JPH0564005A - Compressed data expansion processing method - Google Patents

Abstract

PURPOSE:To obtain a compressed data expansion processing method in which processing time is short, and a large-capacity storage means is not required. CONSTITUTION:Each compressed code corresponding to one line of picture data is added with information to show the data quantity of the corresponding compressed code, and at the time of image development, the compressed code of only the necessary line is developed by skipping the unnecessary line by referring to it, and only this necessary part is stored in a storage means. Thus, the compressed data expansion processing method in which the processing time can be shortened drastically compared with the case that the whole compressed data is image-developed, and the capacity of the storage means for storing developed image data can be small as well is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed data decompression processing method for decompressing a necessary portion of compressed data obtained by compressing image data.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of an image processing apparatus to which the present invention and a conventional compressed data expansion processing method are applied. In the figure, 1 is compressed data obtained by encoding and compressing image data as image data, 2
Is image data expanded from the compressed data 1.

Reference numeral 3 is a main storage device as a storage means for storing the compressed data 1 and image data 2, and 4 is an image data 2 obtained by expanding the compressed data 1.
Is a central processing unit (hereinafter referred to as a CPU) which is developed to control the entire image processing apparatus.

Reference numeral 5 is an output device for outputting the expanded image data 2, and reference numeral 6 is an input / output device which comprises a display section and an input section and serves as a man-machine interface between the image processing apparatus and an operator.

Next, the operation will be described. Here, FIG.
FIG. 7 is an explanatory diagram showing a conventional expansion processing of compressed data 1 into image data 2 executed by the CPU 4 of the image processing apparatus configured as described above.

When only the necessary portion of the compressed data 1 is expanded and output from the output device 5, the CPU 4 first reads the compressed data 1 stored in the main storage device 3 and decompresses it by software or the like. The means 7 is used to perform image processing on all of them to develop an image, and the obtained image data 2 is stored in the main storage device 3.

Next, the CPU 3 similarly cuts out only a necessary portion of the rectangle 9 in the image data 2 stored in the main memory 3 by using the cutting-out processing means 8 which is also realized by software or the like, and cuts it out. It is stored in the storage device 3.

In this way, the main memory 3 stores the rectangle 9 of the necessary portion in the image data 2 obtained by expanding the entire compressed data 1, and this is stored in the display unit or the output of the input / output unit 6. It is sent to the device 5 and displayed or output.

As a document in which a technique related to such a conventional compressed data decompression processing method is stored,
For example, the catalog “Mitsubishi Drawing Management System Drawing Service Station“ GX-3000 ”issued by Mitsubishi Electric Corporation.
Series ”(April 1990).

[0010]

Since the conventional decompression processing method is configured as described above, when it is desired to display or output only the rectangle 9 of the necessary part of the image data 2 expanded from the compressed data 1, Compressed data 1 in decompression processing unit 7
It is necessary to cut out the rectangle 9 of the necessary portion of the image data 2 obtained by expanding the whole by the cutting processing unit 8,
There is a problem that not only a long time is required for processing, but also a storage means for storing the image data 2 needs to have a large capacity.

The present invention has been made to solve the above problems, and an object thereof is to obtain a compressed data decompression processing method which requires a short processing time and does not require a large-capacity storage means.

[0012]

In the compressed data decompression processing method according to the present invention, data amount information indicating the amount of data is added to each compressed code corresponding to one line of image data, and the compressed code is expanded into image data. At this time, by referring to this, the compressed code of the unnecessary line is skipped, only the compressed code of the necessary line is expanded, and the necessary portion is stored in the storage means.

[0013]

The compressed data decompression processing method according to the present invention is
By skipping unnecessary lines of compressed data, decompressing only the necessary lines into image data, and storing only the necessary parts in the storage means, the processing speed is faster than when decompressing all the compressed data, (EN) A compressed data decompression processing method capable of reducing the memory capacity of a storage means for storing expanded image data.

[0014]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. 1 is a flow chart showing an embodiment of a compressed data decompression processing method according to the present invention.
FIG. 4 is an explanatory diagram showing a data structure of the compressed data.

