JPH06217110A - Image converting method - Google Patents

Abstract

PURPOSE:To facilitate a data processing and to enable an image conversion processing such as the enlargement/reduction and work of images without restoring information by encoding the binary data of images with a run length in the unit of a byte. CONSTITUTION:An image converting means calculates the run length by successively extracting the binary data from a pixel string for one line. When the run is the first run of the line and the black run, the run length of white run is turned to '0' and the '0' of one byte is written so as to arrange the picture elements from the biginning of the line in the order of white run and black run. Next, it is discriminated whether the run length exceeds a length 255 for expressing it with one byte or not, when the run length exceeds it, '255' is written and the '0' of one byte is continuously written. Then, the '255' is subtracted from the run length, it is discriminated again whether the run length exceeds the value or not and when the run length does not exceed it, the run length is written. When there is the next run, it is extracted and similarly processed, when processing for one line is completed, the '0' of two bytes is written as a line end code, and the encoding processing is performed to all the lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image conversion method for performing image conversion such as image enlargement / reduction and processing, and more particularly to an image conversion method for performing image conversion based on image data encoded by run length. .

[0002]

2. Description of the Related Art A binary image (including pseudo halftone) compression technique is used for transmitting halftone image data and newspaper image data by facsimile. This is because it is inefficient to transfer the data as it is or store it in the memory because the image data is huge. In order to efficiently transmit data in facsimile data transmission, a run length encoding method is generally used to encode the lengths (run lengths) of white and black pixels respectively. MH, which has become an international standard for run-length coding
(Modified Huffman) encoding and MR
There are many methods such as (Modified Read) coding, all of which perform variable length coding in consideration of the deviation of the occurrence frequency with respect to each length of the run, and there is a difference depending on the code word allocation method (Japanese Patent Laid-Open No. 2004-242242). 64-4937
(See Japanese Patent Publication No. 3). Also, when enlarging or reducing the image,
There has been proposed a method of directly performing enlargement / reduction processing on the basis of image data compression-encoded by a run-length code, without going through a process of restoring compression information (Japanese Patent Laid-Open No. 56-13).
8356).

On the other hand, in an image processing system for reading a character image and an image of a design of a layout mount (blockboard mount, rough designation paper, etc.), laying it out and outputting it, an image enlargement / reduction process required for a facsimile or the like. Besides, it is necessary to perform complicated image processing such as character decoration (white edge characters, bag characters, etc.). Therefore, without performing image processing on the workstation side, for example, an apparatus that performs image processing processes image information such as white edge characters and bag characters based on the attribute information such as character processing specified by the workstation side and the image data. It is designed to process. This is because the image data is compressed with emphasis on the compression rate in order to improve the data transfer efficiency between workstations and reduce the data storage area on the storage medium. This is because the program becomes complicated to perform the image conversion and the problem of processing efficiency occurs (see Japanese Patent Laid-Open No. 3-108073).

[0004]

As described above, when the run length data is encoded, the data compression rate is usually emphasized, so that the processing for performing image conversion such as image enlargement / reduction and processing is not required. It becomes complicated, and there is a problem in processing efficiency in a personal computer class computer that handles run length data and performs image conversion processing. Therefore, it has been strongly desired to realize an image conversion method in which image processing such as character processing can be easily performed and image conversion processing can be performed at high speed even in a personal computer class.
The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to perform image conversion processing such as image enlargement / reduction and processing with run length data as it is, easily and at high speed even in a personal computer class. It is to provide an image conversion method capable of

[0005]

SUMMARY OF THE INVENTION The present invention relates to an image conversion method for performing image conversion such as image enlargement / reduction and processing. The above object of the present invention is to convert binary data of an input image into byte units. This is achieved by performing run-length coding and performing the image conversion based on the coded run-length data in byte units.

[0006]

In the present invention, since the image data is encoded by the run length in byte units, it becomes easy to handle by software and hardware. Moreover, since the data represents the run length, the run length data Image conversion processing such as image enlargement / reduction and processing can be performed easily and at high speed. Furthermore, since the image thickening process is performed by calculating only meaningful pixels (black pixels), the image conversion process can be performed at a higher speed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, when encoding run length data, the target image is assumed to be a line drawing such as an illustration, and processing is easier than data compression ratio, and image processing with run length data is easy. Encode with emphasis on. Then, based on the encoded run length data, image conversion such as image enlargement / reduction and processing is performed. FIG. 1 is a flow chart showing the flow of image conversion processing in the image conversion method of the present invention. Binary data of an input image is read (step S1), and the binary data is converted into byte run lengths by the run length encoding method. Is encoded by (step S10)
2). This encoding is performed by arranging the white run and the black run in order from the beginning of the line in 1-byte units. Then, the encoded run length data in bytes is read (step S103). Image conversion processing such as image enlargement / reduction and processing is performed directly based on the run length data without passing through the information restoration process (step S104), and the processing is terminated.

The run length coding method and the image conversion method in the run length domain in the image conversion method of the present invention will be described in detail below. First, an example of the run-length coding method in the image conversion method of the present invention will be described with reference to the flowchart of FIG. The binary data of the input image is read line by line by an image conversion means (not shown) (step S201), and the following run length encoding process is performed line by line. The image conversion means sequentially extracts binary data from the pixel line of one line (step S
202), continuous length of white pixels or black pixels (number of pixels)
The run length RL is calculated (step S203). If the run is the first run of the line and is the black run, the run length of the white run is set to 0 in order to arrange the white run and the black run from the beginning of the line, and 1 byte of "0" is written (step S204). , S205).

