JP2003101770A - Image processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing apparatus which can absorb the difference in characteristics of inputted images between reading with an SDF mode and reading with a fixed document mode and output high quality images in both the modes without difference in picture quality. SOLUTION: A CPU 21 transmits an instruction via a bus 24 according to a reading mode, i.e., a fixed document mode or an SDF mode. An instruction decoder 34 generates a selection signal for a selector 33 according to the instruction signal. The selector 33 selects an output signal of a γ-correction table 31 in the fixed document mode and selects an output signal of a γ-correction table 32 in the SDF mode according to the selection signal generated by the instruction decoder 34. As the image processes such as the γ-correction processes, filtering processes, image region separating processes, color correction processes, etc., are switched according to the image reading modes, i.e., the SDF is used or the pressed is used, the high quality image can be reproduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a document feeding function such as a sheet-through document feeder (hereinafter referred to as SDF), image reading means for sub-scanning by feeding a document, and pressing the document by a pressure plate. A copier, a scanner, which has an image reading unit for performing sub-scanning by moving the scanner carriage, and which performs image processing on an input image input by the image reading apparatus,
The present invention relates to an image processing device such as a facsimile.

[0002]

2. Description of the Related Art Generally, an image reading apparatus (scanner) used for inputting an image in a copying machine or a fax is of a fixed document type in which an original is fixed and a scanner carriage is moved to sub-scan to input an image. , A sheet-through type in which an image is input by sub-scanning by moving a document. Previously, the fixed document type was compatible with book manuscripts, so it was often installed in copiers.
The sheet-through type was often used for fax applications. On the other hand, a document feeder (hereinafter referred to as DF) may also be used to copy a sheet document with a copier, but conventionally, generally, after moving the document from the document tray to the contact glass, A type of DF is used in which conveyance of an original is once stopped and subscanning is performed by the scanner carriage. In this case, the operation of reading the document was constant regardless of whether the DF was used or not. In recent years, there has been an increasing demand for high speed copying machines, and the number of models using a DF sheet-through type, that is, a so-called sheet-through document feeder is increasing. By using SDF, it is possible to scan while manuscripts are being conveyed. Therefore, compared to conventional DF, it takes a very short time to read not only one manuscript, but especially multiple manuscripts. It is getting worse.

FIG. 14 is a diagram showing the structure of a scanner having an SDF. As shown in FIG. 14, the scanner is
Standard white plate 1, contact glass 2, slit glass 3,
The document tray 4, the transport roller group 5, the paper discharge roller 6, the reflection guide plate 7, the light source 8, the mirror group 9, the carriage 10, the imaging optical system 11, and the CCD (photoelectric conversion element) 12 are provided. The carriage 10 and the CCD 12 are provided on the main body side, and the document tray and the document conveying path are SD.
It is F. The SDF is separated from the main body side and can be opened and closed. The operation of the SDF will be described below. The document placed on the document tray 4 is fed by the paper discharge roller 6, and the reading optical system is made to act through the slit glass 3 on the document surface guided in contact with the reflection guide plate 7 in the middle of the conveyance path. It is a thing. Therefore, when a document is read using the SDF, the carriage 10 on which the reading unit is placed is fixed under the slit glass 3 so that the reading position is fixed, and the document is moved on the carriage 10 so that the sub-scanning is performed. The original is read. Such a reading operation is called SDF mode.

On the other hand, in the case of a book original or a thick original, the original placed on the contact glass 2 is sub-scanned by moving the original, and the original is read, as in the conventional case. Such a reading operation is referred to as a document fixed mode. In this case, a pressure plate for pressing the document is generally provided on the SDF contact glass 2 to prevent the document from floating. The optical and electrical reading of the original is common to both cases, and the light diffused and reflected by irradiating the original with light from the light source 8 is photoelectrically converted by the CCD 12 via the mirror group 9 and the imaging optical system 11. It becomes an electric signal. The CCD 12 is a line-type CCD and apparently reads one main scanning line at the same time. SD
There is a difference in the mechanical operation as described above between the F mode and the document fixed mode. By the way, JP-A-2000-19
In Japanese Patent No. 6881, the shading correction process and the black streak correction process are switched between the SDF mode and the document fixed mode, and the SDF reading correction optimization and the platen reading correction optimization are independently performed. An image processing apparatus capable of optimally reproducing a copy output image and a FAX binary image is described.

