JPH09321992A - Image processing apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily control a plurality of colors of print output sequence by grasping an expansion time for each image information based on each compression rate in the image processing unit compressing image information in a plurality of colors and storing the compressed information. SOLUTION: A compression rate for each color at compression is calculated and stored and a compression rate for each color at expansion is compared (S503), and an expansion time Tc of color image information is calculated based on a smaller compression rate (S504, S505, S506). When the expansion time reaches the calculated expansion time Tc (S508), the expansion in all colors is finished and image forming is started (S510).

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 and a method thereof, for example, an image processing apparatus and a method thereof for compressing and storing image information.

[0002]

2. Description of the Related Art Generally, in an image processing apparatus for processing image information, the amount of information to be processed is enormous even for a single color. Therefore, for example, in a conventional image processing apparatus that reproduces an image in a single color, a configuration has been proposed in which image information is stored in a large-capacity storage device such as a hard disk.

For example, in a copying machine, this structure enables a large amount of image information to be stored, rearranges image information page by page, changes the page layout when printing on both sides, and Various additional functions have been realized, such as combining the read image and the previously stored image.

Also in an image processing apparatus for processing image information of a plurality of colors, the same function as in the case of a single color is realized by including a plurality of the above-mentioned mass storage devices for each color.

[0005]

However, the above conventional example has the following problems.

Particularly in an image processing apparatus that requires high-speed image processing, it is required that the data communication speed in a mass storage device such as a hard disk is also high.
However, since a storage device that realizes a high data communication speed is generally expensive, it has been difficult to inexpensively realize the above-described additional functions in an image processing device that performs high-speed image processing.

Therefore, a method of shortening the data transfer time in the storage device can be considered by compressing the image information to be stored. In this way, by improving the apparent data communication speed in the storage device, it becomes possible to use an inexpensive storage device for a high-speed image processing device.

However, when this method is applied, the compression rate differs depending on the image information, so that even image data of the same length will be stored with different data lengths as a result of compression. Therefore, for example, when the compressed image information is decompressed and read from the storage device and is printed out, it is difficult to grasp the time required for reading from the storage device.

Therefore, particularly in an image processing apparatus for processing a plurality of colors, the time required to read the image information to be output on the same page is different for each color, so the sequence control of print output is complicated. .

The present invention has been made to solve the above-mentioned problems, and in an image processing apparatus for compressing and storing image information of a plurality of colors, the expansion time for each image information is grasped and the print output sequence is performed. An object of the present invention is to provide an image processing device and a method thereof that facilitate control.

Another object of the present invention is to provide an image processing apparatus for compressing and storing image information, which grasps the expansion time of the compressed image information and facilitates print job scheduling control, and a method therefor. And

[0012]

As one means for achieving the above object, the image processing apparatus of the present invention has the following configuration.

That is, the compression means for compressing the image information of a plurality of colors for each color, the storage means for storing the image information compressed by the compression means for each color, and the image information read from the storage means. In an image processing apparatus having an expansion means for expanding and expanding each color and an image forming means for forming an image based on the image information for each color expanded by the expansion means, the image information is compressed by the compression means. It is characterized by having a calculating means for calculating the compression rate for each color for each color and a control means for controlling the image formation by the image forming means based on the compression rate for each color.

Further, there is a holding means for holding uncompressed image information for each color, and the expanding means expands the image read from the storage means for each color and expands it on the holding means. It is characterized by doing.

For example, the compression ratio for each color calculated by the calculation means is stored in the storage means together with the image information.

For example, the control means estimates the expansion time in the expansion means based on the minimum compression rate among the compression rates for each color.

For example, the control means estimates the expansion time of the image signal of the color having the minimum compression ratio in the expansion means, and estimates the expansion time of all colors in the expansion means according to the expansion time. Is characterized by.

For example, the control means is characterized in that the expansion in the expansion means is carried out for an expansion time of an image signal of a color having a minimum compression rate for each color.

