JPS60176084A - Character pattern data 2-d compression - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention is applicable to high-resolution printing machines, character display devices, etc.
6 electronic character processing, using 6 characters A)) -J/.

Regarding a two-dimensional compression method for character pattern data that compresses data two-dimensionally, in particular, a method that dramatically increases the data compression rate by applying data compression two-dimensionally according to the run length of the character pattern. It is.

[Prior Art] In general, printing machines such as laser printers and laser typesetters having high resolution, or printing machines such as 200
0 lines/screen Electronic character processing in character display devices such as CRT displays, especially when handling character information such as kanji in electronic computing systems, involves the use of electronically generated character patterns. is necessary.

This type of character pattern is usually used after being stored in a memory device as character pattern data divided into a two-dimensional matrix.

However, a relatively small-scale character pattern matrix,
For example, for a dot matrix of 24×24 dots or 32×32 dots, the memory capacity per character is small, for example, 72 bytes or 128 bytes.

However, when printing or displaying high-quality characters on a high-resolution output device, for example, 84
It is necessary to use a character pattern consisting of dots or a large dot matrix such as 128x128 dots. In that case, the memory capacity per - character becomes enormous, for example 512 bytes or 2 kilobytes. Therefore, in order to store 4,000 characters such as kanji that are normally used, an extremely large memory capacity of 2 or 8 megabytes is required, and such a large amount of character pattern data can be stored as is without compressing the character pattern data. It is extremely uneconomical to retain it.

In order to alleviate such uneconomical problems, character pattern data has traditionally been compressed using a so-called run-length method. That is, character pattern data is compressed by using each row of a character matrix as a processing unit and encoding the continuous length of white pixels and black pixels. Data compression by such a run-length method is extremely effective, and the larger the size of the character matrix, the greater the data compression ratio.

However, in conventional compression of this type of character pattern data, no data compression was performed in the vertical direction of the dot matrix. For this reason, as the size of the matrix increases, the data increases in the vertical direction, resulting in a drawback that the effect of reducing the memory capacity described above is reduced accordingly.

[Objective] Therefore, the object of the present invention is to eliminate the above-mentioned conventional drawbacks and to apply the run-length method also in the vertical direction of a single character pattern matrix, thereby achieving highly efficient data compression. An object of the present invention is to provide a two-dimensional pattern data compression method.

Another object of the present invention is to apply the conventional run-length method to horizontal data of a character pattern matrix, and to add data indicating that the line is a line break at the end of each line of compressed data, and to indicate that the line is the starting point. It is an object of the present invention to provide a two-dimensional compression method for guest room pattern data in which the run-length method can be applied two-dimensionally by adding run-length compressed data in the column direction.

[Example] The present invention will be described in detail below with reference to the drawings.

First, the basic principle of two-dimensional compression of character pattern data according to the present invention will be explained using FIGS. 1(A) and 1(B).

FIG. 1(A) shows the character pattern "HIGH" by the NXN dot matrix, and FIG. 1(B) shows the character pattern from the (m+1)th row to the nth row being processed in both the vertical and horizontal directions by the method of the present invention. The encoded result is shown.

In the illustrated character pattern, there are no black pixels from the first line to the first line, so as shown in Figure 1 (^), [EOL・i] (here, EOL is , and i is the repetition count).

From the (i+1)th row to the first row, there are no black pixels following the self-pixel length ◇ and the black pixel length BO, so [Wo, Bo
, EOL conflict (j − i)].

Similarly, from the (m+1)th row to the nth row, as shown in FIG. 1(B), [W+ +BI].

w2+Ilh lW3183.11141B4 +EO
L.(n-m) ].

As mentioned above, according to the two-dimensional data compression method that applies run-length encoding to both the vertical and horizontal directions of the character pattern, the character pattern matrix can be as large as 128 x 128 dots, and it can also be When storing data encoded with a character pattern that consists of many lines, the data compression efficiency can be extremely high. For example, 115 to l.
A data compression ratio of about /15 can be achieved.

Note that this data compression rate is slightly influenced by the design of the character pattern to be encoded.

Next, FIG. 2 shows a flowchart of data processing in two-dimensional compression of character pattern data according to the method of the present invention.

