JPH10147016A - Image processor and processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To store a large volume of data in a memory resource having a specified size while reducing the memory by degrading a raster data when a compressed raster data can not be stored in a specified raster memory. SOLUTION: Control section of a printer delivers an image data, generated from an external unit and described with a page description language, to a host I/F. A CPU generates a band encoded representation information divided into band units which is stored in a band encoded memory 701. When all image data can not be stored, an available raster memory having maximum size is acquired and a resolution for printing an input data as full raster is determined from the memory size thus acquired. Subsequently, the raster data is compressed reversibly and stored in a compressed band memory 703. If the memory 703 is deficient, a reversible compressed band is decompressed in units of band in a rastering memory 702 and degraded before being stored in a raster memory 704.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing apparatus and method for forming an image on a recording medium.

[0002]

2. Description of the Related Art Conventionally, such as a laser beam printer,
In an image forming apparatus called a page printer, one page of raster data is held in a raster memory to form an image. Raster data as such an image processing device handles not only text but also all kinds of images from simple figures to images such as photographs.

In recent years, the resolution of these image forming apparatuses has been improved. For example, at a resolution of 600 dpi, an A4 size memory of 4 Mbytes for one page is required. Thus, the resolution tends to increase more and more. In addition, the gray scale which was conventionally expressed by two gray scales (1 bit) per pixel has been improved from 16 gray scales (4 bits) to 256 gray scales (8 bits), and an increasingly large amount of raster memory is required. It is becoming.

[0004] In order to suppress an increase in cost due to such an increase in memory, various memory saving techniques, especially compression techniques have been proposed.

[0005] As compression techniques, there are a reversible compression method in which data is lost during compression and decompression, and an irreversible compression method in which data is lost during compression and decompression.

In particular, as a method of compressing raster data in a raster memory, there is a method of performing compression by switching a plurality of compression methods according to a compression ratio.

[0007]

However, even if the raster data is compressed, it is meaningless if it does not fit in the raster memory. Even if the compression method is changed or the compression method is changed from lossless compression to irreversible compression, there is no guarantee that the size after compression will always be smaller than before compression, and the raster data after compression will fit in the raster memory. There was no guarantee that.

[0008]

Therefore, if the compressed raster data does not fit in the predetermined raster memory, the memory is surely reduced by degrading the raster data, and the size of the memory reduction is always fixed. The above problem is solved by setting the size.

[0009]

FIG. 1 is a sectional view showing an internal structure of a laser beam printer (hereinafter abbreviated as LBP) applied to the present embodiment. The LBP is a character pattern from a data source (not shown). Registration and registration of fixed forms (form data) can be performed. In the figure, reference numeral 1000 denotes an LBP main body, which inputs character information (character code), form information, macro instructions, and the like supplied from an external device (2001 in FIG. 2) typified by an externally connected host computer. In addition, a corresponding character pattern, form pattern, and the like are created according to the information, and an image is formed on a recording sheet as a storage medium. 10
Reference numeral 12 denotes an operation panel on which switches for operation and an LED display are arranged. Reference numeral 1001 denotes a printer control unit that controls the entire LBP 1000 and analyzes character information supplied from a host computer. The control unit 1001 mainly converts character information into a video signal of a corresponding character pattern,
Output to 2. The laser driver 1002 is a circuit for driving the semiconductor laser 1003, and switches on and off a laser beam 1004 emitted from the semiconductor laser 1003 according to an input video signal. Laser 100
Reference numeral 4 denotes a rotating polygon mirror 1005 which is swung right and left to scan on an electrostatic drum 1006. Thereby, the electrostatic drum 100
An electrostatic latent image of a character pattern is formed on 6. This latent image is stored in a developing unit 1007 around the electrostatic drum 1006.
And then transferred to recording paper. This recording paper uses a cut sheet, and the cut sheet recording paper is LBP
1000 stored in a paper cassette 1008
Paper feed roller 1009 and transport rollers 1010 and 101
1 and the electrostatic drum 1006
Supplied to

