JP2001211318A - Device and method for image processing, storage medium, and image processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the handing of an image, to reduce storage capacity, and to improve image deterioration resulting from the capacity reduction. SOLUTION: This device has a compressing means which compresses inputted image data, a generating means which generates flag data showing features of the 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 data storage means which stores the compressed flag data, and an output means which obtains and decompresses the compressed image data and flag data from the image data storage means and flag data storage means and then outputs the decompresses flag data and the decompressed data having been processed by filtering determined adaptively to the compressibility of the compression.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing apparatus, an image processing method storage medium, and an 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.

[0005] In FIG. 7, reference numeral 701 denotes an image scanner which reads an original and performs digital signal processing. Reference numeral 702 denotes a printer unit.
This portion prints out an image corresponding to the document image read by the image scanner 701 on a sheet in full color.

In the image scanner 701, 70
Reference numeral 0 denotes a mirror pressure plate, and a platen glass (hereinafter, platen) 7
The original 704 on the original 03 is illuminated by a lamp 705, guided to mirrors 706, 707, 708, and three-line solid-state image sensor (hereinafter referred to as CCD) 7 by a lens 709.
An image is formed on the image 10, and three image signals of red (R), green (G), and blue (B) as full-color information are sent to the signal processing unit 711. Note that 705, 70
Numeral 6 denotes a speed v, and 707 and 708 move at a speed of 1/2 v mechanically in a direction perpendicular to the electrical scanning (main scanning) direction of the line sensor, thereby scanning the entire original surface (sub-scanning).
I do. Here, the original 704 is read at a resolution of 400 dpi (dots / inch) together with the main scanning and the sub-scanning.

[0005] In a signal processing section 711, the read image signal is electrically processed, decomposed into magenta (M), cyan (C), yellow (Y), and black (Bk) components. Send to 702. Further, M, C,
One component of Y and Bk is sent to the printer unit 702, and one printout is completed by a total of four document scans.

The image signals of M, C, Y, and Bk sent from the image scanner unit 701 are sent to a laser driver 712. Laser driver 712
Corresponds to the semiconductor laser 71 according to the image signal sent.
3 is modulated. The laser light is reflected by the polygon mirror 71
4. Scan the photosensitive drum 717 via the f-θ lens 715 and the mirror 716. Here, similarly to reading, 400 dpi (dots / inc.
h) written at the resolution.

Reference numeral 718 denotes a rotary developing unit, which includes a magenta developing unit 719, a cyan developing unit 720, a yellow developing unit 721,
The developing unit includes a black developing unit 722. The four developing units alternately contact the photosensitive drum 717 to develop the electrostatic development formed on the photosensitive drum with toner.

Reference numeral 723 denotes a transfer drum, which winds a sheet supplied from a sheet cassette 724 or 725 around the transfer drum 723 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 726, 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.

It is not always necessary to perform the document reading operation four times in a row, but the image data read only once is stored in the temporary storage means and is 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.

When a plurality of originals are copied in a plurality,
It is necessary to perform an operation of reading one original a plurality of times in accordance with the output of a plurality of copies, and this operation must be performed for each of the plurality of originals, so that the time that a user must spend is enormous. .

In the latter configuration, the scanner unit can perform the original reading operation without synchronizing with the printer unit.
Also, in the case of a copy output of a plurality of copies, the document reading operation may be performed once for one document. But,
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 at the same time. Therefore, if a plurality of document images are read in a batch and replacement of pages or combined output of a plurality of document images is realized after the reading is completed, a huge storage device is required, which is not practical. Further, even if compression is performed to reduce the storage capacity, image degradation cannot be avoided.
An object of the present invention is to solve the above problems.

[0015]

