JPH05227415A - Picture processor - Google Patents

Abstract

PURPOSE:To obtain a reduced picture with less degradation of picture quality. CONSTITUTION:This processor is provided with a CCD line sensor 20C inputting a picture signal, a timing control part 900 executing the thinning processing of the picture signal inputted from the CCD line sensor 20C, a FIFO memory 275A storing the picture signal and a rate multiplier 275B which reads the picture signal from the FIFO memory 275A at a high speed. The picture is selectively outputted to a laser driver 280 in accordance with a picture reduction rate to execute a picture reduction processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for reducing an image signal.

[0002]

2. Description of the Related Art Recently, digital copying machines have come to be widely used in which a document image is photoelectrically read by a CCD image sensor or the like and an image is recorded by using a printer device such as a laser beam printer based on the read image signal. ing.

According to such a digital copying machine, it is possible to perform various kinds of image editing processing, which is difficult or impossible with the conventional analog copying machine, by electrically processing the image signal. Becomes

Among the image editing processes provided in this digital copying machine, the reduction reproduction of the original image is frequently used.

Conventionally, in the reduction processing of the original image, the writing frequency of the image signal to the memory is made variable according to the reduction magnification,
A configuration is used in which image signals are thinned out and stored in a memory.

[0006]

However, in the above-mentioned conventional example, since the thinned-out image signal is stored in the memory at the time of reduction, when an image is formed from this image signal, a copy image at the same magnification is obtained. However, the quality of the copied image is inferior because the image signal is less in number due to thinning out than the quality of No. 2.

[0007]

The present invention has been made in view of the above points, and an object thereof is to obtain a reduced image with little image deterioration, and input means for inputting an image signal and input from the input means. First reduction means for performing a thinning process on the generated image signal, storage means for storing the image signal output from the first reduction means, and second reduction means for high-speed reading of the image signal from the storage means. And an image processing device which performs image reduction processing by selectively operating the first and second reduction means according to the image reduction ratio.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional structural view showing an example of an image forming apparatus showing an embodiment of the present invention. Reference numeral 1 denotes a copying apparatus main body, which is an original scanning section 2, a paper feeding section 3, an image recording section 4, It is composed of the intermediate tray portion 5 and the like.

First, the structure of the document scanning section 2 will be described.

Reference numeral 2a is a controller section, which is a control section for generally controlling a copy sequence, and a CCD line sensor 20.
The image processing unit is configured to process the image signal read by c.

Reference numeral 2b is a power switch, and 2c is an original exposure lamp which constitutes a scanning mirror and an optical scanning system, and scans and moves at a predetermined speed.

20a is a half mirror, and the passing light is a CCD
After passing through the imaging lens 20b, it is photoelectrically converted by the CCD line sensor 20c and sent as an image electrical signal to the image processing section of the controller section 2a (details will be described later).
In addition, the reflected light from the half mirror 20a is the red filter 20d for removing red or the blue filter 20 for removing blue.
e, or it may pass without a filter or shutter.

An image forming lens 2d forms an image of the reflected light on the photosensitive drum 11 of the image recording section 4 (analog image recording).

Reference numeral 2e is a buzzer which warns of a copy mode error or the like set by the operation unit 41. An optical system drive motor (optical motor) 2f drives the optical scanning system and the like with high accuracy.

Next, the paper feeding section 3 will be described.

The paper feed rollers 3a and 3d are the paper feed rollers 3.
The cut sheet SH is moved to the image forming unit 4 by driving a and 3b.
Delivered inside.

Next, the structure of the image recording section 4 will be described.

Reference numeral 12 is a registration roller, which is a paper feed roller 3
The cut sheet SH fed by driving a and 3b is once stopped, and after synchronizing the leading edge of the image, the cut sheet SH is fed again.

Reference numerals 13a and 13b denote developing units, which contain color-specific developers (red and black), and a solenoid 14
By selectively driving a and 14b, the developing unit 13a,
Either one of 13b is disposed close to the photosensitive drum 11, and the other is retracted from the photosensitive drum 11.