FIG. 2 is a block diagram of the LBP applied to the present embodiment. Reference numeral 2001 denotes an external device such as a host computer, 2002 denotes the entire printer controller unit, 2003 denotes an address data bus, 2004 denotes a host I / F including a buffer unit, and 2.
Reference numeral 005 controls the print controller. CPU,
2006 is a program for performing controller control and the like;
A ROM section storing the control program of the CPU represented by the flowcharts of FIGS.
U is a DMA unit controlled by U, 2008 is a panel unit, 2
Reference numeral 009 denotes an I / F circuit unit including an output buffer unit for storing data to be sent to the 2011 engine;
010 indicates a RAM unit.

The normal image output will be described with reference to the block diagram of FIG.

First, the control unit 1 of the printer 1000
001, image data described in a page description language generated by the external device 2001 is input to the host I / F 2004.

Next, the CPU 2005 converts the page description language input from the external device 2001 into band-encoded expression information divided in band units by the band-encoding processing program stored in the ROM 2006,
Band encoding memory 701 secured in M2010
Is stored. Here, the band-encoded expression information refers to drawing objects and backgrounds such as “bitmap”, “run-length”, “trapezoid”, “box”, “high-speed boundary-encoded bitmap” divided into band units. It is a general term for patterns and drawing logic when drawing them in a raster memory. The details of the band coded expression information are disclosed in Japanese Patent Laid-Open No. 6-87251.

Next, the band-encoded expression information is raster-developed in a raster memory 704 in band units.

After raster data is developed in the raster memory 704, the first band is sent to the engine by the shipper and output. While outputting the raster data of the band,
The raster data is rasterized to the next band. In this way, image data is developed and output by performing raster development and engine output to bands existing in the raster memory alternately.

However, there are many complicated drawing objects in the image data, and the band coding memory 701 becomes full.
In some cases, not all drawing objects can be stored as band-encoded expression information. For example, even if one band area is taken, all the objects to be drawn in the band may not be stored. In this case, since all the drawing objects do not exist in the band encoding memory 701, if raster development is performed on the raster memory 704 as described above, a drawing object that cannot be output will be generated. The following processing is performed to avoid this problem.

(Embodiment 1) Description will be made with reference to a flowchart of FIG. 3 and a block diagram of FIG. This flowchart is realized by the CPU 2005 included in the printing apparatus 2002 executing a program stored in the ROM 2006.

In step 301, the control unit 1001 of the printer 1000 sends the external device 2 to the host I / F 2004.
001 is input as image data described in a page description language.

In step 302, the CPU 2 executes the band encoding processing program stored in the ROM 2006
005 generates band coding expression information divided in band units from the page description language input from the external device 2001, and converts the band coding expression information generated in the band coding memory 701 secured in the RAM 2010. Store as much as possible. If image data input in all page description languages is stored, the above-described normal processing is performed. If image data input in all page description languages cannot be stored, the process proceeds to step 303.

In step 303, the CPU 2005
A raster memory (703, 70) that can be secured in the AM 2010
4 total).

In step 304, R
CPU from the raster memory size acquired in AM2010
2005 determines the resolution at which the input data can be printed as a full raster. For example, assuming that the maximum value of the raster memory is 1 MByte in step 303, and the original resolution is 600 DPI and the print paper size is A4 in step 304, the acquired raster memory (703, 704)
300 DPI to make full raster memory
That is, it is only necessary to lower the resolution.

"N" in step 305 indicates the current band being processed. “A” represents a band that reduces the resolution of raster data.

In this case, the range of "N" is 0 <= N <= N MAX. However, "N" and "N MAX ”is an integer. MAX is the last band. In this case, the range of “a” is 0 ≦ a <N. Here, a is an integer.