In the flowchart shown in the second figure, one line of character pattern is input in step Sl, and the next step S
In step 2, it is determined whether or not the data processing is for the first row. Here, if the data processing is for the first line, step S
Move to 5. On the other hand, if it is not data processing for the first row, it is determined in step S3 whether the data is the same as the previous row.

However, if the data are not the same, the process moves to step S5.

After clearing the repetition count in step S5, the process proceeds to step S6, where it is determined whether the pattern includes only white pixels. If there is only a white pattern, the process moves to step S8. If it is not only the own pattern, run length data is created for the black and white pattern in step S7, and then the run length data is created in step S7.
Move to 8.

Next, in step S8, after adding a line end code, the process proceeds to step S, where the repetition count is written or rewritten. In the next step SIO, it is determined whether the data compression process for the character i-bine matrix has been completed or omitted, and if it has not been completed, the process returns to step S1 and the above-described series of data processing is repeated.

Note that if it is determined in step S3 that the data is the same as the previous row, the process advances to step S4, where the repetition count is incremented by 1, and then the process immediately advances to step S8 to write the repetition count. I do.

Next, FIG. 3 shows a flowchart of data processing for decompressing character pattern data that has been two-dimensionally compressed by the method of the present invention and restoring it to the original character pattern.

In the flowchart shown in the third figure, step Sit
Input data for one line in step S12.
In step 1, it is determined whether the data is run-length compressed data. If the data is compressed data, the data is expanded based on the run length data in step S14 to restore it to black and white pattern data, and then the process moves to step S15. On the other hand, if the data is not compressed data, the process proceeds to step S13, where one line of white pattern data is created, and then the process proceeds to step S15.

Then, in step S15, it is determined whether or not the same data is repeated in the subsequent rows. Here, if there is no repetition, the process moves to step S17. If there is repetition, the process proceeds to step S1B, where the same pattern data is repeatedly created for a predetermined number of lines, and then the process proceeds to step S17.

Next, in step S17, it is determined whether or not the restoration of the character pattern matrix by data expansion has been completed, and if it has not been completed, the process returns to step Sll and the above data processing is repeated.

Next, FIG. 4 shows a schematic configuration of a circuit device for executing data processing for two-dimensional compression and decompression for restoration of character pattern data according to the above-described method of the present invention.

In the configuration shown in FIG. 4, CPU is a central processing unit, ■ is a main memory device that stores a program for causing the CPU to execute the processes shown in FIGS. 2 and 3, and DISC is the invention of the present invention. This is a fixed disk memory for storing compressed data. CRT is a cathode ray tube display device that can display and edit character input, and LBP is a laser beam printer that prints out character output. These components are interconnected by a data bus B to perform the above-described data processing.

Note that in the above explanation, the code indicating the line break and the data for the number of repeated rows of the same data are added to the end of each row of compressed data, but these codes and data are added to the beginning of each row of compressed data. Exactly the same data processing can be performed even if the

[Effects] As is clear from the above explanation, according to the present invention, data compression by the run-length method of single character pattern matrix data is applied not only in the horizontal direction as in the past but also in the vertical direction, resulting in two-dimensional data compression. Since data compression is applied to the data, it is possible to realize extremely highly efficient character pattern data compression.

[Brief explanation of the drawing]

Figures 1 (A) and (B) are diagrams illustrating the basic principle of two-dimensional compression of character pattern data according to the method of the present invention, Figure 2 is a flowchart showing the process of data compression, and Figure 3 is FIG. 4 is a flowchart showing a data decompression process for restoring character pattern data compressed by the method of the present invention. FIG. 4 is a block diagram showing a schematic configuration of a circuit device for implementing the method of the present invention. -cpu...central processing unit, MW...main memory device, DISC...fixed disk memory, CRT...cathode ray tube display device, LBP...laser beam printer. Patent applicant Canon Co., Ltd. Figure 3 Figure 4

Claims (1)

[Scope of Claims] l) In generating a character pattern for use in electronic character processing, horizontal data of each line in a dot matrix constituting the character pattern is compressed according to the run length, and each line of data is compressed according to the run length. Character pattern data 2 characterized in that character pattern data is compressed two-dimensionally by adding a code indicating a line break and data indicating the number of lines in which the same pattern is repeated in the vertical direction to the end.
Dimensional compression method. (Hereafter, margin)