JPH0630282A - Image extending system - Google Patents

Abstract

PURPOSE:To provide the system for efficiently and partially extending a compressed data without decoding the compressed data at a part, for which it is not necessary to be extended for retrieving the line position of instructed extension start when partially extending the compressed data concerning a system to image compressed data by a facsimile coding system. CONSTITUTION:Image compressed data 4 are scanned for the unit of plural bits by a detecting means 2 and the bit pattern of a line termination code is detected so as to retrieve the line position of extension start instructed by an instructing means 1 for the line position of extension start and the number of lines to be extended. Next, the number of lines to be extended instructed by the instructing means 1 is extended for the unit of a line from that position by an extending means 3 for the unit of a line so as to provide the system for efficiently and partially extend the compressed data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image decompression system for partially decompressing image compression data by a facsimile coding system.

[0002]

2. Description of the Related Art In recent years, it has become popular to connect a facsimile machine and a computer device to display, edit and print image compression data by facsimile coding on the computer device. ing. When the image compression data is displayed on the computer device, the resolution of the computer display device is lower than the resolution of the image, and the image is efficiently drawn on the display device. For this reason, there is an increasing demand for a method of partially expanding the entire image compression data at a time, rather than expanding it all at once.

Conventionally, CCITT with line termination code
Recommendation T. In the case of extracting a partial image from the image compression data by the facsimile encoding method such as No. 4, the entire image compression data is expanded at a time and then the expanded image data is extracted. After extracting the required partial image data or decoding the coded sequence from the beginning of the image compression data, counting the number of line end codes and deciding the row position to start decompression, It is conceivable to expand the image of a certain part.

[0004]

However, in the above-mentioned conventional method, the compression data of the portion of the image compression data that does not need to be expanded is scanned bit by bit and decoded according to the encoding rule. Therefore, there is a problem that the efficiency in the case of partially expanding the image compression data is extremely low.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a method for efficiently partially expanding image compression data.

[0006]

In order to achieve this object, an image compression data decompression method according to the present invention uses an instruction for instructing the line position at which decompression is started in the compression data and the number of lines to be decompressed. And a means for scanning the compressed data in units of a plurality of bits to detect the line end code, and a means for expanding the compressed data in units of image lines.

[0007]

With this configuration, the image compression data is scanned in a unit of a plurality of bits to detect the bit pattern of the line end code, thereby searching the line position of the instructed decompression start, and then from that position, By decompressing the instructed decompression line number on a line-by-line basis, the image compression data can be efficiently decompressed partially.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 designates an instruction means for instructing a row position at which decompression starts in the image compression data and the number of rows to be decompressed.
Reference numeral 2 is a detecting means for scanning the image compression data in units of a plurality of bits to detect the line end code, 3 is decompression means for decompressing the image compression data in image line units, and 4 is an image compression to be decompressed. It is data.

Regarding the decompression method of the image compression data configured as described above, CCITT recommendation T.264 shown in FIG. The operation of the image compression data according to the coding method of No. 4 will be described as an example. The T. The image compression data according to the coding method of No. 4 scans a two-dimensional binary image from left to right and from top to bottom, and is coded row by row, with a line termination code at the beginning of each row. (EOL), and a control return code (RTC) exists at the end of the compressed data. Here, the line termination code is 12 consecutive bits "0000000".
It is a bit string represented by 00001 ", and a fill in which 0 or more" 0 "bits are consecutive may exist before the line termination code. First, the image compression data as described above.
In order to decompress a part of the data, the decompression start line position and the decompression line number indicating means of the compression data shown in FIG.
Specify the line position to start decompression and the number of decompressed lines. Then, the detection means for scanning the compressed data indicated by 2 in FIG. 1 in a unit of a plurality of bits to detect the line end code searches the compressed data for the instructed decompression start row position. . Finally,
The decompressing means for decompressing the compression data indicated by 3 in FIG. 1 for each line of the image decompresses the instructed decompression line number. Here, regarding the operation of the above-mentioned line termination code detecting means,
Further description will be given with reference to FIG. The T. According to the line termination code and fill specification of the coding method of 4, it is possible to determine a bit pattern in which 11 or more "0" bits are immediately followed by "1" bits as a line termination code. An example of an algorithm for detecting such a bit pattern is shown in FIG. In FIG. 3, the number of bit units for scanning compressed data is eight. First, at 1, the number N of consecutive "0" bits from the right of the bit string scanned immediately before is set to 0. In 2, the next 8 bits to be scanned are extracted. In 3, when the bit string to be scanned is “00000000”, N is incremented by 8 and the process returns to 2, otherwise the process proceeds to 4. In 4, it is continuous from the left of the bit string to be scanned.
The number of 0 ″ bits is L0. In 5, L0 is added to N, and if 11 or more, it is determined that the line termination code exists as described above, and the process ends. If not, the process proceeds to 7. In 7, consecutive bits from the right of the bit string to be scanned ”
Substitute the number of 0 "bits for N and return to 2. 4 and 7 above
In "," consecutive "0" from the left or right of the bit string
To obtain the number of bits, a table as shown in FIG. 4 may be used. The table of FIG. 4 has eight scanning bit units.
In the case of, the item number of the table can be determined by using the bit string to be scanned as a numerical value, which is composed of 255 items. It is possible to extract the bit length.

As described above, according to the present embodiment, the table for rapidly determining the coincidence between the scan bit string and the bit pattern of the line termination code is detected in detecting the line termination code by scanning in units of a plurality of bits. By providing, the line position of the decompression start instructed for the partial decompression of the compressed data can be searched at high speed.

Although the number of scanning bit units is 8 in the embodiment, it may be any value of 1 or more. The table in FIG. 4 is CCITT recommendation T.264. Although it is configured to detect the line termination code defined by No. 4, it is also possible to configure to detect the line termination code defined by other regulations.

[0013]

As described above, according to the present invention, the instructing means for instructing the line position at which the expansion is started and the number of lines to be expanded in the image compression data, and the compression data are scanned in a unit of a plurality of bits. By providing a detecting means for detecting the line termination code and a means for expanding the compressed data for each line of the image, an excellent expansion method capable of partially expanding the image compression data is realized. It is possible.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of an image decompression method in an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the structure of image compression data according to an embodiment of the present invention.

FIG. 3 is a flow chart for detecting a line termination code in compressed data according to an embodiment of the present invention.

FIG. 4 is a block diagram of a table for detecting a line termination code in an embodiment of the present invention.

[Explanation of symbols]

 1 indicating means 2 detecting means 3 expanding means

Claims (1)

[Claims] 1. An instructing means for instructing a row position to start decompression in compressed data and the number of rows to be decompressed, and a detecting means for scanning the compressed data in units of a plurality of bits to detect a line end code. And a decompression means for decompressing the compressed data in image line units, and image expansion of compressed data of a two-dimensional binary image according to a facsimile encoding system having a line termination code. method.