JPS59161970A - Picture processor - Google Patents

Abstract

PURPOSE:To reproduce at a high speed a color picture of high quality in a simple constitution by performing the multi-gradation processing in response to the digital picture signal obtained through a masking process. CONSTITUTION:Signals B, G and R underwent photoelectric conversion through CCDs 210, 220 and 230 are converted into digital signals of 8-bit by CCD drivers 240, 250 and 260 and then into signals Y, M and C which are complementary colors of B, G and R. These signals Y, M and C are sent to a masking processing circuit 150 after the shading correction (130) and gamma correction (140) to receive the proper correction of colors for printing. A UCR processing circuit 160 calculates the foundation color deletion quantity from the color corrected signals Y, M and C to obtain the black BK quantity. Then the dither processing of three different threshold values is applied to the new signals Y, M and C obtained by subtracting BK from each of colors Y, M and C through a dither processing circuit 170. Then a dinary signal underwent the modulation of pulse width is supplied to a laser modulating unit via a multi-value processing circuit 180.

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to an image processing device that performs image processing using digital processing. Conventional technology Conventionally, an original image is separated into three colors using a color separation filter.
The original image is scanned for each color separation, a latent image is formed on a photoreceptor by the color-separated light image, and the latent image is developed using a developer of a complementary color.
There are color copying machines that reproduce color images by overlapping multiple colors. This type of color copier uses the analog characteristics of electrophotography to achieve color balance, halftone expression, etc. necessary for color image reproduction, making adjustments to image exposure, photoreceptor charging conditions, etc. complicated. Not only that, but corona charging, the photoreceptor, etc. are directly affected by temperature and humidity, resulting in large fluctuations in image quality due to environmental changes. Furthermore, since everything from reading the original image to forming the latent image is performed by a two-dimensional optical system, it is not possible to process each point of one image. Purpose The present invention was made in view of the above points, and an object of the present invention is to provide an image processing device capable of reproducing high-quality color images. A further object of the present invention is to provide an image processing device capable of reproducing high-quality color images with a simple configuration. Another object of the present invention is to provide an image processing device that can reproduce high-quality color images at high speed. EXAMPLES Hereinafter, examples of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a copying apparatus to which the present invention is applied. The original 1 is placed on the transparent plate of the original table 2. The original is held down by the original cover 3 from above. The light focused by the document illumination halogen rung 5.6 and the reflector 7.8 is irradiated onto the document, and the reflected light is reflected by the movable reflective mirror 9.10, passes through the lens 11-1, and is reflected in the red light. After passing through the outer cut filter 11-2, the light enters the dichroic mirror 12, where it is separated into three wavelengths: blue (mountain), green (G), and red (2). Spectralized B%
Based on G1R, the intensity adjustment and spectral characteristic correction of the three color lights are performed using a blue filter 13, a green filter 15, and a red filter 17, respectively, and a solid-state image sensor (CC) is used.
D) Receive light at 210.220.230. The reflected image from the original 3 is a halogen lamp for illuminating the original 5.6
The movable reflective mirror 9 moves in unison with the movable reflective mirror 9, and the optical path length is kept constant by the movable reflective mirror 10 in the same direction at a moving speed of 1/2 of the movable reflective mirror 9. Outer cut filter 11-2
After passing through the dichroic mirror 12, the images are formed on solid-state image pickup devices (COD) 210, 220, and 230 for each color as described above. The output of each solid-state image sensor 210, 220, 230 is converted into a digital signal by each COD light receiving unit 200 (described later), the image processing unit 100 performs necessary image processing, and the image signal is modulated by the laser modulation unit 300 and the polygon mirror 22. emits a laser beam,
The photosensitive drum 24 is irradiated. The polygon mirror 22 is
The scanner motor 23 rotates at a constant speed.
The laser beam described above travels perpendicularly to the rotation direction of the photosensitive drum 24. Further, a photosensor 64 is installed in front of the scanning start position of the laser beam on the drum, and generates a laser horizontal synchronization signal BD as the laser beam passes. Photosensitive drum 2
After being uniformly neutralized by the neutralizing electrode 63 and the neutralizing lamp 71, the negative charger 25 connected to the high voltage generator 77 uniformly charges the negative charger 4 to a negative charge. When a laser beam modulated by an image signal is uniformly irradiated onto the negatively charged photosensitive drum 24, a photoconductive phenomenon occurs, and the charges on the photosensitive drum 24 flow to the main body ground and disappear. Here, the laser is not turned on in areas where the document density is low, and the laser is turned on in areas where the document density is high. In this way, the potential on the surface of the photosensitive drum 24 corresponding to the high-density portion of the original will range from -100V to -
50V, and the potential of the light density part of the original is -600V.
V, and an electrostatic latent image is formed corresponding to the density of the document. This electrostatic latent image is transferred to the selected yellow (2) developer 36, magenta developer 37, . Developed by a cyan (C) developer 38 and a black (Bk) developer 39, and then transferred to the photosensitive drum 2.
4. Form a toner image on the surface. At this time, a voltage is applied to the developing bias generator 84 in order to set the potentials of the developing sleeves 85, 86, 87, and 88 in the developing units of each color to -300 V to -400 V, respectively. The toner in the developing device is stirred and negatively charged, and the toner is transferred to the photosensitive drum 24.
The 0 surface type adheres to a location where the potential is higher than the development bias potential, and a toner image corresponding to the original is formed. Thereafter, unnecessary charges on the photosensitive drum 24 are removed by a negatively charged post electrode 41 using a lamp 40 and a high pressure generator 77 for eliminating the potential on the surface of the photosensitive drum 24. Make the potential uniform. On the other hand, the transfer paper stored in the cassette 43 or 44 selected by the operation board 72 is fed by the paper feeding operation of the paper feeding roller 46 or 47.
0 to correct the skew, the transport roller 51 and the second registration roller 52 transport the paper at a predetermined timing, the gripper 57 of the transfer drum 53 holds the leading edge of the transfer paper, and the transfer drum 53 electrostatically charges the transfer paper. Wrap it around the target. The toner image formed on the photosensitive drum 24 is transferred to the transfer drum 53.
The image is transferred onto the transfer paper 48 by the transfer electrode 54 at the position where it contacts the image. The toner image is transferred to the transfer paper a predetermined number of times depending on the selected copy color mode. After all the toner images are transferred, the transfer paper is Perform static electricity removal. After completing the transfer a predetermined number of times, the transfer paper is transferred to the transfer drum 5 by the separating claw 90.
3 and is sucked onto the conveyor belt 59 by the conveyor fan 58 and guided to the fixing section 60 . On the other hand, the residual charge remaining on the photosensitive drum 24 is further removed by a pre-cleaner static eliminator 61, and the residual toner on the photosensitive drum 24 is removed by a cleaning blade 89 in the cleaner unit 62. Further, the charge on the photosensitive drum 24 is removed by the ACC front charger 63 and the charge removal lamp, and the process proceeds to the next cycle. Incidentally, %19%20 is a fan for cooling the optical system and discharges the illumination system. Here, the main body operation sequence will be explained using a four-color (YlM, 01BK) full color mode as an example. Prior to scanning the original 1, the white calibration plate 4 is scanned each time. This is for reading the white calibration plate 4 into the one-scan line image processing unit 100 for shedding correction, which will be described later. Next, the document is scanned and three colors (B
,G. R) CCD210, CCD220, CCD230 at the same time
reads the image, and in the image processing unit 100,
Y%M%C, which is the complementary color of B, G, H, and B of the sumi version
The amount of K is calculated and processing such as color correction is performed. The document is scanned four times, and in the first scan, the yellow (g) component signal calculated by the image processing unit 100 is laser-modulated to form a latent image on the photosensitive drum 24. This latent image is developed by a yellow developing device 36 and transferred onto a transfer paper wound around a transfer drum 53. Similarly, in the second scan, an image corresponding to magenta (B) and in the third scan, cyan (Q). In the fourth scan, an image corresponding to plaque (BK) is transferred to the transfer paper, and then fixed by the fixing device 60. Image recording in pull color mode is completed.The spectral energy distribution of the halogen lamp for exposing the original is as shown in Figure 2-1. The light output is low near the dorsal region.Also, the spectral sensitivity characteristics of COD are 500 ~ 500 as shown in the figure.