When performing multiple development, the controller section 2a controls the driving of the solenoids 14a and 14b.

Reference numeral 15 is a transfer charger, which is a developing unit 13.
The toner image developed by a and 13b is cut sheet S
After the transfer, the cut sheet SH is separated from the photosensitive drum 11 by the separation charger 16 after the transfer. A pre-exposure lamp 17 neutralizes the surface potential of the photosensitive drum 11 to prepare for the primary charging. A cleaner device 18 is composed of a cleaning blade and a cleaning roller and collects the toner remaining on the photosensitive drum 11.

A fixing device 19 fixes the toner image transferred to the cut sheet SH by heat and pressure. A conveyance roller 20 conveys the cut sheet, which has been subjected to the fixing process, to the sheet discharge tray 24.

Next, in the case of multiple copy, the flapper 21 is switched to the position shown by the dotted line by the operation of a solenoid (not shown), and the cut sheet SH which has been fed, transferred, separated and fixed is conveyed to the conveying path 22. After passing through the sheet, the sheet is sequentially conveyed in the conveying direction 22a, the paper is detected by the sensor S5, then detected by the sensors S6, S8, and the like, and laterally aligned by the solenoid for lateral registration.

Next, the registration roller 12 is driven by a multiple copy command from the operation unit 41, and the cut sheet SH is sent to the position of the registration roller 12.

After that, the sheet is discharged to the sheet discharge tray 24 in the same manner as the above-mentioned operation.

During double-sided copying, the transfer sheet is partially discharged by the paper discharge roller 23 as in the case of the normal copying operation, but after the trailing edge of the cut sheet SH has passed the flapper 21, it is discharged. The paper roller 23 is driven in reverse, and the cut sheet SH is guided by the flapper 21 and introduced into the transport path 22.

This reverse rotation drive is performed by a solenoid that controls forward and reverse rotation. Subsequent operations are the same as in the case of the multiple copy described above. In this way, in the case of double-sided copying, the sheet is once ejected from the paper ejection roller 23, and the cut sheet SH is turned upside down / upside down by the reverse rotation drive of the paper ejection roller 23 and is fed in the transport direction 22a.

Although the multiple copy and the double-sided copy of one copy have been described above, in the case of multiple copy or double-sided copy of a plurality of copies, the intermediate tray section 5 is used. As shown in FIG. 1, the intermediate tray portion 5 is provided with an intermediate tray 30 that temporarily stores the cut sheets SH on the transport path 31. In the case of multiple copy of a plurality of sheets, the fixed cut sheet SH is controlled by the discharge roller 23 under the same control as in the case of double-sided copy of the single copy.
After the sheet is partially discharged by, the sheet discharge roller 23 is reversely driven to be stored in the intermediate tray 30 via the transport time 22, the flapper 32, and the transport path 36.

By repeating this operation, after the first side is completely stored in the intermediate tray 30, the feeding roller 33 is driven on the second side by the next copy command, and the second side is copied through the conveying path 36. ..

On the other hand, in the case of a plurality of double-sided copies, the above 1
The flapper 21 passes the conveyance paths 22 and 36 from the fixing device 19 and stores them in the intermediate tray 30 under the same control as in the multiplex copying.

The subsequent operation is the same as in the case of the above-mentioned multiple copy, and will be omitted.

Next, a scanner motor 25 rotates the rotary polygon mirror at a predetermined speed to deflect the laser beam emitted from the semiconductor laser 26. The scanner motor 2
5, a semiconductor laser 26 and the like constitute a digital scanning unit, emit a laser beam corresponding to the digital image information input from the image processing means of the controller section 2a, and the image obtained by the analog image recording and this digital image. The image is recorded as a superposed image, and at the time of analog image recording, the latent image area recorded on the photosensitive drum 11 is irradiated with a laser beam to selectively erase the latent image. An exposure shutter 27 blocks a part or the whole of the reflected image light to suppress latent image formation.

28 is a primary charger.

