JPH09214709A - Picture processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive picture processor by which the deterioration of a picture is restricted and bit map data is generated at high speed. SOLUTION: Bit map data is generated in a RIP part (picture data generating means) 3 in accordance with page description data so as to be expanded at every block in a cache part 10 and paint area data is generated, compressed by a compressing part 5 and sequentially stored in a first storage part 11 in description order of page description data. After the generation of bit map data equivalent to one page is finished, stored picture data is read from the first storage part 11, extended by an extending part 7, synthesized in a synthesizing part 13 at the time of plural kinds of picture data of a same page position and stored in the second storage part 12 in page raster order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image for producing bitmap data for each page from page description data in a page printer (including a printer section of a digital copying machine) such as black and white and color laser printers and LED printers. Regarding a processing device.

[0002]

2. Description of the Related Art A page printer typified by a laser printer is equipped with a memory called a frame memory for holding bitmap data (image data). A printer (image forming apparatus) that converts data (page description data) in a page description language such as Post Script into bitmap data has a frame memory having a capacity of one page of paper to be printed.

With the development of printer engines in recent years, it has become possible to perform printing with higher resolution and higher gradation, and as a result, the required capacity of the frame memory is also increasing. Particularly in the case of a color printer, more memory capacity is required.

Therefore, some techniques have been proposed for reducing the huge memory capacity to reduce the cost. For example, in Japanese Unexamined Patent Publication No. 4-88749, 1
It is described that a page is divided into a plurality of blocks, bit map expansion is performed for each block, and the data is compressed to reduce the total memory capacity.

FIG. 9 is a block diagram of a conventional image processing apparatus as described in the above document. One page is divided into a plurality of blocks and managed as shown in FIG. Memory) is also divided into a plurality of areas corresponding to each block. In the example shown in FIG. 10, the number of pixels in the main scanning direction and the sub scanning direction of one page is 4096.
With respect to pixels, one block has 4096 pixels in the main scanning direction and eight pixels in the sub scanning direction, and one page consists of 512 blocks.

In FIG. 9, reference numeral 1 is a host for creating data to be printed by a personal computer or word processor and outputting it as page description data. Reference numeral 2 is a page for inputting the page description data and printing it on a paper of a designated size. It is a printer. This page printer 2 is composed of an image processing device including a RIP unit 3, a combining unit 4, a compression unit 5, a storage unit (memory) 6, an expansion unit 7, and a selector 8, and an engine (image forming unit) 9. There is.

The RIP unit 3 is the PDL in the above publication.
Image data creating means called an interpreter,
Bitmap data is created for each block according to the page description data sent from the host, and sent to the synthesizing unit 4. The synthesizing unit 4 reads the bitmap data that has already been generated and is compressed and stored from the memory area corresponding to the block of the newly generated bitmap data in the storage unit 6, and the decompression unit 7 decompresses it. Selector 8
Via the input, and the combining process with the newly generated bitmap data is performed.

The combined bitmap data is compressed by the compression unit 5 and stored again in the memory area of the corresponding block of the storage unit 6. The above procedure is repeated for one page of page description data. afterwards,
Data is sequentially read from the memory area at the head of the page in the storage unit 6, decompressed by the decompression unit 7, transferred to the engine 9 and printed on paper to obtain an image output.

[0009]

In such a conventional image processing apparatus for a page printer, when the RIP unit 3 tries to write bitmap data to a new block, the RIP unit 3 has already been combined in the combination unit 4. It is necessary to compress the stored bitmap data, store it in the storage unit 6, and read the bitmap data of the corresponding new block to expand it.

Since the RIP unit 3 is in a waiting state during execution of this series of processing, there has been a problem that the processing time for creating one page is lengthened accordingly. Further, when the lossy compression method is used, if the same block is repeatedly compressed / expanded in accordance with the description order of the page description data, the image quality is deteriorated accordingly. The present invention has been made in view of the above points, and an object of the present invention is to provide an inexpensive image processing apparatus that suppresses image deterioration and can create bitmap data at high speed.

[0011]

In order to achieve the above-mentioned object, an image processing apparatus according to the present invention comprises an image data creating means for creating bitmap data as image data according to input page description data, and an image data creating means. First storage means for storing data, and at least a part of the bitmap data created by the image data creating means and data indicating a range of the bitmap data are stored in the first storage means as the page description data. And a storage processing unit for sequentially storing the description.

Further, after the second storage means for storing the image data and the image data creating means have finished creating one page of the bit map data of the page description data, the image data is stored from the first storage means. When there are a plurality of image data items that have been read out and have the same page position, it is desirable to provide a synthesis storage processing unit that synthesizes them and stores the data in the second storage unit in raster order of pages.

