JPH05205015A - Image processor - Google Patents

Abstract

PURPOSE:To use a page describing language PDL with high efficiency. CONSTITUTION:This processor is provided with an input means (external interface) 6 for inputting the PDL data together with a compressing means (CPU) 1 which compresses at least a part of the PDL data, a PDL memory means (page PDL memory) 14 which stores the partly compressed PDL data by an amount equal to at least one page, the raster image memory means (segment image memories 15-1-15-4) which correspond to a segment smaller than a page, and an expanding/evolving means (CPU) 1 which expands the compressed PDL data an then evolves the expanded data into a raster image to write the image into a raster image memory means.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a page description language (hereinafter referred to as P
The present invention relates to an image processing apparatus that receives and processes PDL data described in (DL), and particularly relates to an image processing apparatus that outputs image data to an image forming apparatus that forms an image in segment units obtained by dividing one page into a plurality of segments. Is.

[0002]

2. Description of the Related Art Conventionally, from a host computer or the like to PDL
(Page DescriptionLanguage
e) A printer that receives data and forms an image is configured as shown in FIG. As shown in the figure, the PDL data sent from the host computer 12 via the interface 11 and the external interface circuit 6 is
After being temporarily stored in the PDL buffer 13, it is rasterized into raster image data by the CPU 1 and written in the full page image memory 7. At this time, the ROM 2 is used to hold a program, the RAM 3 is a work RAM for work, and the font ROM 4 is used to hold a font for converting a character code in PDL data into bit image data. Be seen. Further, the dither pattern ROM 5 holds a dither pattern when the dither method which is one of the binarization methods is used, and 10 connects them.
It is a PU bus.

On the other hand, the image forming section 8 is, for example, an electrophotographic black and white printer, and forms an image based on the image signal 53 read from the full page image memory 7.
The address generator 9 uses the synchronization signal 51 from the image forming unit 8.
The read address from the full page image memory 7 is generated based on

Generally, the printing speed of an electrophotographic printer is high, and the image signal 53 read from the full page image memory 7 is also significantly faster than the image writing speed of the CPU 1 to the full page image memory 7. .. Further, in general, an electrophotographic printer cannot stop halfway while printing one sheet, so that it is necessary to expand all the image data required for printing in a full image memory for one page.

Further, since the data received from the host and put in the PDL buffer is immediately expanded and written in the full page image memory every time the expandable unit is received, the PDL buffer receives and expands the PDL data. 4 Kbytes is enough for smoothing, and it is not necessary to hold one page of PDL data.

In some cases, PDL data received from a computer or the like is sent in a compressed form in whole or in part. This is intended to shorten the communication time by reducing the communication volume. In that case,
The received PDL data is immediately decompressed, then expanded into a raster image and written in the full page image memory. Therefore, it is not necessary to hold the compressed data for one page and the decompressed data for one page, and it is only necessary to hold the raster image data for one page.

[0007]

The above-mentioned conventional example is directed to a page printer, but a printer which forms an image in segment units obtained by dividing one page into a plurality of pages (for example, BJ (Bubble Je manufactured by Canon Inc.) is used.
t) system printer), instead of having a full page image memory for holding all raster image data for one page, there is a segment image memory for holding one segment of raster image data. Good. Therefore, the segment printer is more cost effective than the page printer.

However, it is general that PDL data can describe an arbitrary position of description for one page and an image of arbitrary coordinates on one page. Therefore, in order to obtain raster image data of each segment. All PDL data for one page is required. That is, both when printing the first segment of one page and when printing the last segment, all the PDL data for one page is required, and when rasterized by the CPU 1, the raster image data in each segment is It is written into the image memory and the others are discarded.

Therefore, the PDL buffer needs to hold PDL data for one page. Generally, PDL data does not require a memory as compared with raster image data. However, PDL data can generally describe raster image data within the framework, and one page of PDL data can be described.
Since a large amount of raster image data may be included in the data, the following drawbacks may occur.

1) If the capacity of the PDL buffer is determined in accordance with the worst value, the capacity becomes the same as that of the raster image memory for one page, and the advantage of the segment system cannot be utilized.

2) If the capacity of the PDL buffer is reduced, the PDL data containing a large amount of raster image data cannot be processed and cannot be printed.