Therefore, according to the present invention, there is provided an input means for separating an original image into colors and reading it as a color digital signal for each pixel, and temporarily storing R, G, B color image signals read by the input means. Image data storage means for temporarily storing, image data compression means for generating compressed image data obtained by removing redundancy from the image signal, compressed image data storage means for storing the compressed image data, and simultaneous reading of the original. Detecting means for detecting a characteristic amount of each pixel of a document image; generating means for generating flag data for identifying a characteristic of the pixel from the detected characteristic amount; and flag data for temporarily storing the flag data Storage means; flag data compression means for generating compressed flag data from which redundancy is removed from the flag data; A compressed flag data storage means for storing the compressed image data and compressed flag data stored in the compressed image data and compressed flag data storage means, and decompressing the image data and flag data. Decompressing means, output means for forming the output color image by transferring the image data and the flag data decompressed by the decompressing means to the printer unit in a pixel unit, A compression / expansion control means for controlling the means, and a compression rate associated with the compression / expansion are calculated, and a spatial filter coefficient of an output image processing means for forming an output color image is selected according to the compression rate, thereby forming an output color image. By doing so, it is possible to eliminate the above-mentioned inconveniences, perform compression / decompression, and reduce storage capacity. In this case, it is possible to solve the problem of image sharpness due to image quality deterioration, especially deterioration of image sharpness due to large changes in spatial frequency characteristics, by performing correction by selecting a spatial filter processing coefficient according to the compression ratio as described above. I made it.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> An 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 the case of FIG. 10, the scanner section digitally reads a document image for each pixel using a color 3-line CCD and transfers a color image signal to the input image processing section 102. The input image processing unit 102 performs known image processing such as shading correction, CCD line-to-line correction, and color correction on the RGB color image signals sent from the scanner unit.

Reference numeral 103 denotes a block for performing image area separation processing on the input image-processed color image signal output from the image processing unit 102. Image characteristics such as a photograph area, a character area, and a halftone area are provided 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. It is performed. For example, a document usually contains various image areas such as a continuous tone full-color photograph area, a solid black character area, and a halftone print area such as newspaper printing. 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 by 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 and 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 respectively 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. Explaining the characteristics of each area, since 202 is a silver halide photographic area, the change 302 depending on the position of the image signal to be read is relatively gentle, and the difference 312 between the pixel values at a short distance becomes a small value. Three
03 is a characteristic of the black character area 203, and a black character is written on a white background.
The characteristic is such that the read signal value changes rapidly from 13 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. At the edge portion 315 of the graphic, the signal value sharply decreases, and the inside colored portion 316 has such a characteristic that a constant 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 figure flag, which is 1 in a graphic area and becomes 0 otherwise, and (c) is a halftone flag which represents an area which becomes 1 in a halftone area and becomes 0 in other areas. I have. Since the photograph area does not correspond to any of these, all the flags are set to 0 and will not appear in FIG. When the attribute of the image is detected for each pixel by the above-described image area separation processing, 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 enhanced 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 moiré component unique to the digital image. Such processing can be performed. Switching between these processes can be performed in pixel units according to the attribute flag data generated in 103.

(Storing of Image Data) The image data read by the scanner and subjected to various input image processing, and the attribute flag data generated by the above procedure are each 1
05 is temporarily stored in the flag memory 1 of the image memory 1 and 106. At this time, the image data and the attribute flag data are stored as one whole page of the document or as a partial image of a predetermined size of one page. With this storage configuration, it is possible to hold the image data and the flag data 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 in order to reduce the redundancy and perform encoding. After the data compression by the data compression unit 109, the compressed data is sequentially transferred to the storage device 110 and stored in the storage device 110. The compression / decompression control unit 113 calculates a compression ratio (compressed data amount / original data amount) accompanying the compression. The storage device 110 is preferably a high-speed storage device such as a semiconductor storage device. The data compression unit performs different data compression processing on the image data and the flag data, respectively.
In other words, the image data is irreversible, such as JPEG compression, but is subjected to a highly efficient compression process that makes image degradation less noticeable in consideration of human visual characteristics.
It is desirable to use a reversible compression method such as JBIG compression in order to prevent loss or change of attribute flag information from occurring for flag data.

With such a configuration, data reduction using an appropriate compression method according to the type of data can be realized. In this way, image data and flag data subjected to different compression processing 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 preferably uses 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 a semiconductor storage device, it is possible to efficiently store and accumulate many pages of document images.

(Reading of Image Data) 110 or 1
The image data and the attribute flag data stored in
Read for output from the print unit. The data decompression unit 112 receives from the compression / decompression control unit 113 information such as factors used for compressing image data and attribute flag data, a compression ratio, and a code amount allocated to each block. The compressed data is decompressed according to the above circumstances, and the decompressed image data and attribute flag data are written to the image memory 2 114 and the flag memory 2 115, respectively.

(Data compression / expansion of image data) FIG.
It is a flowchart which shows the operation | movement procedure from the data input to memory storage in the data compression / decompression process accompanying the accumulation | storage and readout of the image mentioned above. In the figure, in step S1, the input of image size information, that is, the data compression unit 109 and the compression / decompression control unit 113
105, a process of receiving image data and attribute flag data from the flag memories 1 and 106.

