JP4126466B2 - Image compression processing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image compression processing method and apparatus.
[0002]
[Prior art]
In an image processing apparatus such as a copying machine, image data read by an image scanner is compressed and temporarily stored in a memory, and the stored image data is read and decompressed to the original image data as necessary. Duplicate output is performed. Then, in consideration of economic efficiency, in order to perform image compression at high speed, a plurality of relatively widely used compression chips (for example, those for facsimile) are used, and the image data is divided and the plurality of compressions are performed. Processing time is shortened by distributing to chips and processing in parallel.
[0003]
[Problems to be solved by the invention]
However, according to the conventional image data dividing method, image data obtained by reading an original image with an image reader (image scanner) is converted into the number of compression chips in the extending direction of the image reader (hereinafter referred to as the main scanning line direction). Since it is a method of dividing together, if the size of the original image (for example, the size of A ₀ , A ₁ , A ₂ , A _3, etc.) changes, the usage rate of the memory storing the compressed image data There is a problem that decreases.
[0004]
That is, for example, when an image compression processing apparatus is manufactured using four compression chips for A ₀ , the main scanning line is divided into four data areas according to the four compression chips, and the compression chip is divided into each data area. Are assigned one by one and image compression is performed. And that processes the original image A ₃ by such image compression processing apparatus, the length of the image data corresponding to the main scanning line is shortened, for example, two compression chip will not work. In addition, since the image data is not stored in the memory area allocated to the compression chip that does not operate, the utilization rate of the memory is deteriorated.
[0005]
By the way, if the memory area is not fixedly allocated to the compression chip and the image data can be appropriately stored in an arbitrary memory area, the memory utilization rate can be improved. However, since the plurality of compression chips operate independently of each other, it is difficult to control the fluctuation of the memory area.
[0006]
Therefore, the present invention provides an image compression processing method and apparatus capable of increasing the utilization rate of a memory for storing compressed image data even if the length of the image data in the main scanning direction varies due to the change in the size of the original image. The issue is to provide.
[0007]
[Means for Solving the Problems]
The problem is that the number of image compression processing circuits is an even number, the image data is divided into data areas more than twice the number of image compression processing circuits for each main scanning line, and the image data in each data area is compressed into a plurality of images. This can be solved by sequentially allocating image data to processing circuits (compression chips). That is, for example, the image data of one main scanning line can be divided into units of bytes, and can be divided into two compressed chips for each odd byte (8 bits) and even bytes. According to this, even if the data length of the main scanning line changes, the compression processing is distributed in units of bytes, so the load on the two compression chips becomes substantially uniform, and the memory utilization rate is accordingly increased accordingly. No bias. Although it is not limited to dividing into byte units, by increasing the number of divided data areas as much as possible, it is possible to maintain a high memory utilization rate even for original images of various sizes.
[0008]
Further, it is preferable that even number n (n ≦ m / 2) compression chips different from each other are assigned to a plurality of main scanning lines to compress the image data. That is, for example, the image data of one main scanning line is divided into bytes, and divided into a first compression chip and a second compression chip for each odd byte (8 bits) and even bytes, and processed. For each of the even main scanning lines, the processing is divided into the first and second compression chip groups and the third and fourth compression chip groups, and the compression is performed while maintaining a high memory utilization rate. Processing can be performed at high speed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an image compression processing apparatus to which an image compression processing method according to the present invention is applied. In the figure, image data read by an image scanner is input to a distribution circuit 1 and divided, and distributed to four compression chips 2a to 2d. The image data distribution circuit 1 temporarily stores input image data, and divides the image data into odd lines and even lines of the main scanning line, and the odd line images divided by the line distribution circuit 11. Once the data is stored, the odd-numbered byte distribution circuit 12 and the even-numbered byte distribution circuit 13 divide the data into odd-numbered bytes and even-numbered bytes, and the odd-numbered and even-numbered byte images divided by these byte-distributed circuits 12 and 13. And buffers 14a to 14d for accumulating data. Compression chip 2a~2d is provided for each buffer 14 a to 14 d, the compression chip 2a~2d is subjected to known image compression processing by sequentially capturing the image data from the buffer 14 a to 14 d, respectively made to correspond to the compressed image data Store in the determined memory banks 3a to 3d. Further, the compression chips 2a to 2d perform image compression processing using the compressed image data of the adjacent areas stored in the memory banks 3a to 3d as necessary.
[0010]
Alternately Thus from being configured, as shown in FIG. 2, for example, among the image data input from the image scanner 21 having a length corresponding to the A ₀ size, image data of the odd-numbered lines for each byte Are taken into the compression chips 2a and 2b and compressed. Similarly, even line image data is alternately taken into the compression chips 2c and 2d for each byte and compressed. The compressed image data is stored in the corresponding memory banks 3a to 3d.
[0011]
Here, when the size of the original image is smaller than the _A0 size, the length of the image data corresponding to the main scanning line output from the image scanner 21 is shortened, but the image data of one main scanning line is expressed in bytes. Since the data is divided and divided into compression chips 2a and 2b (or 2c and 2d) for every odd-numbered byte (8 bits) and even-numbered bytes, processing is performed even if the data length of the main scanning line changes. The processing loads of 2a and 2b (or 2c and 2d) become substantially uniform, and accordingly, the memory utilization rate is not biased, and the memory capacities of the memory banks 3a to 3d can be used effectively.
[0012]
In contrast, as shown in FIG. 3, for example in correspondence with the four compression chips to d, according along the main scanning line on the conventional method of compression processing is divided into four image data, A ₃ Size In this case, since the two compression chips c and d do not operate, the corresponding memory bank is not used. As a result, while have a memory capacity corresponding to A ₀ size, in the case of A ₃ size is there was a problem that it is impossible to utilize the memory capacity.
[0013]
The present invention is not limited to the division into byte units as shown in the above embodiment. In short, the image data is divided into even m (m ≧ 4) data areas along the main scanning line, and even n (n ≦ m / 2) compression chips are alternately allocated to the data area. The image data may be compressed. Further, by increasing the number m of the divided data areas, it is possible to maintain a high memory utilization rate even for original images of various sizes.
[0014]
【The invention's effect】
As described above, according to the present invention, even when the length of image data in the main scanning direction varies, the utilization factor of the memory for storing the compressed image data can be increased.
[Brief description of the drawings]
FIG. 1 is a block diagram of an image compression processing apparatus according to an embodiment to which an image compression processing method of the present invention is applied.
FIG. 2 is a diagram for explaining the operation of the image compression processing apparatus of FIG. 1;
FIG. 3 is a diagram for explaining the operation of a conventional image compression processing apparatus in order to explain the effect of the present invention.
[Explanation of symbols]
1 distribution circuit 2a, 2b, 2c, 2d compression chip 3a, 3b, 3c, 3d memory bank 11 line distribution circuit 12, 13 byte distribution circuit 14a, 14b, 14c, 14d buffer