[0005]

However, in the image processing apparatus described in Japanese Unexamined Patent Application Publication No. 2000-196881, the difference in mechanical operation and mechanism between the SDF mode and the fixed document mode is corrected, and the reading is performed. The characteristics themselves, so-called read image quality problems, are not mentioned. The difference in image quality between the SDF mode and the fixed document mode does not appear as a significant problem when only characters and line drawings in monochrome reading are targeted, but when reading a photographic image in monochrome or C for color
Differences in image quality may become a problem when reading in color using a CD. The differences include (1) reading γ characteristic, (2) MTF, (3) tint, and (4) reading position shift when SDF is used. The cause of the difference in image quality can be inferred as the following. First, in the document stationary mode, the entire document surface is at a right angle to the reading direction, whereas in the SDF mode, only the document reading portion is at a right angle and the periphery thereof is a curved surface as shown in FIG. . Therefore, there is a difference in the wraparound (flare) of light from around the reading unit. Also, SD
In the F mode, compared to the document stationary mode, the document is likely to be slightly lifted for the above reason. They are (1)
It is thought that this causes a difference in the read γ characteristic, (2) MTF, and (3) tint.

Next, in the document original setting mode of the normal copying machine,
The color of the back side (pressure plate) of the original is often white. This is because the present copying machine has a function of detecting the size of the original document, and executes it based on the color difference between the original document and the pressure plate. In the past, there were models that used mirror surfaces to suppress show-through. SD
The color of the back surface in the F mode is described in JP-A-2000-196881.
In the image processing device described in Japanese Patent Publication No.
When the reflection guide plate 7 of 4 is a roller in terms of the structure of the machine, or when it is black for the purpose of preventing show-through, (1) reading γ characteristics and (3) influence of tint occur. Will end up. Further, FIG. 15 shows the outer shape of a color CCD sensor for a reduction optical system which is commonly used. Figure 15
As for the color CCD, Red (red), Gr
CCD sensors of een (green) and Blue (blue) are arranged at equal intervals in the sub-scanning direction. For convenience, here, the interval is 600 dpi and 8 lines. In the RGB output signal of the CCD having such a form, the R signal reads the position 8 lines before when the G signal is used as a reference, and the B signal reads B.
The signal reads the position 8 lines ahead. That is, the positions read at the same time are different in RGB.

In the document original setting mode, periodical positional deviation occurs due to vibration of the carriage or the like. Figure 16 (a)
Represents the amount of positional deviation in each pixel of the G signal in the sub-scanning direction in a given scanner. For the sake of convenience, the horizontal axis is a pixel number in the sub-scanning direction, and the direction of the arrow indicates the sub-scanning advancing direction. The vertical axis represents the amount of positional deviation (%) when the distance for one line is 100%. FIG. 16B shows this with pixels of RGB. The positional deviation amount in the G signal appears in the pixel eight lines before in the R signal, and appears in the pixel eight lines ahead in the B signal. Due to the difference in the amount of positional deviation due to RGB,
Conventionally, there has been a problem such as a phenomenon in which an edge portion of a black character is colored. However, the amount of positional deviation due to this phenomenon is relatively small, and the amount of positional deviation between RGB is usually about several percent, and is about 20% at maximum, so the effect on the image is relatively small.

On the other hand, in the SDF mode, since the carriage is fixed, it is basically not affected by the vibration of the carriage. However, the same problem occurs due to the influence of uneven feeding of the original document and the influence of jitter, and the problem that is especially caused is the influence of the jitter that occurs suddenly due to the slip of the conveying system. In such a case,
In many cases, the positional deviation amount becomes 0%, and coloring on the output image becomes a big problem. FIG. 17 shows the relationship between the RGB output image signal (vertical axis) and the sub-scanning pixel position (horizontal axis) when a black thin line (horizontal line) in the main scanning direction is read in the SDF mode. In FIG. 17A, it can be seen that in a normal state where there is no positional deviation, RGB is reduced from the rising portion of the density (falling portion of the data) to become a gray color. In FIG. 17B, it can be seen that RGB is shifted, and coloring is generated at the rising and falling portions of the density, in the state where a sudden positional deviation occurs due to the above influence. From this data, it can be seen that the R and B data have a deviation amount of nearly 2 lines (200%). For this reason, the above-described (4) reading position shift when using the SDF occurs.

Therefore, a first object of the present invention is different between reading in the SDF mode and reading in the document fixed mode due to differences in flare, floating of the document surface, color of the back surface, misalignment amount, and the like. Absorbs the characteristics of the input image,
It is an object of the present invention to provide an image processing apparatus capable of outputting a high-quality image having no difference in image quality between the read images in the SDF mode and the document fixed mode, which are different in reading method. A second object of the present invention is to provide an image processing apparatus capable of absorbing different reading γ characteristics between reading in the SDF mode and reading in the document fixed mode. A third object of the present invention is to provide an image processing apparatus capable of absorbing different MTF characteristics between reading in the SDF mode and reading in the document fixed mode.