By doing so, only writing to the storage means is performed during the period in which the page description data is converted into image data, that is, bitmap data.
After the bitmap data for one page is created, during the period of combining the image data at the same position on the page and rearranging in the page raster order, only reading is performed to the storage unit, so writing and reading do not overlap, Since the waiting time resulting from this can be reduced, the conversion work from page description data to bitmap data can be performed at high speed.

In these image processing devices, data compression means for compressing the image data to be stored in the first storage means in a variable length in block units composed of a plurality of pixels, and read from the first storage means. By providing the data expansion means for expanding the image data, the memory capacity of the first storage device can be significantly reduced. Even in this case, since the image data at the same position is subjected to the compression / decompression process only once, the deterioration of the image quality can be reduced.

Further, when the composite storage processing means reads out the image data from the first storage means, the plurality of image data at the same page position are read out in the reverse order of the description of the page description data. , The composition process is performed in the order of description of page description data, and when the created image data is overlaid in the overwrite mode after that, it is not necessary to perform the composition process for the image data that does not remain as the finally completed image data. The creation speed can be increased.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a page printer provided with an image processing apparatus showing an embodiment of the present invention, and the same portions as those in FIG. 9 are denoted by the same reference numerals. Then, in place of the storage unit 6 in the conventional example of FIG. 9, a first storage unit 11 and a second storage unit 12 are provided, a cache unit 10 is newly provided, and the selector 8 is not provided. The combining unit 13 has a different function from the combining unit 4 of FIG.

FIG. 2 is an explanatory diagram showing the management state of the page. In this example, the number of pixels in the main scanning direction and the sub scanning direction of one page is 8192 pixels, which is 32 × 3.
It is divided into 2 = 1024 blocks, and an area of 256 × 256 pixels is set as one block. Each block is numbered (B1 to B1024) over the entire page.

FIG. 3 shows a RIP which is means for creating image data.
It is a figure which shows the state of 1 block of the cache part 10 which carried out the bit map expansion from the page description data by the part 3, (a) is 32 bits / pixel (4 bits / pixel, 8 bits).
/ Color) represents the bitmap data painted on one block of 256 × 256 pixels. (B) is 1-bit / pixel paint area data (data indicating the range of image data) for distinguishing an area (white) painted on this block from an area (black) not painted on this block.
Is shown.

The cache unit 10 holds a plurality of blocks of block data composed of two types of data as described above. The RIP unit 3 is currently using this cache unit 1.
When attempting to paint a block that is not held at 0, the bitmap data in the cache unit 10 is compressed by the compression unit 5 and stored in the first storage unit 11.

At this time, irreversible compression is applied to the bitmap data shown in FIG. 3A, and reversible compression is applied to the paint area data shown in FIG. 3B. At the same time, a table as shown in FIG. 5 is created which shows where in the first storage unit 11 the data of which block is stored. In the figure, H1, H2, ... Are address numbers of memory areas in the first storage unit 11.

The first storage unit 11 is constructed by a hard disk drive (HDD) whose unit price per bit is lower than that of DRAM. FIG. 4 shows a memory map in the HDD. A predetermined capacity is secured for each memory area H1, H2, ... In consideration of the compression rate. The block data from the cache unit 10 is sequentially stored in the order of the addresses of the HDD. Once the data of a certain block is H
Once the data is stored in the DD, the previous data will be recorded in HD even if a paint request is made again for the block at the same position.
The data is not read from D but stored in the HDD one after another.

In the example shown in FIG. 5, the data of the block B3 is stored in the memory areas H2 and H4 in the HDD. The above procedure is repeated for one page of the page description data, and when this process ends, the next phase starts.

FIG. 6 is a flow chart showing the processing procedure by this image processing apparatus. The above-described processing procedure is the rendering phase, and the processing procedure described below is the sorting phase. In this sort phase, the bitmap data is stored in the first storage unit (HD
D) 11 is read out, decompressed by the decompressing unit 7 of FIG. 1, combined by the combining unit 13, and stored in the second storage unit 12.

The synthesizing procedure will be described with reference to the flowchart of FIG. First, the bitmap data is called A and the paint area data is called B, and both are considered to be 0 in the initial state. The block data is read out and expanded in order from the last generated block data (in the reverse order of the description of the page description data). At this time, the table of FIG. 5 is used.

The read block data is A ′,
B ', new synthetic block data A and B can be created based on the following theoretical formula. However, the "overwrite" mode is set.

[0026]

(Equation 1)

This is repeated for all the data in the block. However, during the repetition, "B" is 1,
In other words, if all areas in the block are in the paint state,
After that, reading or logic synthesis of the block is not performed.