Also, compression means for compressing the image information, storage means for storing the image information compressed by the compression means, decompression means for decompressing and expanding the image information read from the storage means, An image processing apparatus having an image forming means for forming an image based on the image information expanded by the expanding means, a calculating means for calculating a compression rate when the image information is compressed by the compressing means, and the compression means. Control means for controlling image formation by the image forming means based on the rate.

For example, the control means calculates a decompression time of the image information in the decompression means based on the compression rate, and determines an image forming order of the image information in the image formation means based on the decompression time. It is characterized by controlling.

As one method for achieving the above-mentioned object, the image processing method of the present invention includes the following steps.

That is, image information of a plurality of colors is compressed for each color, the compressed image information is stored for each color in storage means, and the image information read from the storage means is expanded for each color. An image processing method of expanding and forming an image based on the expanded image information of each color, wherein a compression rate when the image information is compressed is calculated for each color, and the compression rate is calculated for each color. Based on the above, the image formation is controlled.

Further, the image information is compressed, the compressed image information is stored in the storage means, the image information read from the storage means is decompressed and expanded, and based on the expanded image information. An image processing method for forming an image, characterized in that a compression rate when the image information is compressed is calculated, and image formation is controlled based on the compression rate.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings.

<First Embodiment> FIG. 1 is a side sectional view of an image processing apparatus to which the present embodiment is applied. In the figure,
Reference numeral 101 denotes a document table glass on which a document is placed at a predetermined position. Reference numeral 102 denotes a document illumination lamp composed of, for example, a halogen lamp, which exposes a document placed on the platen glass 101. Scanning mirrors 103, 104, and 105 are housed in an optical scanning unit (not shown) and reciprocally move, while the reflected light from the document is reflected by the CCD unit 106.
Lead to. The CCD unit 106 includes an imaging lens 107 that forms an image of reflected light from a document, an image sensor 108 including a color CCD, and a CCD that drives the image sensor 108.
The driver 109 and the like are included. Image sensor 108
The image signal output from the controller is converted into, for example, 8-bit digital data for each of R, G, and B, and then the controller unit 139 that performs image processing and sequence control of the apparatus.
Is input to

Further, 110 is a photosensitive drum, and 112
The pre-exposure lamp eliminates the charge in preparation for image formation.
A first charger 113 charges the photosensitive drum 110 uniformly. Reference numeral 114 denotes a laser unit B, which is a first exposure unit, and is configured by, for example, a semiconductor laser, and exposes the photosensitive drum 110 based on image data of a color other than black among image data processed by the controller unit 139. Then, an electrostatic latent image is formed. 115 is a replaceable first
This is a developing device, and the user can easily set it at a predetermined position in the printer. The first developing device 115 is filled with a developer other than black, but in the present embodiment, it is assumed that a developer (toner) that develops a red development color is filled, for example.

Reference numeral 116 is a second charging device, which uniformly charges the photosensitive drum 110 after the development by the first developing device 115. Reference numeral 117 denotes a laser unit A which is a second exposure unit, and is composed of, for example, a semiconductor laser or the like, and exposes the photosensitive drum 110 on the basis of black image data among the image data processed by the controller unit 139, and the static exposure is performed. Form a latent image. Reference numeral 118 denotes a second developing device, which contains a black developer (toner).

Reference numeral 119 denotes a pre-transfer charger, which applies a high voltage before the toner image developed on the photosensitive drum 110 is transferred to a sheet. Reference numerals 120, 122, and 124 denote paper feeding units, and by driving the paper feeding rollers 121, 123, and 125, the transfer paper is fed into the apparatus, and the registration rollers 12
The sheet is temporarily stopped at the disposition position of 6, and the sheet is re-fed after the writing timing with the image formed on the photosensitive drum 110 is set. 127 is a transfer charger, which is the photosensitive drum 110.
The toner image developed on is transferred to the transfer paper fed. Reference numeral 128 denotes a separation charger, which separates the transfer sheet after the transfer operation from the photosensitive drum 110. The toner remaining on the photosensitive drum 110 without being transferred is cleaned by the cleaner 111.
Will be recovered by

