JP2510847B2 - Image processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for scanning a document and generating a plurality of color component signals, and an image processing apparatus capable of selectively inputting a plurality of color component signals from a host computer. is there.

[0002]

2. Description of the Related Art Conventionally, there has been known a technique of discriminating whether or not a document image is a halftone image having a halftone density level and performing halftone processing such as dithering on the halftone image based on the discrimination. ing.

[0003]

However, conventionally, the original image input by the image reading means in the copying apparatus is the object of discrimination, and the image input from the external device is the object.

The present invention has been made in view of the above circumstances, and is an image in which good halftone processing can be performed on both the image read by the image reading means and the image input from the host computer. An object is to provide a processing device.

[0005]

In order to solve the above-mentioned problems, an image processing apparatus of the present invention comprises an image reading means for scanning an original and generating a plurality of color component signals, and a plurality of color component signals from a host computer. Is an image processing apparatus capable of selectively inputting, and a determination means for determining whether or not the input image is a halftone image based on a plurality of color component signals from the image reading means. When a plurality of color component signals are input from the image reading means, the processing means performs predetermined halftone processing on the signal, and the processing means operates according to the determination result of the determining means. When the halftone processing is controlled and a plurality of color component signals are input from the host computer, the halftone processing by the processing means should be controllable according to the command signal from the host computer. Characterized in that the configuration was.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. A document 1 is placed on a transparent plate 2 of a document table and fixed by a document mat 3. Photosensitive drum 24, transfer drum 53
Rotates in the direction of the arrow to perform the color process. 12
Is a spectral dichroic mirror, and 14, 16, and 18 are CCDs that generate spectral signals B, G, and R by sensing spectral light. The lamp 8 and the mirrors 9 and 10 reciprocate to scan the original 1 and simultaneously output color signals B, G and R from each CCD to generate a reproduction Y signal, and then reciprocate again to output an M signal. The above scanning is repeated four times to form Y, M, C and Bk signals, and the laser is controlled to sequentially form each color latent image on the drum 24. Each color is sequentially developed, and the transfer drum 53 is rotated four times to repeatedly transfer the paper onto the paper to obtain a full-color copy.

The optical system emits light from the illumination lamps 5 and 6, and is combined with the light from the reflecting mirrors 7 and 8 to illuminate the original, and the reflected light is reflected by the movable reflecting mirrors 9 and 10. It passes through a lens 11 and a dichroic filter 12. Here, the light is separated into light having a blue wavelength, light having a green wavelength, and light having a red wavelength. The decomposed light having the blue wavelength among the decomposed lights is received by the solid-state imaging device 14 through the blue filter 13. Similarly, light of a green wavelength passes through a green filter 15 and is received by a solid-state imaging device 16. The light of the red wavelength passes through the red filter 17 and is received by the solid-state image sensor 18. That is, the original 3 is further moved while maintaining the optical path length by the moving reflecting mirror 9 that moves integrally with the illumination lamps 5 and 6 and the moving reflecting mirror 10 that moves in the same direction at a moving speed of 1/2 of the moving reflecting mirror 9. Lens 11
And solid-state image sensor 1 of each color through dichroic filter 12.
Images are formed at 4, 16 and 18. Each solid-state image sensor 14, 1
Outputs 6 and 18 are emitted as light output from the semiconductor laser 21 to the polygon mirror 22 via the image processing unit 27 described later. Since the polygon mirror 22 is rotated by the scanner motor 23, laser light is scanned perpendicularly to the rotation direction of the photosensitive drum 24. Further, there is a photo sensor 64 at a position 11 mm before the laser beam starts scanning on the drum, and when the laser beam hits the photo sensor 64, B and D signals are generated.

