JP2001211329A - Image processing apparatus, image processing method, storage medium, and image processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that an image of high quality can not be outputted while the handling of the image and storage capacity are reduced. SOLUTION: This system has a compressing means which compresses inputted image data, a generating means which generates flag data showing features of an image corresponding to the image data from the image data, a data generating means which generates compressed flag data from the flag data, an image data storage means which stores the compressed image data, a flag storage means which stores the compressed flag data, and an output means which obtains and compresses the compressed image data and flag data from the image data storage means and flag data storage means and then outputs the image data and flag data unfrozen by pixels to a printer part.

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, method, storage medium, and image processing system.

[0002]

2. Description of the Related Art Conventionally, a so-called color original copying apparatus as shown in FIG. 7 has been known as a system for digitally reading a color original image to generate a copied image.

In FIG. 7, reference numeral 1001 denotes an image scanner, which reads a document and performs digital signal processing. Reference numeral 1002 denotes a printer unit;
This portion prints out an image corresponding to the document image read by the image scanner 1001 on a sheet in full color.

In the image scanner 1001, 1
Reference numeral 000 denotes a mirror pressure plate. A document 1004 on a platen glass (hereinafter, referred to as a platen) 1003 is irradiated by a lamp 1005, guided to mirrors 1006, 1007, 1008, and three-line solid-state image sensor (hereinafter, referred to as a lens 1009) by a lens 1009. An image is formed on a CCD (CCD) 1010, and three image signals of red (R), green (G), and blue (B) as full-color information are sent to a signal processing unit 1011. 1005 and 1006 are speeds v, 1007,
Reference numeral 1008 scans the entire surface of the document (sub-scanning) by mechanically moving the line sensor in the direction perpendicular to the electrical scanning (main scanning) direction at a speed of 1/2 v. Here, the original 1004 is 400 dpi in both the main scanning and the sub-scanning.
(Dots / inch) resolution.

In a signal processing unit 1011, the read image signal is electrically processed, decomposed into magenta (M), cyan (C), yellow (Y), and black (Bk) components. Send to 1002. Further, M, M
One component of C, Y, and Bk is the printer unit 1002
And one printout is completed by a total of four document scans.

The M, C, Y, and Bk image signals sent from the image scanner unit 1001 are sent to a laser driver 1012. Laser driver 1012
Is a semiconductor laser 10 according to the transmitted image signal.
13 is driven by modulation. Laser light is polygon mirror 1
014, scans on the photosensitive drum 1017 via the f-θ lens 1015 and the mirror 1016. Here, similarly to the reading, both the main scanning and the sub-scanning are performed at 400 dpi (dot).
s / inch).

Reference numeral 1018 denotes a rotary developing unit, which includes a magenta developing unit 1019, a cyan developing unit 1020, and a yellow developing unit 1
21 and a black developing section 1022, the four developing sections alternately contact the photosensitive drum 1017, and develop the electrostatic development formed on the photosensitive drum with toner.

Reference numeral 1023 denotes a transfer drum, which winds a sheet supplied from a sheet cassette 1024 or 1025 around the transfer drum 1023 and transfers an image developed on the photosensitive drum to the sheet.

After the four colors of M, C, Y, and Bk are sequentially transferred in this manner, the sheet passes through the fixing unit 1026, and is discharged after the toner is fixed on the sheet.

[0010]

In the prior art described above, it is basically necessary that the image scanner section for reading a document and the printer section for outputting a copied image operate synchronously. That is, the R, G, and B image signals read by the CCD sensor are processed by the signal processing unit for each pixel, converted into M, C, Y, and Bk, and sequentially sent to the printer unit to be transferred onto the photosensitive drum. It is written with a laser to form a copied image. However, in this conventional example, the image is formed on any one of M, C, Y, and Bk, and the image forming process is repeated for each of them, so that the original is read four times in succession.

The reading operation of the document need not always be performed four times in a row, but the image data read only once is stored in the temporary storage means and synchronized with the image formation of each of M, C, Y and Bk. A configuration for reading and outputting the stored image data is also conceivable.

However, in the former configuration, it is not necessary to store the image data in the storage means. However, since the scanner unit and the printer unit need to operate at the same time, for example, the fixing unit of the printer unit (normal heating and fixing) If the heater unit is not sufficiently heated, the printer unit is in the standby state, so that the copying operation and the original reading operation cannot be performed.
Also, when copying a plurality of copies of a plurality of documents, it is necessary to perform an operation of reading one document a plurality of times corresponding to the output of the plurality of copies, and this operation must be performed for each of the plurality of documents. The time that must be spent is enormous.