Reference numeral 129 is a conveyor belt, which conveys the transfer sheet after the transfer process to the fixing device 130, and
At 30, the toner on the transfer paper is fixed by heat, for example. Reference numeral 131 denotes a flapper, which controls the transfer path of the transfer sheet having undergone the fixing process in one of the arrangement directions of the sheet discharge tray 132 and the intermediate tray 137.
Numerals 133 to 136 are feeding rollers, which reverse the transfer paper once the fixing process is completed when performing multiplex recording, and non-reverse when double-sided recording is performed, to the intermediate tray 13.
Deliver to 7. A re-feeding roller 138 conveys the transfer sheet placed on the intermediate tray 137 to the position where the registration roller 126 is arranged again.

The controller section 139 is provided with a microcomputer, an image processing section, etc., which will be described later, and controls the above-mentioned image forming operation in accordance with an instruction from the operation panel 140. 142 is an image server,
The CCD unit 10 is connected to the controller unit 139.
The image information of the original read by the controller 6 and image-processed by the controller unit 139 is temporarily stored.

FIG. 2 shows a detailed block configuration of the controller section 139. In the figure, 201 is a CPU that controls the controller unit 139 in an integrated manner,
The control procedure (control program) stored in No. 3 is sequentially read and executed. The address bus and data bus of the CPU 201 are connected to respective loads described later via a bus driver circuit and an address decoder circuit 202. A RAM 204 is a main memory used as a storage area for input data, a work storage area, and the like.
It is.

An image processing unit 206 receives an image signal output from the CCD unit 106, performs image processing described later, and then outputs control signals for the laser unit A 117 and the laser unit B 114 according to the image data. Laser unit A117 and laser unit B
As described above, the laser light output from 114 irradiates and exposes the photosensitive drum 110, and at the same time, the laser light is detected by the beam detection sensor A 213 and the beam detection sensor B 214, respectively. The CPU 201 generates a synchronization signal when each laser beam exposes the photosensitive drum 110 based on the detection result.

The CPU 201 also controls the operation panel 14 via the I / O controller 205 which controls the load of the apparatus.
I / O that controls the interface with the image processing unit 206 and the image server 142 according to the setting contents set with 0
Control F207. For example, when the copy mode is set to perform the trimming process on the operation panel 140, the image server 14 is operated via the I / F 207.
2 reads out predetermined image data, and the image processing unit 206
After performing the trimming process with the laser unit B11
4 and the laser unit A 117 to transfer the image data.

Further, the sequence control of the apparatus is performed by the CPU2.
01 via the I / O controller 205, motors 207, clutches 208, solenoids 209,
This is performed by controlling the paper detection sensors 210, the toner remaining detection sensor A211, the toner remaining detection sensor B212, the high voltage control unit 215, and the like.

Next, FIG. 3 shows a detailed block configuration of the image processing unit 206. In the figure, the CCD unit 106
The image signal converted into the R, G, B electric signals by
First, shading correction is performed in the shading unit 301 to correct variations between pixels, which is then input to the two-color separation unit 302 and separated into a red component (RED) and a black component (BK) of the original image by a known technique. To be done.

The two-color image data RED and BK are composed of, for example, an edge emphasizing section 303 composed of a digital filter circuit using a 7 × 7 matrix, and a scaling section for thinning out or interpolating data according to the scaling rate. 304, the γ conversion unit 305 that converts the brightness data into the density data by referring to the table is processed. Then, the black image data BK and the red image data RED converted into the density data are sent to the I / F 207 by the selector 306. In this way, the image data read by the CCD unit 106 is stored as two-color image data in the image server 142 via the I / F 207.

The black image data BK and the red image data RED input from the image server 142 to the image processing unit 206 via the I / F 207 are first input to the selector 306. Then, the black image data BK output from the selector 306 is delayed by a time difference between the exposure position of the laser unit A 117 and the exposure position of the laser unit B 114 via the memory controller 309 to a memory configured by a DRAM, for example. It is stored in 310. Then, after being delayed for a certain period of time, the pulse width signal corresponding to the image data is output to the laser unit A117, which is input to the PWM unit A311 that converts the laser drive signal.