For example, FIG. 7 shows a block B3 in FIG.
FIG. 6 is an explanatory diagram showing a generation order and a combination order of bitmap data in the case of, and bitmap data A sequentially read out from the memory areas H4 and H2 of the HDD which is the first storage unit 11 in the order reverse to the generation order. When ‘′ and paint area data B’ are combined in the order of reading, the logically combined data sequentially changes from right to left at the bottom of FIG. 7.

In the case of the block B4 in FIG. 5, if the bitmap data A'and the paint area data B'which are sequentially read from the memory areas H7, H5 and H3 are as shown in the upper side of FIG. At the stage of synthesizing the data of H5 and H5, the entire paint area data B of the logically synthesized data shown in the lower part of the figure becomes black, and this block is completely covered by the data.

Therefore, the previously written H3 data does not appear at all in the final image. Therefore, the final image can be obtained by only combining the data of H7 and H5. According to this method, it is possible to omit redundant processing such as logical synthesis with H3 included in the page description data.

In this way, the bitmap data created by combining in the combining unit 13 is stored in the second storage unit 12.
To store in raster order of pages. This synthesizing process is repeated for all the blocks of one page, and the page creating process is completed. Even when the combined data is stored in the second storage unit 12, if the data is compressed, the memory capacity of the storage unit 12 can be reduced.

As described above, according to the above-described embodiment,
During the period in which the page description data is converted into bitmap data by the RIP unit 3, only writing to the first storage unit 11 is performed, and after the bitmap data for one page is created, During the period of synthesizing the image data at the same upper position and rearranging in the page raster order, only reading is performed in the first storage unit 11, so writing and reading in the first storage unit 11 do not overlap, Since the waiting time resulting from this can be reduced, the conversion work from page description data to bitmap data can be performed at high speed.

When storing the bitmap data and paint area data for each block expanded in the cache unit 10 in the first storage unit 11, the compression unit 5 compresses the data and the data is read into the synthesis unit 13. At this time, since the decompression unit 7 decompresses the memory, the memory capacity of the first storage device can be significantly reduced, and the cost can be reduced. In addition, when there are a plurality of image data at the same page position, the image quality is deteriorated because compression and decompression are repeated many times in the conventional method, but according to the method of the present invention, the image data at the same position is Since the compression / decompression process is performed only once, the deterioration of the image quality can be reduced.

Further, in the case where the image data once created is subsequently overlaid in the overwrite mode according to the description order of the page description data and does not remain as the finally completed image data, the image data that does not remain is combined. Since no processing is required, the page creation process can be sped up.

[0035]

As described above, according to the present invention, bitmap data for each page can be created from page description data at high speed with almost no deterioration in image quality, and can be realized at relatively low cost.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration example of a page printer including an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a management state of the page.

FIG. 3 is a diagram showing a state of one block of a cache unit 10 which is bitmap-developed from page description data by a RIP unit 3 of FIG.

FIG. 4 is a diagram showing a memory map in a first storage section 11 in FIG.

FIG. 5: Similarly, the data of each block is the first storage unit 11.
It is a figure which shows the table which shows where in which was stored.

FIG. 6 is a flowchart showing a processing procedure by the image processing apparatus of the page printer shown in FIG.

7 is an explanatory diagram showing a generation order and a combination order of bitmap data in the case of the block B3 shown in FIG.

8 is an explanatory diagram showing a generation order and a combination order of bitmap data in the case of the block B4 shown in FIG.

FIG. 9 is a block diagram illustrating a configuration example of a page printer including a conventional image processing device.

FIG. 10 is an explanatory diagram showing a management state of the page.

[Explanation of symbols]

 1: host 2: page printer 3: RIP unit (image data creating means) 5: compression unit 7: decompression unit 9: engine 10: cache unit 11: first storage unit (HDD) 12: second storage unit 13 : Composite part A: Bitmap data B: Paint area data

Claims (4)

[Claims] 1. An image data creating means for creating bitmap data as image data according to input page description data, a first storing means for storing image data, and an image data creating means. Image processing, comprising: storage means for storing at least a part of the bitmap data and data indicating a range of the bitmap data in the first storage means sequentially in the order of the description of the page description data. apparatus. 2. The image processing apparatus according to claim 1,
After the second storage unit for storing the image data and the image data creation unit have created one page of bitmap data of the page description data, the image data is read from the first storage unit and the same page is read. An image processing apparatus comprising: a plurality of pieces of image data at a position, which are combined, and combined storage processing means for storing the data in the second storage means in raster order of pages. 3. The image processing device according to claim 1, wherein the image data to be stored in the first storage means is compressed in a variable length in a block unit composed of a plurality of pixels, and An image processing apparatus comprising: a data decompression unit for decompressing image data read from the first storage unit. 4. The image processing apparatus according to claim 2,
When the image data is read from the first storage unit, the composite storage processing unit has a unit that reads a plurality of image data at the same page position in the reverse order of the description of the page description data. Image processing device.