In step 306, the band N being processed by the CPU 2005 is the last band N Check if it does not exceed MAX. If (N> N If (MAX), the processing system ends in step 325. If (N <= N If (MAX), the flow advances to step 307 to process the current band raster.

In step 307, the CPU 2005
Rastering memory 70 previously acquired in RAM 2010
2 (part of the raster memory) is used to rasterize the N-band coded expression information.

In step 308, the N-band raster data stored in the rastering memory 702 is
The CPU 2005 performs a reversible compression process (lossless compression process). In this case, the compressed data is stored in the compressed band memory 703 (part of the raster memory) acquired in advance.

In step 309, the lossless compression process is performed in step 308. If all of the compressed data cannot be stored because the compression band memory 703 is insufficient, the CPU 2005 determines that the memory is insufficient and executes step 31.
Proceed to 1. If the compression band memory 703 is sufficient, the process proceeds to step 310.

In step 310, the CPU 2005 increments the value of the band N being processed and prepares to move to the next band. Then, the process returns to step 306 to continue the process.

In step 311, it is determined whether or not there is band-encoded expression information that has already been raster-expanded in the band-encoding memory 701. If there is band-encoded expression information already rasterized, step 31
Proceed to 2. If not, the process proceeds to step 313.

In step 312, the band-encoded representation information in the band-encoded memory 701 that has been raster-expanded for the band that needs raster-expansion is cleared, and a part of the vacated band-encoded memory 701 is cleared. Is transferred to the compression band memory 703, and the process returns to step 306 to continue.

In step 313, the CPU 2005 expands the reversible compression band stored in the compression band memory 703 to the rastering memory 702 in band units. For example, the zeroth reversible compression band is expanded and stored in the rastering memory.

The processing for lowering the resolution to be described below is shown in FIG.
It is explained based on.

At step 314, C at step 313
The PU 2005 lowers the resolution of the band data in the rastering memory 702 to the resolution determined in step 304 for the decompressed band, and stores the data in the raster memory 801. For example, 60 rasterized in the rastering memory 702
Reduce the resolution of 0 DPI data to 300 DPI,
00DPI band raster data is stored in a raster memory 801.
To be stored. Here, a method of reducing the resolution will be described by a simple thinning method. The main operation direction is changed from 600 DPI to 300 DPI every other dot. As for the sub-operation direction, an odd-numbered column is extracted and an even-numbered example is deleted. By doing so, 300 DPI raster data is simply created.

In step 315, the CPU 2005 checks whether or not the band a for which the resolution reduction processing is being performed does not exceed the band (N-1) immediately before the compression processing is being performed. If (a> = N−1), the process proceeds to step 317, and the current N band raster process is performed. If (a <N−1), the process proceeds to step 316.

At step 316, the CPU 2005 increments the value of the band a being processed, and prepares to move the processing to the next band. Then, returning to step 313,
continue processing.

In step 317, the CPU 2005 develops raster data in the rastering memory 702 as in step 307. In this case, the raster data is created at the resolution before the resolution is reduced.

In step 318, the CPU 2005 lowers the resolution of the raster data stored in the rastering memory 702 to the same resolution as that in step 314, and stores it in the raster memory 801, as in step 314.

In step 319, the band being processed by the CPU 2005 is changed to the last band (=
= N_MAX). If (N <= N_MAX), the process proceeds to step 320, where the CPU 2005 increments N to the next band of the processing band and prepares for the next band. If (N> N_M
If AX), the process proceeds to step 321.

In step 321, the image data generated and stored in the band encoding expression information in step 302 is stored in the band encoding memory 70 included in the RAM 2010.
It is determined whether or not all of them are stored in No. 1. If all the image data generated and stored in the band coding expression information is not stored in the band coding memory 701, the process proceeds to step 322. If all the image data is stored in the band encoding memory 701, all the image data has been rasterized into raster data, so that this processing system is terminated at step 325.