On the other hand, the red image data RED output from the selector 306 is input as it is to the PWM section B312 for converting it into a laser drive signal, and a pulse width signal corresponding to the image data is output to the laser unit B114.

Although details will be described later in this embodiment, the apparent transfer speed between the controller unit 139 and the image server 142 is controlled by compressing and holding the image data in the image server 142. There is. As a result, in the image processing unit 206, the data transfer speed from the I / F 207 to the selector 306 is apparently faster than the data transfer speed from the γ conversion unit 305 to the selector 306.

Next, FIG. 4 shows a detailed block configuration of the image server 142, and its operation will be described in detail. In the figure, memory A 401 and memory B 402
Is a memory for temporarily storing the image data transferred from the image processing unit 206 via the I / F 207, and is composed of a DRAM in this embodiment. 40
3, 404 are compression / expansion processing units A and B, respectively.
The apparent transfer rate control in the present embodiment is performed by performing the compression and decompression processing of image information as described above using the memories A401 and B402 as work areas. Reference numerals 405 and 406 denote SCSI interface units (SCSI-a, SCSI-b), respectively.
Reference numerals 7 and 408 denote hard disks (HD-a, HD-b) for each color that store compressed image data.

Reference numeral 409 is a compression rate calculation unit,
The compression ratios of the compression / expansion units A and B of 3,404 are calculated.

The memory A401 and the compression / expansion unit A40
3, a system composed of SCSI-a405 and HD-a407 is used for black image data, and a system composed of the memory B402, compression / expansion unit B404, SCSI-b406 and HD-b408 is used for red image data. That is, the image data processed by the image processing unit 206 always passes through one of these systems.

The operation of the image server 142 will be described below.

First, consider a case where image data is transferred from the image processing unit 206 to the image server 142. In this case, the memory A401 and the memory B4
The image data of each color input to 02 is temporarily stored in each memory and then input to the compression / expansion unit A403 and the compression / expansion unit B404. Then, the input image data is compressed in each compression / expansion unit. At this time,
In the compression rate calculation unit 409, the image data amount Q before compression
From in and the compressed image data amount Qout, the compression rate R is calculated according to the following equation.

R = Qin / Qout As can be seen from the above equation, the compression rate R indicates that if R = 1, there is no change in the data amount before and after compression, and R <
If it is 1, it means that the amount of data has increased due to compression.
If R> 1, it means that the data amount is reduced by the compression. For example, when the compression rate R = 2, it indicates that the image data amount has been halved by the compression. This compression rate R is
It is calculated as Ra and Rb for the compression / expansion unit A403 and the compression / expansion unit B404, respectively.

Compression / expansion section A403 and compression / expansion section B
The output image data from the 404 is transmitted via the SCSI interface units (SCSI-a405, SCSI-b406) to the hard disk (HD-a407, HD) for each color.
-B 408). At this time, the compression rate calculation unit 40
The compression ratios Ra and Rb of each color calculated in 9 are both H
It is stored in the D-a 407 and the HD-b 408.

Next, consider the case where image data is sent from the image server 142 to the image processing unit 206. In this case, first, HD-a407 and HD-b408
The black image data to be transmitted and its compression ratio Ra, and the red image data and its compression ratio Rb are read from the respective units, and are compressed / decompressed by the compression / expansion unit A403 and compression / expansion unit B404 via SCSI-a405 and SCSI-b406. Are input respectively. Then, the image data is decompressed in each compression / decompression unit to be returned to the original image, and is held in the memory A 401 and the memory B 402. On the other hand, the compression rates Ra and Rb for each color are calculated by the controller unit 13 via the I / F 207.
It is provided to the CPU 201 in the CPU 9 and stored in the RAM 204.