3) When the compressed PDL data is processed, if the decompressed PDL data for one page is held for one page, the required memory amount increases and the advantage of the low cost of the segment system is obtained. I can't make use of it. Further, if the memory amount is limited, the proportion of PDL data that cannot be handled increases.

4) When processing the compressed PDL data, if the PDL data before decompression is held for one page, the decompression process needs to be performed every time the expansion into each segment is performed. It will cost you.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an image processing apparatus capable of efficiently handling PDL data.

[0015]

In order to solve the above problems, the image processing apparatus of the present invention has at least input means for inputting PDL data, compression means for compressing at least part of the PDL data, and at least Partially compressed P
PDL memory means for holding at least one page of DL data, raster image memory means corresponding to one segment less than one page, compressed PDL data is expanded and expanded into a raster image, and raster image memory means is created. A plurality of segments forming one page, having a decompression / expansion unit for writing and raster image data necessary for forming an image for one segment, read from the raster image memory unit, and transferred to the image forming unit. On the other hand, the above-described decompression, expansion, and transfer are repeated to form an image of one page.

A compressed PD at least a part of which is compressed
Input means for inputting L data, PDL memory means for holding at least one page of compressed PDL data at least partially compressed, raster image memory means corresponding to one segment less than one page, and compressed PDL data Has a decompressing / expanding means for decompressing, decompressing into a raster image and writing in a raster image memory means, and a transfer means for reading an image for one segment from the raster image memory means and transferring it to the image forming means. It is characterized in that a one-page image is formed by repeating the above-mentioned expansion, expansion, and transfer for a plurality of segments constituting the.

[0017]

【Example】

(Embodiment 1) In the first embodiment of the present invention, at least input means for inputting PDL data, compression means for compressing at least a part of the input PDL data, and PDL data at least a part of which is compressed. PD holding one page
L memory means, raster image memory corresponding to one segment less than one page, and compressed PDL data are expanded, expanded into a raster image, and written in the raster image memory means. By having a means for reading an image from the raster image memory means and transferring it to the image forming means, by repeating the above expansion, expansion and transfer for a plurality of segments forming one page, one page of image is formed. The PDL data containing a large amount of raster image data can be processed with a small capacity of the PDL buffer. This will be specifically described below.

FIG. 1 is a block diagram showing an image processing apparatus 50 compatible with color PDL in the first embodiment of the present invention.

As shown, the host computer 12
The PDL data sent from the interface 11 and the external interface circuit 6 by the CPU 1 is compressed by the CPU 1 in accordance with an algorithm described later and is written in the page PDL memory 14.

One page of PDL data is page PDL
When the data is stored in the memory 14, the CPU 1 sets the page PDL
The PDL data in the memory is read little by little, decompressed in accordance with an algorithm described later, expanded into raster image data corresponding to one pixel, and written in the segment image memory. Segment image memory 15
Is a memory for holding a raster image corresponding to a segment, which is a unit smaller than one page, as described later. The ROM 2 is used to hold a program showing the image processing procedure, and the RAM 3 is a work RA for work.
The font ROM 4 is M and is used to hold a font for converting a character code in PDL data into bit image data. Also, dither pattern RO
M5 holds a dither pattern when the dither method which is one of the binarization methods is used, and 10 is a CPU bus connecting them.

On the other hand, the image forming section 8 is a color printer which forms an image in units of segments. This type of system is often used in a printer of the BJ system, which is a type of inkjet system. Figure 2 (a) for the BJ method
An image is formed on a sheet by using the recording element 19 as shown in FIG. In FIG. 2, the ink supplied from the ink tank 23 is ejected from each nozzle 20 under the control of the ejection controller 21 and printed on an output medium such as paper. In the case of this embodiment, the number of nozzles is 128, and ejection and non-ejection are controlled for each nozzle. FIG. 2B shows a method of printing on the paper 24 using the print element 19. The print head 19 is (25) in FIG.
-1 to 25-4), printing is performed with a width of 128 pixels while moving in the X direction of the paper 24. Then (26
Similarly, printing is performed by moving 128 pixels in the Y direction as shown in -1 to 26-3). The area printed by this single movement in the X direction is called a segment. The image of one page is composed of a plurality of segment images.
As a feature of BJ method, while printing one segment,
I can't stop halfway. However, since it can be stopped between each segment, it is sufficient that the segment image memory 15 contains the raster image data necessary for printing one segment, and the capacity for one page is not required. As described above, since the image is formed in the image forming unit 8 in the unit of segment, all the processes are performed in the unit of segment. That is, for each segment forming one page,
PDL data is read from the page PDL memory, decompressed, and expanded into a raster image, and this is repeated for all segments to form a one-page image.