Incidentally, S1 to S15 and S19 to S2 in the figure
Reference numeral 3 denotes a sensor, and sensor S1 detects the home position of the optical system serving as the analog scanning unit, and the optical system at this position is stopped during standby. The sensor S2 detects that the optical system has moved to a position corresponding to the leading end position of the original image, and controls the timing of the copy sequence by the output of this sensor. The sensor S3 is the limiter position (reverse position) at the time of maximum scanning. The optical system reciprocates with a scan length according to the cassette size and the magnification that are instructed and input by the operation unit described later.

FIG. 2 shows the controller section 2a shown in FIG.
2 is a block diagram for explaining the configuration of FIG. 1, and the same components as those in FIG. 1 are denoted by the same reference numerals.

In FIG. 2, reference numeral 41 denotes an operation unit, which is a copy mode (single-sided, double-sided, multiplex, etc.) and copy mode (magnification,
A key for setting a paper size, etc., and further, a first recording mode for superimposing digital information previously stored by the digital scanning unit on all originals fed from the automatic document feeder (ADF) is set. And a second mode setting means for setting a second recording mode for superimposing digital information stored in advance by the digital scanning unit on a specific document fed from the automatic document feeder. It is arranged (details will be described later).

Reference numeral 42 denotes a control unit (controller), which is a CPU
42a, ROM 42b, RAM 42c, etc.,
The copy sequence is comprehensively controlled based on the control program stored in the ROM 42b.

An editor 43 inputs an area designation for a predetermined area of the original. A shutter portion 44 is composed of an exposure shutter 27 and a solenoid. Reference numeral 45 denotes a laser section, which is composed of a semiconductor laser 26, a scanner motor 25, and the like. Reference numeral 46 is an AC driver, which is the original exposure lamp 2c.
AC power is supplied to the AC load 47 such as. A motor control unit 48 controls driving of the motor unit. A DC load control unit 49 controls driving of the solenoids 14a and 14b, clutches, fans, and the like.

A feeder control unit 50a controls driving of the document feeding unit. Reference numeral 50b is a sorter, which discharges the cut sheet SH discharged by driving the discharge roller 23 to a designated discharge bin.

The HVT is a high-voltage unit that applies a voltage of a predetermined potential to the charging system and the developing sleeves of the developing units 13a and 13b.

DCP is a DC power source and supplies a control potential + 5V to the controller section 2a and the like.

When the power switch 2b is turned on, the heater in the fixing device 19 is first energized to wait (wait time) for the fixing roller to reach a predetermined fixing temperature.
When the fixing roller reaches a predetermined temperature, the main drive motor MM is driven for a certain period of time to drive the photosensitive drum 11, the fixing device 19 and the like, and the rollers in the fixing device 19 are set to a uniform temperature (weight release rotation). Then main drive motor MM
Stop and wait in the copy ready state (standby state). Here, the main drive motor MM is the photosensitive drum 1.
1, the fixing device 19, the developing units 13a and 13b, and various transfer paper conveying rollers are driven. And the operation unit 4
When a copy command is input from 1, the copy sequence (copy sequence) is started. The above is the outline of the overall configuration and operation of the image recording apparatus of the present invention.

Next, the operation during image recording will be described in detail.

At the time of normal image recording, the optical filter 20
A latent image is formed on the drum 11 without using d and 20e. At that time, the laser 26 can irradiate a laser beam to a preset arbitrary region in the image to erase a part of the image.

When the reddish color erasing mode is selected, the optical red filter 20d is set in the path of the reflected light from the original, the reddish color is erased, and image recording is performed. Similarly, in the case of erasing blue colors, the optical blue filter 20e
Using.

Hereinafter, an example of the case where the red and black automatic color separation is performed will be described in the following order. (1) Latent image of black image (2) Development of black image (3) Latent image of red image (4) Development of red image

(1) Latent Image of Black Image The latent image of the black image on the drum 11 will be described with reference to FIGS. 1 and 3.

As a pre-operation for forming a latent image of a black image, the optical red filter 20d is set in front of the imaging lens 2d.