Then, the memory A 401 and the memory B 40
The image data of each color stored in No. 2 is sequentially read according to an instruction from the CPU 201 based on the procedure of the image forming sequence control described later, and is sent to the image processing unit 206 via the I / F 207. That is, in the present embodiment, the compression rate for each color is calculated when the image data is transferred to the image server 142, and when the image data is transmitted from the image server 142, the read control of the image data according to the compression rate is performed. Characterize.

In the above-mentioned configuration of the image server 142, it has been explained that there is a system for black image data and a system for red image data respectively. However, depending on the setting of the selector 306 in the image processing unit 206. For example, it is possible to use any of the systems only with black image data and realize image processing with a single black color.

The image forming sequence control in this embodiment, that is, the control for reading the image data stored in the image server 142 to form an image will be described below with reference to the flowchart of FIG. still,
A control program that implements the processing of the flowchart of FIG. 5 is stored in the ROM 203, read by the CPU 201, and executed on the RAM 204.

First, in step S501, the compression rate Rb of the red image data that is the object of image formation is read from the HD-b 408 in the image server 142, and then in step S502, similarly, the black that is the object of image formation from the HD-a 407 is read. The compression ratio Ra of the image data is read. Then, in step S503, the respective compression rates Ra and Rb are compared. If Rb ≦ Ra, that is, if the compression rate of the red image is less than or equal to the compression rate of the black image, the process proceeds to step S504, and if not, the step Proceed to S505.

In step S504, the decompression time required for decompressing the compressed red image data on the memory B402 is calculated based on the compression rate Rb, and step S5
The expansion time calculated in 06 is set in the variable Tc. On the other hand, in step S505, the decompression time required to decompress the compressed black image data on the memory A401 is calculated based on the compression ratio Ra, and the decompression time calculated in step S506 is set in the variable Tc. . That is, the calculated expansion time Tc is set according to the smaller compression rate, in other words, the longer expansion time.

Here, a method of calculating the development time of the image data will be briefly described. The CPU 201 obtains the compression ratio R for each color. Here, the total amount of data (Qin) before compression for each color can be calculated by the document image size and the reading resolution in the CCD unit 106.
The reading resolution is a constant, but the original image size may be held together with the compression ratio R, for example. Since the total amount of data Qin before compression and the compression ratios Ra and Rb, the amount of data (Qout) after compression for each color, that is, the amount of data stored in the HD-a 407 and HD-b 408 is obtained.
Further, by taking into consideration the predetermined decompression processing speed in the compression / decompression units 403 and 404, the CPU 201 can estimate the time required for decompression for each color.

Then, in step S507, HD-
Memory A401 and memory B402 for the compressed image data of each color stored in a407 and HD-b408.
The upward expansion and expansion are started, and at the same time, the expansion time Te is measured.

Then, in step S508, the development processing for each color is continued until the measured development time Te becomes equal to the calculated development time Tc set in step S506. Here, if Te = Tc, it means that the development of both the red image data and the black image data is completed.

Next, in step S509, the memory A4
01 and the memory B402, it is confirmed that the development of the image data of each color is completed. If the development of any image data is not completed, the development processing is performed until the development of all the image data is completed. continue. I do. Note that the process in step S509 is merely a confirmation process, and therefore, if there is image data that has not been expanded, error processing may be performed assuming that some abnormality has occurred. It is also possible to omit the process of step S509 itself.

When the expansion processing of all the image data is completed, the red image data and the black image data are read from the memory A 401 and the memory B 402 to the image processing unit 206 via the I / F 207 in step S510, and the image forming processing is started. .

Then, in step S511, the end of image formation, that is, the end of reading of image data from the memory A 401 and the memory B 402 is monitored. If the image formation has been completed, it is determined in step S512 whether there is an image formation output request for the next page. If there is a next page output request, the process returns to step S501, and the above-described processing is repeated to repeat the above-described processing. The image data output from is repeated. On the other hand, if there is no next page output request, the image forming output operation from the image server 142 ends. More than,
It is the image formation sequence control in the present embodiment. That is, the compression rates of the red and black image data are compared, and the image formation is controlled according to the smaller compression rate.