A fourth object of the present invention is to provide an image processing apparatus capable of absorbing different image area separation processing performances during reading in the SDF mode and reading in the document fixed mode. A fifth object of the present invention is S
An object of the present invention is to provide an image processing apparatus capable of absorbing different tint characteristics between reading in the DF mode and reading in the document fixed mode. According to a sixth aspect of the present invention, there is provided an image processing device capable of absorbing a different positional deviation between reading in the SDF mode and reading in the document fixed mode, and further capable of outputting a high quality gray edge portion regardless of the reading method. It is to be.

[0011]

According to a first aspect of the present invention, there is provided a first image reading means for reading an original image by moving a light source, and the original is moved on a light source arranged at a fixed position. Second image reading means for reading a manuscript image, reading judgment means for judging whether the manuscript image is read by the first image reading means or the second image reading means, and judgment by the reading judgment means Image processing means for performing image processing on the original image read by the first image reading means or the second image reading means by changing a predetermined image processing parameter based on the result; The first object is achieved by including an image output unit that forms an image of a document image that has been subjected to image processing by the processing unit on a sheet and outputs the image. It is formed.

According to a second aspect of the invention, in the invention of the first aspect, the image processing parameter changed by the image processing means is a γ correction process, thereby achieving the second object. According to the invention of claim 3, in the invention of claim 1, the image processing parameter changed by the image processing means is a spatial filter process, thereby achieving the third object.

According to a fourth aspect of the invention, in the first aspect of the invention, the image processing parameter changed by the image processing means is image area separation processing.
The fourth objective is achieved. According to the invention of claim 5,
In the invention according to claim 1, the image processing parameter changed by the image processing means is the color correction process, and thus the fifth object is achieved. According to a sixth aspect of the invention, in the first aspect of the invention, the image processing parameter changed by the image processing means is the positional deviation correction process, thereby achieving the sixth object.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS.
First, the first embodiment will be described. Figure 1
FIG. 3 is a block diagram showing a schematic configuration of an image processing apparatus according to the exemplary embodiment. In this embodiment, a color copying machine will be described as an example of the image processing apparatus. The operation of the image processing apparatus according to this embodiment will be described below with reference to FIG. When a start button (not shown) of the operation unit 22 is pressed, the SDF control unit 20 detects the presence / absence of a document on the document tray by the document detection sensor 23 before the copying operation. If the document is set on the document tray based on the detection result, the SDF control unit 20 performs S
When the DF mode is set and the document is not set, the document stationary mode is set and the CPU 21 that controls the drive of the image processing apparatus is notified. The CPU 21 sets parameters of each image processing in each processing unit via the data bus 24 according to the reading mode. The details of this setting will be described later. After this setting, the scanner 110 (S
(Including DF) starts reading according to the setting of the reading operation. The read image data is output to the printer unit 19 through each image processing shown in FIG. 1 and printed on a recording paper (not shown). Printer unit 19
The recording operation of is a part that is not directly related to the present embodiment, and therefore its explanation is omitted. The flow of image data will be described below.

The original is optically read by the scanner 110, photoelectrically converted into a digital image signal of 8 bits (0 to 255), and then shading correction and RGB 3 line C are performed.
The CD data delay (processing for correcting the CCD 8-line interval) is executed and output. The image signal output from the scanner 110 is input to the scanner γ correction processing unit 13 and read by the scanner rgb (red, gree).
n, blue) signal to RGB signal of density signal LUT
(Look Up Table) or the like. At the same time, they are respectively input to the image area separation processing section. The image area separation processing unit identifies the input image as a black character image and other than that. On the other hand, the RGB signal converted into the density signal is input to the filter processing unit 14 and subjected to spatial filter processing. The RGB signal after the filter processing is processed by the color correction processing unit 15 into CMY (Cyan, Magenta, Ye).
low) signal. Although various methods can be used for the color correction processing, the following calculation is performed here. C = α11 × R + α12 × G + α13 × B + β1 M = α21 × R + α22 × G + α23 × B + β2 Y = α31 × R + α32 × G + α33 × B + β3 where α11 to α33 and β1 to β3 are predetermined color correction factors, and the output It is also assumed that the CMYK to be processed is also an 8-bit (0 to 255) signal.

Next, the BG / UCR processing unit 16 generates (BG) a K signal, which is a black component, and also CMY.
Undercolor removal (UCR) is performed on the signal. Generation of the K signal and removal of the undercolor from the CMY signal are performed by the following equation. K = Min (C, M, Y) × β4 C ′ = C−K × β5 M ′ = M−K × β5 Y ′ = Y−K × β5 Here, Min (C, M, Y) is CMY. It shall represent the smallest of the signals. Further, β4 and β5 are signals of 8 bits with predetermined coefficients.
Next, the printer γ correction processing unit 17 performs γ correction processing on each of the input CMYK density signals so as to correspond to the γ characteristics of the printer. γ correction is LUT
(Look-up table). Printer γ
The CMYK data after the correct correction processing is subjected to pseudo halftone processing such as dither processing and error diffusion processing in the halftone processing unit 18 and output to the printer unit 19 where a series of image forming processes are performed to print on paper or the like. To be copied.