FIG. 3 is a diagram for explaining PDL data. PDL (Page Description) represented by PostScript language of ADOBE
onLanguage), as shown in FIG.
The image of one page is (i) the image by the character code
This is a language for combining and describing elements such as (ii) image description by graphic code and (iii) image description by raster image data, and the data described by P is P
This is DL data.

FIG. 3B shows an example of the description by the character code. l100 is a description that specifies the color of the character,
In the parentheses, the luminances of Red, Green, and Blue are shown in order. The minimum is 0.0 and the maximum is 1.0. In l100, the character is designated to be black.
Next, l101 is the character string "IC" in the variable String1.
Is substituted. Next, in l102, the first and second parameters indicate the x coordinate and the y coordinate of the start position coordinates on the paper on which the character string is laid out, the third parameter indicates the character size, and the fourth parameter indicates the character interval. The fifth parameter indicates the character string to be laid out. In short, l102 is from the coordinate (0.0,0.0),
The instruction is to lay out the character string “IC” with a size of 0.3 and an interval of 0.1.

FIG. 3C shows an example of the description by the graphic code. Like l100, l103 specifies the color of the line, and here, Red is specified. Next, l10
Reference numeral 4 designates to draw a line. The first and second parameters are the start coordinate of the line, and the third and fourth parameters are the end coordinate, respectively, and the X and Y coordinates. The fifth parameter indicates the line thickness.

FIG. 4A shows an example of description by raster image data. l105 designates the raster image as a variable image
It is assigned to 1. Here, the first parameter represents the image type of the raster image and the number of color components, the second parameter represents the number of bits per color component, and the third and fourth parameters are the x and y directions of the raster image. Represents the image size of. The fifth and subsequent parameters are raster image data. The number of raster image data is the product of the number of color components forming one pixel and the image size in the x and y directions. 1105, the RGB image has three color components (Re
d, Green, and Blue), the number of raster image data is 3 × 5 × 5 = 75.

FIG. 4 (b) shows one page of FIG.
4B, FIG. 4C, and FIG. 4A show how the graphic description is interpreted and rasterized into raster image data. R
100, 101, and 102 are respectively shown in FIG.
4C is an expanded version of the PDL data shown in FIG. Here, when the entire FIG. 4B corresponds to one sheet (24 in FIG. 2B), the segments 27-1 and 27-
2, 27-3 and 27-4 correspond to the first to fourth segments in FIG. 4B. At this time, focusing on the third segment, for example, when printing the third segment, the segment memory includes only a part of R102 and a part of R101 and does not include R100. That is, R100 may be ignored when printing the third segment. In such a case, the position information of each segment and the PDL data (l102, l104, l) can be ignored.
It can be determined from the layout position information in 106). For example, the third segment has a y coordinate of 0.4 to
Since it is in the range of 0.8, it overlaps with l104 and l106, but does not overlap with l102.

FIG. 5, FIG. 6 and FIG. 7 are flow charts of control of the image processing apparatus of this embodiment. First, in S101, one unit of PDL data is received. One unit is the number b
It may be one page or one page, but may be a unit suitable for processing, for example, one line unit in FIGS. 3 and 4. S10
In 2, S103 and S104, the received data is processed from the beginning. That is, in S102, it is determined whether or not the PDL data of interest is a raster image (for example, l105 in FIG. 4A), and if it is a raster image, compression processing according to an algorithm described below is performed and the data is written in the page PDL memory. On the other hand, if it is other data, it is written in the page PDL memory 14 as it is in S104. After this is performed for all PDL data included in one unit of PDL data, it is determined in S105 whether one page of PDL data is stored in the page PDL memory 14.
EOF (End of Fil) is used for normal PDL data.
e) Since information such as a symbol indicating the end of the page or information for instructing the start of printing is included, determination is performed using this. If it is not included, S101 to S105 are repeated, but if it is included, 1 is assigned to the focused segment number n in S106. Next, in S107, the page PDL
The PDL data stored in the memory 14 is sequentially read from the head, and the nth segment is decompressed and expanded in accordance with an algorithm described later, and written in the segment image memory 15. Next, in S108, the image is expanded in the segment image memory 15. The raster image data for the nth segment is read out, and the image forming unit 8 forms one segment. In S109, it is determined whether or not image formation has been completed for all the segments forming one page, and if not completed, S10 is determined for the next segment.
Repeat 7 to S109. If it is finished, the paper discharge process is performed in S111, and the process returns to S101.