It has high sensitivity in the edge region of 600 nm. Ru. Therefore, after the light reflected from the original is output from the dichroic mirror, it becomes as shown in FIG. 2-2 according to the spectral characteristics of the halogen lamp. In addition, the spectral characteristics of the dichroic mirror are as follows:
As shown in Figure 3, the spectral characteristics are not good, so this is
By passing the light through a multilayer interference filter having a spectral transmittance as shown in FIG. 4, a color separated image without unnecessary wavelength components as shown by the broken line in FIG. 2-2 can be obtained. Furthermore, by stacking a plurality of filters for each color, it is also possible to change the spectral transmittance and correct the imbalance in output as shown by the broken line in FIG. 2-2. Figure 3-1 shows a block diagram of the main body control section. Reference numerals 422 and 421 are operating unit units used by an operator to operate the machine, where 422 is referred to as a main control unit and 421 is referred to as a sub-control unit. The main control unit 422 corresponds to the operation board 72 in FIG. Main control unit 422 is shown in Figure 3-2. 72-9 is a copy button for starting the copy operation, 72-19
is the numerical value input key for setting the number of copies - 172-16,7
2-17 are upper and lower cassettes (Figure 1 42.43)
The cassette selection keys 72-2 to 72-8 select the
This is a color mode selection key that selects a color copy mode. For example, the 4FuLL mode selected with the 72-2 key performs an original exposure scan four times, and separates the colors into B, G, and H for each scan. Each image was developed with Y1M%C toner corresponding to the original exposure image, and in the fourth scan, it was developed with BK) toner corresponding to the BK acid component of the original, resulting in a color image of all four colors. In this mode, a full-color image copy is obtained by superimposing the image. Similarly, 3FuL
In the L mode, Y, MlC are set for each of the three original exposure scans, and in the (BK10M) mode, BK and M, BK; Y, M, are set for each of the two original exposure scans. C
In this mode, a predetermined copy is obtained using each monochrome toner image in response to one original exposure scan. 72-23 is a 7-segment LED for displaying the number of copies to be set; 72-18 is a 7-segment LED for displaying the number of copies to be copied; 72-15 is a 7-segment LED for displaying a copy number count; 72-15 is for detecting the absence of replenishing toner in a hopper (not shown) by a detection device (not shown). , an indicator 72-
14 is an indicator 72-2 that displays this when a jam is detected by a jam detection device provided in the paper conveyance path of the present apparatus;
0 is an indicator that displays this when a detection device (not shown) detects that there is no paper in the selected cassette, and 72-
1 is a weight indicator that lights up when the surface temperature of the fixing roller of the heat-pressure fixing device 60 has not reached a predetermined value; indicators 72-15.72-14.72-20.72-1. Copying operations are prohibited while is lit. 72-21.7
Reference numeral 2-22 is a paper size indicator, and 72-21 lights up when the copy paper in the selected cassette is F3 size, and 72-22 lights up when it is A4 size. Also, 72-
Reference numeral 12 denotes a copy density adjustment lever, and when the lever is moved in the direction 1, the lighting voltage of the halogen lamp 5.6 for document illumination is lowered, and when it is moved in the direction 8, the lighting voltage is increased. Next, the sub-control unit 421 will be explained according to FIG. 3-3. 421-14. -15.
-16 is a switch group connected to an r correction circuit 140 (described later) that corrects the gradation of the read data for 8-bit pixel data read by the COD and quantized by the A/D converter. It is composed of a plurality of rotary digital code switches each generating a digital code.As will be described later, data having a desired γ characteristic is extracted from a plurality of memory elements in which data conversion tables in the γ correction circuit are stored. It is connected to select a conversion memory element. 421-5 to -13 are a group of switches for masking processing; 1, input yellow image data Yi1, magenta image data Mi
A coefficient aL bL ci (i=1.2.3) is determined when the following equation is applied to the 1 shea/image data Ci, and these are determined by the switch group 421-14, -15, -1
6, it is composed of a rotary digital code switch that generates digital codes from 0 to 16. Note that data conversion for masking processing is as shown in the following equation. Further, 421-1, -2, -3, and -4 are loader digital code switches that provide correction coefficients for each Y and M%01BK data in a UCR processing circuit 160, which will be described later. Further, 421-20, 21, 22, and 23 are controls respectively connected to the high-pressure generator 77, which control the current flowing to the charger 25 that performs negative uniform charging of the photosensitive drum. You can adjust the shading of each color in the image and change the color balance. Further, 421-24 is a switch for selecting gradation during multi-level dither processing, as will be described later. Historically, in Fig. 3-1, 411-65 is a sequence controller that controls the load of all the internal components of the device, and the load shown in the timing chart of Fig. 3-3, which will be described later.
For example, the photosensitive drum drive motor, static eliminator, exposure lamp, etc. are activated at a predetermined timing by the sequence control table in the ROM 423, the sequence controller → I10 port 419 → negative 4 drive circuit 42.
It is driven through a path of 0. In the figure, Ll, L2...
- LN corresponds to each load, but since the method of driving each load, for example, a solenoid, motor, lamp, etc., and the method of sequence control according to the ROM are well known, a description thereof will be omitted here. Main control unit) 422,? 421 companies,
The loads to be driven are keys, lamps, LEDs, etc., and the driving or input of these is performed by the key and display controller 412, which correspond to the respective operation units. Further, for example, the driving of LEDs and lamps, the scanning of keys, and the input method are performed by well-known methods, and detailed explanations thereof will be omitted. The sequence progresses according to the timing chart in Figure 3-3.This timing chart is as follows:
- As an example, a sequence is shown in which a full-color image is obtained by superimposing three colors of Y%M and C. With this device,
In order to obtain the full color images of Y1M and C mentioned above, it is necessary to rotate the photosensitive drum 5 times and the transfer drum 10 times, and therefore the diameters of the photosensitive drum 24 and the transfer drum 53 are configured at a ratio of 2:1. . In addition, this sequence includes the photosensitive drum 2
The clock board 24 is driven by a gear 24-9 which is driven by the drive shaft of the photosensitive drum 24, as shown in FIG. -7 and a sequence clock generator consisting of a photointerrupter 24-8, and a photosensitive drum 24.
The transfer drum progresses according to the drum clock C generated as the transfer drum rotates, and the drum clock reaches 40 when the transfer drum 5301 rotates.
0 clocks are counted. Therefore, the on/off control of the load is performed based on the count value from the reference point (hereinafter referred to as home position) of the transfer drum 53 (not shown). 3rd-
In the timing chart shown in FIG. 4, the numbers indicating the operating timing and non-operating timing are the respective clock count values when the transfer drum HP is set to the number of clocks O. For example, the exposure lamp 6 is set at clock 1 of the third rotation of the transfer drum.
ONL at 20 counts, 120 counts on the 5th rotation, 120 counts on the 7th rotation, 118 counts on the 4th rotation, 118 counts on the 6th rotation, and 118 on the 8th rotation.
Controlled to turn off by count. Hereinafter, according to this timing chart, the configuration shown in FIG. 1 will be described below: 1! An outline of the device operation will be explained based on the construction. Copy button 72-
When the key & display controller 412 detects 9-on, the sequence control 4-2411-65 starts the copy sequence, and the photosensitive drum 24, the transfer drum 53, the second registration row 252, and the second registration row 252 to drive. At the first rotation of the photosensitive drum 240, the surface of the photosensitive drum is neutralized and standardized by the pre-static eliminators 61 and 63, the static eliminator lamp 71, and the like. The original l is placed on the platen glass stand 2, and at 120 in the third rotation of the transfer drum 53.
From the clock mark, the halogen lamp 5.6 for exposing the original is turned on and scanning for exposing the original is started. The reflected image from the original is reflected by the mirror 9.7, and is sent to the CCD by the lens 11.
The light is condensed to form an image on the light receiving surface of CCD 13.15.17 and enters the dichroic mirror 12, and the reflected light image from the document, which is color separated into B1G%R, is displayed on each CCD 13.15.17.
is incident on the The color-separated optical image corresponding to the document received by this COD is photoelectrically converted and then subjected to necessary real-time data processing in an image processing unit, which will be described later.
As described above, the photosensitive drum is sequentially exposed in the order of Y, M, and C (7) with laser light t modulated with the above image data, and a latent image corresponding to the original image is formed on the surface of the photosensitive drum. . Corresponding to the first exposure scan in the timing chart of FIG. 3-4, the latent image formed on the photosensitive drum 24 starts operating at the 254th clock of the third rotation of the transfer drum 53. The Y (yellow) developer 36 stops operating at clock 293 of the 4th rotation, and starts operating at clock 196 of the same rotation, starting at 1 of the next rotation of the transfer drum.