In the latter configuration, the image scanner can perform an original reading operation without synchronizing with the printer unit. In the case of a multiple-copy output, the original reading operation may be performed once for one original. Will be. However, since the capacity of image data to be stored in the storage means is extremely large, it is difficult to store a plurality of document images simultaneously. Therefore, a plurality of original images are read at once,
Attempting to replace pages or combine and output a plurality of original images after reading is completed, requires a huge storage device, which is not practical. Also, layout synthesis or the like by enlarging or reducing stored image data cannot be performed.

An object of the present invention is to solve the above-mentioned problems.

[0015]

Therefore, according to the present invention, there is provided means for separating an original image into colors and reading as color digital signals for each pixel, and temporarily storing the read R, G, B color image signals. Means, means for generating compressed image data obtained by removing redundancy from the image signal, means for storing the compressed image data, and means for detecting a feature amount for each pixel of the original image while reading the original. Means for generating flag data for identifying the feature of the pixel from the detected feature amount; means for temporarily storing the flag data; and generating compressed flag data from which redundancy is removed from the flag data. Means for storing the compressed flag data and the compressed flag data, wherein the stored compressed image data and the compressed flag data are read from the storage means. And, transferred to the printer unit in association with each pixel to extract the image data and flag data to form the output color image, configured as the so as to solve the above problem.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an example of a configuration for implementing the present invention.

(Reading Unit) A document to be copied is placed on a document table glass (not shown) of the scanner unit 101 and read. As in FIG. 10, the scanner unit 101 digitally reads a document image for each pixel using a color three-line CCD and transfers a color image signal to the input image processing unit 102. The input image processing unit 102 performs shading correction, CCD line-to-line correction, color correction, and the like on the RGB color image signal sent from the scanner unit.
The well-known image processing is performed.

Reference numeral 103 denotes a block for performing image area separation processing on the input image-processed color image signal output from 102. Image characteristics such as a photograph area, a character area, and a halftone area for each pixel of the input image. And an image area separation processing unit that generates flag data representing an attribute of each image area.

(Image Area Separation Processing) The image area separation processing section will now be described. The image area separation process is to extract a characteristic of an original image and generate a signal indicating an image area attribute (hereinafter, referred to as flag data) in order to perform optimal image processing according to the characteristic of an image included in the original image. Done in For example, in a manuscript, a continuous tone full-color photograph area, a solid black character area, or a halftone print area such as newspaper printing,
Usually, various image areas are mixed. If these are uniformly processed and output in the same image processing procedure, the output image generally does not often have a desirable image quality. Therefore, in the first embodiment, the attribute of the image data included in the original image is detected using the color image signal input from 102, and flag data for identifying the attribute is generated. FIG. 2 shows a specific procedure.

FIG. 2 shows an example of a document image.
This shows a state in which a silver halide photograph area 202, a black character area 203, a halftone dot printing area 204, and a color graphic area 205 are mixed in one page 201. Here, the scanner section scans the original image with a color CCD sensor and outputs color digital signals (R,
G, B). The read RGB signals have characteristics determined by attributes of each area of the image.
The signal value (R,
When the G signal of (G, B) is plotted in the arrangement direction of the CCD, for example, the result is as shown in FIG. 302, 3 in FIG.
03, 304, and 305 are 202 to 20 in FIG.
The horizontal axis indicates the pixel position in the CCD and direction, and the vertical axis indicates the pixel value closer to white (brighter) in the read signal value as it goes upward. Represents.

The feature of each area will be described. Since 202 is a silver halide photographic area, the change 302 due to the position of the image signal to be read is relatively gradual, and the difference 312 between the pixel values at a short distance is a small value. Become. Reference numeral 303 denotes a characteristic of the black character area 203. Since a black character is written on a white background, the plot of the signal value is such that the read signal value changes abruptly from the white background portion 313 to the character portion 323. Reference numeral 304 denotes the characteristic of the halftone dot region 204. The halftone dot region is a repetition of a white background 314 and a halftone dot 324 printed thereon. It becomes a characteristic that repeats at a high frequency. 305 is a plot diagram of a graph area. The signal value sharply decreases at the edge 315 of the graphic,
The inner colored portion 316 has such a characteristic that a certain intermediate level follows.