FIG. 6 is a flowchart detailing the compression process of S103 of FIG. First, in S201,
It is determined whether the type of raster image of interest is (A) a document image, a CG image, (B) a gradation-oriented image, or (C) a resolution-oriented image. For this determination, grouping may be performed based on the image type and the number of bits in FIG. 4B,
You may judge by seeing a part of characteristic of a raster image. For example, in the former case, the type (A) is used when the raster image is monochrome 1 bit, and the type (C) is used when the raster image is a plurality of monochrome bits and type (B). In the latter case, for example, a binary image with many white backgrounds is type (A), an image with many high frequency components is type (C), and others are type (B). In the case of type (A), in step S202, reversible compression is performed by the MR method or the like performed by a facsimile or the like. Since this type of image has a small amount of data, lossless compression with a low compression rate is sufficient. On the other hand, in the case of the tone-oriented type (B), first, S2
In 03, the compression method and the compression ratio are determined from the relationship between the raster image size and the raster image memory size. That is, the raster image size is a certain criterion 1 compared to the raster image memory size.
If it is smaller, it is not compressed in S206. If it is larger than the reference 1 but smaller than the reference 2, lossless compression is performed in S207. Examples of lossless compression methods for color multi-valued images include run length coding, MH, and MR. In addition, an image larger than the reference 2 needs to be compressed at a high compression rate, which is a lossy compression. That is, S208
Compress data by thinning out the data. The thinning rate at this time is determined based on the compression rate determined in S203.

On the other hand, in the case of the type (C) which emphasizes resolution,
In S204, the compression method and compression rate are determined in the same manner as in S203. Next, S210 and S211 are respectively S2.
06, S207, but in S212, S208
Unlike, the compression is performed by reducing the number of bits per pixel. For example, image data originally having 1 pixel of 8 bits can be compressed to 1 bit while maintaining gradation to some extent by using a binarizing method such as a dither method.

Next, in S213, the data compressed by each method is written in the page PDL memory together with the compression method. In the present embodiment, these compression processes are performed by the image data string of raster image data (for example, R in FIG. 4B).
₀ , G ₀ , B ₀ ...)), and the layout position information portion is not compressed.

FIG. 7 is a block diagram showing in detail the decompression and decompression processing in S107 of FIG. First, in S301,
One unit of PDL data is read from the page PDL memory. Next, in step S302, it is determined from the position information of the target segment and the layout position information of the target PDL data whether or not the PDL data is related to the target segment. If not relevant, S303 to S30
The process of 5 is not performed. If there is a relation, in S303, it is determined whether the PDL data of interest is compressed. If it is compressed, in step S304, decompression is performed according to the compression method. Next, in step S305, the PDL data is expanded into a raster image that is a collection of pixel rows, and the segment memory 15
Write in. The steps S304 and S305 may be performed at the same time, that is, the expansion is performed while expanding the segment memory 1
You can write in 5. By doing so, the amount of intermediate data can be reduced. Next, in S306, it is determined whether or not all PDL data has been processed, and if not processed, S301 to S306 are repeated.

In this embodiment, the received PD
Although the L data is compressed, it may be compressed by some preprocessing. Although the layout coordinate position information is not compressed in the raster image information, instead of this, the whole may be compressed, and at the time of expansion, only this part may be expanded and determined in S302. Further, not only the raster image information but the whole may be compressed. In these cases, parts other than the raster image need to be losslessly compressed. Further, in the present embodiment, the image forming unit 8 is separated from the image processing unit 50, but this may be integrated.

(Embodiment 2) FIG. 8 is a block diagram showing a color PDL compatible image processing apparatus 50 according to a second embodiment of the present invention.