The transfer charger 54, which stops operating at 96 clocks, transfers a yellow toner image corresponding to the yellow component of the original onto the transfer paper wound around the transfer drum 53. Similarly, in the 5th, 6th, and 7th rotations of the transfer drum 53, the magenta toner image corresponding to the magenta component of the original is 7.8
．． By nine rotations, a cyan toner image corresponding to the cyan component of the original is transferred to the transfer paper, and YlM and C are multi-transferred to the same location. Note that the reflected light image from the original is separated into three components of B, G, and R by the guichroic mirror 12, and each of them is divided into CC.
When the image is read to form a yellow toner image, the G and H signals are incident on D13.15.17. When the image is read to form the magenta toner image, the signals are B and H.
When reading an image to form a cyan toner image, the R signal is used for color correction, and the B and G signals are used for color correction.
On the other hand, at the 225th clock of the third rotation of the transfer drum where the first exposure scan is performed, the transfer paper is fed into the cassette 42 or 43 selected by the operation section. In order to do this, the paper feed roller 46 is operated in the case of an upper cassette, and the paper feed roller 47 is operated in the case of a lower cassette. The transfer paper fed from the cassette is conveyed by the conveyance roller 50 or 49, the skew is corrected by the first register straw 251, and the second registration roller 52 securely holds the transfer paper by the gripper 57 of the transfer drum 53. At a predetermined timing, the tip of the transfer drum 5 is held firmly by the gripper 57.
3, and multiple transfer of toner images as described above is performed. After the multiple transfer is completed, it is peeled off from the transfer drum 53 by the separating claw 58 and transferred to the fixing device 6 by the conveyor belt 59.
0, undergoes heat and pressure fixing, and is ejected. The operation timing of each of the above-mentioned loads is as shown in the timing chart of FIGS. 3-4. FIG. 4 is a block diagram showing a schematic configuration of the present invention centering on the image processing unit 100. In the image processing unit 10o, there is a part that calculates the appropriate amount of each signal of yellow (2), magenta-1 cyan (Q, and black (BK)) necessary for printing based on the three-color image signals read by the CCD light receiving unit 200. Then, each color is output to the laser modulation unit 300. Therefore, in order to form a color image with this device, four-color printing (Y, M
. C, BK), the document must be scanned 94 times by the CCD light receiving unit 200, and in the case of three-color printing (YlM.C), the document must be scanned three times. In other words, in the case of multi-color overlapping Ingiri, the overlapping portion of the original is scanned. The image processing unit) 1θ0 is composed of the following circuit clocks. 130 is a CCD light receiving unit 20
This is a shading correction circuit that corrects optical unevenness in the image signal read at zero, and performs the correction on the color-separated Y%M and C signals individually for each scan. 140 is a γ correction circuit that corrects the gradation of each color signal in accordance with masking and UCR correction. 150 is a masking processing circuit that calculates appropriate amounts Y%M and C required for printing. Further, 160 is a UCR processing circuit which calculates an appropriate amount of K for creating a black plate from Y and M%C. A dither processing circuit 170 binarizes a halftone image using a dither method. Reference numeral 180 denotes a multi-value processing circuit which further performs pulse width modulation on the image signal binarized by the dither processing circuit 170 to improve the gradation in intermediate tones. The image processing unit 100 is composed of ξ processing circuits and a synchronous control circuit 190 that synchronously controls these processing circuits. The CCD light receiving unit 200 transmits the optical image to the dichroic filter 1.
This is the part that separates the colors into 93 colors B%G%R according to 2 and converts them into electrical signals. Three-color separated light B and G%R are CCDB210, CCDG220, and CCDR23, respectively.
It is photoelectrically converted to 0. The photoelectrically converted B, G, and R signals are each converted into 8-bit digital by a COD driver B240, COD Dryno-G250, and COD driver R260, and then converted into 8-bit digital signals. It is converted into Y, M, and C signals, which are complementary colors of R. The digitized 8-bit Y%M%C signals are VIDEOY, VIDFJOM, and VIiOC, respectively. We will call them VIDEOY, VIDEOM,
VIDEOC is signal line 271.272.27 respectively
3 to the shading correction circuit 130, and the shading correction circuit 130 performs the shading correction as described in uiJ - the shading corrected Y%M, C signals VIDEOY, VIDEOM, VI
DEOC is supplied to the γ correction circuit 140 via signal lines 105, 106, and 107, respectively. The γ correction circuit 140 converts the gradation into characteristics that are easy to color correct. Here, to simplify the following processing, VIDEOY, V
IDEOM and VIDEOC each convert into 6-bit signals. γ corrected 6 hira) OVIDEOY, VIDE
OM. VIDEOC is connected via signal line 108.109.110,
The signal is sent to the masking processing circuit 150. In the masking processing circuit 150, VIDEOY, VIDEOM, VI
Perform appropriate color correction for printing from DEOC, and UC the color corrected VIDEOY, VIDEOM, and VIDEOC.
It is sent to the R processing circuit 160. The UCR processing circuit 160 calculates the under color removal amount using the color-corrected Y, M, and C signals to obtain the black BK amount. Y, M, C to BK
The Y%M1C amount obtained by subtracting the Y%M1C amount becomes the color-corrected Y%M,C amount. These four color image signals Y, M, C, and BK are supplied to the dither processing circuit 170 via the signal line 114 in the order of Y, M, C, and BK for each scan. Here, the signal line 114 supplies a 6-bit digital signal. Based on this signal, the dither processing circuit 170 digitally performs halftone expression using the dot density per unit area, and performs dither processing with three different threshold values (described later). It is output as a binary signal to lines 115-1.115-2.115-3. The multilevel processing circuit 180 processes three binary signals 115-1.
．． 115-2 and 115-3, and supplies a pulse width modulated binary signal to the laser modulation unit via the signal line 116. A laser driver 310 and a laser unit 320 emit a laser beam to form a latent image on the photoreceptor 24. The main body control unit 400 performs sequence control of this device, and
Controls each processing unit. Sequence controller 411- in the present control unit 400
65 (FIG. 3) transmits a yellow exposure signal to the image data processing unit 100 before starting the document exposure scan for the first yellow toner image formation. At the start of the original exposure scan, a magenta exposure signal is used, a cyan signal is used for the third time, and a BK double signal is used for the fourth time, respectively, as shown in Fig. 440.
The exposure start signal (shading start signal) is sent to the shading correction circuit 130 when the exposure lamp is irradiating the white calibration plate 4 at the start of the exposure scan for each color. ) 402, and in response to this, the shading correction circuit 130 reads correction image data corresponding to the white calibration plate for shading correction, as will be described in detail later. FIG. 5-1 shows the configuration of the synchronous control circuit 190 shown in FIG. 4. The synchronous control circuit is a crystal oscillator 190-i, CC
It has a D readout timing generator 190-2 and an address control section 190-3, and the C readout timing generator 190-2 and address control section 190-3 are provided, and the C
It drives the OD, counts serial pixel data output from the CCD, and controls the address of the scanning line. A clock CLK190-4 with a frequency four times that of the image transfer locks 2φT190-8 and 190-12 is supplied from the crystal oscillator 190-1 to the COD continuous timing generator 190-2 and the address control unit 190-3. There is. Image transfer lock 2φT190-8 is a clock that transfers serial image data output from COD, and is supplied to CCD driver R240, CCD driver 0220, and CCD driver R260 via signal lines 102.103.104. There is. In addition, image transfer locks 190-12 are connected to signal lines 101.119.120, 121.118 to each processing circuit in the image processing unit 100.
．． 117 (FIG. 4). In the address control section 190-3, the beam detect signal B
In synchronization with D321-1, horizontal synchronization signal l-l5YNC
190-5 and 190-11. This signal causes the CCD read timing generator 190-2 to
210, CCDG 220, and CCDR 230.
240, CCD driver 0250, and CCD driver R260 to start outputting one line each. φ
1190-7, φ2190-8, R8190-10 are C
This is a signal necessary for OD driving, and is sent from the CCD read timing generator 190-2 to the CCD driver R240 and the COD driver G via signal lines 102, 103, and 104.
250, and supplies the CCD driver R260. These signals will be described later. Address line ADRIOI-1 is a 13-bit signal line.
- Image signal 4752 from COD output line by line
This is an address line that counts bits. This signal is supplied to the shading correction circuit 130 via the signal line 101. Shading start signal 5HbST
401 is a link from the main body control unit 400 to the address control unit 190-
With the signal input to 3, the white calibration plate 4 mentioned above (Fig. 1)
This is the signal generated when scanning. This signal becomes active when the original illumination lamp 5.6 is lit and the optical system is at the white calibration plate 4 position. At this time, the address control unit 190-3 sends the signal 5WEIOI-2 to the signal line 10 only in the section where one line of image data for the white calibration plate is output more than COD.