In order to determine these attributes, the above-described features of each area may be read from the read signal value to make the determination. For this purpose, the change amount of the image data in the vicinity of the pixel of interest or the integrated value of the change amount in a certain section, the luminance value of a peripheral pixel (white background or colored background), the white to black of the image data in the certain section It is possible to use a feature extraction method using a known method such as the number of times of change, and to use a well-known attribute discrimination method based on the feature extraction method.

FIG. 4 shows an example of the attribute flags generated for the document image of FIG. 2 in this way. Here, three types of flags, ie, a character flag, a graphic flag, and a halftone flag, are generated as attribute flags (flag data), but are not limited to them. FIG. 4A shows a character flag, in which a pixel represented by black in the figure is a pixel having a character attribute, and a character flag = 1 is generated, and in other cases, a character flag = 0 (white portion in the figure). . (B) is a graphic flag, which is 1 in a graphic area and becomes 0 in other cases, and (c) is a halftone flag which represents an area which becomes 1 in a halftone area and becomes 0 in other cases. .
Since the silver halide photographic area does not correspond to any of these, all the flags are set to 0, and FIG. 4 does not appear.

When the attribute of the image is detected for each pixel by the above-described image area separation processing, next, the second input image processing unit 104 performs image processing according to the image attribute. Here, for example, the high-frequency component of the image is emphasized for the character region to enhance the sharpness of the character, and the halftone dot region is subjected to a so-called low-pass filter process to remove a moire component unique to the digital image. Can be performed. Switching between these processes can be performed in pixel units according to the attribute flag data generated in 103.

(Storage of image data) Image data read by a scanner and subjected to various input image processing, and attribute flag data generated by the above procedure are stored in the image memories 1 and 106 of the flag memories 105 and 106, respectively. Is stored temporarily. At this time, the image data and the attribute flag data are stored as an entire document page or as a partial image of a predetermined size of one page. With this storage configuration, the image data and the flag data can be held independently for a period corresponding to the time required for the compression processing that changes variously according to the data amount of one page.

The temporarily stored image data and attribute flag data are compressed by the data compression unit 109 and stored in the storage device 110. Desirably, 110 is a storage unit such as a semiconductor storage device that can process data at high speed. The data compression unit performs different data compression processing on the image data and the flag data. In other words, image data is irreversible, such as JPEG compression, but is subjected to high-efficiency compression processing that makes image degradation less noticeable in consideration of human visual characteristics. It is preferable to use a reversible compression method such as JBIG compression in order to prevent loss or change of attribute flag information. With this configuration, it is possible to reduce the amount of data using an appropriate compression method according to the type of data. In this way, the image data and flag data which have been subjected to different compression processes are stored in the document 110 in units of one page of the document. The stored data may also be written to 111 auxiliary storage devices. The auxiliary storage device is preferably a medium, such as a hard disk, which can store a large amount of data although the recording speed is slightly slow. As described above, by using an auxiliary storage device such as a hard disk in addition to the semiconductor storage device, a document image of many pages can be efficiently stored.

(Reading of Image Data) 110 or 11
The image data and the attribute flag data stored in 1 are read out for output from the printing unit,
The decompressed data is decompressed by the data decompressor 2 and written into the image memory 2 at 114 and the flag memory 2 at 115, respectively. At this time, the pixel density conversion unit 113 may convert the pixel density of the stored image data. This means, for example, to enlarge the stored image data,
Or, it is used when the user wants to print out the image in a reduced size, or when he / she wants to output a plurality of stored pages by synthesizing the layout on one print output sheet.

The composite output of a plurality of pages is, for example, as shown in FIG. That is, two original images 501 and 5
02 is stored in the storage device in advance. This is a case where two sheets are combined on an output sheet of the same size as the original to obtain a print output like 503. For this purpose, first, the stored image data 501
From the storage means to decompress the compressed data,
The image data is reduced at a predetermined magnification by the pixel density conversion unit 3 and rotated 90 degrees to the left by a rotation processing unit (not shown) and written into a predetermined area of the image memory 2 (an area corresponding to 504 in FIG. 5).

Next, the image data 502 is read out and subjected to decompression, resolution conversion and rotation processing in the same manner, and
Write to the area corresponding to 05. At this time, originals A and B
Are decompressed, converted in resolution, and rotated (same magnification and same rotation as the image data) in the same manner and written in the corresponding area of the flag memory 2. As described above, since the variable-magnification rotation processing is performed on the flag data corresponding to the image data in the same manner, the adaptive image processing described later according to the flag data can be performed even when performing the layout printing. Here, it is desirable to apply different methods to the resolution conversion of the image data and the resolution conversion of the flag data, respectively. For example, a known method such as a linear interpolation method or a bicubic spline interpolation method can be applied to image data. It is desirable to use a resolution conversion method suitable for binary data such as a nearest neighbor processing method for the resolution conversion of the flag data.