The photosensitive drum 24 is negatively charged by a negative charger 25 supplied with a negative high-voltage current from a high-voltage power supply 25. Then, when it reaches the exposure unit 26, the original 1 on the transparent plate 2 of the original table is illuminated by the illumination lamps 5 and 6, and the movable reflection mirrors 9 and 10, the lens 11, the dichroic filter 12, the blue filter 13, the green filter 15, and the red. Solid-state image sensor 1 with filter 17
The image output from the CCD imaged at 4, 16 and 18 is
With the image processing circuit of FIG. 2, each color passes through the shading unit 104, the γ correction unit 105, the masking processing unit 109, and the UCR processing unit 119.
Through the dither processing unit 124, the multi-value processing unit 125, and the laser driver unit 126.
1 and the laser light is imaged on the photosensitive drum 24. There, an electrostatic latent image is formed and four color developing devices 36, 3 are formed.
Enter 7, 38, 39. 3 in one exposure scan here
Color separation is performed and the above processes are performed, but the output of each UCR is B,
It is sequentially selected for each G, R, and black scan. When the one-color separation optical signal in the image processing unit 27 is selected by the main body control signal (E signal for UCR), the corresponding developing device is selected. The developing device selected there is performed by powder development using a magnetic blade method, and the electrostatic latent image is visualized. After that, the ghost miniature lamp 40 for erasing the electrostatic latent image and the negative post electrode 41 supplied from the negative voltage power source 25 are negatively charged to erase the electrostatic latent image.

Next, the copy paper 48 sent by rotating the paper feed rollers 46 and 47 from the cassette selected from the upper and lower cassettes 43 and 44 by the operation unit 45 is above and below the first registration rollers 49 and 50. Then, it is wound around the transfer drum 53 from the conveyance roller 51 through the second registration roller 52. Then, the toner on the photosensitive drum 24 is transferred to the copy paper 48 by the transfer electrode 54. After the transfer, the photosensitive drum 24 removes electricity from the copy paper 48 by the electricity removing electrode 55 supplied with a high voltage from the high voltage generator 25.

In the case of a normal color original, the above operation is repeated four times for four colors and the transfer drum is rotated four times to superimpose each color. If the original has only one black color, when it is detected that the original has only one black color at the time when one optical movement is completed as described later, the processes such as G, R scanning, development and transfer jump. Then, the copy operation of the black image is started. That is, in the case of a color original, the operating time for four colors is required, but in the case of an original of one black color, the operating time for two colors or one color can be shortened. The copy paper that has been transferred twice or four times is gripper 57.
The sheet is peeled off, adsorbed on the belt 59 by the conveyance fan 58, guided to the fixing section 60, fixed, and then sent out of the apparatus.

2 and 3 show image processing circuit diagrams.
The light of the original separated into three colors by the dichroic filter is C
When irradiating CD14,16,18, the output is CCD
The signals are amplified by the substrates 101, 102 and 103, A / D converted and sent to the next shading unit 104 in 8-bit parallel. When the incident light quantity of CCD is the same (when it is white) C
The shading unit 104 has a RAM configuration that corrects the output data for each bit of the CD to be equal and further eliminates the variations in the CCDs 14, 16 and 18 for the three colors. To be done.

Next, an optimum γ curve is selected by changing the values of the switches 106, 107 and 108 in order to linearize the gradation between the input and output by the γ correction unit 105. The processing from 8 bits to the upper 6 bits is performed in order to perform processing in a significant level area.

Next, the B, G, and R signals are simultaneously processed by the masking processing unit 109 to change the mixing ratio of each color component to perform color correction. This calculation is a multiplication factor RO
M, addition / subtraction ROM. The mixing ratio of each color is performed by switching the values (coefficients) of the switches 110 to 118. The reason why the calculated value is set to the upper 4 bits is that the calculated value is narrowed down to a significant area level.

Next, in the UCR processing unit 119, the minimum value signals of B, G and R are discriminated by the logic of each comparator COMP and each gate MiN. A value obtained by multiplying the minimum signal by an arbitrary diameter according to the value of the switch 120 is used as a black level signal. The value is subtracted from each color by each UCR. The signal is branched into two systems, and one of them is sent to the dither processing unit 124 by a select signal 121, 122, 123 from the main body control unit. In the dither processing unit 124, each color signal is a deep signal and, for example, a 6-bit signal is used as a table-referenced dither R.
The OM is used for comparison so that a 1-bit digital signal of 1 or 0 is converted to facilitate laser modulation. Next, this signal is passed through the R / W line memory and the multi-value processing unit 12
Laser multi-valued by 5 and laser 2 by laser driver unit 126
Drive 1 The dither processing unit has a ROM ₁ in which low threshold levels are arranged, a ROM _{3 in} a high array, and a ROM ₂ in the middle.
The output from each comparator is placed in a memory, latched, and divided into three equal parts for one pixel. In other words, one pixel is divided by pulses with different widths of φ ₁ to φ ₃ , and each is divided into ROM _{1 to 3}
In accordance with the above, the four-valued output is used to perform pulse width modulation in four ways to represent one pixel.

