JPH08274999A - Image data processing method and image processing unit - Google Patents

Abstract

PURPOSE: To provide a method for compressing image data simply at a high speed and for reducing surely a buffer capacity when output data to a printer or a display device or the like are tentatively stored in the buffer. CONSTITUTION: A compression processing section 12 divides image data into plural data areas and generates a data frame including a basic picture element pattern and combination information of the basic picture element patterns for each division area where data are in existence. Then a buffer write processing section 13 compares data sizes before and after the compression and when the data size after compression is smaller, it is judged that the compression effect is obtained and the compression data are stored in a frame buffer 14. On the other hand, when the data size before compression is relatively smaller, the non-compression data are stored. When the data storage amount reaches a prescribed value, the stored data are outputted, and in this case, the compressed data are outputted while being expanded by an expansion processing section 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data processing technique used when temporarily storing in a buffer image data to be output to a printer or a display of an information processing apparatus.

[0002]

2. Description of the Related Art As a technique for processing image data of this type, there has been conventionally proposed a system for compressing and storing image data to realize a small capacity of a buffer. For example, Japanese Unexamined Patent Publication No. 1-149185 discloses a technique of performing rotation processing with a small buffer capacity by processing image data compressed by the run length method in a compressed state. An example of conventional image data processing that realizes such a method will be described with reference to FIGS.

As shown in FIG. 7A, it is assumed that image data (compressed data) compressed by the run length method is input for each line. Where Wn and Bn are n
A white or black concatenation part of the bit length is shown.
For reference, an original pattern obtained by expanding these compressed data is shown in FIG. Next, the rotation angle θ and the rotation direction are input. From this rotation angle θ, an appropriate series of monotonically increasing points is obtained as follows.

As shown in FIG. 13, if the data for one line is divided into integers closest to n / tan θ and the data is shifted, the rotation operation can be performed approximately. These values may be calculated at any time, or may be stored in a table in advance. n / t
When an θ is used, the point sequence is as shown in FIG.
FIG. 7B is an example in the case of θ−10 °. When the original pattern of FIG. 7A is divided according to these point sequences, a pattern as shown in FIG. 8 is obtained. The part surrounded by each rectangular block in FIG.
In the case of clockwise rotation, the lines are rearranged one line at a time, and the connected part Wn is added to the beginning of each line to be a figure after rotation. FIG. 9 shows an example in the case of counterclockwise rotation of 10 °. When the connected portions are subsequently recombined, final result data as shown in FIG. 10 is obtained. If you decompress this final result data,
The pattern shown in FIG. 12 is obtained.

FIG. 14 (S201 to S208) shows a flowchart for realizing the above processing. In the figure,
"R", "S", "j", "i", "a" are natural numbers,
“Leng” represents the length. According to the procedure of FIG. 14, each line has a point sequence {a,
j} points are divided to obtain a new line sequence.
After such a procedure, one line of data including image data is rearranged as follows. When “aj ≦ i ≦ aj + 1” is satisfied, “j” is obtained, and a white bit is added to the head of the run length to length j. Data of j blocks of j lines are i-j lines when clockwise, and i + j when counterclockwise.
Rearrange from the line. Then, when the white run is continuous, or the part where the black run is continuous is found and recombined.

[0006]

However, since the conventional image data compression method uniformly compresses the data for each line, depending on the type of image data, the data after compression may be better than the data before compression. However, there was a problem that the data size became large. Further, the conventional compression method has a problem in that the processing is complicated because there are many parameters and the time until the data is transferred to the output medium becomes long. further,
Conventionally, compressed data is used for image data input processing and pattern conversion, but no consideration has been given to compressed data for output processing.

In view of the above problems, an object of the present invention is to easily and rapidly compress image data when temporarily storing the image data to be output to a printer, a display, etc. in a buffer and to ensure a buffer capacity. It is an object of the present invention to provide an image data processing method which can be reduced to a large number, and an image processing apparatus suitable for implementing this method.

[0008]

An image data processing method provided by the present invention comprises a step of compressing individual image data to be processed, a step of comparing data sizes before and after compression, and a data size after compression. Is relatively small, the compressed data is stored, and if the data size before compression is relatively small, non-compressed data is stored, and the stored data is stored when the data storage amount reaches a predetermined value. The step of outputting the accumulated data includes the step of outputting the compressed data included in the accumulated data while decompressing the compressed data.

In the step of compressing the image data, for example, each image data is divided into a plurality of data areas, and data including a basic pixel pattern for each divided area in which the data exists and combination information of the basic pixel patterns. It is characterized by generating a frame. In this case, a compression identification code for identifying the presence or absence of compression of the image data is added to the data frame after the comparison of the data sizes. Further, the image processing apparatus of the present invention compares compression processing means for compressing individual image data to be processed with data size before and after compression for each image data, and selects either compressed data or uncompressed data. It is characterized by having a data storage means for storing and a decompression processing means for decompressing the compressed data contained in the stored data when the data storage amount reaches a predetermined value.

