JPH06338806A - Mh compression device - Google Patents

Abstract

PURPOSE:To execute code conversion by providing data structure capable of generating plural codes simultaneously at a device which converts by compressing image information to a code. CONSTITUTION:A picture element length judging means 13 receives one or plural pieces of picture element length from a picture element length detecting means 12, and judges whether or not they can be processed simultaneously. When it is possible, the plural codes can be generated simultaneously by using code tables 2, 16. While, it is not, they are converted to codes one by one by using code tables 1, 15. The compression of image information can be performed at high speed by employing such constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MH compression device for compressing image information and converting it into an MH code.

[0002]

2. Description of the Related Art The MH coding method is widely used as a compression method for binary images in facsimiles and the like. The MH code is a code corresponding to the number of consecutive white or black pixels of the same color in the image information. As shown in (Table 1), this is divided into a termination code used alone corresponding to the pixel lengths 0 to 63, and a makeup code placed before the termination code when a pixel length of 64 or more is represented. .

[0003]

[Table 1]

The makeup code is 64 from 64 to 2560.
Is a multiple of. FIG. 5 shows the structure of an actual MH code. In FIG. 5A, the white pixel length of 3 is represented by the MH code. This is 1000 as shown in Table 1.
It is represented by the code. Further, in FIG. 5B, the white pixel length of 130 is represented by the MH code. in this case,
Since it exceeds the limit of 63 that can be represented by one code, the pixel length of 128, which is a multiple of 64 of 130, is 10
The remaining two are coded as 010 and the remaining two are coded as 0111 to represent a total of 130.

Further, in FIG. 5C, the white pixel length of 2625 is represented by the MH code. Also in this case, since the limit of 63 that can be represented by one code is exceeded, 262
The pixel length of 2560, which is a multiple of 64 out of 5, is 00000
Coded as 0011111. Furthermore, the remaining 65 is 6
Since there are more than three, 64 of the remaining 65 are coded as 11011. The remaining 1 is coded as 000111 and represents a total of 2625.

In order to create such a code, the pixel length is checked, and if it is 64 or more, a makeup code is generated, the length corresponding to that is subtracted from the initial pixel length, and the pixel length is again calculated. It was necessary to check and continue the same operation until the pixel length became 63 or less.

[0007]

However, in the above-mentioned conventional method, a plurality of codes must be generated even when the pixel length slightly exceeds 63 bits, and similarly, the maximum number of makeup codes is increased. The corresponding pixel length is 2560
In some cases, more than one make-up code may have to be generated.

Further, when an image such as a fine drawing or a pseudo halftone image is compressed, a large number of short pixels frequently occur, resulting in a long processing time.

Further, in order to speed up these operations, it was necessary to combine complicated devices to process the operations in parallel.

The present invention solves the above-mentioned conventional problems, and simultaneously outputs a plurality of codes for one pixel length and a plurality of codes for a plurality of pixel lengths at the same time without adding a complicated device. The purpose is to provide a means of doing.

[0011]

In order to achieve this object, the image compression apparatus of the present invention provides an MH terminate code and an MH make-up code corresponding to the pixel length at one address accessed by the pixel length. It is provided with a table storing the combined codes and the combined code lengths, and further, at one address accessed by a plurality of pixel lengths, an MH terminate code and an MH make-up code corresponding to the corresponding plurality of pixel lengths. It has a table that stores the combined codes and the combined code lengths.

[0012]

With this configuration, when one pixel length falls within a certain range, or when each of a plurality of pixel lengths falls within a certain range, by referring to the above table,
The corresponding code can be generated at once.

[0013]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of an MH code compression apparatus according to this embodiment. The image information sent from the image input means 11 is converted into a pixel length by the pixel length detection means 12. Then, the pixel length determination means 13 is configured to instruct the MH coding means 14 to refer to the code table 1 (15) if it is longer than the specified value, and to refer to the code table 2 (16) otherwise. (Table 1)

[0014]

[Table 2]

The operation of the image compression apparatus configured as above will be described with reference to the flowchart of FIG. First, considering the case where the pixel lengths 0 to 127 are coded, in that case, by referring to Table 2 once, the corresponding code can be obtained.