As described above, in the resolution conversion, by performing interpolation according to the type of data such as image data and flag data, image data after resolution conversion with high accuracy can be obtained.
Acquisition of flag data can be realized.

(Output of Image Data) When the image data and the flag data temporarily stored in the image memory 2 and the flag memory 2 reach a predetermined size, they are transferred to the output image processing section 116. In the output image processing unit 116, R
Well-known image processing for printing and outputting GB image data, that is, luminance / density conversion, RGB → CMYK conversion,
Processing such as gamma correction, binarization processing, and the like is performed, and the image data is transferred to the printer unit 117. The printer 117 drives the laser with the transferred CMYK image signals, and
A visible image is formed and output on transfer paper in the same procedure as in the above.

Here, the flag data stored in the flag memory 2 is used for switching the processing of the output image processing unit 116. That is, in the photograph area and the character area, RGB → C
By making the masking coefficients of the MYK conversion different, the quality of the output image can be improved. For example, for a character area, that is, for a pixel with a character flag = 1, a conversion coefficient such that a black character can be reproduced with only black toner (that is, a coefficient such that C, M, and Y = 0 when the image data is achromatic). And C, even if it is achromatic otherwise
M and Y do not become 0, and a coefficient that can reproduce deep black can be used. In the binarization processing, the C, M, Y, and K signals are converted into binary signals of 0 or 1 by using well-known error diffusion processing or dither processing. The content of the binarization process is also determined by the attribute flag data, such as applying error diffusion processing because sharpness is prioritized, and applying dither processing in photographs and halftone dot areas because the gradation is important. By switching, the image quality of the output image can be improved.

An example of a block diagram of the configuration at this time is shown in FIG.
Shown in The image memory 2 at 114, the flag memory 2 at 115, and the printer unit 117 are the same as those in FIG. The RGB color image data read from the image memory 2 is converted into two RGB data of 601 and 602 in parallel.
The signals are input to the YK conversion circuit and are converted into CMYK image signals independently. Either the output of 601 or 602 is selected by the selector 1 of 603 according to the flag signal of the flag memory. When a conversion coefficient for a character area is set in 601 and a coefficient in other cases is set in 602, the output of 601 is selected when the character flag in the flag memory = 1, and the character flag is set. When = 0, the output 602 is selected.

The output of the selector 1 is also separated into two systems in parallel, one of which is a gamma correction circuit 1
Is input to the selector 2 of 608 as a binary CMYK signal through the error diffusion binarization processing unit. The other is 60
The gamma correction circuit 2 of No. 5 and the dither processing binarization circuit of 607 are also input to the selector 2 of 608 as binary CMYK signals.

The selector 2 selects one of the outputs 606 and 607 and transfers it to the printer unit. Here, since the error diffusion process is selected in the character area and the graph area, the character flag = 1 or the graphic flag = 1 , The selector 2 selects the output of 606, otherwise, 6
07 output may be selected.

<Other Embodiments> In the above description, the flow of image data from the scanner unit 101 in FIG. 1 has been described. Similarly, image data input from the external communication path 119 via the communication interface 118 is described. The above processing can be applied to this.

A typical example of the image data sent from 119 is image data described in so-called PDL (Page Description Language). The PDL data input here is a group of commands that describe an image. If the PDL data is interpreted and converted into bitmap data similar to the image read by the scanner, the first embodiment can be applied as it is.

That is, the PDL data input from 118 is converted by the interpreter 108 into an intermediate language format called a display list. This display list is sent to a RIP (raster image processor) 107 to develop it into bitmap data. The developed image data is stored in the image memory 1 of 105. At this time, the RIP 107 simultaneously generates the attribute information of the developed image data as flag data and stores it in the flag memory 1 of 106.

Here, it is not necessary to generate the flag data by the image area separation processing referring to the image data as described in the first embodiment, and the PDL data input to the RIP is held for each component. The flag data of the corresponding pixel of the developed image may be generated with reference to the attribute information (such as a photograph, a character or a graphic). That is, P which generates a character part
When a DL command is input to the RIP, the RIP may generate a bitmap image of the character data and generate a character flag = 1 as flag data corresponding to an area in which the character is generated. After the image data and the flag data are generated as described above, the subsequent processing can be handled exactly the same as in the first embodiment. As a result, for example, image data read from a scanner and P
When performing printing by synthesizing data described by the DL, printing of an optimal character area, halftone area, and photograph area according to the flag data can be realized by similar processing.