In the above-mentioned image forming sequence control, when outputting the same image for a plurality of pages, the image data once expanded in the memory A 401 and the memory B 402 is repeatedly read by the set number of copies to form the image. Therefore, the sequence control according to the flowchart shown in FIG. 5 is performed only when the first page is output.

As described above, according to this embodiment, in the image processing apparatus for compressing and storing the image data of the plurality of color components, the image of each color is printed when the stored image data is printed out. The decompression processing time can be grasped according to the data compression rate. Therefore, by comparing the compression ratios of the image data for each color, it is possible to easily realize the print output sequence control for a plurality of colors.

Further, since the throughput of a job (server job) for reading out and printing out the image data stored in the image server 142 can be estimated, a job for reading an original image from the CCD unit 106 and printing it out (a reader job), etc. , Scheduling with other jobs is easily possible. For example, if it is determined that the development time of the image data in the server job is longer than the time required to read the image data in the reader job, the print job is prioritized even if the server job comes first. Output to the laser unit. In addition, such scheduling control is possible even among a plurality of server jobs by considering their respective deployment times.

Although the image processing apparatus for forming an image with two colors of red and black has been described in the present embodiment, the present invention is not limited to this example. For example, the same applies to configurations of other colors such as blue and black or red and blue. Further, the number of colors is not limited to two, and, for example, even in an apparatus that forms an image in full color of Y, M, and C, the expansion time of the color component based on the compression ratio for the image data stored for each color component. By performing image formation according to the above, the same effect as that of the present embodiment can be obtained.

Further, even in the image processing apparatus for forming a single color image, the expansion time can be grasped in accordance with the compression ratio of the image data compressed and held, so that the scheduling control as described above is possible. Become.

<Other Embodiments> In the present invention, a plurality of devices (eg, host computer, interface device,
The present invention may be applied to a system including a reader, a printer, or the like, or may be applied to an apparatus (for example, a copying machine, a facsimile machine, or the like) including one device.

Another object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or the apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided on a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the above-mentioned storage medium, the storage medium stores the program code corresponding to the above-mentioned flowchart. Briefly, the memory map example of FIG. Each module shown will be stored in the storage medium. That is, at least "compression module""storagemodule""decompressionmodule"
The program code of each of the “image forming module”, the “compression rate calculating module”, and the “expansion control module” may be stored in the storage medium.

In the above example, the compression is performed as multi-valued data, but the multi-valued data may be compressed after being binarized.

As the compression method, various compression methods such as compression using orthogonal transformation in block units and entropy coding can be applied.

The control of the image forming means includes supply of image data to the image forming unit, supply of an instruction signal for starting the image forming operation, and the like.

[0074]

As described above, according to the present invention, in an image processing apparatus that compresses and stores image information of a plurality of colors, the expansion time for each image information can be grasped based on each compression rate. This makes it possible to easily control the print output sequence of a plurality of colors.

Further, by grasping the development time for each image information, the scheduling of print jobs in the apparatus becomes easy.

[0076]

[Brief description of drawings]

FIG. 1 is a side sectional view of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a controller unit in the present embodiment.

FIG. 3 is a block diagram showing a detailed configuration of an image processing unit in the present embodiment.

FIG. 4 is a block diagram showing a detailed configuration of an image server according to the present embodiment.

FIG. 5 is a flowchart showing image forming sequence control in this embodiment.

FIG. 6 is a diagram showing an example of a memory map when the present invention is applied to a storage medium.