In step 322, the band coded expression information stored in the band coded memory 701 included in the RAM 2010 is cleared, and the data is input in the remaining page description language which has not been converted to the band coded expression information yet. The image data is generated as band coding expression information, and stored in the band coding memory 701 as much as possible.

In step 323, it is determined whether or not the resolution of the created raster data is reduced. If the raster data has not been reduced in resolution, step 30
Return to 5. If the resolution of the raster data is reduced, the process proceeds to step 324.

In step 324, N = 0 and a = 0 are set as in step 305, and the process returns to step 317.

In this way, raster data is formed from the image data input in the page description language.

(Embodiment 2) Description will be made with reference to the flowchart of FIG. This flowchart is for the printing apparatus 2002.
Is executed by executing a program stored in the ROM 2006 by the CPU 2005 included in the program.

First, an entry is made to step 401, and the control unit 1001 of the printer 1000
The image data described in the page description language generated by the external device 2001 is input to F2004.

In step 402, the CPU 2 executes the band encoding processing program stored in the ROM 2006
005 converts the page description language input from the external device 2001 into band-encoded expression information divided in band units, and converts the converted band-encoded expression information into the band-encoded memory 701 secured in the RAM 2010. Store as much as possible. Here, when the image data input in all the page description languages is stored, the above-described normal processing is performed. When the image data input in all the page description languages is not stored, the process proceeds to step 403. move on.

In step 403, the CPU 2005
A raster memory (703, 70) that can be secured in the AM 2010
4 total).

In step 404, the CPU 2005 determines the resolution at which the input data can be printed as a full raster from the raster memory size obtained in step 403.

"N" in step 405 indicates the current band being processed. “A” represents a band that reduces the resolution of raster data.

In this case, the range of “N” is 0 <= N <= N MAX. However, "N" and "N MAX ”is an integer. MAX is the last band.

In this case, the range of “a” is 0 ≦ a <N. Here, a is an integer.

At step 406, the CPU 2005 performs processing.
The current band N is the last band (N MAX)
Check if. If (N> N MAX)
If so, this processing system ends in step 425.
If (N <= N MAX), proceed to step 307
Only the current band raster is processed.

In step 407, the CPU 2005
Rastering memory 702 previously acquired in AM 2010
(Part of the raster memory) is used to rasterize the N-band coded representation information.

In step 408, the N-band raster data stored in the rastering memory 702 is
The CPU 2005 performs an exclusive OR operation on the adjacent sub-scanning directions. This processing is performed by the rastering memory 7 shown in FIG.
This is performed before raster data 02 is losslessly compressed. Here, the method of the exclusive OR will be described with reference to FIGS.
First, assume that there is a bitmap as shown in FIG. First, pay attention to line 0 and line 1. The exclusive OR of each bit of line 0 and the corresponding bit of line 1 is calculated. Due to the nature of exclusive OR, if each bit value is the same, it becomes 0. That is, when all of the lines 0 and 1 are the same, 0 bits are all generated. The result of the exclusive OR of line 0 and line 1 is overwritten on line 0. Similarly, exclusive OR is performed on line 1 and line 2 to overwrite line 1. Thus, the exclusive OR processing is performed up to the last line. As a result, a bit map after exclusive OR as shown in FIG. 6 is completed. That is, only the last line has the actual bits of the bit map in FIG. When returning to the original bitmap, the final line and the line immediately above it are subjected to an exclusive OR operation to overwrite the line immediately above the final line. This will return the bit on the line one above the last line. Similarly, the original bitmap can be reproduced by performing an exclusive OR operation on all the lines. This reproduction process is performed after raster data in the compression band memory 703 is expanded and before overwriting in the rastering memory 702. By taking exclusive OR in this way, the advantage of using a reversible compression method (simple compression such as run-length compression, Packbits compression, etc.) that requires a very small compression ratio is that the compression ratio can be increased. There is.

The raster data subjected to the exclusive OR is subjected to a lossless compression process (lossless compression process). In this case, a compressed band memory 703 previously acquiring the compressed data
(Part of the raster memory).