In step S2, the compression / expansion controller 113 sets a target compression ratio. The target compression ratio is set in order to efficiently compress the size information of the input image data and attribute flag data to the full memory capacity of the storage device 110. For example, if the memory capacity for the maximum image size of the printer is A, the memory capacity owned by the storage device 110 is B, and the memory capacity for the size of the input image data and attribute flag data is C, the target compression rate is C /
Set to B. If the memory capacity such as A = B exists in the storage device 110, no compression is necessary, and if B = C, no compression is necessary.

In step S3, a quantization condition is selected according to the determined target compression ratio, and the information is transmitted from the compression / decompression control unit 113 to the data compression unit 109, and to the data decompression unit 112 during decompression. In step S4, data compression is performed in accordance with the quantization condition set by the compression / decompression control unit 113, and the compressed data is stored in the storage device 110.
(Step S5).

In step S6, it is determined whether or not compression of all the images of the input size has been completed. If the result is NO, the processes in steps S3 to S5 are repeated. In this way, the image information for the input size is stored in the storage device 110. At the time of decompression, the data decompression unit 112
However, based on the condition information at the time of compression from the data compression unit 109, decoding is performed in synchronization with the timing of the printer engine. By performing such compression / decompression, 1 /
It is possible to reduce the memory capacity such as 4, 1/8, and 1/12.

(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. The output image processing unit 116 uses RGB
Image data for print output, that is, processing such as luminance density conversion, RGB → CMYK conversion, gamma correction, and binarization processing, and the like, and transfers the data to the printer unit 117. The printer unit 117 performs laser driving based on the transferred CMYK image signals, and forms and outputs a visible image on transfer paper in the same procedure as in FIG.

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 coefficients of the MYK conversion different, the image 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, M, and Y are 0 even if they are achromatic.
Instead, a coefficient that can reproduce deep black can be used.

In the binarization process, C, M, Y, K
The signal is converted into a binary signal of 0 or 1 using a well-known error diffusion process or dither process. At this time, the sharpness of the output image is prioritized in the character region and the graph region, so the error diffusion process is applied. In a photograph or a halftone dot region, gradation is emphasized, so that dither processing is applied. For example, the content of the binarization processing is switched by attribute flag data, so that the image quality of an output image can be improved.

Here, the image data processed by the data compression unit 109 and the data decompression unit 112 may be accompanied by image deterioration depending on the compression ratio. To increase the compression ratio,
Since the high-frequency component band is cut, noise called mosquito noise occurs, causing image degradation, and as the compression ratio increases, the spatial frequency characteristics become larger than before compression, This results in a decrease in image contrast, that is, a so-called nemi image. Therefore, the output image processing unit 116 selects and performs image processing to be performed by the output image processing unit 116 in order to correct the above-described image degradation that occurs according to the above-described compression ratio.

FIG. 6 shows an example of the configuration of the output image processing section 116. 114 image memories 2, 115
The flag memory 2 and the printer unit 117 are the same as those in FIG. The RGB color image data read from the image memory 2 includes two RGs 601 and 602 in parallel.
B → CMYK conversion circuit
It is converted to a YK image signal. The outputs of 601 and 602 are
The data is input to the spatial filter units 603 and 604, respectively, is subjected to filtering processing independently, and performs correction on image data for each spatial frequency component, such as smoothing and edge enhancement. The outputs of 603 and 604 are output to the selector 1 of 606 according to the flag signal of the flag memory.
Selects one of them. When the conversion coefficients for the character area are set in 601 and 603 and the coefficients in other cases are set in 602 and 604, the output of 603 is selected when the character flag in the flag memory = 1. When the character flag = 0, the output 604 is selected.
Reference numeral 605 denotes a spatial filter coefficient storage unit used for the spatial filter units 603 and 604. The spatial filter coefficient storage unit 605 includes a compression / decompression control unit 1 not shown in FIG.
13 based on the compression ratio, and selects an optimal spatial filter coefficient corresponding to the compression ratio.
3, and transfer to 604. For example, when the compression rate is 100% (no compression), the standard coefficient is determined, and then the LUT and the compression rate when the compression rate is 50% (the data is compressed to a maximum of 1/2) in that order. LUT in case of 25% (data is compressed to 1/4 at the maximum), compression ratio is 1
LUT for 2.5% (data is compressed to 1/8 at maximum), compression ratio is 8.3% (data is compressed to 1/12 at maximum)
A spatial filter is prepared in the case of (1), and according to the compression rate at the time of compression / expansion, the filter is switched to a filter that improves the contrast and improves noise removal as the compression rate increases. As a result, the spatial frequency characteristic that changes depending on the compression ratio can be corrected to a constant value, for example, the same as the spatial frequency characteristic without compression, regardless of the compression ratio.