The original 999 containing red information is illuminated by the original exposure lamp 2c and the scanning mirror. The original exposure lamp 2c and the scanning mirror are moved in the arrow direction of FIG. 1 by an optical system drive motor (optical motor) 2f. In addition, the imaging lens 2
d moves according to the copy magnification set by the operation unit 41.

Light reflected from the original 999 is reflected by the half mirror 2.
After being reflected by 0a, it is input to the optical red filter 20d. The optical red filter 20d erases red information in the original 999. The reflected light from the original 999 from which the red information is erased passes through the imaging lens 2d and forms an image on the drum 11.

As described above, the latent image of the information other than the red information of the original 999 is formed on the drum 11.

(2) Development of Black Image Development of a black image will be described with reference to FIGS. 1 and 3.

The cut sheet SH is supplied to the paper feed rollers 3a, 3
By b, the paper is fed and fed into the image forming unit 4.

The latent image excluding the red information on the drum 11 is developed by the black developing unit 13a and cut sheet SH
Is transcribed to. Cut sheet SH after transfer is separated charger 1
It is separated from the drum 11 by 6. The cleaner device 18 collects the toner remaining on the drum 11.

Cut sheet SH which has been developed and separated
Next, the black toner image on the cut sheet SH is fixed by heat and pressure by the fixing device 19. The cut sheet SH on which black information is recorded is conveyed by the flapper 21 to the conveyance path 22 for the next development. The cut sheet SH is conveyed from the conveyance path 22 to the registration roller 12 via the conveyance path 22a.

(3) Latent image of red image The latent image of the red image on the drum 11 will be described.

As a pre-operation for forming a latent image of a red image, the shutter 27 (FIGS. 1 and 3) is closed. By closing the shutter 27, the optical information from the imaging lens is blocked.

The original 999 is illuminated by the original exposure lamp 2c and the scanning mirror. The original exposure lamp 2c and the scanning mirror are moved in the arrow direction of FIG. 1 by an optical system drive motor (optical motor) 2f. In addition, this moving speed is
It changes according to the copy magnification set by.

The reflected light from the original 999 passes through the half mirror 20a and is reflected by the lens 20b at the CCD linear sensor 2.
Image on 0c.

Next, a detailed description of the CCD line sensor 20c will be given with reference to FIG. The photosensor section in which the red and cyan optical filters are fitted accumulates the reflected light from the original 999 for a predetermined time, where photoelectric conversion is performed,
Optical information becomes electrical information.

In the photoelectrically converted electrical information, all the pixels of the shift register C are collectively composed of CCDs.
After being transferred to the CD1 and the CCD2 and shifted by the shift clock, the output from the CCD1 and the output from the CCD2 are combined, and the R signal and the C signal are alternately output from the output terminal.

The output signal from the CCD line sensor 20c is input to the controller 2a as an analog electric signal.

A block diagram of the image processing unit in the controller 2a is shown in FIG.

The output signal from the CCD line sensor 20c is input to the analog processing section 100.

In the analog processing section 100, when the CCD line sensor 20c reads a white plate (not shown) installed in the document scanning section 2, the output of the analog processing section is the full scale of the A / D converter 110 in the next stage. The signal from the CDD line sensor 20c is amplified so that

The output signal from the analog processing unit 100 is analog / digital converted by the A / D converter 110 at the next stage, and becomes 8-bit digital information.

The output of the A / D converter 110 is input to the shading circuit 120. Here, variations in the sensitivity of the CCD line sensor 20c, unevenness in the light amount of the document exposure lamp 2c, and the like are corrected. The output of the shading 120 is input to the RC separation circuit 125 of the next stage.

The RC separation circuit 125 will be described in detail with reference to FIG.

As shown in FIG. 6, the shading output signals are the R signal and the Cy signal in the color order of the CDD image sensor 20c.
The signals are output alternately. A weighted average is taken from the shading output signals R _n , C _n ... By the RC separation circuit 125, and R _m and C _m signals 300R and 300C are obtained. In particular

[0071]

[Outer 1] Perform the operation as in the above formula.