It should be noted that the processing X, Y, and Z shown in FIGS. 2 and 3 are performed in real time (real time) substantially at the same time.

On the other hand, the other branched signal is the halftone judgment circuit 1.
Sent to 27. Memories 128-1, 128-2, 12
For 8-3, θ is stored from θθ to θF, 1 is stored from 1θ to 2E, and θ is stored from 2F to 3F. The signal of 6BiT input to the memory B128-1 has 64 kinds from θθ when there is a lot of light (the density of the original is low) to 3F when there is little light (the density of the original is high) due to the intensity of the light input to the CCD. Change.

As an example, when the signals of θθ to θF are low density,
It is assumed that the signal of 1θ to 2E is an intermediate density and the signal of 2F to 3F is a high density signal. When the intermediate density signal is input to the memory B, 1 is output, and otherwise, θ is output. The latch circuit 129 inputs this to the hold circuit 130 in synchronization with the clock.

This operation will be described with reference to the flowchart of FIG. From 69 in FIG. 1, R immediately before the optical scan 201
Enter the ESET signal 200 in advance to reset the output Q ₁ to Q _3. If there is an intermediate density signal even once in the first optical scan, the hold circuit outputs 1 and, as a result, the output 140 of the OR gate becomes H. The control circuit 69 (FIG. 1) checks this signal immediately after the optical scan completion 202, and if 203 is an H signal, the control circuit 69 determines that the switching signal 1
44, the selectors 141 to 143 are switched to the dither side (step 204) and the dither processing is performed. If the signal is an L signal, the selector signals 141 to 143 are switched to the fixed data side by the switching signal 144 (step 205) and the dither processing is omitted.

It is also possible to perform dither selection control in advance by performing a pre-scan (not forming a reproduced image) of the image at a high speed, instead of the main scan directly relating to the reproduction image formation as the first optical scan.

The range for determining the intermediate density can be freely determined by switching the memories having different memory patterns of 1 and θ.

A circuit as shown in FIG. 5 is added to or replaced with x, y, z in FIG. 2, and the BD signal (signal due to detection of completion of beam scanning of one line) from FIG. 1-64 is counted by the counter 145.
To the appropriate count value (for example, if the dither matrix is 4 × 4), apply a RESET signal at 4
By inputting 0 to the switching signal 144 of FIG.
If there is an intermediate density portion for every four lines, dither processing can be sequentially performed. Therefore, the dither can be selectively controlled for each area.

With such a simple circuit, it is possible to obtain a high-resolution print by subjecting an original having an intermediate density to dither processing and printing a high gradation without performing a dither processing. .

Even if the B, G, and R input signals in FIG. 2 are from the host computer, the present invention is effective, and at the X, Y, and Z connection points, the host and CC can be connected as required.
The D reader can be switched. In this case, when a command signal without halftone is added to the head of the transmission signal from the host, it is possible to judge this and perform selector control so as to omit the dither processing. The present invention can also be applied to a 1-pixel 4-dot type printer, a thermal printer, and an inkjet printer.

In this example, when the dither processing is omitted, since the pulse width modulation of the laser drive signal is performed by the above-mentioned four values, a slight halftone can be reproduced, and a low-level halftone (when the dithering is performed at the deadline is performed). Can be reproduced). In addition, the determination can be performed every several pixels, and the above-mentioned selection control can be partially performed by making the synchronization accurate.

FIG. 6 is a circuit diagram for inserting characters, numbers and the like into the above color image.

Reference numeral 200 is a code generating means for generating characters and numerical values as code data, M ₁ is a buffer memory for storing the code data at the same time as the code is generated, and ADC ₁ controls an address for writing and reading the memory. The address counter, CG is a well-known character generator for outputting characters and numerical values as dot pattern image data according to the code data read from the memory M ₁ , M ₂
Is a buffer memory which stores the dot data from the CG at the same time as the output, and stores so that one pixel of the image data corresponds to one pixel of the CG. That is, a dot pattern for a plurality of characters and numbers is stored with each character and each numerical value having a predetermined interval similar to that of the reproduced image. The ADC ₂ is an address counter for controlling an address for writing and reading the memory M ₂ , and it determines the read start timing in synchronism with the progress of color image data processing. The character composition position of can be determined. 201
Is a signal input source for presetting its timing.
When the image processing according to FIG. 2 reaches the preset coordinates X and Y by 1, the reading from the memory M ₂ is started, and the character output is synthesized from the color reproduction output corresponding to the above position after the dither processing.