[Explanation of symbols]

 106 CCD unit 139 controller section 142 image server 201 CPU 206 image processing section 207 interface 306 selector 401, 402 memory 409 compression rate calculation section

Claims (17)

[Claims] 1. A compression unit for compressing image information of a plurality of colors for each color, a storage unit for storing the image information compressed by the compression unit for each color, and image information read from the storage unit. An image processing device having a decompression unit for decompressing and decompressing each color and an image forming unit for forming an image based on the image information for each color developed by the decompression unit; An image processing apparatus, comprising: a calculating unit that calculates a compression rate for each color when the image is compressed; and a control unit that controls image formation by the image forming unit based on the compression rate for each color. . 2. The image forming apparatus further comprises a holding unit that holds uncompressed image information for each color, and the decompressing unit expands the image read from the storage unit for each color and stores the image on the holding unit. The image processing apparatus according to claim 1, wherein the image processing apparatus is developed as follows. 3. The image processing apparatus according to claim 1, wherein the compression ratio for each color calculated by the calculating unit is stored in the storage unit together with the image information. 4. The image processing apparatus according to claim 1, wherein the control unit estimates the decompression time in the decompression unit based on the smallest compression ratio among the compression ratios for each color. 5. The control means estimates a decompression time in the decompression means of a color image signal having a minimum compression ratio,
The image processing apparatus according to claim 4, wherein the development time of all colors in the development means is estimated according to the development time. 6. The image processing apparatus according to claim 5, wherein the control unit performs the expansion in the expansion unit for an expansion time of an image signal of a color having a minimum compression rate for each color. 7. A compression unit for compressing image information, a storage unit for storing the image information compressed by the compression unit, and a decompression unit for decompressing and expanding the image information read from the storage unit. An image processing apparatus comprising: an image forming unit that forms an image based on the image information expanded by the expanding unit; a calculating unit that calculates a compression rate when the image information is compressed by the compressing unit; An image processing apparatus, comprising: a control unit that controls image formation by the image forming unit based on a compression rate. 8. The control unit calculates a decompression time of the image information in the decompression unit based on the compression ratio, and determines an image formation order of the image information in the image formation unit based on the decompression time. The image processing apparatus according to claim 7, which is controlled. 9. Image information of a plurality of colors is compressed for each color, the compressed image information is stored for each color in storage means, and the image information read from the storage means is expanded for each color. An image processing method of expanding, forming an image based on the expanded image information of each color, wherein a compression rate when the image information is compressed is calculated for each color, and the compression rate is calculated for each color. An image processing method characterized by controlling image formation based on the above. 10. The image processing method according to claim 9, wherein the calculated compression rate for each color is stored in the storage unit together with image information. 11. The image processing method according to claim 9, wherein the expansion time is estimated based on a minimum compression rate among the compression rates for each color. 12. The image processing method according to claim 11, wherein the expansion time of the image signal of the color having the minimum compression rate is estimated, and the expansion times of all colors are estimated according to the expansion time. . 13. The image processing method according to claim 12, wherein the expansion is performed for an expansion time of an image signal of a color having a minimum compression rate for each color. 14. The image information is compressed, the compressed image information is stored in a storage unit, the image information read from the storage unit is expanded and expanded, and based on the expanded image information. An image processing method for forming an image, comprising: calculating a compression rate when the image information is compressed, and controlling image formation based on the compression rate. 15. The expansion time of the image information is calculated based on the compression rate, and the image formation order of the image information is controlled based on the expansion time.
4. The image processing method described in 4. 16. A computer-readable memory in which a program code for image processing is stored, wherein a code for a step of compressing image information of a plurality of colors for each color, and the compressed image information in a storage means for each color. Code of a step of storing, code of a step of expanding and expanding the image information read out from the storage means for each color, and code of a step of forming an image based on the expanded image information of each color And a code for a step of calculating a compression rate for each color when the image information is compressed, and a code for a step of controlling image formation based on the compression rate for each color. Readable memory. 17. A computer-readable memory in which a program code for image processing is stored, the code of a step of compressing image information, the code of a step of storing the compressed image information in a storage means, and the storage. A code of a step of expanding and expanding the image information read from the means, a code of a step of forming an image based on the expanded image information, and a compression ratio when the image information is compressed A computer-readable memory comprising: a process code; and a process code for controlling image formation based on the compression ratio.