First, the difference from the first embodiment is that P
This is that it has a DL page memory for two pages and has a so-called double buffer configuration. By doing this,
The compression process and the decompression process can be performed in parallel.

The second difference is that the segment image memory has two segments and has a so-called double buffer structure. By doing so, the decompression / expansion process and the transfer process can be performed in parallel.

The third difference is that the compression / decompression process, which was performed by software in the first embodiment, is performed by hardware. The data before processing is put in the first buffer 30,
The compression / expansion circuit 31 performs hardware processing according to a preset parameter such as a compression ratio, and stores it in the second buffer 32. Then, the CPU 1 reads the processed data from the second buffer. The contents of the compression / expansion circuit vary depending on the compression method.
Since various compression methods such as the CT method and the AVQ method are integrated into an IC, they can be used.

The fourth difference is that in the first embodiment, PDL data is received from an external host computer or the like by communication, but in the present embodiment, PDL data is read from the internal floppy disk 59. Is.
A hard disk or the like may be used instead of the floppy disk, and PDL data created by an application program (not shown) may be delivered on the main memory.

The fifth difference is that in the first embodiment, the image is transferred using the so-called video I / F, which is to send the image via the image signal line 53 according to the synchronizing signal 51. In this embodiment, the image is sent by the communication module 61 via the communication line 62. This communication module is also used when sending a print start command or the like to the image forming unit. Communication lines in this case include GPIB and SCS.
A general-purpose asynchronous interface such as I is used. At this time, since the transfer speed is generally slower than the forming speed of the image forming unit, an image memory for speed conversion is required in the image forming unit.

As described above, according to the above-described embodiment, in the segment type printer, P for one page is used.
By having at least part of the DL data compressed,
There is an effect that the capacity of the PDL memory can be reduced and the advantage of the segment type printer that the raster image memory only needs to be provided for the segment and the cost is lower than that of the page printer can be utilized.

(Third Embodiment) In the third embodiment of the present invention, input means for inputting PDL data at least partially compressed and at least one page of PDL data at least partially compressed are held. PDL memory means for
A raster image memory unit corresponding to one segment smaller than a page and a compressed PDL data are expanded, expanded into a raster image, and expanded in a raster image memory unit,
It has a developing means and means for reading an image for one segment from the raster image memory means and transferring it to the image forming means.
By decompressing, expanding, and transferring the plurality of segments forming one page to form one page image, a compressed PDL containing a large amount of raster image data with a small PDL buffer capacity. The data can be processed.

In the present embodiment, in FIG. 1, at least a part of the PDL data compressed from the host computer 12 via the interface 11 and the external interface circuit 6 is compressed by the CPU 1 according to an algorithm described later. Decompression processing is performed and the data is written in the page PDL memory 14. The other points are almost the same as in the first embodiment.

FIG. 10 is a flow chart of control of the image processing apparatus of this embodiment. First, in S401, one unit of PDL data is received. 1 unit is 1 even with several bytes
Pages may be used, but a unit suitable for processing, for example, in FIG.
It may be in units of one line. S102, S103, S10
In 4, the received data is processed from the beginning. That is,
In S402, it is determined whether or not the PDL data of interest is compressed PDL data other than the raster image (for example, l105 in FIG. 4D), and if so, decompression processing is performed according to the compression method, and page PDL is performed. Write to memory.
On the other hand, if the data is other than that, the data is directly written into the page PDL memory 14 in S404. At this time, regarding the raster image, its layout position information (for example, l10
The first 4 parameters of 5) are decompressed and only the data string portion is written in a compressed form.
This is performed for all PDL data included in one unit of PDL data, and then in step S405, one page of PD
It is determined whether L data is stored in the page PDL memory 14. For normal PDL data, EOF (Endo
Since information indicating the end of a page and information instructing to start printing, such as the f File) symbol, is included, determination is performed using this. If not included S401 to S40
5 is repeated, but if it is included, 1 is assigned to the focused segment number n in S406. Next, in step S407, the PDL data stored in the page PDL memory 14 is sequentially read from the beginning, and the nth segment is decompressed and expanded according to an algorithm described later, and written in the segment image memory 15. Next, in S408, the segment image memory 1
Expanded to 5. The raster image data for the nth segment is read out, and the image forming unit 8 forms one segment. In step S409, it is determined whether image formation has been completed for all the segments that form one page. If not, step S is performed for the next segment.
407 to S409 are repeated. If it is finished, S411
Then, the paper discharge process is performed and the process returns to S401.