<Other Embodiment 2> In the above description, the image data and the flag data are compressed so as to effectively utilize the resources of the storage means. Of course, the compression means will be described in the embodiment. In addition to the configuration described above, it is also possible to use other compression methods including non-compression.

<Another Embodiment of the Present Invention> A program for operating the configuration of the above-described embodiment so as to realize the functions of the above-described embodiment is stored in a storage medium, and the program stored in the storage medium is stored in a code. A processing method of reading the present embodiment and executing the present embodiment on a client computer and a server computer is also included in the category of the above-described embodiment, and a storage medium storing the above-described program is also included in the above-described embodiment.

As such a storage medium, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, magnetic tape, nonvolatile memory card, and ROM can be used.

The present invention is not limited to the one which executes the processing by the program stored in the storage medium alone, and operates on the OS in cooperation with the functions of the other software and the expansion board and operates in the above-described embodiment. Is also included in the category of the above-described embodiment.

[0045]

As described above, according to the present invention, it is possible to easily handle images, obtain a high-quality image output without imposing a great burden on the user, and reducing the image storage capacity. It becomes possible.

Further, the same processing can be performed between the case where a document image is read and printed and the case where a printed image using a page description language is output, and optimal image processing is performed on individual parts constituting the image. Can be performed, and in any case, a high-quality output image can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a configuration for implementing the present invention.

FIG. 2 is an example of a document image applied to the present invention.

FIG. 3 is a diagram illustrating an image area separation process according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating flag data according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a layout synthesis output according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of an output image processing configuration according to the present invention.

FIG. 7 is a diagram illustrating a conventional color image copying apparatus.

Claims (37)