[0010]

According to the present invention, each image data is divided into, for example, a plurality of data areas, and a data frame including a basic pixel pattern for each divided area in which the data exists and combination information of the basic pixel patterns is generated. Perform compression processing. Then, the data storage means compares the data size before and after compression, that is, the size of the data frame. If the data size after compression is smaller, it is determined that the compression effect is obtained and the compressed data is stored together with its identification code. . On the other hand, when the data size before compression is relatively small, non-compressed data is stored together with its identification code. As a result, the data can be always stored with a small capacity.
When the data storage amount reaches a predetermined value, the storage data is output. At this time, the compression data is output while being expanded by the expansion processing means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a main part of an image processing apparatus of the present invention, showing a portion interposed between a data receiving section from an information processing apparatus (not shown) and an output medium such as a printer or a display.

The image processing apparatus 1 includes a received data analysis processing unit 11 for converting received data into intermediate data which is image data to be processed, for example, bit map expanded data, and a compression process for inputting the intermediate data and performing compression processing. Processing unit 12
A buffer write processing unit 13 that compares the data size before and after compression for each intermediate data and stores either the compressed data or the uncompressed data in the frame buffer 14, and the data storage amount is a predetermined value, for example, one page. Decompression processing unit 1 that decompresses the compressed data included in the accumulated data when the number of minutes is reached
5, a transfer processing unit 16 for transferring decompressed data or intermediate data to an output medium, and a main control unit 17 for controlling the processing start timing of the decompression processing unit 15 and other units. The data size may be compared by the compression processing unit 12.

An example of the intermediate data which is the image data to be processed according to this embodiment is shown in FIG. This intermediate data is obtained by expanding the character “F” on a 16-byte × 16-byte map, and corresponds to the received data “46hex”. When it is output to a printer or a display, it is generally converted into such data and transferred. In compressing the intermediate data, as shown in FIG. 2B, a data area having an X size in the row direction and a Y size in the column direction is divided into offset 1 to offset 4. However, the offset region can be omitted for the region where no pixel exists.

Next, the processing contents of the compression processing section 12 will be described. In this embodiment, data compression is achieved by generating a data frame including a basic pixel pattern for each offset area in which pixel data exists and combination information of the basic pixel pattern. The format of this data frame is shown in FIG.
And a compression identification code area indicating the presence or absence of compression, an intermediate data size (X size, Y size) area,
It includes an offset identification code area, a compression information area of each offset, and a corresponding data (basic pixel pattern) area. If this data frame is not adopted when the compression effect cannot be obtained, this compression identification code and its storage area can be omitted.

At the time of compression, the data of the first line of each offset, that is, the basic pixel pattern and its compression information are stored in the corresponding area. Next, the immediately preceding row and the next row are compared, and if they are the same, the pixel pattern is not stored and the reference information (described later) of the previous row is stored. If the immediately preceding row is different from the next row, the data is stored in the data area as a new basic pixel pattern. A data frame (compressed data) is generated by repeating this process.

FIG. 3B shows a specific data frame format corresponding to the intermediate data example of FIG. 2A. In the illustrated example, “1” indicating that the data is compressed data is added to the compression identification code area. In addition, both XY size is 1
6 bytes indicates that the data area is offset 1 to offset 3. No pixel is present at offset 4, so it is excluded. The compression information “01000101” corresponding to the offset 1 is the basic pixel pattern of the corresponding X line when it is “1”, and is the copy (the reference) of the immediately preceding pattern when it is “0”. Means that. That is, the pixel pattern of offset 1 is 8 pixels whose first line is the basic pixel pattern, and 2
The second line has 8 pixels, the third line has 2 pixels which is the next basic pixel pattern, the 4th to 6th lines have 2 pixels which are the same as the third line, and the 7th line has 8 pixels which is the next basic pixel pattern,
The 8th line has 8 pixels. The offset 2 and the offset 3 combine the compression information and the basic pixel pattern in the same procedure. In such a compression method, for example, as shown in FIG.
Intermediate data that requires a large number of bits as shown in (a) can be represented by 13 bits as shown in FIG. 3 (b), and it becomes possible to easily perform data compression.
The decompression process described later can also be easily performed.

Although the compression effect is remarkably obtained in this example "F", the data size after compression is not always smaller than that before compression in all the intermediate data. Therefore, the size of the data frame is compared with the size of the intermediate data before compression, the compressed data is adopted only when the compression effect is obtained, and the intermediate data is adopted as it is in other cases. A known technique can be used for the determination process and the like in this case.