Reference numeral 205 denotes a gate for outputting the CG dot output as H (black) when the output of the comparator 206 is L (white, halftone), and 204 denotes L when the output of the comparator is H (black).
It is an inverter that outputs in (white). The comparator 206 outputs H when the output A of the black component in FIG. 2 is above a certain level L _{1 and} L when it is below. Therefore, when the image is a dark background color, the signal of the above level is output from B in order to make the character image from CG white from the background color and to make the character image black when the tone is light. The signal from B is input to the OR gate 210 in FIG. 3 and is combined with the image data after dither processing. In this case, since the inserted characters are not dithered, the resolution is not impaired.

The R / W signal is a write and read signal, and the read signal of the memory M ₂ is applied to the black scan and the black process in synchronization with the black processing step, which is output so as to form black as a character. If you want to insert characters in red when the color image is a blue monochromatic image,
The read signal is given to the memory M ₂ in synchronization with the red processing so that the red processing step is further executed and the B signal is output only during that step.

The address counter ADC ₂ counts dots (CLK) and lines of image data processing in order to determine the read start timing of the memory M ₁ .
When the count value reaches the preset X, Y by 201, the reading of the memory M ₂ is started in synchronization with the clock CLK. The dot count starts counting bits for each 1-line end signal, and the line count starts a beam detection signal in the laser scanner indicating the end of 1-line scanning or a 1-bit bit count end signal from the start of color data processing. . The processes of FIGS. 5 and 6 are also performed in real time (real time).

As shown in FIG. 7, when the code "1984" is stored in the memory M ₁ by the key or transmission line attached to the copying machine of FIG. 1, the CG converts it into a dot pattern and stores it in the memory M ₂ . Store. After that, the above-mentioned color data processing becomes possible (in this example, the original document can be scanned by the optical system. It is prohibited until a command is input that there is no inserted data.) Color data processing Start and 201 in the black scan process
When the preset coordinates X and Y are reached, the reading of the memory M ₂ is started, the B signal of the character is sequentially output in synchronization with CLK, and the latent image of the black character is formed on the drum as synthesized in FIG. A color print containing characters is obtained by transferring and synthesizing the color image. If necessary, it can be inserted in other color characters such as red and blue as described above.

However, when a character is added to a position where a part of a dark color (black) is used as a background, as described above, the background is automatically determined from the signal A and a white character signal is formed. And outputs as signal B. This procedure has a circuit configuration with a precise synchronization relationship so that it can be achieved in real time with respect to color image processing. Note that the preset data 201 can be made by the key of the copying machine shown in FIG. 1 or transmitted code data. Memory ROM storing format as 200
Can be

By the way, when the background color is repeated in a short range such as a stripe pattern, it may be unsightly to process the white color according to it, and a delay circuit is provided at point W in FIG. 5 in order to eliminate the inconvenience. Thus, whitening can be performed only when the base of the predetermined range is dark.

By the way, when all characters are to be added with a white outline, the read timing of the memory M ₂ can be determined so that the processing can be performed in the color image processing step at that time.

[0034]

As described above, according to the present invention, good halftone processing can be performed on both the image read by the image reading means and the image input from the host computer.

[Brief description of drawings]

FIG. 1 is a sectional view of a color copying machine according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of an image processing unit.

FIG. 3 is a circuit diagram of an image processing unit.

FIG. 4 is a flowchart for halftone determination.

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

FIG. 6 is a circuit diagram of an image processing unit.

FIG. 7 is an explanatory diagram of a reproduced image.

[Explanation of symbols]

 27 Image processing unit 127 Black judgment circuit

Claims (1)

(57) [Claims] 1. An image processing device capable of selectively inputting a plurality of color component signals from a host computer and an image reading device for scanning a document to generate a plurality of color component signals, the image reading device comprising: Based on the multiple color component signals of
A plurality of color component signals from the image reading means are provided, having a judging means for judging whether or not the input image is a halftone image, and a processing means for performing a predetermined halftone process on the given signal. Is input, the halftone processing by the processing means is controlled according to the determination result by the determination means, and when a plurality of color component signals from the host computer is input, the halftone processing is performed by the host computer. An image processing apparatus configured to control the halftone processing by the processing means in accordance with the command signal.