In step 409, the lossless compression process is performed in step 408. If all of the compressed data cannot be stored due to the shortage of the compression band memory 703, the CPU 2005 determines that the memory is insufficient and proceeds to step 41.
Proceed to 1. If the compression band memory 703 is sufficient, the process proceeds to step 410.

In step 410, the CPU 2005 increments the value of the band N being processed and prepares to move the processing to the next band. Then, the process returns to step 406 to continue the process.

In step 411, it is determined whether or not there is band-encoded expression information that has already been raster-expanded in the band-encoding memory 701. If there is band-encoded expression information already rasterized, step 41
Proceed to 2. If not, the process proceeds to step 413.

In step 412, the band-encoded representation information in the band-encoded memory 701 that has already been raster-expanded for the band requiring raster-expansion is cleared, and a part of the vacated band-encoded memory 701 is cleared. Is transferred to the compression band memory 703, and the process returns to step 406 to continue the processing.

In step 413, the CPU 2005 expands the reversible compression band stored in the compression band memory 703 into the rastering memory 702 in band units. For example, the zeroth reversible compression band is expanded and stored in the rastering memory.

In step 414, C in step 413
The PU 2005 lowers the resolution of the band data of the rastering memory 702 to the resolution determined in step 404 for the decompressed band, and stores the data in the raster memory 801. For example, 6 expanded in the rastering memory 702
Reduce the resolution of 00 DPI data to 300 DPI,
The band raster data of 300 DPI is stored in the raster memory 80.
1 is stored. Here, a method of reducing the resolution will be described by a simple thinning method. The main scanning method converts the sound from 600 DPI to 300 DPI every other dot. In the sub-scanning direction, odd columns are taken out and even columns are deleted. This simply creates raster data of 300 DP.

In step 415, the DCPU 2005 checks whether the band a for which the resolution reduction processing is being performed does not exceed the band (N-1) immediately before the compression processing is being performed. If (a> = N-1),
Proceeding to step 417, the current N band raster processing is advanced. If (a> N−1), the process proceeds to step 416.

In step 416, the CPU 2005 increments the value of the band a being processed and prepares to move the processing to the next band. Then, returning to step 413,
continue processing.

In step 417, the CPU 2005 develops raster data in the rastering memory 702 as in step 307. In this case, the raster data is created at the resolution before the resolution is reduced.

In step 418, the CPU 2005 lowers the resolution of the raster data stored in the rastering memory 702 to the same resolution as that in step 414, and stores it in the raster memory 801, as in step 414.

In step 419, the band being processed by the CPU 2005 is changed to the last band (=
= N MAX) is checked. If (N <= N If (MAX), the process proceeds to step 420, where N is incremented to the band next to the processing band, and the next band is prepared.

If (N> N MAX)
Proceed to step 421.

In step 421, the image data generated and stored in the band encoding expression information in step 402 is stored in the band encoding memory 70 included in the RAM 2010.
It is determined whether or not all of them are stored in No. 1. If the image data generated and stored in all the band coding expression information is not stored in the band coding memory 701, the process proceeds to step 422. If all the image data is stored in the band encoding memory 701, all the image data has been rasterized into raster data, so this processing system ends in step 425.

In step 422, the band coding expression information stored in the band coding memory 701 included in the RAM 2010 is cleared, and the remaining image data input in the page description language is converted into band coding expression information. , Are stored in the band encoding memory 701 as much as possible.

In step 423, it is determined whether or not the resolution of the created raster data is reduced. If the raster data has not been reduced in resolution, step 40
Return to 4. If the resolution of the raster data is reduced, the process proceeds to step 424.

In step 424, N = 0 and a = 0 are set as in step 405, and the process returns to step 417.

In this way, the raster data is formed from the image data input in the page description language.