Here, the operation of each processing in the document stationary mode and the SDF mode will be described in detail. First, the case of scanner γ correction processing will be described. FIG. 2 is a block diagram showing the configuration of the scanner γ correction processing unit 13. The CPU 21 issues a command via the bus 24 in accordance with the document stationary mode and the reading mode of the SDF mode. The instruction decoder 34 generates a select signal for the selector 33 according to the instruction signal. γ correction table 3
Reference numeral 1 denotes a scanner γ correction table for the fixed document mode, and γ correction table 32 is an LUT for storing the scanner γ correction table for the SDF mode, which is a ROM (read only memory). It is configured. The selector 33 outputs the output signal of the γ correction table 31 in the document stationary mode and the γ correction table 3 in the SDF mode according to the select signal output from the instruction decoder 34.
The two output signals are respectively selected.

FIG. 3 is a diagram showing RAWγ characteristics when a G signal for a black dot document is read in the document stationary mode and when it is read in the SDF mode. In the figure, the horizontal axis represents the dot rate (%), where 0 is white and 100 is black. The halftone dot ratio can be treated as a synonym for the density and the brightness. The vertical axis is the average value of the constant area of the image data obtained by reading the halftone dots. It can be seen that there is a nonlinear difference in γ characteristics depending on the reading method. This is corrected by the above-mentioned γ correction table according to each γ characteristic. The setting method of each γ correction table is required for each system because density data (there may be brightness or reflectance, and END guarantee by scanner γ correction also requires tint data). It is sufficient to read an original document whose data is selected) by each reading method and create a γ correction table by a known method. In the present embodiment, the γ correction table is composed of two ROMs, but one RAM
(Random access memory), and the γ correction table is directly RA from the CPU 21 when the reading mode is set.
You may make it write in M.

Next, the filtering process will be described. FIG. 4 is a block diagram showing the configuration of the filter processing unit 14. The CPU 21 generates a command via the bus 24 in accordance with the document stationary mode and the SDF mode, and the command decoder 47 generates a select signal for the selector 43 and the selector 46 according to the command signal. The RGB signals output from the scanner γ correction processing unit 13 are input to the smoothing processing unit 41 and the smoothing processing unit 42, respectively, and the R, G, and B signals are smoothed. The selector 43 selects the output signal of the smoothing processing unit 41 in the document stationary mode and the output signal of the smoothing processing unit 42 in the SDF mode according to the select signal output from the instruction decoder 47. R2, G2, B
It is output as two signals.

The R2, G2, and B2 are input to the edge enhancement processing unit 44 and the edge enhancement processing unit 45, respectively, and R
Edge enhancement processing is performed on the signals of 2, G2, and B2. The selector 46 selects the output signal of the edge emphasizing processor 44 in the document stationary mode and the output signal of the edge emphasizing processor 45 in the SDF mode by the select signal output from the instruction decoder 47.
3 and B3 signals are output. These smoothing and edge enhancement processes are generally performed by a spatial filter process, and can be easily realized by a convolution operation or the like. Further, even when the feature amount such as the edge amount is calculated and the filter processing is adaptively performed, the correction amount such as the edge amount may be changed. The characteristics of these spatial filters may be the characteristics having the optimum attenuation and gain amount for each reading method. Also, if you do not need
For example, it is possible to adopt a configuration in which smoothing or edge enhancement is not performed in the document fixed mode. These filter characteristics are the mechanical characteristics and M for each reading method.
It is desirable to be determined experimentally in consideration of the TF characteristics.

Next, the color correction process will be described. Figure 5
FIG. 3 is a block diagram showing the configuration of the color correction processing unit 15. Although only the calculation unit for C (cyan) is shown for simplification of description, there are actually M (magenta) and Y (yellow) components having the same configuration as that of C shown in FIG. I shall. According to the document stationary mode and the reading mode of the SDF mode, the CPU 21 generates an instruction via the bus 24 as in the other processes, and the instruction decoder 60 generates the select signals of the selectors 56 to 59 according to the instruction signal. . The selectors 56 to 59 select the coefficients (α11 to α13 and β1 in Expression 1) by which the RGB signals are multiplied by the multipliers 51 to 53, according to the respective select signals. Further, in the document original setting mode, A11 to A14 change to S
In the DF mode, B11 to B14 are selected and output. The R, G, and B signals are respectively multiplied by α11 to α13, and then input to the adder 54 together with the coefficient β1 to be added and output as a C signal.