Output signal 300 from RC separation circuit 125
R and 300C are lookup tables (LUT) 140
Is input to the inverting circuits 130R and 130C.

The LUT 140 is the red digital information 300.
R and the color discrimination signal 31 from the blue digital information 300C
0A, 310B and 310C are output. 7 and 8 are diagrams showing the color discrimination of the LUT.

FIG. 7 is a table for producing the red discrimination signal 310A and the black discrimination signal 310C, and FIG. 8 is a table for producing the blue discrimination signal 310B and the black discrimination signal 310C.

For example, when the red signal 300R is 200 and the blue signal 300C is 100, the red discrimination signal 310A is "1" because this value is in the red region from FIG.
In FIG. 8, the blue discrimination signal 310B is "0" because the region is other than blue.

The black discrimination signal 310C is the contact extraction circuit 230.
Entered in. The selector 160 is controlled by an I / O port (not shown) of the CPU to set the control line to "0" when performing red color separation, and sets the control line to "1" when performing blue color separation.

Hereinafter, a case where the control line is "0", that is, a case where red-based color separation is performed will be described. The red discrimination signal 310A is selected as the output signal 330 of the selector 160, and the contact extraction circuit 230 and the AND circuit 21 are selected.
Connected to 0.

Contact extraction will be described with reference to FIG.

The contact point extraction method is constituted by a 3 × 3 matrix, and the contact point information is set to 1 when both red and black information are included in the four pixels around the target pixel. This state is shown in FIG.

If neither of the red and black information is included in the four pixels around the target pixel, the contact information is set to 0. This state is shown in FIG. FIG. 9C is a diagram showing contact information 400 when the red and black images intersect.

Next, the expansion function which is the function of the expansion circuit 240 will be described with reference to FIG.

FIG. 10 shows the basic matrix for expansion.

The basic matrix has a size of 9 × 9. When the contact information 400 exists in the matrix excluding the pixel of interest, the pixel of interest is set to 1 and the pixel of interest is set to 0.

FIG. 11 shows two pieces of contact information A and B as shown in FIG.
It is the figure expanded using the matrix of. Expansion information A
Is a diagram expanded from the contact information A, and is indicated by a dashed line. The expansion information B is a diagram expanded from the contact information B.
It is shown by a dotted broken line.

The expansion information AB is input to the compression circuit 250 via the signal line 410. The compression circuit 250 is also formed of a 9 × 9 matrix (see FIG. 10) similarly to the expansion circuit 240. When all the matrix except the pixel of interest is expansion information, the pixel of interest is set to 1 and the other pixels are set to 0. To do.
This is shown in FIG. This set of "1" information is used as compression information through the signal line 420, and the synthesizing circuit 26
Input to 0.

The red signal 300R output from the shading circuit 120R and the shading circuit 120C.
The bluish signals 300C, which are the outputs from the
Signals 320B and 320 inverted by 30R and 130C
It becomes A. The signal 320B is a cyan-based density signal because it is an inversion of the red-based luminance signal 300R. Further, the signal 320A is an inversion of the bluish luminance signal 300C, and is therefore a reddish density signal.

Further, the selector 150 is selected in the red system by the control line, and the output signal 34 of the selector 150 is
For 0, the signal 320A is selected.

The red density signal 340 is input to the X terminal of the selector 170, and a fixed value (32 in this embodiment) is input to the Y terminal.

Further, the S terminal of the selector 170 is ANDed
The output signal 380 from the circuit 210 is connected.

The AND circuit 210 supplies the red area signal 330.
13 to 15 are diagrams showing the inputs and outputs of the AND circuit to which the contact signal 390 obtained by inverting the contact signal 400 by the inverting circuit 220 is input.

FIG. 13 shows a case where there is a red round image in the black image. The red area signal 330 showing the red area and the contact information 400 showing the portion where the red image and the black image are in contact with each other.
Indicates. The control signal 380 input to the S terminal of the selector 170 is obtained by subtracting the contact information 400 from the red area signal 330.

FIG. 14 shows that the red-based density information 340 is selected by the control signal 380.