[Claims] A compression unit that compresses input image data; a generation unit that generates, from the image data, flag data indicating characteristics of an image corresponding to the image data; a compression unit that generates compressed flag data from the flag data Data compression means, image data storage means for storing the compressed image data, flag storage means for storing the compressed flag data, image data storage means for the compressed image data and flag data, and flag data An image processing apparatus comprising: output means for outputting image data and flag data decompressed on a pixel-by-pixel basis after being obtained from a storage means and decompressed, to a printer unit. 2. The image processing apparatus according to claim 1, wherein the flag data is a character flag, a graphic flag, and a halftone flag. 3. The image processing apparatus according to claim 1, wherein the feature of the image is a change in image data near a pixel of interest. 4. The image processing apparatus according to claim 1, wherein image processing is performed on the decompressed image data according to the decompressed flag data. 5. When the flag data is a character flag,
The image processing apparatus according to claim 4, wherein sharpness enhancement is performed on the image data. 6. When the flag data is a halftone flag,
The image processing apparatus according to claim 4, wherein a low-pass filter process is performed on the image data. 7. The image processing apparatus according to claim 1, wherein the image data is subjected to irreversible compression that makes image degradation less noticeable in consideration of human perceptual characteristics. 8. The image processing apparatus according to claim 1, wherein the flag data is subjected to lossless compression. 9. The apparatus according to claim 1, wherein the input image data is temporarily stored as a partial image for one page of the image or a predetermined size before being compressed. Image processing device. 10. The image data storage means and the flag data storage means use a storage medium capable of high-speed data processing and a storage medium which has a low recording speed but can store a large amount of data. The image processing apparatus according to any one of the preceding claims. 11. The image processing apparatus according to claim 1, further comprising image processing means for performing at least one of resolution conversion processing, rotation processing, and layout synthesis processing on both the decompressed image data and the flag data. apparatus. 12. The image processing apparatus according to claim 11, wherein one of a linear interpolation method and a bicubic spline interpolation is used for resolution conversion of the image data. 13. The image processing apparatus according to claim 11, wherein the resolution conversion for the flag data includes performing a resolution conversion suitable for binary data. 14. The image processing apparatus according to claim 2, wherein in the color conversion processing of the decompressed image data, a color conversion coefficient is changed according to the decompressed character flag data. 15. The image processing apparatus according to claim 2, wherein in the binarization processing of the decompressed image data, error diffusion processing and dither processing are switched according to the decompressed character flag and graphic flag. 16. The image according to claim 1, wherein the input image data is data described in a page description language, and the flag data is attribute information of the page description language. Processing equipment. 17. Compressing input image data, generating flag data indicating characteristics of an image corresponding to the image data from the image data, generating compressed flag data from the flag data, Storing the decompressed image data, performing the compressed flag data, obtaining and decompressing the compressed image data and flag data, and outputting the decompressed image data and flag data in pixel units to the printer unit. An image processing method comprising: an output unit. 18. The flag data according to claim 17, wherein the flag data is a character flag, a graphic flag, and a halftone flag.
The image processing method described in the above. 19. The image feature according to claim 1, wherein the feature of the image is a feature of a change in image data near a pixel of interest.
7. The image processing method according to 7. 20. The image processing method according to claim 17, wherein image processing is performed on the decompressed image data according to the decompressed flag data. 21. The image processing method according to claim 20, wherein when the flag data is a character flag, sharpness enhancement is performed on the image data. 22. The image processing method according to claim 20, wherein when the flag data is a halftone dot flag, the image data is subjected to low-pass filtering. 23. The image processing method according to claim 17, wherein the image data is subjected to irreversible compression that makes image degradation less noticeable in consideration of human perceptual characteristics. 24. The image processing method according to claim 17, wherein the flag data is subjected to lossless compression. 25. The image processing apparatus according to claim 17, wherein the input image data is temporarily stored as a partial image of one page or a predetermined size of the image before being compressed. Image processing device. 26. The image data storage and flag data storage using a storage medium capable of high-speed data processing and a storage medium that is slow in recording speed but capable of storing a large amount of data. The image processing method described in the above. 27. The image processing method according to claim 17, wherein at least one of a resolution conversion process and a rotation process is performed on both the dislodged image data and the flag data. 28. The image processing apparatus according to claim 27, wherein one of a linear interpolation method and a bicubic spline interpolation is used for the resolution conversion of the image data. 29. The image processing method according to claim 27, wherein the resolution conversion for the flag data includes performing a resolution conversion suitable for binary data. 30. The image processing method according to claim 18, wherein in the color conversion processing of the decompressed image data, a color conversion coefficient is changed according to the decompressed character flag data. 31. The image processing method according to claim 18, wherein in the binarization processing of the decompressed image data, error diffusion processing and dither processing are switched according to the decompressed character flag and graphic flag. 32. The image according to claim 17, wherein the input image data is data described in a page description language, and the flag data is attribute information of the page description language. Processing method. 33. A storage medium storing a code for executing the image processing method according to claim 17. Description: 34. A means for color-separating an original image and reading it as a color digital signal for each pixel; a means for temporarily storing the read R, G, B color image signals; Means for generating compressed image data from which is removed, means for storing the compressed image data, means for detecting a feature amount for each pixel of the original image while reading the original, and Means for generating flag data for identifying a feature of a pixel; means for temporarily storing the flag data; means for generating compressed flag data obtained by removing redundancy from the flag data; and storing the compressed flag data Means for reading the stored compressed image data and compressed flag data from the storage means, An image processing system, characterized in that decompresses the Gudeta transferred to the printer unit in association with each pixel to form an output color image. 35. A means for inputting and temporarily storing R, G, B color image signals, means for generating compressed image data from which redundancy is removed from the image signals, and storing the compressed image data Means for inputting, for each pixel, flag data for identifying a feature of the input image signal simultaneously with the input of the color image signal; means for temporarily storing the flag data; Means for generating compressed flag data from which the compressed flag data has been removed, and means for storing the compressed flag data. An image processing system comprising: reading out the stored compressed image data and compressed flag data from storage means; And an image processing system for decompressing the flag data, associating the decompressed data on a pixel-by-pixel basis and transferring the decompressed data to a printer unit to form an output color image. 36. A means for color-separating a document image and reading it as a color digital signal for each pixel; a means for temporarily storing the read R, G, B color image signals; An image processing system comprising: means for detecting a feature amount of each pixel of a document image; means for generating flag data for identifying a feature of the pixel from the detected feature amount; and means for storing the flag data And reading out the stored image data and flag data from the storage means, converting the image data and flag data into respective pixel densities at the same magnification, and transferring them to the printer unit in association with each pixel. An image processing system for forming an output color image. 37. A means for inputting and temporarily storing R, G, B color image signals, and simultaneously inputting the color image signals, and inputting flag data for identifying characteristics of the input image signals for each pixel. And a means for temporarily storing the flag data, comprising: reading out the stored image data and flag data from storage means; and decompressing the image data and flag data. An image processing system, wherein each pixel density is converted at the same magnification and then transferred to a printer unit in association with each pixel to form an output color image.