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 611 as a binary CMYK signal through the error diffusion binarization processing unit. The other is 60
The gamma correction circuit 2 and the dither processing binarization circuit 610 are also input to the selector 2 611 as binary CMYK signals.

The selector 2 selects the output of either 609 or 610 and transfers it to the printer unit. Here, since error diffusion processing 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 609, otherwise 61
An output of 0 may be selected.

<Other Embodiment 1> In the above description, FIG.
Although the flow of image data from the scanner unit 101 has been described, the same filter correction as in the first embodiment can be applied to image data input from the external communication path 119 via the communication interface 118. .
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 describing an image, and the present invention can be applied as it is if it is interpreted and converted into bitmap data similar to an image read by a scanner. That is, the PDL data input from 118 is
Is converted into an intermediate language 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, when a PDL command for generating a character part is input to the RIP, the RIP generates a bitmap image of the character data and, at the same time, generates a character flag = 1 as flag data corresponding to the area where the character is generated. You just have to do it. 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.

<Other Embodiment 2> In the above description, the image data and the flag data are compressed to effectively use the resources of the storage unit. However, the compression unit 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 that is read as a computer and executed by a computer is also included in the scope of the above-described embodiment, and a storage medium that stores the above-described program is also included in the above-described embodiment. Examples of such a storage medium include a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, and a CD-RO.
M, a magnetic tape, a nonvolatile memory card, and a ROM can be used. Further, the present invention is not limited to the one that executes processing by the program alone stored in the above-described storage medium, and operates on the OS and executes the operation of the above-described embodiment in cooperation with other software and functions of the extension board. This is also included in the category of the above-described embodiment.

[0043]

As described above, according to the present invention, it is possible to easily handle an image, output a high-quality image without imposing a great burden on a user and reducing the capacity of an image storage means. It is possible to obtain. Since spatial filtering is performed in accordance with the compression rate of compression and decompression due to capacity reduction, it is possible to correct image degradation such as deterioration of image sharpness due to large changes in spatial frequency characteristics due to compression and decompression. Regardless of the compression ratio, a constant image quality can always be maintained.

Further, the same processing can be performed when a document image is read by a scanner and printed out, and when a printed image using PDL is output, the same processing can be performed. Processing can be performed, and in any case, a high-quality output image in which deterioration due to noise is reduced 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 example of the present invention.

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

FIG. 5 is a diagram showing an example of a flowchart of compression and decompression according to the present invention.

FIG. 6 is a block 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.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/41 H04N 1/40 101D 9A001 1/46 1/46 Z F-term (Reference) 2C087 AC08 BA04 BA05 BA07 BA12 BA14 BB10 BD05 BD24 BD36 BD40 5B057 CA01 CA18 CB01 CB16 CE03 CE05 CE06 CE13 CG01 CH12 DC30 5C077 MP02 MP05 NN08 NN11 NP07 PP01 PP03 PP15 PP27 PP28 PP32 PP37 PP47 PQ08 PQ12 PQ18 PQ22 RR21 A0C07A03A03A03B03A01 LB01 LC04 LC09 NA02 NA10 PA02 9A001 BB02 BB03 BB04 EE02 EE04 HH23 HH27 HH34 JJ35 KK42

Claims (35)