1 to the shading correction circuit 130. CCD VIDEOEN 117 is a signal indicating the section in which 4752 bits of data are output per line from the CCD.
17. 5-2'' IgJ is a timing chart showing the timing of each part of the synchronization control circuit 190. 2φT is an image transfer lock, and the beam detect signal BD for each line generated by the laser scanner is transferred to the image transfer lock 2φT. synchronized and generates a 1-clock horizontal synchronization signal H8YNC.This signal also serves as a COD readout start shift pulse S.
It's also H. φ1, φ2 are image transfer lock 2φT 2
These clocks are signals having double periods and different phases, and are used to shift the analog shift registers of the odd and even parts of the CCD, which will be described later. From the image data signal VIDEODATA from the COD, the first image data D1 is read out from the output of the shift pulse SH, and the first image data D1 is read out sequentially from D2. D3,..., 5000 bits are read out, but DI to D4 are 2×1 pixel on the CCD, and 4752 bits from D5 to D4756 are 1.
This is image data for a line, and this section CCD VID
The ○ signal R8, in which EOEN becomes active, is a pulse that resets the shift register of the CCD for each shift, and is generated at the trailing edge of image data. The shading start signal 5HDST is a signal input from the main body control section 400 as described above, and is a signal input from the CCD of the first line that becomes active.
This is a signal generated during the VIDEOEN section. Next, details of the 'kCCD light receiving unit 200 shown in FIG. 4 will be explained. The COD light receiving unit includes a dichroic filter 12 for separating three colors, a blue filter 13 for adjusting the intensity of B, G, and R light obtained by the dichroic filter, a green filter 15, a red filter 17, and receives blue light. CCDB 210. CCDG220 receives green light, CC receives red light
DR230, COD driver B240, CC that A/D converts these outputs and converts them into digital quantities of complementary colors yellow (7), cyan (C), and magenta (goods).
It consists of a D driver 0250 and a COD driver R260. Each CCDCCCDB210, CCDG2
20, CCDR230 are each COD driver 82
40% COD 2 driver G250. COD Driver R
It is installed on 260. Figure 6-1 shows the structure of each COD. In the figure, the original image that has passed through the infrared cut filter Gyrofilter 12 and the spectral correction filter is irradiated onto photodiodes D1 to D5036 as slit images. The photocurrent of the photodiode is stored in a charge storage section (not shown) in the form of a charge proportional to the irradiation time, and by applying a shift pulse MO8SH, a shift pulse MO8SH is applied to a shift register C.
Charge is transferred to CD 5hift Reg 1 and 2 o CCD 8hift Reg 1 and 2 are MO8
Continuous pulses with opposite phases of φl and MO8φ2 are applied, and the image charge transferred from the photodiode charge storage section is the same as the clock pulses MO8φl and MO8φ.
2 is transferred in series along the charge wells formed in the channels p CCD 5hift Reg 1 and 2 to the output transistor/distributor 2 circuit Q1. At the same time, a switching noise component due to the reset signal R8 corresponding to the image charge is applied to the output transistor circuit G2. This switching noise component is later used to cancel out the switching noise component mixed into the image charge. The image charge transferred to the output transistor circuit Ql by the clock pulse MO8φ1sMOSφ2 is converted into an image voltage output vS here. Further, the corresponding switching noise component is also converted into a switching noise voltage output VH8 by the output transistor circuit Q2. In addition to this, a reset pulse Mo5Rs is applied to the output transistor circuits Ql and Q2 each time one image charge reaches the output transistor circuit Q1 and is converted into voltage, thereby preventing image charge accumulation in the output transistor circuit Q1. . Fig. 6-2 shows a block diagram of the COD ``liper'' that converts the original image into an electrical signal in the embodiment of the present invention.20
1 is a COD linear image sensor IMSENS that converts image light that has passed through a dichroic filter 12 and a light intensity v4 adjustment filter into an electrical signal. The differential input video amplifier V-AMP1203 that differentially amplifies the image voltage output vS and the switching noise voltage output VH8 outputted from the 202 line IMSEN8 and creates the correct image output voltage VIDEO is the image output voltage VIDEO.
Video A/ that converts from analog signal to digital signal
D converter A/D-C, 204 is A/D converter 2
a reference voltage source V-REF that supplies a conversion reference voltage to 03;
205 to 208 are pulse drive amplifiers for operating the IMSENS 201, 209 is a variable resistor VR2 for eliminating the DC voltage difference between the image voltage output VS, which is the IMSENS output, and the switching noise output VMS, and 210 is a V-AM
This is a variable resistor VRI that sets the amplified output of P. In the above circuit, the image output S and the noise output VNS from the IMSENIS 201 are applied to the V''-AMP 202 after being made equal to the DC voltage level at the time of no light signal by VB2.
NS is differentially amplified, noise components included in the image output vs are attenuated, and an image signal VI DEO suitable for NA/D-C203 human power is created by VRI. In this embodiment, as described above, the dichroic filter 12
However, due to the characteristics of the dichroic filter 12, the color sensitivity characteristics of the COD linear image sensor in the COD driver, and the characteristics of the light source, B
The optical input vs. electrical signal output characteristics of the three COD drivers for %G and H are adjusted by V-AMP202 so that they are accurately proportionate from the lightless state without being saturated even when receiving the maximum amount of light, and are appropriate. B, G to have a dynamic range.
Select VRI and VB2 resistance for %R and select Blue1
The gain is adjusted to decrease in the order of Green%Red. The VIDEO signal which is an analog signal is A/D-C20
3 is converted into a digital signal. The timing of conversion is the timing according to the image transfer lock 2φT sent from the address control unit 190-3, and the VIDEO signal converted into a digital signal is transferred to the image data processing unit 100 and subjected to various image processing steps. administered. In this way, by adjusting the gain of the amplifier so that B>G>R, the characteristics of the light source, etc. can be corrected. In this embodiment, high-speed A/D converter A/D-C203
REF, 3/4REF, 1/2RE with lower output resistance than the reference voltage source V-REF204.
A reference voltage of F and 1/4 REF is applied, which makes high-speed A/D conversion linearity advantageous. IMSENS
I is φ11 sent from the image data processing unit.
Each signal of φ2R8 and SH is connected to a pulse drive amplifier 205 to 2.
Appropriate drive voltage waveform MO8φ1, M, O8φ using 08
2. After setting MO8R8 and MO8SH, input the receiver as the drive input. (Shading Correction) FIG. 7-1 shows a diagram of the principle of shading correction performed in this embodiment. In an apparatus that reads an image by irradiating a light source onto a document and condensing the reflected light with a lens, an uneven amount of light called shading is obtained due to optical problems with the light source, lens, etc. In FIG. 7-1, if the image data in the main scanning direction is 12...n...4756, the amount of light attenuates at both ends. Therefore, in order to correct the shading kNi, the shading correction circuit 130 performs the following processing. In Figure 7-1, MAX is the maximum value of the image level, S
n is the image level of the n-th bit when the white calibration plate 4 is read. If the image level when the image is subsequently read is Dn, the corrected image level D'n is D
Correction is performed for each bit so that 'n = Dn * MAX/sn (4-1). Details of the shading correction circuit 130 are shown in FIG. 7-2. 130-2, 130'-4, 130-6 are shading RAMs for reading one line of the white calibration plate 4;
130-1, 130-3, and 130-5 are shading correction ROIMs that refer to the shading data stored in the shading RAM and output correction data when reading an image. CCD driver B240. CCD driver G2
The 8-bit I1IiI image data read by the 50° CCD driver B 260 is input to the shading correction circuit 130 via signal lines 271 and 272° 273, respectively. First, image data obtained by reading one line of the white calibration plate 4 is stored in the shading RAMs 130-2 and 130-2, respectively.
0-4, 130-6. At this time, signal line 1
01-2, the address control unit 190-3 (5th-1st
A shading light enable signal SWE is inputted from FIG. Further, an image transfer lock 2φT is input to the signal line 103-3, and is gated by a Nant gate 130-20. The output of the Nant gate 130-20 is each shading RAM 130-2.130-4.13.
They are connected to the write enable terminals WE of 0 to 6, and shading data is stored in these RAMs only when one line of the white calibration plate is read. At this time, the address signal ADHIOI-1 is controlled by the address control section 19o-3, and the pixel data of 4752 pixels of the COD output is stored in each shading RAM. C
Signal lines 271, 272, 2 from OD light receiving unit 200
Output to 73 image signal VI DEOY, VID
EOM and VIDEOC are each 8-bit digital signals, and each bit of each signal is divided into VIDEOO to VID.