The color correction processing of the color image processing apparatus corrects the difference in color space (gamut) between the image input device (scanner) and the image output device (printer), but the same image as in the present embodiment is used. The correction may be performed by configuring the image processing unit so that the original stationary mode and the SDF mode have different color spaces even if the signal is an input signal from the input device. In addition to this embodiment, various methods can be used for the color correction processing. For example, a three-dimensional L with a bit number smaller than the bit number of the RGB input signal.
In the case of data that constitutes the UT and does not exist on the LUT,
A method of performing interpolation calculation from data existing in the LUT is known. In such a case, a plurality of LUTs should be provided or selection should be made according to the reading mode, or the LUT should be RA
The content of the RAM may be rewritten in accordance with the reading mode by configuring M.

As described above, according to the present embodiment, the difference in the characteristics of the image data read γ, MTF, and the tint of the image data read by the different reading methods of the original fixed mode and the SDF mode is absorbed, and which one is read. Data read in the mode can also be reproduced as a high quality image. In the present embodiment, the description has been made assuming a color copying machine, but the image processing unit is realized by software using a personal computer or the like in both monochrome and an image processing apparatus having only a scanner. It can be easily applied to things. In addition, in the present embodiment, the document detection sensor 23 for detecting the document setting on the SDF is provided, and
Although the presence / absence of the DF document is automatically detected, it may be manually set by, for example, pressing a button or a key of the operation unit 22. In this case, the document stationary mode / SDF of the operation unit 22
The CPU 21 may detect that the mode determination button has been pressed and set according to the selected reading mode.

Next, a second embodiment will be described.
FIG. 6 is a block diagram showing a schematic configuration of the image processing apparatus according to the second embodiment. In the second embodiment, as in the first embodiment, a color copying machine will be described as an example of the image processing apparatus. The description of the same components as those of the image processing apparatus according to the first embodiment will be omitted. The image processing apparatus according to the present embodiment has a configuration in which the image area separation processing unit 120 is further provided in the image processing apparatus according to the first embodiment. The image area separation processing unit 120 uses the scanner γ
The rgb signal before the γ correction processing by the correction processing 13 is input, and character / non-character, achromatic / chromatic color is determined on a pixel-by-pixel basis, and the target pixel is any one of a black character area, a color character area, and a picture area. Determine whether it belongs to crab. Filter processing unit 1
4, each of the image processing units of the color correction processing unit 15, the BG / UCR processing unit 16, the printer γ correction processing unit 17, and the halftone processing unit 18 is for black characters according to the determination result of the image area separation processing unit 120. The input image data is processed and output by switching between the process (1), the process for color characters, and the process for patterns. Since it is a known technique to switch the processing depending on the determination result of the image area separation, the description thereof will be omitted.

FIG. 7 is a block diagram showing the configuration of the image area separation processing unit 120. The CPU 21 generates a command via the bus 24 in accordance with the document stationary mode and the SDF mode, and the command decoder 65 generates a select signal sel in response to the command signal, and the edge determination processing unit 61, Inputs are made to the halftone dot determination processing unit 62 and the color determination processing unit 63, respectively. The edge determination processing unit 61 inputs the g signal,
An edge signal is generated by determining whether the pixel of interest is an edge. The halftone dot decision processing unit 62 inputs the g signal, decides whether or not it is a halftone dot region, and generates an AMI signal. The color determination processing unit 63 inputs the r, g, and b signals, determines whether the pixel of interest is chromatic or achromatic, and generates an iro signal. Comprehensive determination processing unit 6
4 inputs the Edge signal, the AMI signal, and the iro signal, determines the pixel of interest as the character region when the edge region and the non-halftone dot region, and color characters when the iro signal is chromatic, and black characters when the achromatic signal is achromatic. To generate an image area separation signal. In the case of a non-edge area or a halftone area, an image area separation signal is output as a picture area regardless of whether it is chromatic or achromatic.