In FIG. 2, 10 is a compression code corresponding to one line of the image data in the compressed data, and 11
Is added to the compressed code 10 and the compressed code 1
This is data amount information indicating a data amount of 0.

Denoted at 12 is an end-of-line code (hereinafter referred to as "EOL") indicating the end of each line of the image data in the compressed data and the end of the entire compressed data. Indicates the end of the entire compressed data.

Next, the operation will be described. First, in step ST1, the CPU 4 initializes the count value "n" of the counter for designating each row of the image data in the compressed data, and in step ST2 the row designated by the count value "n" of the counter in the compressed data. That is, the data of the first row is taken out.

Next, in step ST3, the data is E
Check if it is OL12, and if it is not EOL12,
The process proceeds to step ST4 to identify whether or not the line is a line for which image development is to be performed.

As a result, if the line is not to be subjected to image expansion, the data amount information 11 of the first line is referred to in step ST5, and the compression code 10 of the first line is skipped in step ST6. And then step S
At T7, the count value "n" of the counter is incremented and the process returns to step ST2.

Thereafter, while incrementing the count value "n" of the counter on the second line, the third line, ..., Step ST4
The series of processes of steps ST2 to ST7 are repeated until the line for which the image development is to be performed is detected in.

When it is detected in step ST4 that the image is to be expanded, the CPU 4 advances the process to step ST8 to apply the compressed code 10 of the nth line designated by the count value "n" of the counter. Expand to one line of image data.

Next, in step ST9, the CPU 4
Is the main storage device 3 which stores only the necessary part of the image data of one line obtained by expanding the image of the compressed code 10 of the nth line.
To store. After that, in step ST10, the count value “n” of the counter is incremented, and the process proceeds to step ST.
Return to 2.

By repeating the processes of steps ST2 to ST10 for all the rows of the compressed data, an image of only the rectangle of the necessary portion in the image data is obtained in the main storage device 3.

When the processing for all the compressed data is completed, EOL12 is detected in step ST3 and the process proceeds to step ST11.
When it is detected that L12 has continued six times, the compressed data decompression process is ended.

In this way, the rectangular image of the necessary portion in the image data stored in the main memory 3 is
It is sent to the display unit of the input / output device 6 or the output device 5 to be displayed or output.

Example 2. Although the compressed data is stored in the main storage device 3 in the above-described embodiment, it may be stored in another storage means such as an optical disk, and the same effect as that in the above-described embodiment is obtained. ..

Example 3. Further, in the above embodiment, the case of the compressed data obtained by encoding and compressing the image data has been described, but the present invention can be applied to the decompression process of the compressed data obtained by compressing other image data such as a photograph and a map.

[0028]

As described above, according to the present invention, when each compressed code corresponding to one line of image data is added with the information indicating the data amount of the compressed code and is expanded into image data. , It is configured so that unnecessary lines are skipped by referring to them, only the compression code of the necessary lines is expanded, and only the necessary parts are stored in the storage means. The processing time can be greatly shortened as compared with the above, and there is an effect that a compressed data decompression processing method can be obtained in which the memory capacity of the storage means for storing the expanded image data can be reduced.

[Brief description of drawings]

FIG. 1 is a flowchart showing a compressed data expansion processing method according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a data structure of compressed data in the above embodiment.

FIG. 3 is a block diagram showing an example of an image processing apparatus to which the present invention and a conventional compressed data expansion processing method are applied.

FIG. 4 is an explanatory diagram showing a conventional compressed data expansion processing method.

[Explanation of symbols]

 3 memory means (main memory device) 10 compressed code 11 data amount information

Claims (1)

[Claims] 1. A compressed data decompression processing method for decompressing only a necessary portion of compressed data obtained by compressing image data into the image data and storing the image data in a storage means. Data amount information indicating the data amount of the compressed code is added to each of the compressed codes corresponding to one line of the above, and when the compressed image data is expanded, the compressed code of the line that is not necessary for the image data is A compressed data decompression processing method, characterized in that the information is referred to and skipped, the compressed code is expanded for a necessary line, and only the necessary part is stored in the storage means.