If the red-based density information 340 is simply selected by the red area signal 330, black information is mixed in a desired red area at the point where the resolution of the CCD changes from black to red. Therefore, the control signal 380 of the selector 170 is created using the contact signal 400 that changes from black to red and from red to black. In this way, the signal 350 of only the desired red region can be extracted.

FIG. 15 shows how the red-based density signal 350 is extracted from the red-based density signal 340 by the control signal 380.

The output signal 350 of the selector 170 is then input to the edge emphasizing circuit 180 and the averaging circuit 190.

The edge enhancement circuit 180 enhances the edge portion of the input signal 350. Further, the averaging circuit 190 averages the input signal 350 with a 9 × 9 matrix.

Edge enhancement circuit 180 and averaging circuit 19
The output signals 360E and 360S of 0 are input to the binarization circuit 200 of the next stage. The binarization circuit 200 uses the 8-bit output signal 360E of the edge enhancement circuit 180 and the averaging circuit 19
The 8-bit output signal 360S of 0 is compared and the 1-bit red signal 370 is generated.

The red signal 370 is input to the combining circuit 260 at the next stage.

The synthesis circuit 260 will be described with reference to FIG.

The upper part of FIG. 16 shows how the red and black images intersect, and the middle right part is a separation of red from the image and corresponds to signal 370. The middle left figure is the compression circuit 25.
It is a figure showing the content of output signal 420 of 0. The figure below shows a combination of the signal 370 and the signal 420.
Which corresponds to an output signal 430 of zero.

As described above, by combining the compressed information signal 420 with the red information signal 370, it is possible to interpolate the missing of red information due to the intersection of red and black.

The output signal 430 of the synthesis circuit 260 is input to the noise removal circuit 270 at the next stage.

The noise removing circuit 270 is composed of a 3 × 3 matrix, and the isolated red information in the white information is converted into white information,
Further, FIG. 17 shows how to change the isolated white information in the red information into the red information.

The output signal 440 of the noise removal circuit 270 is input to the scaling circuit 275 at the next stage.

A detailed description of the scaling circuit 275 will be given with reference to FIGS.

Output signal 44 from noise removal circuit 270
0 is a signal 440 input to DATA IN of the FIFO memory 275A, CLK and HS from the timing control unit.
It is stored in the FIFO memory 275A in synchronization with YNC and WE.

Reading from the FIFO memory 275A is performed according to the timing of CLKB. CLK
B is formed by dividing the CLKA signal from the timing control unit 900 by the rate multiplier 275B. The frequency division ratio is set by the CPU according to the magnification set by the operation unit 41.
The rate multiplier 275B is set by the data bus.

19 to 22 respectively show a magnification ratio of 50% and 10
It is a timing chart at 0%, 200%, and 33%.

FIG. 19 is a timing chart when the scaling ratio is 50%, and the CPU is set so that the frequency division ratio in the rate multiplier 275B is 1: 1.

That is, the signal of CLKA is CLK as it is.
It is a B signal. CLKB has twice the frequency of CLK, and FI is half the write time.
By reading from the FO memory 275A, the scaling of 50% is performed.

FIG. 20 is a timing chart when the scaling ratio is 100%, and 100% output is performed by reading at the same time as the writing time of the FIFO memory 275A.

FIG. 21 is a timing chart when the scaling ratio is 200%, and 200% scaling is performed by reading the data in the FIFO memory 275A in a time twice as long as the writing time.

FIG. 22 is a timing chart when the scaling ratio is 33%.

Writing to the FIFO memory 275A
It is controlled by the WE (write enable) signal, as shown in FIG.
At m ₀ , m ₁ , m ₃ , m ₄ , m ₆ , m ₇ of the signal 440 at
Are written in the FIFO memory 275A in this order. That is, the signal 440 is thinned out by one pixel out of three pixels, and
It is written in the FO memory 275A.

The frequency division ratio of the rate multiplier 275B is set by the CPU to be 1: 1.