FIG. 8 is a block diagram showing the configuration of the edge determination processing section 61. The g signal output from the scanner is input, and is discriminated by the ternarization processing unit 71 into three types: black pixels, white pixels, and other types. Ternary processing unit 71
Is ternarized by two types of threshold values. For example, when the input image data is 8 bits (takes a value of 0 to 255), when it is 0, it is black, when it is 255, it is white, the input image data of the pixel of interest is X, and the threshold values W, K (W>W>
K) is set, if X is less than or equal to K,
X is a black pixel, and when X is smaller than W, it is a white pixel. The ternarization process as described above is expressed as follows. IF X <= K THEN X = black pixel ELSE IF X> W THEN X = white pixel

In the case of this embodiment, the selector 7 switches the threshold values of W and K by the sel signal.
5, 76 are configured. W in the document original mode
a and Ka are selected, and in SDF mode, Wb and Kb
By selecting, it becomes possible to set the optimum threshold value according to the reading mode. This ternarization processing unit 71
Black pixel by pattern matching,
The continuity of white pixels is detected. FIG. 9 is a diagram showing an example of a pattern in the present embodiment. 9 (a)-
FIG. 9D shows a pattern for detecting black pixel continuity, and FIG.
(E) to (h) show patterns for white pixel continuity detection. The black pixel determination unit 72 uses the black pixel continuity detection pattern to determine whether the ternary data matches these patterns. In parallel, the white pixel determination unit 73
Uses white pixel continuity detection patterns to determine if the ternary data matches these patterns. In the case of the present embodiment, it is assumed that these determination results are binary values indicating whether or not there is a match. The determination unit 74 determines the result of the black pixel determination unit 72 and the white pixel determination unit 73 in the block of 5 × 5 pixels as the target block when there is one or more matches with the pattern. Edge regions are defined as non-edge regions.

FIG. 10 is a block diagram showing the configuration of the halftone dot decision processing unit 62. The halftone dot area detection unit 84 detects a halftone dot area. As a method for detecting a halftone dot area, "Journal of the Institute of Electronics, Information and Communication Engineers '92 / 1 Vol 75-D-II N
o. 1 pp. 39-47 characters / design (dots, photographs)
The halftone dot area detection method of "image area separation method of mixed image" (hereinafter referred to as a publicly known paper) shall be used.
Pixels (peak pixels) representing peaks and valleys of pixels in an image are detected, and then a block area having a high density of peak pixels is detected, and the detection result of the block area is corrected based on the surrounding block information. . In this embodiment,
MTF correction is performed prior to detection of a halftone dot area. MTF
As for the correction, the MTF is corrected by the well-known spatial filter processing like the edge enhancement filter. In the case of the present embodiment, the selector 83 performs this MTF correction by the sel signal.
It is designed to be selected in. As a result, the output signal of the MTF correction 81 is selected in the document original setting mode, and the output signal of the MTF correction 82 is selected in the SDF mode, and the optimum MTF correction according to the reading mode is performed as the preprocessing of the halftone dot area detection processing. It becomes possible.

FIG. 11 is a block diagram showing the configuration of the color determination processing section 63. With respect to the input r, g, and b signals, the calculator 91 calculates the maximum difference value max (| r
-G |, | g-b |, | b-r |) is calculated. The chromatic / achromatic determination processing unit 92 compares this with a predetermined threshold value to determine chromatic / achromatic for each pixel. Maximum difference value max (| RG |, | GB |, | BR
The larger the value of | is, the higher the saturation is, and the lower the value is, the lower the saturation is. Therefore, when it is equal to or more than a predetermined threshold value, it is determined to be a chromatic color pixel. Next, the chromatic pixel counting processing unit A
The number of chromatic pixels of the 5 × 5 pixel block centered on the target pixel is counted by 93, and the number of chromatic pixels of the 5 (main scanning) × 9 (sub scanning) pixel block is counted by the chromatic pixel counting processing unit B (94). . In the document original mode, the chromatic pixel counting processing unit A9
The output of 3 is the chromatic pixel counting processing unit B in the SDF mode.
The output of 94 is a selector 95 using the sel signal as a selection signal.
Selected by. The selected signal is compared with the threshold value signal output from the selector 97 by the chromatic color determination processing unit 96. If it is equal to or more than the threshold value, it is determined to be chromatic color, and if it is less than the threshold value, it is achromatic color. Is determined as.
This threshold is also a selector 9 using the sel signal as a selection signal.
Selected by 7. In this way, by changing the effective area of the chromatic / achromatic judgment block according to the reading mode, the influence of color bleeding around black characters, etc. is minimized even when there is a sudden large positional deviation in SDF mode. Without it, chromatic / achromatic can be determined.

Hereinafter, changing the effective area of the chromatic / achromatic judgment block according to the reading method will be described. If there is no positional deviation of the scanner, chromatic / achromatic determination can be made only for a single pixel, and there is no need to add processing to correct the determination in the block, but the positional deviation of the scanner can be zero.
Is extremely difficult to do. Therefore, for the purpose of improving the determination accuracy, it is necessary to make the determination in blocks as described above and improve the determination accuracy. However, determining chromaticity / achromaticity with an area larger than necessary tends to tend to take a value in the achromatic direction, which also causes deterioration of determination accuracy. Further, if the judgment area is expanded more than necessary, the amount of hardware and the amount of calculation are increased, which leads to an increase in cost and an adverse effect on processing speed. Not limited to the case of the present embodiment, it is desirable that the effective area in the case of determining the chromatic / achromatic color due to the scanner position shift and the saturation is set to the minimum required by each system or configuration. In the present embodiment as well, description has been made assuming a color copying machine, but the present invention can be similarly applied to a monochrome image processing apparatus and a scanner-only image processing apparatus. It can be easily applied to realization by software.