(Other Embodiments) (Other Embodiment 1) In the above-described embodiment 1, a simple thinning process is used as a means for lowering the resolution. However, an error diffusion method may be used. Further, any method may be used as long as it reduces the resolution.

(Other Embodiment 2) In Embodiment 1 described above,
Although a means for reducing the resolution is used to reduce the data amount of the raster data, a means for reducing the data amount by reducing the gradation may be used. For example, step 303
Assuming that the maximum value of the raster memory is 4 Mbytes in step 304, if the original resolution in step 304 is 600 DPI, the printing paper size is A4, and the gradation is 16 gradations (4 bits), the acquired raster memory (702, 703, 704) In order to make a full raster memory with the sum of the two, it is only necessary to reduce the gradation to two gradations (1 bit). As described above, the level of gradation reduction can be determined and can be reliably stored in the memory, so that the processing as in the first embodiment can be performed. That is, other means may be used as long as the method reduces the data amount of the raster data to a data amount that can be reliably recognized.

(Other Embodiment 3) In Embodiment 2 described above,
Exclusive OR The method of taking the exclusive OR from the top line of the bitmap to the bottom was used, but even when the exclusive OR was applied from the bottom line of the bitmap to the top. I do not care.

(Other Embodiment 4) In Embodiment 2 described above,
Although exclusive OR processing is performed in the case of lossless compression, it may be in the case of irreversible compression.

(Other Embodiment 5) The functions of the above-described embodiment can be performed by a host computer which is an external device. That is, an object of the present invention is to provide 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 CP) of the system or the apparatus.
U and MPU) read out and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the novel function of the present invention, 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, magnetic tape, nonvolatile memory card, ROM, etc. 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. ) Performs part or all of the processing of the embodiment, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. , The CPU provided in the function expansion board or the function expansion unit performs part or all of the actual processing,
The case where the function of the above-described embodiment is realized by the processing is also included.

[0082]

As described above, when the compressed size becomes large and does not match with the memory resources, the predetermined amount is surely reduced by means for reliably reducing the amount of raster data such as a decrease in resolution or a decrease in gradation. It can be stored in the size of the memory resource.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an internal structure of a printing apparatus.

FIG. 2 is a block diagram of a printing apparatus.

FIG. 3 is a flowchart illustrating a flow of a process according to the first embodiment.

FIG. 4 is a flowchart illustrating a flow of a process according to a second embodiment.

FIG. 5 is a schematic diagram for explaining an exclusive OR;

FIG. 6 is a schematic diagram for explaining an exclusive OR;

FIG. 7 is a block diagram illustrating a flow of a compression process according to the first embodiment.

FIG. 8 is a block diagram illustrating a flow of a resolution reduction process according to the first embodiment.

FIG. 9 is a block diagram illustrating a flow of a process when performing a normal output.

[Explanation of symbols]

701 Band encoding memory 702 Rastering memory 703 Compressed band memory 704 Raster memory 801 Raster memory for storing raster data with reduced resolution 1000 LBP body 1001 Printer control unit 1002 Laser driver 1003 Semiconductor laser 1004 Laser light 1005 Rotating polygon mirror 1006 Electrostatic Drum 1007 Developing unit 1008 Paper cassette 1009 Paper feed roller 1010 Conveyor roller driver 2001 External device 2002 Printer controller 2003 Address / data bus 2004 Host I / F 2005 Printer controller controller CPU 2006 ROM unit 2007 DMA unit 2008 Panel unit 2009 I / F circuit section 2010 RAM section 2011 Engine section conductor laser

Claims (31)