That is, the signal of CLKA is CLK as it is.
It is a B signal. CLKB has a frequency twice that of CLK, and is read from the FIFO memory 275A in half the write time. The information written in the FIFO memory 275A is thinned out from 3 pixels to 1 pixel.

[0117]

[Outside 2] Is reduced and the read frequency is doubled.

[0118]

[Outside 3] The reduction is 33%.

As described above, the scaling factor can be made variable by changing the enable signal WE written in the FIFO memory 275A and the speed of reading from the FIFO memory 275A.

At the time of 50% reduction, the reduction is performed by increasing the reading speed from the FIFO memory 275A without performing thinning processing on the image signal, so that a reduced image can be formed without loss of image information.

Further, at the time of reduction of 33%, not only the thinning processing but also the operation for increasing the reading speed is performed in combination, so that a reduced image in which the image deterioration due to the thinning processing is suppressed as much as possible can be formed.

As described above, by selectively operating the two types of scaling processing according to the set magnification, reduction processing with a small image deterioration can be performed.

Signal 4 scaled by scaling circuit 275
50 is input to the laser driver circuit 280 in the next stage.

Laser driver circuit 280 performs a process for driving laser 26. The laser 26 converts the electric signal 460 from the laser driver circuit 280 into optical information, which is reflected by the rotary polygon mirror 259, and then latent image of red information is formed on the surface of the drum 11.

Next, the development of a red image will be described with reference to FIGS.

The red information latently formed on the drum 11 by the laser 26 is developed by the red developing unit 13b. The black sheet is finished, and the cut sheet SH conveyed to the registration roller 12 is conveyed with the start of the document, and the red toner image on the drum is transferred. The post-transfer cut sheet SH is separated from the drum 11 by the separation charger 16.

Cut sheet SH which has been developed and separated
Then, the fixing device 19 fixes the red toner image on the cut sheet SH by heat and pressure.

Cut sheet SH on which black and red information is recorded
Is discharged to the discharge tray by the flapper 21.

As described above, by performing multiple development, it is possible to copy two colors, red and black.

[0130]

As described above, according to the present invention, image reduction processing is performed by selectively operating reduction processing by thinning out image signals and reduction processing by high-speed reading of image signals according to the reduction ratio. Therefore, it is possible to obtain a reduced image with little image deterioration.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus.

FIG. 2 is a block diagram of a controller unit.

FIG. 3 is a schematic configuration diagram of an image forming unit.

FIG. 4 is a configuration diagram of a CCD line sensor.

FIG. 5 is a block diagram of an image processing unit.

FIG. 6 is an operation timing chart of the RC separation circuit.

FIG. 7 is a diagram showing a method of color discrimination.

FIG. 8 is a diagram showing a method of color discrimination.

FIG. 9 is a diagram showing a method of contact extraction.

FIG. 10 is a diagram of a matrix for expansion processing.

FIG. 11 is a diagram showing a method of expansion processing.

FIG. 12 is a diagram showing a method of expansion processing.

FIG. 13 is a diagram showing a method of forming area information.

FIG. 14 is a timing chart of an operation for selecting color information.

FIG. 15 is a diagram showing a method of extracting a red-based density signal.

FIG. 16 is a diagram showing a method of a combining operation.

FIG. 17 is a diagram showing a method of removing noise.

FIG. 18 is a block diagram of a scaling circuit.

FIG. 19 is an operation timing chart of a scaling process.

FIG. 20 is an operation timing chart of a scaling process.

FIG. 21 is an operation timing chart of the scaling process.

FIG. 22 is an operation timing chart of the scaling process.

[Explanation of symbols]

 20c CCD line sensor 900 Timing control unit 275A FIFO memory 275B Rate multiplier

Claims (1)

[Claims] 1. An input unit for inputting an image signal, a first reduction unit for thinning out the image signal input from the input unit, and an image signal output from the first reduction unit are stored. A storage unit and a second reduction unit that reads out an image signal from the storage unit at high speed are provided, and the image reduction processing is performed by selectively operating the first and second reduction units according to an image reduction ratio. Characteristic image processing device.