It will be called EO7 (LSB→MSB order). In this embodiment, the shading RA of shading data
When storing in M130-2, 130-4, 130-6,
6-bit digital data VIDEOI-V'IDE via signal lines 130-8, 130-10, 130-12
Each RA uses only O6 as shading data.
Store each pixel in M. The reason why the shading data is set to 6 bits is to reduce the storage capacity and at the same time to avoid sudden changes in the shading characteristics. When you start scanning the document after storing the shading data,
Image data VI DEOY, VI DEOM. 8-bit data VIDEOO for each VIDEOC
From ~v, EO7 is the signal line 130-7, 130-9, 13
0-11 to the address terminals AO to A7 of the shading correction ROM 130-1, 130-3, and 130-5. On the other hand, Shiniding RAM 130-2, 13
4752-bit shading data address signal ADRIOI-1 stored in 0-4, 130-6
controlled by the terminals ■/, respectively. □〜”106 to shading correction ROM130-1, 130-3゜1
It is output to address terminals A8 to A13 of 30-5. At this time, the shading light enable signal 5W
EIOI-2 does not become active and the shading correction RAMs 130-2, 130-4 and 130-6 perform read operations. Shading correction ROM130-1.
130-3. In 130-5, the calculation power as shown in equation (4-1); ROM data is created so as to be performed, and 8-bit image signal VIDEOO-VIDEO7
By accessing the shading correction ROM using and 6-bit shading data as an address, the shading corrected output i=8 from terminals 01 to 08.
It is designed to be output as a bit image signal. In addition, when using shading correction in multicolor overlay mode,
Perform each time the document is scanned. Further, this shading correction is performed on all image data. (γ Correction) Next, γ correction will be explained. FIG. 8-1 is a block circuit diagram showing details of the γ correction circuit 140. In this embodiment, γ correction is performed for each color using a ROM for gauze, and the configuration is such that the γ characteristic can be arbitrarily selected. The signal VIDEOY outputted from the shading correction circuit 130 in 8' bits is sent to the synchronization part 301 by the synchronization part 2 which is output from the control circuit 190 to the signal line 119.
Synchronization is achieved by φT. The synchronized output is input to the lower address 8 bits of the γ correction ROM 302. In addition, the main body control unit 40 is located at the upper address 2 pit.
The γ correction selection signal 40″3 output from 0 is input, and the area of the γ correction ROM 302 is selected according to this signal. That is, the γ value control of the sub control unit 73 in the main body control unit 400 The yellow switch 421-14 can be selected in four stages, and is accessed by a high-speed digital signal input to the upper 2 bits and lower 8 bits of the γ correction ROM 302 and written in the ROM 302. Data is output. The data output from the ROM has a 6-bit level. This data is synchronized by the latch 303 and the synchronization signal 2φT which is further output to the signal line 119. Then, the masking circuit vIpgo after γ correction to 150
The y signal is output to the signal line 108. In this manner, the γ correction ROM 302 converts the yellow (Y,) signal component into data. Also, the image signals VIDEOM and VIDEOCVC are
Similar processing is also performed. That is, shading circuit 1
Image signal V output from 30 to signal line 106.107
IDEOM and VIDEOC are synchronized by latches 304 and 307 and then input to γ correction ROM 305 and 308. Then, the γ value control switch 421-15, 4 of the sub-control unit 73 in the main body control section 400
21-16 selection signal and image signal VIDEOM. ROM 305°308 for Te gamma correction according to VIDEOC
accesses the area and outputs γ-corrected 6-bit data. VIDEOM and VIDEOC after this γ correction
After the signals are synchronized by latch circuits 306 and 309, they are sent to masking circuit 150 via signal lines 109 and 110.
Next, the γ value control switch 42 of the sub control unit 73 of the main body control section 400
Selection of 1-14 to 421-16 and ROM30 for γ correction
The address input data and output data conversion tables of 2, 305, and 308 will be explained. Here, as an example, the ROM 1302 for gamma correction of the image signal V I DEOY will be described. First, in γ correction, when a color original is read and expressed on transfer paper, the density of the read original (abbreviated as OD) is compared to the density when expressed on the transfer paper (abbreviated as CD). It is desirable to express it on the transfer paper so that it is the same. In this case, the characteristics of the CCDB 210 that reads the density of the color original, and the image processing unit 10 that outputs the signal obtained from the COD as a laser modulation signal.
The three characteristics that matter are the zero characteristic and the image density characteristic expressed on transfer paper by outputting a laser-modulated signal. This point will be further explained with reference to FIG. 8-2. In the figure, the vertical axis of the fourth quadrant represents O and D, and the horizontal axis is
Represents a shading-corrected VIDEOY. Original density is 0. Since D is a logarithmic display, the image signal VIDEO
Y has a logarithmic relationship with the document density. This property is C
It is fixed depending on the characteristics of the CDB 210 and the CCD driver 240. Also, the second quadrant is the dither cumulative frequency and C,
Represents the relationship D. Here, the dither cumulative frequency is expressed as a ratio between a certain constant area (here, a dither matrix expressed by a dither processing circuit 170 described later) and a developed partial area within that area. Therefore, if we look at the changes in C and D when the dither cumulative frequency changes from 0 to 1oos, C and D are at the white level at the 0 coefficient, and when the dither cumulative frequency is gradually increased from 0, the CD suddenly changes from the middle. It becomes a characteristic to stand up, and at 100chi,
The photosensitive drum 24 saturates at a certain density1.
The color is fixed to a certain value by the yellow color imager 36 and the like. For this reason, if the characteristics shown in the first quadrant cannot be changed in the image processing unit) 100, C, D and OD of the third quadrant
The relationship between is constant 1. Image processing unit 10
In particular, the γ correction circuit 140 and the dither processing circuit 170 can control the relationship between the CCD output and the dither cumulative frequency at 0. However, since the data handled by the dither processing circuit is 6 bits, the second . If an attempt is made to correct the nonlinear part of the fourth quadrant, the quantum error will increase, and even if the relationship between C, D, and OD becomes linear, it will not be faithfully expressed. The input data of the γ correction circuit 140 is 8 bits,
Since the output data is 6 bits, the quantum error will be reduced even if correction is applied. In the dither processing circuit 170, if the relationship between the signal output as the dither cumulative frequency and the signal from the UCR processing circuit 160 is a linear relationship, the characteristics of the first quadrant are determined by the nine data stored in the γ correction ROM 302. I end up. Therefore, if the relationship between the dither cumulative frequency and the COD output in the first quadrant is made into the characteristic of A by γ correction, then C, D in the third quadrant and 0. The relationship of D is 1= like A'
It can be made to correspond to 1. Next, as a specific example of a table, Table 1 shows the contents of the ROM 302 for γ correction. Its characteristics are indicated by the upper 2 bits of the address.
A at roi-+, B at rlt)-1, C at ``il
D is represented by l. Yellow image signal V in lower 8 bits
When IDI;OY is input. 6-bit data as shown in Table 1 is output. In this way, the relationship between CD and OD can be one-to-one. In addition, the characteristics of the copy density CD such as B' in the third quadrant where the copy density CD becomes low, the characteristics of the copy density CD such as C' with a high contrast characteristic, and B' with a characteristic of almost fogging are determined by the γ of the sub control unit 73. This becomes possible by selecting the correction switch 421-14. By applying the gamma correction circuit to the yellow signal characteristics in this way, it is possible to copy at high speed and faithful to the original. or,
It goes without saying that the characteristics of the magenta M and cyan C signals can be similarly selected freely. Table 1 It is also possible to control the relationship between the output of the CCD and the dither cumulative frequency by the γ correction circuit 140 and the dither processing circuit 170. As a specific example, since the document density OD and the output signal VIDEOY after shading correction do not have a linear relationship, the VIDEOY signal obtained by correcting the VIDEOY signal is stored in the γ correction ROM 302. In addition, the dither processing circuit 170, which is supplied with the γ-corrected VIDEO signal from the signal line 114, converts the signal so that it is proportional to V.