Next, a third embodiment will be described.
FIG. 12 is a block diagram showing a schematic configuration of the image processing apparatus according to the third embodiment. In the third embodiment, a color copying machine will be described as an example of the image processing apparatus, as in the first and second embodiments. Further, in the image processing apparatus of FIG. 12, description of the same components as those of the image processing apparatuses of the first and second embodiments will be omitted. The image processing apparatus of the third embodiment has a configuration in which the image processing apparatus of the first embodiment is further provided with a positional deviation correction processing unit 25. Position deviation correction processing unit 25
Is a process of inputting the rgb signal before the γ correction process of the scanner γ correction process 13, detecting the positional deviation of rgb of the gray pixel portion, and performing the gray correction.

FIG. 13 is a block diagram showing the configuration of the positional deviation correction processing unit 25. According to the document stationary mode and the reading mode of the SDF mode, the CPU 21 uses the bus 24
The instruction decoder 103 generates a select signal for the selector 102 in response to the instruction signal. The selector 102 passes (does not process) the output signal of the scanner in the document stationary mode according to the select signal.
The output signal of the color misregistration correction processing unit 101 is output in the SDF mode. In this embodiment, the misalignment correction is not performed in the document stationary mode, but it may be performed if necessary. Further, as described with reference to FIG. 16, the amount of positional deviation in the document stationary mode is SD.
Compared with the abrupt position shift amount in the F mode, it is extremely small and often causes no problem. Therefore, similar to the purpose of changing the effective area of chromatic / achromatic determination in the second embodiment,
In the present embodiment, an example of through is shown in the document fixed mode. There are various processes for the misalignment correction process 101, but a suitable example is Japanese Patent Laid-Open No.
There is a positional deviation correction method as described in Japanese Patent Application Publication No. 00-341549. This misalignment correction method is
The presence or absence of an edge of each signal in the specific area is detected from the rgb signal, and when an edge is detected in all of r, g, and b, the area is determined to be an achromatic area, and the gray balance of r, g, and b is determined. Is to correct.

As described above, the image processing apparatus according to the present embodiment, depending on whether the image reading is using the SDF or the pressure plate, is a γ correction process, a filter process, an image area separation process, and a color separation process. Since image processing such as correction processing can be switched, high-quality image reproduction is possible. Further, in the image processing apparatus according to the present embodiment, in order to suppress the image quality deterioration due to the difference in the reading method, the characteristics of the input image which are different between the reading by the SDF and the reading by the pressure plate are absorbed, and the correction is performed according to each reading method. Therefore, high-quality image reproduction can be realized. Further, in the image processing apparatus according to the present embodiment, the γ correction table is switched between the reading by the SDF and the reading by the pressure plate, so that the difference in γ is absorbed and the correction is made according to each reading method. Image reproduction can be realized. Further, in the image processing apparatus according to the present embodiment, the spatial filter is switched between the reading by the SDF and the reading by the pressure plate to absorb the difference in MTF and correct according to each reading method. Playback can be realized.

Further, in the image processing apparatus of this embodiment,
By switching the parameters for image area separation between SDF scanning and pressure plate scanning, the differences in reading characteristics and problems in SDF are eliminated, and correction is made according to each reading method, so high-quality image reproduction is possible. Can be realized. Further, in the image processing apparatus of the present embodiment, the image area separation (edge separation, color determination) parameters are switched between the SDF reading and the pressure plate reading, so that high-quality image reproduction can be realized.
Further, in the image processing apparatus according to the present embodiment, the color correction parameter is switched between the SDF reading and the pressure plate reading, so that it is possible to eliminate the difference in the output color between the reading methods and realize high-quality image reproduction. can do. Further, in the image processing device of the present embodiment, S
Since RGB color shift correction processing is added when using DF, SD
Images can be reproduced with high image quality even when F is used.

[0035]

According to the first aspect of the invention, a predetermined image processing parameter is applied to the original image read by the first image reading means or the second image reading means based on the result of the judgment by the reading judgment means. Since the image processing means for performing the image processing by changing the image reading method is provided, the difference in the image quality characteristic caused by the difference in the reading method is absorbed, and there is no difference in the image quality when the image is read by either reading method. A high quality image can be output.