[Claims] 1. An image processing apparatus comprising: a lossless compression means for reversibly compressing raster data; a degrading means for degrading raster data; and a raster data storage means for storing raster data. When the size of the raster data losslessly compressed by the means is larger than the capacity of the raster data storage means, the raster data is stored in the raster data storage means via the degrading means. apparatus. 2. The apparatus according to claim 1, wherein said degrading means is means for lowering resolution of raster data.
The image processing apparatus according to any one of the preceding claims. 3. The image processing apparatus according to claim 2, wherein said degrading means is means for lowering resolution by error-diffusion of raster data. 4. An image processing apparatus according to claim 1, wherein said degrading means is means for lowering the gradation of raster data. 5. A means for generating band-encoded expression information from image data described in a page description language, and the band-encoded expression information generated by the band-encoded expression generating means are stored. 2. The image processing apparatus according to claim 1, further comprising: a band-encoded expression information storage unit; and a rasterization unit for raster-expanding the band-encoded expression information stored in the band-code expressible information storage unit. . 6. When all of the band encoded expression information can be stored in the band encoded expression information storage means,
2. The method according to claim 1, wherein the raster data is output as it is without using the lossless compression means, and all the band coded expression information can be stored in the band coded expression information storage means.
The image processing apparatus according to claim 5, wherein the processing is performed. 7. The band-encoded expression information storage means,
The image processing apparatus according to claim 5, wherein the image processing apparatus is included in the raster data storage unit. 8. When the raster data compressed by the lossless compression means becomes larger than the storage capacity of the raster data storage means, the band coding stored in the band coding expression information storage means is performed. In the expression information,
6. The image according to claim 5, wherein the band-encoded expression information that has already been rasterized is cleared, and a part of the storage capacity vacant in the band-encoded expression information storage means is used as the raster data storage capacity. Processing equipment. 9. A reversible compression means, comprising: a degrading level determining means for determining a degrading level of the raster-expanded raster data which can be stored in the raster data storage means, according to a storage capacity of the raster data storage means. If the raster data compressed by the above is larger than the storage capacity of the raster data storage means, the raster data expanded by the expansion means to the degrade level determined by the degrade level determination means is degraded by the degrade means. The image processing apparatus according to claim 1, wherein: 10. A line-exclusive-OR means for performing an exclusive-OR operation on lines in contact with raster data, and after applying said line-exclusive-OR means to raster data, said lossless compression means 2. The method according to claim 1, wherein
The image processing apparatus according to any one of the preceding claims. 11. The image processing device according to claim 1, wherein the image processing device is a printing device. 12. An image processing method comprising: a lossless compression step of reversibly compressing raster data; a degrading step of degrading raster data; and a raster data storing step of storing raster data. If the size of the raster data to be losslessly compressed is larger than the storage capacity of the storage medium used in the raster data storing step, the raster data is degraded in the degrading step and the raster data storing step is performed. An image processing method characterized by storing in a storage medium used in (1). 13. The image processing method according to claim 12, wherein said degrading step is a step of lowering resolution of raster data. 14. The image processing method according to claim 13, wherein the degrading step is a step of lowering the resolution by error diffusion of raster data. 15. The method according to claim 1, wherein the degrading step is a step of lowering gradation of raster data.
2. The image processing method according to 2. 16. A generation step for generating band-encoded expression information from image data described in a page description language, and a band code for storing the band-encoded expression information generated in the band-code expressible expression generation step. 13. The method according to claim 12, further comprising: a rasterized expression information storage step; and a rasterization step of rasterizing the band encoded expression information stored in the storage medium used in the band code expressible information storage step. Image processing method. 17. When all the band-encoded expression information can be stored in the storage medium used in the band-encoded expression information storage step, raster data is output as it is without using the lossless compression means, 17. The image processing method according to claim 16, wherein the processing according to claim 12 is performed when the band encoded expression information can be stored in a storage medium used in the band encoded expression information storage step. 18. The storage medium used in the method for storing band encoded expression information is included in a storage medium used in the method for storing raster data.