FIG. 11 is a block diagram showing in detail the decompression and decompression processing of S407 of FIG. First, in S501, one unit of PDL data is read from the page PDL memory. Next, in S502, whether or not the PDL data is related to the segment of interest is determined from the position information of the segment of interest and the layout position information of the PDL data of interest. At this time, since the layout position information of all PDL data including the layout position information of the raster image data is expanded, the processing can be performed at high speed. S5 if not related to the segment of interest
The processing of 03 to S505 is not performed. If relevant, S5
In 03, it is determined whether the PDL data of interest is compressed. If it is compressed, decompression is performed according to the compression method in S504. Next, in S <b> 505, the PDL data is expanded into a raster image that is a collection of pixel columns and written in the segment memory 15. The steps S504 and S505 may be performed at the same time, that is, they may be expanded and expanded and written in the segment memory 15. By doing so, the amount of intermediate data can be reduced. Then S50
In step 6, it is determined whether all PDL data has been processed. If not, steps S501 to S5306 are repeated.

In this embodiment, the received PD
Although the L data is subjected to the first decompression processing, what is subjected to some pre-processing may be subjected to the first decompression, or post-processing may be performed after the first decompression and stored in the PDL memory. Also, CP
If the U1 has a sufficient capacity, the first decompression process may be omitted and the data may be written in the PDL memory as it is. Further, when the uncompressed raster image data is received, the CPU 1 may perform the compression process and write it in the PDL memory.

In this embodiment, the image forming section 8 is separated from the image processing section 50, but it may be integrated.

(Fourth Embodiment) The third embodiment may be modified like the image processing apparatus 50 corresponding to the color PDL in the second embodiment.

The point different from the third embodiment is that, firstly, P
This is that it has a DL page memory for two pages and has a so-called double buffer configuration. By doing this,
The first decompression processing and the second decompression / expansion processing can be performed in parallel.

The second difference is that the segment image memory has two segments and has a so-called double buffer structure. By doing so, the second expansion / expansion processing and the transfer processing can be performed in parallel.

The third difference is that the compression / decompression process, which was performed by software in the first embodiment, is performed by hardware. The data before processing is put in the first buffer 30,
The compression / expansion circuit 31 performs hardware processing according to a preset parameter such as a compression ratio, and stores it in the second buffer 32. Then, the CPU 1 reads out the processed data from the second buffer. The contents of the compression / expansion circuit differ depending on the compression method, but since various compression methods have been integrated into an IC in recent years, they can be used.

The fourth difference is that in the first embodiment, the PDL data is received by communication from an external host computer or the like, but in the present embodiment, the PDL data is read from the internal floppy disk 59. It is a point.
A hard disk or the like may be used instead of the floppy disk, and PDL data created by an application program (not shown) may be received on the main memory.

The fifth difference is that in the first embodiment, the image is transferred using a so-called video I / F, which is to send the image via the image signal line 53 by the synchronizing signal 51. In the embodiment, the image is sent by the communication module 61 via the communication line 62. This communication module is also used when sending a print start command or the like to the image forming unit. Communication lines in this case include GPIB and SCS.
A general-purpose asynchronous interface such as I is used. At this time, since the transfer speed is generally slower than the forming speed of the image forming unit, an image memory for speed conversion is required in the image forming unit.

As described above, in the segment type printer, the capacity of the PDL memory can be reduced by holding the received PDL data of at least one copy for one page as it is without decompression. Further, there is an effect that the advantage of the segment type printer that the raster image memory only needs to be provided for the segments and the cost is lower than that of the page printer can be utilized.

Further, at the time of expanding each segment into a raster image, it is determined whether or not each compressed PDL data is necessary for the segment of interest, and only if necessary, decompression and expansion can be performed to increase the processing speed. ..

Further, the above judgment can be speeded up by expanding the compressed PDL data other than the raster image data in the PDL data before writing it in the PDL memory.

[0055]

As described above, according to the present invention, P
It can handle DL data.

[Brief description of drawings]

FIG. 1 is a block diagram of an image processing apparatus according to a first embodiment.