It is also possible to perform correction using a dither processing circuit, which will be described later, so that the copy density CD is proportional to the IDEO signal. (Masking) Coloring materials such as printing ink or toner have a spectral reflectance as shown in Figure 9-1, and Y (yellow) coloring material has a spectral reflectance of 400 to 500 nm. Absorbs light from 500nm
reflect. M (magenta) coloring material is 500 nm ~
60. C (cyan) absorbs light of 600 nm to 700 nm and reflects light of other wavelengths. On the other hand, when developing with Y color material, the reflected light from the original is color-separated by a blue (blue) filter with spectral transmittance as shown in Figure 2-4. In the same way, the color material for M is green (
G) Filter: The coloring material C is used to develop a latent image formed by a light image color-separated by a red (8) filter. As can be seen from both figures, the B, G, and H filters have a relatively good separation of color components at 500 nm and 600 nm, respectively, while the spectral reflectance of the coloring material is has poor wavelength separation. In particular, M (magenta) contains a considerable amount of Y (yellow) and C components, and C (cyan) also contains some M and Y components, which simply correspond to color-separated light images. When developed with the above coloring materials, the reproduced color image becomes cloudy due to unnecessary color components. Therefore, printing technology usually performs masking processing,
This is corrected by converting each color component input to the masking processing system into Yi and Mi. Assuming Ci, each output color component Yo, Mo, C
. is converted as shown below. Coefficients (ai, bi, ci) (
By appropriately setting i=1.2.3), the above-mentioned turbidity can be corrected. Figure 10-1 shows details of the masking processing circuit 150 and the VCR processing circuit 160, which will be described later. In the figure, 150-Y, 150-M, 1'5O-CU
, yellow (2), magenta (b), and cyan (C). , signal line 10
6-bit M component video signal VI outputted via 9
The upper 4 bits of DEOM, the upper 4 bits of the 6-bit C component video signal VIDEOC output via the signal line 110
Let the bits be Yi, Mi, and Ci, respectively, (3
) formula is realized. Color data for correction, M is (3)
Mi, Ci in the formula, Yi, Ci in the formula (4)
, Yi in equation (5). ” Compared to the corrected data Yi, Mi, Ci,
High precision is not required, and the coefficients (ai, bi
l-1, 2, 3), as described later, 1/16.2/16
Since there are 16 steps up to 1, the 6 bits of the data to be corrected, Yi, Mi, and Ci, are each reduced to 4 bits. Moreover, this allows the capacity of the ROM (described later) for changing pockets to be reduced to 174. The circuit of FIG. 9-2 is a block circuit diagram showing in detail the masking processing unit 150-Y of FIG. 10-1, and since the masking processing units 150-M and 150-C are also the same circuit, -M and 150-C will not be described. In FIG. 9-2, 6-bit Y data,
4 pins) M data for correction via signal 5150-12,
4-pit C data via signal line 150-14 and digital code switch 42m-5 on signal line 150-11, 150-13, sub-control unit) 73 (Figure 3-3) via signal line 150-15. 421-13, the 4-bit code data Syy set by the user
, SYM, and Syc are input. SYY. SYM, syc code data

[0]H ~ [F]H
are the coefficients (J 1 b, +
cl) and digital code switch 421-5
If the set value by ~421-13 is N, the coefficient is given by N/16. 150-1,15 (1-2゜1
50-3 is a ROM for performing calculations, and 150-1 is a 6-bit Y signal and 4-bit code data SYY each form a ROM address, which is specified by this address. In the ROM data, when the setting value of 4 bits is m, Dy=Y, bit Xm/16 (Y=O
H to 3FH, m=oH-FH) are stored in 6 bits. Similarly, 150-2 has 4-bit code data SYM, and for setting value n, Dm=M4bit
tXl/16 is stored, and Dm and Dc are each 4 bits. Each data DY obtained here. Dm, Dc are signal lines 150-16, 150--17゜1
5 (outputted to 1-18. Then, perform the calculation of formula (3) on these data, D = Dy-Dm
-Dc is the video data of Y, then Y
Regarding, equation (1) can be corrected. Further, corrections are made in the same way for M and C. That is, the above 6-bit Y data and 4-bit correction M and C data are calculated by the calculation R.
It is connected to the address bus of the OM 150-4, and obtains a predetermined calculated value by searching the ROM table. 150-
Reference numeral 5 denotes a latch element that latches 6-bit data numerically calculated for masking processing in synchronization with video transfer lock 2φT. (UCR Processing) Figure 10-1 shows details of the UCR processing circuit. Normally, when color reproduction is performed by mixing color materials using the subtractive color mixing method, for example, when Y, M, and C are placed equidistantly,
Since the colorant absorbs all spectral components, black (
BK) is reproduced. Therefore, in the BK portion of the document, Y, M, and C toners overlap in equal amounts. However, as shown in Figure 9-1, the spectral reflectance of Y, M, and C toners has poor color separation depending on the wavelength. It has already been mentioned that the C component is included. Therefore, the black component should be reproduced using black toner, and the areas where black is used should be subtracted from the corresponding Y, M, and C toners. This is called undercolor removal (OCR). , No. 10-1
This is done in block 160 of the figure. Signal line 160-30
．． The Y, M, and C 6-bit image data outputted from the masking circuit 150 through 160-31 and 160-32e are first input to comparators 160-1, 160-2, and 160.
-3, the magnitudes of Y and M, and M and C1C and Y are compared. Comparators 160-1, 160-2, and 160-3 provide image data Y. The minimum value of M and C is set as the latch circuit 160-13,
160-14 and 160-15 are compared in size in order to latch them, and depending on the size of the Y, M, and C image data, signals as shown in the table in Figure 10-2 are sent to the signal line 1.
60-33°160-34.Output to 160-35
That is, in comparing image data of y, M, and c for each pixel, when Y is the minimum, 0'' is placed on the signal line 160-33, ``1'' is placed on the signal line 160-35, and similarly, when M is the minimum, When the signal line 160-33 is 'i', the signal line 160-34 is on.
However, when C is the minimum, "1" is output to the signal line 160-34 and "10" is output to the signal line 160-35. Also, Y=M
When =C, the value of Y is representative. In the three comparators 160-4, 160-2, 160-3, Y,
The minimum values of M and C are determined, and the latch circuits 160-13,
160-14 and 160-15 to the signal line 160-36, and this value becomes the basic data for inking. Another latch circuit 160-10, 160-11, 160-12
are Y and M output from the masking circuit 150. The image data of C is latched at the rising edge 9 of the image transfer lock 2φT and is transferred to the subtraction operation ROM 160-16.160- of the next stage.
17, 160-18, and signal line 160-
A signal ffB16O-3 is applied to the basic data for inking (BK) outputted to the inking unit 36 via the selector 160-20.
Multiply 7 by the coefficient value given by 4 pits ROMI 60
-19, and outputs the value of the upper 4 bits of the 6 bits of the obtained value kXBK to the subtraction ROM 160-16.160-17.160-18 via the signal line 160-38. Subtraction ROM160-16.160-17.
At 160-18, this value is subtracted from each image data, and the result is sent to the selector 16 via the signal line 160-39.
Output to 0-21. The selector 160-21 receives data from the multiplication ROM 160-19 through signal lines 160-38.
Bit inking data is input. These image signals are transmitted from the main body control section 400 to the signal line 40.
Y, M, C output through 5. BK identification signal SEL BK, SEL Y, SE
Necessary image quality data is selected by L M and SELC, and output as a 6-bit signal from the selector 160-21. That is, masking processing and UCR processing
(The final output after processing is in 4-color full-color mode (Y,
M, C, BK), the selection signal 5E is sent every time the image is scanned.
LY, SEI: LM, SEL C, SEL BK is output, and the color-corrected image data is selected in the order of Y, M, C, BK1. It is also multiplied by the basic data of BK. The coefficient is
Figure 3-3 Sub-control unit 73 of main body control section
The coefficients are selected by the switch groups 421-1 to 421-4 in the switch group 421-1, and are also selected by the selection signals 405-9 and 405-10 of the switch groups output from the main body control section. given to. As explained above, in the UCR circuit 160 according to this embodiment, the 10th
For a pixel having a color component as shown in Figure 3, inking is performed using the value obtained by multiplying the minimum value, e.g. Y, by a certain coefficient k as BK, and Y is ( Y-BK),
M is performing calculations using (MBK) and C is performing calculations using (CBK) as final color components. (Multi-gradation) FIG. 11 shows a principle diagram of the multi-gradation processing of this embodiment. The multi-gradation processing in this embodiment includes dither processing and multi-value processing. An example of dither processing is shown in FIG. 11(a). In dither processing, when a 6-pit, 64-level (0 to 3F) digital image @signal is binarized, the threshold value is changed within a certain area, and the area ratio of the number of dots within that area (hereinafter referred to as dither matrix) is I'm getting gradation. A in FIG. 11(a) is a 2×2 dither matrix, and the threshold f angle is changed from 8.18 degrees to 28.38 degrees for each dot. For the values of 0 to 3F of the digital image signal Dn, if the white background in Figure 9 is set to "0" and the shaded area is all "1" by the binary signal, then (a) - (0) to (a) - ( 4
), five gradations can be obtained. The larger the dither matrix is, the higher the number of tones can be obtained, but on the other hand, the resolution of the image becomes worse. Therefore, in the present invention, one pixel is further divided and the gradation is increased by pulse width modulation. FIG. 11(b) shows an example in which 3-division pulse width modulation is performed and quaternary dithering is performed. Divide one dot by 3/4'J using the dotted line as shown. In other words, the area ratio of four gradations can be obtained in one dot. If three more threshold values are given in each dot of the 2×2 dither matrix as indicated by B in FIG. 11(b), (b) −(0)・〜(b)−(12) 133 gradations can be obtained, such as 2 with multiple gradations.