Next, it is judged whether or not the run length RL exceeds the length "255" which can be expressed by 1 byte (step S2).
06), if “255” is exceeded, “255” is written, and then 1 byte “0” is written (step S20).
7). Then, "255" is subtracted from the run length RL (step S208), the process returns to step S206, it is determined again whether the run length RL exceeds "255", and if not, the run length RL is written. (Step S20
9). Then, if there is a next run in the line being processed, the process returns to step S202 to take out the run, and the processes from step S203 to step S209 are similarly performed.
When the line processing is completed, 2-byte "0" is written as the line end code (steps S210 and S211), the process returns to step S201, the next one line is encoded, and all the lines are encoded. If it has ended, all processing is ended (step S212).

FIG. 3 is a diagram showing an example of data coded by the above run length coding method. FIG. 3A shows an example in which the first line is a white run, and FIG. An example in which the first line is a black run, and FIG. 7C shows an example in which the run length exceeds the length "255" expressed by 1 byte. And 2 of each input image
The value data 1 is encoded into the run length data shown in the result 2.

Next, as an example of the image conversion method in the run length area, an example of the thickening process when the image is thickened will be described. For character decoration (white edge characters, bag characters, etc.), thickening (expansion) processing of the image is indispensable. The method is to fuse pixels in the image area instead of the frequency converted area. In the present invention, an image is represented by a run length, and a pixel thickening process is performed in this area. When the number of thickening pixels is P, the thickening processing of the image in the run length area is performed as follows.
Next step ~. A line buffer of (2 × P + 1) rows is prepared as a work area for image conversion. Only the run length of the black pixel is enlarged in the ± × coordinate axis direction by the pixel corresponding to the aperture (thickening width). Only the run length of the black pixels is ORed with P rows in the ± Y coordinate axis directions. The logical sum (OR) operation of the length data is performed at the position coordinates of the black pixels in the two rows.

Here, as a specific example, the thickening pixel number P is 2
An example of the thickening process for pixels will be described with reference to FIG. First, as shown in FIG. 7A, five rows (lines L ₂ to
The line buffer 3 for the line L ₋₂ ) is prepared. Then, while sequentially shifting the central row (line L ₀ ),
The following processing is performed. The line L ₀ is thickened by 2 pixels shown in the aperture 4 in the ± X coordinate axis directions. (A) The aperture 4 is set by, for example, an instruction to attach a rounded white edge having a width of N millimeters. Then, based on the instructed information, the same figure (A)
The contents of the aperture 4 are generated. (B) The line L ₁ is thickened by 2 pixels indicated by the aperture 4 in the ± X coordinate axis directions. (C) The thickened line L ₀ and line L ₁ are logically ORed (OR) to form a new line L ₀ (see FIG. 7B showing the logical OR process). (D) Then, the processes of (a) and (b) are performed on all the lines on the line buffer 3 except the line L ₀ .

By the above processing, the black pixel BP of FIG. 4A is converted into the black pixel BP 'of FIG. Although FIG. 4 shows an example of the case where rounded thickening is performed, angular thickening or partially rounded thickening can be performed by setting the aperture 4. In addition, because the data represents the run length when enlarging or reducing the image,
The conversion can be easily done by multiplying by the scaling factor.

[0014]

As described above, according to the image conversion method of the present invention, since binary data of an image is encoded by run length in byte unit, data becomes 1 byte unit and is processed by software or hardware. It will be easier. Also, since the data represents the run length, it becomes possible to easily perform image conversion processing such as image enlargement / reduction and processing with the length data as it is without going through the process of restoring information, and image conversion even in the personal computer class. The processing can be performed easily and at high speed. Further, since image conversion processing such as image thickening is performed by calculating only meaningful images (black pixels), the image conversion processing becomes faster. Therefore, it is possible to perform image conversion processing in the personal computer class while maintaining processing efficiency, so a dedicated device for image processing is not required, and cost reduction in a system that requires image conversion processing. Can be planned.

[Brief description of drawings]

FIG. 1 is a flowchart showing a flow of image conversion processing in an image conversion method of the present invention.

FIG. 2 is a flowchart showing an example of a run length coding method in the method of the present invention.

FIG. 3 is a diagram showing an example of data encoded by a run length encoding method in the method of the present invention.

FIG. 4 is a diagram illustrating an example of an image conversion method in a run length area according to the method of the present invention.

[Explanation of symbols]

 1 Binary data of input image 2 Encoding result 3 Line buffer 4 Aperture

Claims (3)

[Claims] 1. An image conversion method for performing image conversion such as image enlargement / reduction and processing, wherein binary data of an input image is encoded in run lengths in byte units, and based on the encoded run length data in byte units. The image conversion method is characterized in that the image conversion is performed according to the above method. 2. The run length data is encoded by arranging white runs and black runs in order from the beginning of the line, and
If the first line is a black run, the white run is set to "0" and the black run is arranged at the second byte. If the run length exceeds the length "255" expressed by 1 byte, "255" is followed by "0". ”
Is set, the remaining run length is set, and after the completion of one line, two "0" s are set as line end codes to perform coding processing for one line of the binary data, and the coding processing is performed for each line. The image conversion method according to claim 1, wherein the image conversion method is performed by repeating the above. 3. The processing by thickening an image based on the run length data is performed only on the run length of the black pixel of the processing target line of the run length data, and ± is applied to the thickening on the left and right of the pixel. It is performed by thickening in the X coordinate axis direction and enlarging by a pixel corresponding to the width aperture,
2. The upper and lower thickening is performed by logically adding two left and right thickened lines while sequentially shifting the lines in the ± Y coordinate axis direction. Image conversion method.