Next, the processing procedure of the image processing apparatus 1 of this embodiment will be described with reference to FIG. 4 focusing on the control contents of the main control section 17. In the figure, S represents a processing step. When received data (character code or the like) is received from a data receiving unit (not shown) (S101), the received data analysis processing unit 11 analyzes the data and converts it into corresponding intermediate data (S).
Along with step 102), it is determined whether the converted intermediate data is compressible (S103). Whether or not the data can be compressed can be based on, for example, whether or not the size of the intermediate data has reached a predetermined number. If the data can be compressed, the compression processing unit 12 creates a data frame as described above (S10).
4). Then, the data sizes before and after compression are compared (S1
05), if the data size after compression is larger than the data size before compression, the effect of compression is not obtained, and the non-compressed data is passed to the frame buffer writing processing unit 13. Even when it is determined in S103 that compression is impossible (not possible), the non-compressed data is passed to the buffer writing processing unit 13. On the other hand, when the data size after compression is smaller than the data size before compression, it is considered that the compression effect was obtained,
The compressed data is passed to the frame buffer writing processing unit 13.

The frame buffer write processing unit 13 writes the received compressed data or non-compressed data in the frame buffer 14 (S106, S107). It is determined whether or not the writing process has reached a predetermined value, for example, the amount of data for one page (S108), and if not reached, the processes from S101 are repeated, and if reached, the frame buffer 1
Then, the process for transferring the data stored in 4 is started. At this time, it is determined whether the data written in the frame buffer 14 is compressed data or uncompressed data (S10
9) In the case of compressed data (S109: Yes), this is sent to the transfer processing unit 16 while performing decompression processing by referring to the data frame in the format of FIG. 3 (S110). On the other hand, in the case of non-compressed data, it is directly sent to the transfer processing unit 16 without being expanded (S109: No). The transfer processing unit 16 transfers these data to the output medium and ends the processing (S111).

The above description is for an example in which 16 bits × 16 bits of intermediate data is divided into four, but the bit configuration and the number of divisions can be set arbitrarily. For example, it is possible to divide the X size of the intermediate data shown in FIG. 5A into two, cascade them in the Y direction, convert them into 8 bits × 32 bits, and perform the same processing as above.

As described above, in this embodiment, the received data is compressed by a simple method, and when the data size after compression is larger than the data size before compression, the data size before compression is Is stored in the frame buffer 14, and the compressed data is decompressed and transferred to the output medium. Therefore, the data processing speed is faster than the conventional image processing method of this type, and the capacity of the frame buffer is large. Can be surely saved.

[0022]

As is apparent from the above description, according to the present invention, when the image data to be output to the printer or the display of the information processing apparatus is temporarily held in the buffer, the image data can be easily and quickly processed. Has a remarkable effect that the buffer capacity can be surely reduced as well as being compressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an image processing apparatus according to an embodiment of the present invention.

FIG. 2A is a bitmap development diagram showing an example of intermediate data of the present embodiment, and FIG. 2B is an explanatory diagram of how to divide a data area.

3A is an explanatory diagram of a data frame format according to the present embodiment, and FIG. 3B is a specific explanatory diagram of a data frame format in the case of FIG. 2A.

FIG. 4 is an explanatory diagram of a processing procedure of the image processing apparatus of this embodiment.

FIG. 5 is an explanatory diagram showing another example of how to divide the intermediate data.

FIG. 6 is an explanatory diagram showing another example of how to divide the intermediate data.

FIG. 7 is a diagram showing a transition when a run-length code according to a conventional example is processed.

FIG. 8 is a diagram showing a transition when a run-length code according to a conventional example is processed.

FIG. 9 is a diagram showing a transition when a run-length code according to a conventional example is processed.

FIG. 10 is a diagram showing a transition when a run-length code according to a conventional example is processed.

FIG. 11 is a bitmap development diagram showing an example of intermediate data according to a conventional example.

FIG. 12 is a bitmap development view showing a processing result of the data shown in FIG. 11.

FIG. 13 is an explanatory diagram showing the principle of a conventional example.

FIG. 14 is an explanatory diagram of a procedure of image processing according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image processing device 11 Received data analysis processing unit 12 Compression processing unit 13 Buffer writing processing unit 14 Frame buffer 15 Decompression processing unit 16 Transfer processing unit 17 Main control unit

Claims (4)

[Claims] 1. A step of compressing individual image data to be processed, a step of comparing data sizes before and after compression, and a step of storing and compressing the compressed data when the data size after compression is relatively small. If the previous data size is relatively small, the method includes the step of accumulating uncompressed data and the step of outputting the accumulated data when the amount of accumulated data reaches a predetermined value, and outputting the accumulated data. Is an image data processing method, wherein compressed data included in the accumulated data is decompressed and output. 2. The step of compressing the image data comprises dividing each image data into a plurality of data areas, and data including a basic pixel pattern for each divided area in which the data exists and combination information of the basic pixel patterns. The image data processing method according to claim 1, wherein a frame is generated. 3. The image data processing method according to claim 2, wherein a compression identification code for identifying whether or not the image data is compressed is added to the data frame after comparing the data sizes. . 4. A compression processing means for compressing image data to be processed, and a data storage means for comparing data size before and after each image data and storing either compressed data or uncompressed data. An image processing apparatus comprising: a decompression processing unit that decompresses compressed data included in the accumulated data when the amount of accumulated data reaches a predetermined value.