In the value signal, an image with gradation is obtained by emitting laser light only in the shaded area in Fig. 11(b), and in the case of a ternary dither matrix, one dot is divided into two. By doing this, the cymatrix is obtained. In this embodiment, the dither matrix can be varied from 2x2 to 32x32, and multi-value can be selected from binary, 3, and 4 using the switch 421-24 (Fig. 3-3) of the sub-control unit 421. By combining these, various gradations can be obtained. Furthermore, the dither matrix is changed for each color to completely reduce moiré and the like. FIG. 12-1.12-2 is a block circuit diagram showing details of the dither processing circuit 170 and the multi-level processing circuit 180.
The 2-bit signal MM sent through 6 (Figure 4)
C13KO (AI O), YMCBKI ('All
The color to be dithered is determined from Ic. For example, if A+o-I A++= 1, then Y (yellow) 4
If o=I Ao=0, then M (magenta) A. ”-O
If AI+=1, c (cyan) A+o” OAII=
If O, use BK (black). The switches SW1 to SW3 are switches for selecting gradation, and have two contacts, a and b. By turning on the switch SW1'i, one dot of the dither matrix can be divided into three. By turning on switch SW2, one dot of the dither matrix can be divided into two. - For example, Te A, +o = 1 + An "" 1,
SW 1 off. Consider the case where SW2 is off and SW3 is off. In this case, dither ROMA-C is selected. Video signal 6 bits (
Dither ROMA (7) under the condition that 64 level signal)
Address 00 [00,01 address 03,02 address 06,0]
09° at 3rd address, 12° at 20th address, 15° at 21st address.・・・
......01. at address 100 of dither ROMB+C.
Address 01 [04゜07 at address 02...02 at address oo of dither ROMC.05,02 at address 01
The dither pattern is stored at address 08... The circuit operation in the above state will be explained. In this state, if the video signal VIDEOO~5 is 04, the video signal is larger than the content 00 of address OO of dither ROMA, so the output Q of latch A is 1''. Time dither ROMB OO
Since the video signal is larger than the content 01 of the address, the output Q of latch B is 1'', which is 1, and at this time, the video signal is larger than the content 02 of the address OO of the dither ROMC. is larger, so the output Q of latch C is °“1”
becomes. In synchronization with the next image transfer lock WCLK, the output Q of latch A becomes 1'' when compared with the content 03 at address 01 of dither ROMA, and at this time, compared with the content 04 at address 01 of dither ROMB, they are equal. The output Q of latch B is
At this time, compared with the content 05 of address 01 of dither ROMC, the output 2 output Q of latch C becomes "0". In this way, in synchronization with WCLK, dither ROMA, B
, C, respectively, at addresses 02, 03, and 00. The contents of addresses 01, 02, 03, and oo are compared sequentially, and as a result, the output Q of latches A, B, and 'C is '0'.
Or it becomes "1". At this time, when the H8YNC signal is input, the address counter B170-8 counts up by one and the WC
In synchronization with LK, the contents of addresses 20, 21, 22, 23, and 20 are sequentially compared. In other words, in synchronization with the image transfer lock WCLK, the address counter A170-7 (lower address) (xO address to x3 address) counts up, and every time H8YNC is input, the address counter B170-8 (upper address) (0x
Address to 3×Address) counts up. At this time, latch A170-4. B170-5゜C170
-6 is output from line memory A15o-9 by counting up the address of line address counter C180-7 in synchronization with image transfer lock WCLK.
, B18O-10, 0180-11. At this time, when the KH8YNC signal is input, the latch A170-
4, B170-5. Each output of C170-6 is WCL
By counting up the address of line address counter Di 80-8 in synchronization with K, line memory D
180-12. E180-13. Stored in F180-14. Line memory D180-12. E180-1
3. While being sequentially stored in Fl 80-14 in synchronization with WCLK, line memory A 180-9.8180 is stored first.
-10. The contents stored in C180-11 are sent to line address counter C180-7 and read address counter 1 in synchronization with signal RCLK from oscillation circuit 180-3.
By counting up the address 80-5, the data is sequentially sent to the data selector 180-15.The start of counting up the read address counter 180-5 is necessary to form an image at a fixed position tt on the drum. Since it is necessary to delay the start of formation for a certain period of time after H8YNC is input, the read address counter 1so-s is not counted up until the value of the left margin counter 180-6 reaches a predetermined value. It is prohibited. Line memories A, B, C or E after the pinch prohibition is lifted. The contents of F will be sent to the data selector 180-15. This data selector 180-15 switches the input between A side and B side by switching circuit 180-2VC every time H8YNC is input.
data selector 180-
Line memory A is synchronized with RCLK to the output terminal 15.
180-9°8180-10. C180-11 or line memory Di 80-12. El 80-13.
This means that the signal stored in either F180-14 is always output. The multilevel oscillation circuit 180-16 has contacts 5w1-b (400
-6) is ON, the image transfer lock WCLK is activated by three signals φA as shown in FIG. Divide it into φB and φC, and gate it A18O-17,
ANDGATE B18O-18, ANTGATE) C180-
Send to 19th. As a result, the outputs Y, , Y, , Y2 synchronized with RCLK of the data selector 180-15 are gated by AND gates A, B, and C, respectively. Next, the result is input to the OR gate 180-20, and by turning on the laser with the output signal from this OR gate 180-20, the magnitude of the signal VIDEOO~5 input to the comparator during one wave of WCLK is determined. The area to be irradiated can be changed to four types (■ No irradiation, ■ Irradiation for 1/3 of RCLK, ■ R
A time chart of the above-described signals is shown in FIG. 13. To explain the signals again from above, B, D...----......H8YNC occurs every time the laser beam scans the drum once...・・・・・・・・・・・・B,
VIDEO ENBLE becomes H only while the first φ after D becomes H is H...Laser output that stores the dithered video signal in the line memory only while this signal is H... ...... Image transfer lock that irradiates the modulated laser light onto the drum only while this signal is H...Teaser WCL synchronized with this signal
K The video signal after processing (2φT)
φ1 to be stored in line memory・・・・・・・・・・・・・・・・・・・・・
・・・・・・In synchronization with this signal, the word “A” was extracted from the line memory. Divide the frequency of the signal by 3. Next, we will explain the case of changing the surface mff to which the laser is irradiated during the image transfer lock WCLKI wave to three types. This equation, switches SW, ~SW, are 5W1OFF,
5WtON, 5WsOFF. Other conditions are sw
□ Same as the explanation for ON, SW20 FF, 5WsOF - Under this condition, dither RO
M is D170-12. Write address counter 180-1 with Eu2O-13 selected, read address counter 180-5, left margin counter 1'8
0-6, switching circuit 180-2. Address counter C1
The function of the 80-7° address counter D180-8 is exactly the same as the previous explanation, so a description thereof will be omitted. VIDEO, ~. The result of comparing the contents of dither ROMDI 70-12 with the contents of latch Al 70-4 line memory AAO (or BO
) is entered. Similarly V I D E Oo~. The result of comparing the contents of dither ROMEI 70-13 with the contents of data selector 18'O, -15 via latch B170-5 line memory B18O-10 (or line memory E180-13) ) When 5W2-6 is ONt, the multilevel oscillation circuit 180-16 outputs the signals 14, CL, and K to the two signals φA as shown in FIG. At this time of division into φB, φC remains in the O state. As a result, the output Y of the data selector 180-15 is synchronized with RCLK. , Y, are gated by an AND gate 180-17 and an AND gate 180-i8, respectively. Next, take the result with OR gate 180-20,
With this signal, by turning on the image transfer lock, the voltage input to the comparator during one wave of WCLK is
The area irradiated with the laser can be changed to 3 areas depending on the size of IHA of I D E Oo~ (■1
Tsutaku irradiation zeta ■ RCL Irradiation time 1/2 of K ■ R
Irradiation for 2/2 time of CL K). Next, I'iJ of image transfer lock Vv'CLKl wave is 7
- A case will be explained in which the area to which the laser is irradiated is changed to two types. In this case, SW1-3 are 5WIOFF. 3w, o FF, SW, ON. Other conditions are SWI ON, SW'20 F ii, 5
This is the same as in the case of W30FF. Under this condition, dither ROMF170-14 is selected as the dither ROM. Write address counter 180-1. Read address counter 180-5. Left margin counter 1
80-6. Switching circuit 180-2. Address counter C1
80, 7, the function of address counter D180-8 is exactly the same as the previous explanation, so it will be omitted.