[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 An image data storage unit that stores the compressed image data, a flag data storage unit that stores the compressed flag data, and a flag that stores the compressed image data and the flag data in the image data storage unit. Output means for outputting the decompressed image data obtained by decompressing the data after obtaining the data from the data storage means and performing filter processing adaptively determined according to the decompressed flag data and the compression ratio in the compression. Characteristic image processing device. 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 image data after the filtering in accordance with 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 data according to claim 1, wherein the image data is subjected to irreversible compression in which deterioration of the image is made inconspicuous in consideration of human perceptual characteristics before being stored by the storage unit. Image processing device. 8. The image processing apparatus according to claim 1, wherein the flag data is subjected to lossless compression before being stored by the flag data storage unit. 9. The apparatus according to claim 7, 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. 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, wherein the compression ratio is determined by the capacity of the image data and the flag data, and the capacity of the image data storage unit and the flag data storage unit. 12. The image processing apparatus according to claim 1, wherein the filter processing corrects mosquito noise or a decrease in contrast caused by the compression. 13. The filtering process according to claim 1, wherein the filtering process is performed in accordance with the compression ratio so that the image data has the same spatial frequency characteristic when the compression is not performed. Image processing device. 14. An image data obtained by subjecting the image data to one of a color correction process for a character and a color correction process for a character other than a character according to the decompressed character flag data is selectively output. The image processing apparatus according to claim 1, wherein: 15. The image processing is a binarization processing,
5. The image processing apparatus according to claim 4, wherein image data obtained by subjecting the filtered image data to error diffusion processing and dither processing based on the decompressed character flag and graphic flag are selectively output. 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. A method for compressing input image data, generating flag data indicating characteristics of an image according to the image data from the image data, and generating compressed flag data from the flag data. Storing the compressed image data, storing the compressed flag data, decompressing the compressed image data and the flag data, and according to the decompressed flag data and the compression ratio in the compression. An image processing method, comprising outputting image data that has been subjected to adaptively determined filter processing after the decompression. 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 processing method according to claim 17, wherein the feature of the image is a change in image data near a pixel of interest. 20. The image processing method according to claim 17, wherein image processing is performed on the image data after the filtering in accordance with 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 said flag data is subjected to said 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 method. 26. 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 having a low 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 the compression ratio is determined by the capacity of the image data and flag data, and the capacity of the image data storage unit and the flag data storage unit. 28. The image processing method according to claim 17, wherein the filtering process corrects mosquito noise or a decrease in contrast caused by the compression. 29. The filtering process according to claim 17, wherein the filtering is performed in accordance with the compression ratio so that the image data has the same spatial frequency characteristics as when the compression was not performed. Image processing method. 30. Image data obtained by subjecting the image data to one of a color correction process for a character and a color correction process for a character other than a character according to the decompressed character flag data is selectively output. 18. The image processing method according to claim 17, wherein: 31. The image processing is a binarization processing,
21. The image processing method according to claim 20, wherein image data obtained by subjecting the filtered image data to error diffusion processing and dither processing based on the decompressed character flag and graphic flag are selectively output. 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. 34. Input means for separating a document image and reading it as a color digital signal for each pixel, and image data storage means for temporarily storing R, G, B color image signals read by said input means. Image data compression means for generating compressed image data from which redundancy is removed from the image signal; compressed image data storage means for storing the compressed image data; Detecting means for detecting the pixel value, generating means for generating flag data for identifying the feature of the pixel from the detected feature amount, flag data storing means for temporarily storing the flag data, and redundancy from the flag data. Flag data compression means for generating compressed flag data from which compression characteristics have been removed, and compressed flag data for storing the compressed flag data Decompression means for reading out the stored compressed image data and compression flag data from the compressed image data and compression flag data storage means, and decompressing the image data and flag data; An output unit for forming the output color image by transferring the image data and the flag data decompressed by the decompression unit to a printer unit in association with each pixel, and a compression unit for controlling each of the compression units and each decompression unit Decompression control means, calculating a compression rate associated with the compression and decompression, selecting a spatial filter coefficient of an output image processing means for forming an output color image in accordance with the compression rate, and performing output color image formation. Image processing system. 35. Image data storage means for inputting and temporarily storing R, G, B color image signals, image data compression means for generating compressed image data from which redundancy has been removed from the image signals, Compressed image data storage means for storing the compressed image data; detecting means for detecting a characteristic amount of each pixel of the original image while reading the original; and a flag for identifying the characteristic of the pixel from the detected characteristic amount Generating means for generating data; flag data storing means for temporarily storing the flag data; flag data compressing means for generating compressed flag data with redundancy removed from the flag data; and storing the compressed flag data Compression flag data storage means for storing compressed image data and compression flag data Decompression means for reading out the compressed image data and compression flag data storage means and decompressing the image data and flag data, and associating the image data and the flag data decompressed by the decompression means with each other on a pixel basis to the printer unit. Output means for transferring and forming an output color image; compression / expansion control means for controlling each of the compression means and decompression means; and calculating a compression rate associated with the compression / expansion, and outputting the color image in accordance with the compression rate. An image processing system for selecting a spatial filter coefficient of an output image processing means for forming an image and forming an output color image.