FIG. 2 is a diagram for explaining a BJ type printer.

FIG. 3 is a diagram for explaining PDL.

FIG. 4 is a diagram for explaining PDL.

FIG. 5 is a flowchart showing the procedure of the first embodiment.

FIG. 6 is a flowchart showing the procedure of the first embodiment.

FIG. 7 is a flowchart showing the procedure of the first embodiment.

FIG. 8 is a block diagram of an image processing apparatus according to a second embodiment.

FIG. 9 is a block diagram of a conventional image processing apparatus.

FIG. 10 is a flowchart showing the procedure of the third embodiment.

FIG. 11 is a flowchart showing the procedure of the third embodiment.

[Explanation of symbols]

 6 PDL input means 1, 2, 3 compression means 14 PDL memory means 15 raster image memory means 1, 2, 3, 4, 5 decompression / expansion means 53, 1, 9 transfer means

Claims (18)

[Claims] 1. Input means for inputting PDL data, compression means for compressing at least part of PDL data, PDL memory means for holding at least one page of PDL data compressed at least part, and less than one page Raster image memory means corresponding to one segment, decompression means for decompressing compressed PDL data, decompressing it into a raster image, and writing it to the raster image memory means, raster image data necessary to form an image for one segment Is read from the raster image memory means and is transferred to the image forming means, and one page of image is formed by repeating the above expansion, expansion and transfer for a plurality of segments forming one page. An image processing device characterized by the above. 2. The decompression / expansion means, when performing decompression / expansion for a certain segment, determines whether or not the decompression / expansion of the PDL data is necessary for the segment based on the expansion position information of each compressed PDL data. The image processing apparatus according to claim 1, wherein the PDL data is decompressed and expanded only at any time. 3. Compressing according to the relationship between the capacity of the PDL memory means and the size of the PDL data to be compressed,
The image processing apparatus according to claim 1, wherein it is determined whether or not to perform the processing. 4. The image processing apparatus according to claim 1, wherein the compression method or the compression rate is changed according to the relationship between the capacity of the PDL memory means and the size of the PDL data to be compressed. 5. According to the data type of PDL data,
The image processing apparatus according to claim 1, wherein it is determined whether to compress or not to compress. 6. The apparatus according to claim 5, which compresses only raster image data in PDL data. 7. The image processing apparatus according to claim 1, wherein a compression method or a compression rate is changed according to the data type of PDL data. 8. The image processing apparatus according to claim 1, wherein the compression unit performs reversible compression. 9. The image processing apparatus according to claim 1, wherein the compression unit performs compression by reducing the number of bits of raster image data in PDL data. 10. The image processing apparatus according to claim 9, wherein the compression unit performs compression by binarizing the raster image data in the PDL data. 11. The image processing apparatus according to claim 1, wherein the compression unit performs compression by thinning out raster image data in PDL data. 12. The image processing apparatus according to claim 1, wherein the image forming unit is a BJ type printer. 13. A compressed PD at least partially compressed
Input means for inputting L data, PDL memory means for holding at least one page of compressed PDL data at least partially compressed, raster image memory means for one segment less than one page, decompressing compressed PDL data A plurality of units forming one page, having a decompression / expansion unit that expands to a raster image and writes the raster image memory unit, and a transfer unit that reads an image for one segment from the raster image memory unit and transfers the image to the image forming unit. An image processing apparatus, wherein an image of one page is formed by repeating the above expansion, expansion, and transfer for a segment. 14. A determination means for determining, for each segment forming one page, whether the segment needs to be expanded / decompressed based on the expansion position information of each compressed PDL data forming one page. Has,
14. The image processing apparatus according to claim 13, wherein the compressed PDL data determined to be necessary is decompressed and expanded. 15. The image processing apparatus according to claim 14, wherein when each compressed PDL data is compressed together with the expansion position information, the determination is made at the time when the expansion position information is expanded. 16. Further, a part of the compressed PDL data is converted into a PD.
16. The image processing apparatus according to claim 13, further comprising: pre-expansion means for expanding before writing to the L memory. 17. The image processing apparatus according to claim 16, wherein compressed PDL data other than the compressed raster image data in the PDL data is expanded by the pre-expansion means. 18. The image processing apparatus according to claim 13, wherein the image forming unit is a BJ system.