The result of comparing with the contents of 0-14 is latch A170-4 line memory A18O-9 (or line memory D180-
12) to terminal A of data selector 180-15. (or B), while the multilevel heating circuit 180-16 is Y when SWs-b is ON. is '1', Y, is ttO'', and Y, , remains 0' and does not change, so it changes to Y in synchronization with RCLK. is AND gate 180-17 prime a9 and then OR gate 116
By taking an OR with this signal and turning on the laser, W
VIDE input to the comparator during one CLK wave
Depending on the magnitude of the signal from OO to 5, it is determined whether the laser was irradiated or not. The manuscripts to be copied can be roughly divided into three types as follows: 1. One with only a picture, one with only 20 characters, 3
．． Those that have a mixture of pictures and letters, and pictures can be further divided into those that have subtle hues, such as photographs, and those that consist of almost only primary colors, such as manga and coloring books. For photographic originals, by converting them into multiple values, the gradation is improved and subtle color changes can be faithfully reproduced. Furthermore, for manuscripts that are almost exclusively in primary colors, such as manga or cartoon drawings, by binarizing them, it is possible to express clear colors without muddying the colors. Since the text is also expressed as a sharp black and white image with no intermediate density, optimal image reproduction is possible by switching the switches SWt to SW3 depending on the type of document. The switches SW and SW3 are turned on and off by switching the switch 421-24e in the sub-control unit, and the switch 421-24 is set to 4 on the scale.
When set to switch SW. is on, when scale is 3, switch SW2 is on, scale is 2
When the switch SW3 is turned on, the switch SW3 is turned on. Note that although this embodiment has a configuration in which images are recorded using a laser beam, the present invention is not limited to this. For example, it can be applied to inkjet printers and thermal printers. Further, the order of masking processing and UCR processing may be performed either first. Further, the B, G, and R signals may be transmitted from the memory of the host computer or the like. Alternatively, a configuration may be adopted in which each data of Y, M, C, and BK is stored in a single page memory or the like and then read out. Further, in addition to recording on transfer paper or the like, the configuration may be such that the information is filed on a disk. Further, in this embodiment, multi-gradation was performed using a time division signal, but it is also possible to perform multi-gradation using a luminance modulation, etc. As described above, according to the present invention, , Masking Process 1 Since multi-gradation processing is performed, high-quality image reproduction is possible. Furthermore, since a plurality of color data are read simultaneously and one color data is processed and output by referring to other color data, real-time image processing is possible. In addition, since the original image is scanned multiple times, the signal is processed for each color and the recording operation is performed multiple times, there is no need for large-capacity memory, which not only simplifies the configuration but also reduces the cost. can.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a color copying apparatus to which the present invention is applied, Fig. 2-1 is a diagram showing the spectral characteristics of a nitrogen lamp and the spectral sensitivity characteristics of a COD, and Fig. 2-2 is a diagram showing a dichroic mirror and a multilayer filter. Figure 2-3 is a diagram showing the spectral sensitivity characteristics of COD when passing through it. Figure 2-3 is a diagram showing the spectral characteristics of a dichroic mirror. Figure 2-4 is a diagram showing the spectral characteristics of each color filter.
Figure-1 is a block circuit diagram showing the main control unit, Figure 3-2 is a diagram showing the operation unit of the main control unit, and Figure 3-2 is a block diagram showing the main control unit.
-Figure 3 is a diagram showing the operation section of the sub-control unit;
3-4 is a timing chart showing the operation timing of each part of the color copying apparatus shown in FIG. 1, FIG. 3-5 is a diagram showing a schematic configuration of a sequence clock generator, and FIG. Figure 5-1 is a block diagram showing the schematic configuration of the synchronous control circuit, Figure 5-2 is a timing chart of signals in the synchronous control circuit, and Figure 6-1 is a diagram of the COD. Figure 6-2 is a block diagram of the CCD driver; Figure 7-1 is a diagram illustrating the light intensity distribution on the CCD surface;
Figure 8-2 is a block circuit diagram showing the shading correction circuit, Figure 8-1 is a block circuit diagram showing the γ correction circuit, and Figure 8-1 is a block circuit diagram showing the γ correction circuit.
Figure-2 is a diagram showing the relationship between original density, CCD characteristics, image processing unit characteristics, and reproduced image density, Figure 9-1 is a diagram showing toner spectral reflection characteristics, and Figure 9-2 is masking. Fig. 10-1 is a block circuit diagram showing the processing circuit; Fig. 10-1 is a block circuit diagram showing the masking processing circuit and the UCR processing circuit; Fig. 10-2 shows the state of the signal output from the latch circuit depending on the size of image data. Figure 10-3 is a diagram for explaining UCR processing, Figure 11 is a diagram for explaining the principle of multi-gradation processing, and Figure 12-1 is a block circuit diagram showing a dither processing circuit. , FIG. 12-2 is a block circuit diagram showing a multi-value processing circuit, and FIG. 13 is a block circuit diagram showing a multi-value processing circuit.
12-2 is a timing chart of signals in the circuit shown in FIG. 12-2. In the figure, 100 is an image processing unit, 130 is a shading correction circuit, 140 is a γ correction circuit, 150 is a masking processing circuit, 160 is a UCR processing circuit, 170 is a dither processing circuit, 180 is a multi-value processing circuit, and 190 is a synchronization processing circuit. In the control circuit, 200 is a COD light receiving unit, and 300 is a laser modulation unit. Applicant Canon Co., Ltd. Light quantity On 4'756C
H-Z A (of (
f〕B''(0) (Z)O≦
Interval≦2 2〈h≦8 (5) 1B<Dn≦ID 21XDtbesi (2) (B)
r4 nozu8<C, ≦28 28<On≦3
8'5? (C>Ha1≦3FB<Dn≦D
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ni? 2 22<Dn42 days”; a<Dn≦
2D yo × h ≦ King Ice Island ≦ 3D B) αm ≦ Crime 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Co., Ltd. Internal procedure amendment (method) % formula % 1. Indication of the case 1988 Patent application No. 36510 No. 2 Title of the invention Image processing device 3 Person making the amendment Relationship to the case Patent applicant Location 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (+00) Canon Co., Ltd. Representative Ryu Kaku 3rd Department 4th Agent & Amendment Order Date: June 28, 1982 (shipping date) 0 Specification subject to amendment 7, Contents of amendment l/Engraving of specification (no change in content) 2゜3゜4゜Procedures Written amendment (voluntary) Commissioner of the Japan Patent Office Kazuo Wakasugi Case Display Patent Application No. 3651 of 1980 Name of the invention Relationship to the case of person who amends an image processing device Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100)
)Representative of Canon Co., Ltd. Ryu Kaku Third Department Agent Address: 3-30-25 Shimomaruko, Ota-ku, Tokyo, Japan, Drawing 6 subject to amendment, Contents of amendment Drawing 1O-1 of the drawing will be corrected as shown in the attached sheet. .

Claims (3)

[Claims] (1) a masking processing means, a multi-gradation means for expressing gradation according to the digital image signal obtained by the masking processing means, and recording image information on a recording material by repeating the processing; An image processing apparatus comprising: an image signal output means for outputting an image signal according to an image. (2) A reading means for simultaneously decomposing and reading an original image into a plurality of color signals, a processing means for processing the plurality of color signals obtained by the reading means, and a recording material according to the image information obtained by the processing means. and an image recording means for recording an image on the same recording material, and when recording a color image, the reading means scans the original image multiple times, and performs the processing on the same recording material according to the image information obtained for each scan. An image processing device characterized in that it reproduces a color image from image recording. (3) A signal generating means capable of repeatedly generating a plurality of color signals, and a processing means for processing a plurality of color signals generated from the signal generating means, and selecting one of the plurality of color signals. and processing the selected color signal according to other color signals.