6. The image processing method according to 6. 19. When the raster data compressed in the lossless compression step has become larger than the storage capacity of a storage medium used in the raster data storage step, the raster data is used in the band encoded expression information storage step. Among the band-encoded expression information stored in the storage medium, the band-encoded expression information that has already been rasterized is cleared, and one of the storage capacities available in the storage medium used in the band-encoded expression information storage step is cleared. 17. The image processing method according to claim 16, wherein a portion is used as the raster data storage capacity. 20. A degrading level for determining a degrading level of the raster-expanded raster data that can be stored in a storage medium used in the raster data storing step, according to a storage capacity of a storage medium used in the raster data storing step. When the raster data compressed in the lossless compression step is larger than the storage capacity of a storage medium used in the raster data storage step, the degrade level is set to the degrade level determined in the determination step. 13. The image processing method according to claim 12, wherein the raster data developed in the rasterizing step is degraded in the degrading step. 21. A line exclusive-OR step for performing an exclusive-OR operation on lines in contact with raster data, wherein the line in line data is in contact with the raster data in the line exclusive-OR step. 13. The image processing method according to claim 12, wherein after performing an exclusive OR operation on each other, lossless compression is performed in the lossless compression step. 22. A lossless compression step of reversibly compressing raster data, a degrading step of degrading raster data, and a raster data storing step of storing raster data, wherein the raster is reversibly compressed in the lossless compression step. When the data size is larger than the storage capacity of the storage medium used in the raster data storage step, the raster data is degraded in the degrade step in the raster data, and then the storage medium used in the raster data storage step. A computer program product stored in a computer-readable storage medium, characterized by being stored in a storage medium. 23. The computer program product stored in a computer readable storage medium according to claim 22, wherein said degrading step is a step of lowering resolution of raster data. 24. The computer program product stored in a computer readable storage medium according to claim 23, wherein said degrading step is a step of lowering resolution by error diffusion of raster data. 25. The method according to claim 2, wherein the degrading step is a step of lowering the gradation of raster data.
3. A computer program product stored on a computer-readable storage medium according to item 2. 26. A generation step for generating band-encoded expression information from image data described in a page description language, and a band-encoded expression information storage for storing the band-encoded expression information generated in the generation step. 23. The computer-readable computer according to claim 22, comprising: a step of rasterizing band-encoded expression information stored in a storage medium used in the band-code expressible information storage step. Computer program product stored on a simple storage medium. 27. When all the band-encoded expression information can be stored in a storage medium used in the band-encoded expression information storage means, raster data is output as it is without using the lossless compression means, 27. The computer-readable storage according to claim 26, wherein if the band encoded expression information can be stored in a storage medium used by the band encoded expression information storage means, the processing according to claim 22 is performed. A computer program product stored on a medium. 28. The storage medium used in the method for storing band encoded expression information is included in a storage medium used in the method for storing raster data.
A computer program product stored in a computer-readable storage medium according to claim 6. 29. When the raster data compressed in the lossless compression step becomes larger than the storage capacity of a storage medium used in the raster data storage step, the raster data is used in the band-encoded expression information storage step. Among the band-encoded expression information stored in the storage medium, the band-encoded expression information that has already been rasterized is cleared, and one of the storage capacities vacated in the storage medium used in the band-encoded expression information storage step. 27. The computer program product stored on a computer readable storage medium according to claim 26, wherein a part is used as the raster data storage capacity. 30. A degrading level for determining a degrading level of the rasterized raster data which can be stored in a storage medium used in the raster data storing step, according to a storage capacity of a storage medium used in the raster data storing step. A determination step, wherein when the raster data compressed in the lossless compression step is larger than the storage capacity of a storage medium used in the raster data storage step, the rasterization is performed up to the degrade level determined in the degrade level determination step. 23. The computer program product stored in a computer-readable storage medium according to claim 22, wherein the raster data rasterized in the step is degraded in the degrading step. 31. A line exclusive-OR step for performing an exclusive-OR operation on lines in contact with raster data, and a line in which line data is in contact with the raster data in the line exclusive-OR step 23. The computer program product stored in a computer-readable storage medium according to claim 22, wherein after performing an exclusive OR operation with each other, the lossless compression is performed in the lossless compression step.