Claims (4)

Image data scanned by scanning an original image with an image scanner is compressed by a plurality of image compression processing circuits, and the compressed image data is stored in a memory area set corresponding to each image compression processing circuit. In an image compression processing method comprising:
The number of the image compression processing circuits is an even number, the image data is divided into data areas more than twice the number of the image compression processing circuits for each main scanning line, and the image data in each data area is divided into the plurality of image data An image compression processing method, wherein image data is compressed by being sequentially assigned to a compression processing circuit. The image compression processing method according to claim 1,
2. The image compression processing method according to claim 1, wherein the number of the image compression processing circuits is an even number corresponding to an odd number of main scanning lines and an even number of main scanning lines . A plurality of image compression processing circuits for compressing image data, a memory having a memory area for storing image data compressed by the means, and image data read by scanning an original image with an image scanner are divided. An image compression processing apparatus comprising image data distribution means for distributing to the plurality of image compression processing circuits,
The image compression processing circuit is provided in an even number,
The image data distribution means divides the image data into data areas that are more than twice the number of the image compression processing circuits for each main scanning line, and the image data of each data area is divided into the plurality of image compression processing circuits. An image compression processing apparatus that distributes in order. The image compression processing device according to claim 3.
An image compression processing apparatus, wherein an even number of the image compression processing circuits are provided in correspondence with odd-numbered main scanning lines and even-numbered main scanning lines .

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