Next, consider the case where a pixel length of 128 or more is encoded. In this case, even if you refer to Table 2, you will not be able to obtain the corresponding code once, so you can use the conventional method (Table 1).
After getting the relevant makeup code by referring to (Table 2)
To get the corresponding code. When this method is used, the corresponding code can be obtained by referring once even when the pixel lengths of 64 to 127 are coded.

For example, when a white pixel length of 127 is represented by an MH code, in the prior art, it was necessary to refer twice, "white 63 terminate code" and "white 64 makeup code". According to the embodiment, it is possible to code with a single reference.

As is apparent from this operation, for the pixel length within a certain specific range, it is originally necessary to refer to a plurality of times, but according to the present embodiment, it is possible to process with a single reference. I can.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a schematic block diagram of the MH code compression apparatus according to this embodiment. The image information sent from the image input unit 31 is converted into a pixel length by the pixel length detection unit 32. If the white pixel length determining means 33 and the black pixel length determining means 34 are longer than specified, the code table 1 (36) and the code table 2 (3)
7) separately for black and white and processed in the same manner as in Example 1; otherwise, refer to Code Table 3 (38) for MH
The encoding means 35 is instructed.

Tables 1 and 2 are the same as in Example 1. The difference from the first embodiment is that Table 3 in which the contents of Table 2 are expanded to a plurality of pixel lengths is added. (Table 1) (Table 2)

[0021]

[Table 3]

The operation of the image compression apparatus configured as described above will be described with reference to the flowchart of FIG. First, consider encoding a continuous screen with a white pixel length of 20 and a black pixel length of 5. In this case, since (Table 1) and (Table 2) require reference twice, the reference code is obtained by referring to (Table 3) once. Next white pixel length 5
Consider encoding a continuous screen with 0 and a black pixel length of 10. In this case, the black pixel length falls within the range of Table 3 but the white pixel length does not fall within the range, and therefore, Tables 1 and 2 are referred to by the method of the first embodiment.

As is apparent from this operation, two pixel lengths within a specific range (in this case, white 0 to 31, black 0 to 1)
Although it is originally necessary to refer to the item 5) a plurality of times, according to this embodiment, it is possible to perform the process with a single reference.

Although the upper limit pixel length in Table 2 is 127 in the first embodiment, the same applies to 191 and 255. In the second embodiment, the upper limit pixel length in Table 3 is set to white 3.
1, black 15 was used, but white 63, black 31 and white 255, black 12
It goes without saying that the same processing can be performed with a configuration corresponding to 4 pixel lengths, such as 7, 63, black 63, white 63, black 63, and so on.

[0025]

As described above, according to the present invention, by providing a data structure capable of generating a plurality of codes with one reference,
It is possible to realize an excellent MH compression device that can generate an MH code at high speed without adding a complicated device.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an MH code compression device according to a first embodiment of the present invention.

FIG. 2 is a schematic flowchart for explaining an operation of MH code compression in the first embodiment of the present invention.

FIG. 3 is a schematic block diagram of an MH code compression device according to a second embodiment of the present invention.

FIG. 4 is a schematic flowchart for explaining an operation of MH code compression in the second embodiment of the present invention.

FIG. 5: MH code configuration diagram

[Explanation of symbols]

 11 Image Input Means 12 Pixel Length Detecting Means 13 Pixel Length Judging Means 14 MH Encoding Means 15 Code Table 1 16 Code Table 2 31 Image Input Means 32 Pixel Length Detecting Means 33 White Pixel Length Judging Means 34 Black Pixel Length Judging Means 35 MH Encoding means 36 Code table 1 37 Code table 2 38 Code table 3

Claims (2)

[Claims] 1. An MH comprising a pixel length, an MH makeup code corresponding to the pixel length, and an MH terminate code.
An MH compression apparatus comprising a table having a code as an element. 2. The MH compression apparatus according to claim 1, wherein the pixel length is a combination of white pixels and black pixels.