According to the second aspect of the invention, since the image processing parameter changed by the image processing means is γ correction processing, flare, floating of the document surface, and rear surface caused by the difference between the first and second reading methods. It is possible to absorb the difference in the read γ caused by the color and the like.

According to the third aspect of the invention, since the image processing parameter changed by the image processing means is the spatial filter processing, flare or floating of the document surface caused by the difference between the first and second reading methods is caused. It is possible to absorb the difference in MTF characteristics caused by the difference.

According to the fourth aspect of the invention, since the image processing parameter changed by the image processing means is the image area separation processing, flare and floating of the original surface caused by the difference between the first and second reading methods, It is possible to absorb the difference in the image area separation processing result due to the color of the back surface, the amount of positional deviation, and the like, and it is possible to perform the image area separation processing optimal for each reading method.

In the fifth aspect of the invention, since the image processing parameter changed by the image processing means is color correction processing, flare, floating of the document surface, and rear surface caused by the difference between the first and second reading methods. It is possible to absorb the difference in color tint due to the color and the like.

According to the sixth aspect of the invention, since the image processing parameter changed by the image processing means is the positional deviation correction processing, the difference in the positional deviation amount caused by the difference between the first and second reading methods is caused. It is possible to correct the coloring of the gray edge portion and the like and output the gray edge portion with high image quality regardless of the reading method, and it is possible to perform the positional deviation correction processing that is optimal for each reading method.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image processing apparatus according to a first embodiment.

FIG. 2 is a block diagram showing a configuration of a scanner γ correction processing unit.

FIG. 3 is a RAW at the time of reading the G signal for a black halftone dot document in the document stationary mode and in the SDF mode.
It is the figure which showed the γ characteristic

FIG. 4 is a block diagram showing a configuration of a filter processing unit.

FIG. 5 is a block diagram showing a configuration of a color correction processing unit.

FIG. 6 is a block diagram showing a schematic configuration of an image processing apparatus according to a second embodiment.

FIG. 7 is a block diagram showing a configuration of an image area separation processing unit.

FIG. 8 is a block diagram showing a configuration of an edge determination processing unit.

FIG. 9 is a diagram showing an example of a pattern according to the present embodiment.

FIG. 10 is a block diagram showing a configuration of a halftone dot determination processing unit.

FIG. 11 is a block diagram showing a configuration of a color determination processing unit.

FIG. 12 is a block diagram showing a schematic configuration of an image processing apparatus according to a third embodiment.

FIG. 13 is a block diagram showing a configuration of a positional deviation correction processing unit.

FIG. 14 is a diagram showing a configuration of a scanner including an SDF.

FIG. 15 is a diagram showing an outer shape of a color CCD sensor.

FIG. 16 is a diagram showing a positional deviation amount in a document stationary mode.

FIG. 17 is an RGB output image signal (vertical axis) when a black thin line (horizontal line) in the main scanning direction is read in the SDF mode.
FIG. 6 is a diagram showing the relationship between the pixel position of the sub-scan (horizontal axis).

[Explanation of symbols]

1 standard white board 2 contact glass 3 slit glass 4 Original tray 5 Transport roller group 6 Paper ejection rollers 7 Reflection guide plate 8 light sources 9 mirrors 10 carriage 11 Imaging optical system 12 CCD (photoelectric conversion element)

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/19 F term (reference) 5C072 AA01 BA15 CA04 DA02 DA04 EA05 LA18 QA16 UA03 UA17 UA18 UA20 XA01 5C077 LL02 LL19 MP01 MP08 PP01 PP15 PP27 PP32 PP33 PP37 PQ08 PQ12 PQ23 SS01 TT06

Claims (6)

[Claims] 1. A first image reading means for reading an original image by moving a light source, and a second image reading means for reading an original image by moving the original on a light source arranged at a fixed position. Based on a reading determination unit that determines whether the original image is read by the first image reading unit or the second image reading unit, and the determination result by the reading determination unit, the first image reading unit
Image processing means for performing image processing on a document image read by the image reading means or the second image reading means by changing a predetermined image processing parameter, and image processing by the image processing means. And an image output unit that forms an image of a document image on a sheet and outputs the image. 2. The image processing apparatus according to claim 1, wherein the image processing parameter changed by the image processing means is γ correction processing. 3. The image processing apparatus according to claim 1, wherein the image processing parameter changed by the image processing means is a spatial filter process. 4. The image processing apparatus according to claim 1, wherein the image processing parameter changed by the image processing means is image area separation processing. 5. The image processing apparatus according to claim 1, wherein the image processing parameter changed by the image processing unit is color correction processing. 6. The image processing apparatus according to claim 1, wherein the image processing parameter changed by the image processing means is a positional deviation correction process.