is changed in each item data and stored (1206).

The control unit 209 will be described with reference to FIGS. 13 to 16.
The control performed by will be described. Copy on the operation unit 130
Check if the Startkey-1101 is turned on (14
01). When the copy star key 1101 is turned on, the setting of the number of copies and the magnification ratio designated by the operation unit 130 is read (1402). It is confirmed whether the change flag is 1 (1403). When the change flag is not 1, each parameter is assigned to the item data (13) to (24) of the table as shown in FIG. 13 (1404). When the change flag is 1, each parameter is assigned to the item data (01) to (12) of the table as shown in FIG. 13 (1405). Scan the original (140
6). The recognition result of the pattern recognition unit 208 confirms whether or not there is a pattern (1407). When the pattern is not present, the normal copy mode is proceeded to, and when the pattern is present, the generation copy mode is proceeded (140).
8). In the normal copy mode, the image separation unit 207
Set parameters R to T for each block (15)
01). The result of separation by the image separation unit 207 is "character image".
It is confirmed (1502). In the case of "character image", each parameter stored in the item data (01) to (04) of the table is set in each block of the corresponding image processing unit 110 (1503). ). It is confirmed whether the separation result of the image separation unit 207 is a "photographic image" (1504). In the case of "photographic image", each parameter stored in the item data (05) to (08) of the table is set in each block of the corresponding image processing unit 110 (1505). ). If it is not a "photographic image", the image processing unit 110 corresponding to each of the parameters stored in the item data (09) to (12) of the table.
Is set in each block (1506). It is confirmed whether or not all the originals have been read (1507). In case of end, go to end. If not, the original is read again (1508). In the case of the generation copy mode, the parameters U to W are set in each block of the image separation unit 207 (1601). It is confirmed whether the separation result of the image separation unit 207 is a "character image" (1602). If it is a "character image",
Each parameter stored in the item data (13) to (16) of the bull is set in each block of the corresponding image processing unit 110 (1603). It is confirmed whether the separation result of the image separation unit 207 is a "photo image" (160).
4). In the case of "photo image", each parameter stored in the item data (17) to (20) of the table is set in each block of the corresponding image processing unit 110 (1605). ). If it is not a "photograph image", each parameter stored in the item data (21) to (24) of the table is set in each block of the corresponding image processing unit 110 (1606). . It is confirmed whether or not all the originals have been read (1607). In case of end, go to end. If it is not the end, the document is read again (1608).

The relationship between the document reflectance and the scanner output will be described with reference to FIG. At the time of generation copy, the original image has background stains and the like, and the scanner read output of the white image part is reduced.
By lowering the reference voltage (REF voltage) of the converter, the voltage level of white is lowered and the quantization is relatively fined to prevent background deterioration and gradation deterioration.

[0029]

According to the first and second aspects of the present invention, the reproducibility of the original image can be improved by automatically changing the image processing parameters between the normal copy and the generation copy. it can.

According to the third aspect of the present invention, the reproducibility of the original image can be improved by automatically changing the parameters of the image processing depending on the image type, the normal copy and the generation copy. it can.

[0031]

[Brief description of drawings]

[Figure 1] Overall configuration of digital copier

FIG. 2 is a block diagram of control of a digital copying machine.

FIG. 3 is a detailed block diagram of an image separation unit.

FIG. 4 is a detailed block diagram of a pattern recognition unit.

FIG. 5 is a diagram showing characteristics of a color correction / UCR unit.

FIG. 6 is a diagram showing characteristics of a filter unit.

FIG. 7 is a diagram showing characteristics of a gamma correction unit.

FIG. 8 is a diagram showing characteristics of a dither processing unit.

FIG. 9 is a diagram showing a relationship between a density distribution of a document image and a threshold value for image separation.

FIG. 10 is a diagram showing a storage state of a memory

FIG. 11 is a diagram showing a configuration of an operation unit.

[Fig. 12] Operation flow chart in change mode

FIG. 13 is a diagram showing a state in which parameters are assigned to a memory table.

FIG. 14 is a main operation flow chart of the control unit.

FIG. 15 is an operation flow chart of a normal copy mode.

FIG. 16 is an operation flow chart of the generation copy mode.

FIG. 17 is a diagram showing a relationship between document reflectance and scanner output.

[Explanation of symbols]

 101 CCD unit 104 A / D converter 111 Image processing unit 201 Color correction / UCR unit 202 Filter unit 203 Gamma correction unit 204 Dither correction unit 205 Pattern addition unit 206 Video control unit 207 Image separation unit 208 Pattern Recognition unit 209 Control unit 210 Memory 122 Recording unit

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Claims (3)

[Claims] 1. An image processing means for performing image processing on input image data with characteristics according to set parameters, and a predetermined pattern synthesized on the input image data.
Pattern recognition means for recognizing a pattern, storage means for storing normal copy parameters and generation copy parameters, and the pattern recognition means does not recognize the pattern. For normal image data, copy
Parameter for use is read from the storage means and set in the image processing means to perform image processing,
For the image data whose pattern is recognized by the pattern recognition means, the image processing parameters are read out from the storage means and set in the image processing means. An image forming apparatus, comprising: a control unit that controls to perform. 2. The image forming apparatus according to claim 1, further comprising a pattern adding means for adding the predetermined pattern to the image data subjected to the image processing. 3. An image processing means for performing image processing for input image data with characteristics according to set parameters, and an image type by inputting image type of the input image data. Image separating means for separating, pattern recognizing means for recognizing a predetermined pattern combined with input image data, separation result by the image separating means and recognition result by the pattern recognizing means And a control unit that controls the image processing unit by setting parameters according to the above in the image processing unit. [0001]