JP2008219302A - Image processing apparatus, image processing method, and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus which divides image data into a block unit, performs coding processing, and efficiently performs coding processing of the image data. <P>SOLUTION: The apparatus includes a separation data creation unit (102) which creates separation data for determining a character or a non-character based on the image data, a separation unit (104) which separates the image data and separation data into predetermined block units, a JPEG coder (106) which performs coding of the image data and separation data in predetermined block units, and a MMR (Modified Modified Read) coder (105). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image processing apparatus such as a copying machine and a printer, and more particularly to an image processing apparatus, an image processing method, and an image processing program for compressing image data.

  Since the conventional image processing apparatus performs encoding for each input image data, the image data encoding process has not been efficiently performed.

  For this reason, it is considered necessary to develop a technique for efficiently performing image data encoding processing.

  As a technical document filed prior to the present invention, separation data (character non-character determination and color information) is generated from an input image, and the separation data and image data are compressed and accumulated. Further, the accumulated separation data and image data are expanded, edge detection is performed on the image data by the edge detection means, and the edge information and the image data expanded based on the expanded separation data are There is a document that discloses a technique for performing image processing (see, for example, Patent Document 1).

Further, in an image processing apparatus such as an MFP, a document that discloses a technique for generating structured image data that suppresses an increase in processing load, has good character readability, and has compression ratio and image quality scalability. (See, for example, Patent Document 2).
JP-A-9-186866 JP 2006-157371 A

  However, Patent Documents 1 and 2 neither describe nor suggest the necessity of performing encoding processing by dividing image data into blocks.

  The present invention has been made in view of the above circumstances, an image processing apparatus capable of performing image data encoding processing by dividing image data into blocks and performing image data encoding processing efficiently, and an image An object of the present invention is to provide a processing method and an image processing program.

  In order to achieve this object, the present invention has the following features.

An image processing apparatus according to the present invention includes:
Separation data generation means for generating separation data for determining characters and non-characters based on image data;
A dividing means for dividing the image data and the separated data into blocks;
Encoding means for encoding the image data and the separated data in units of blocks;
It is characterized by having.

In the image processing apparatus according to the present invention,
The encoding means includes
Initialization is performed for each block.

In the image processing apparatus according to the present invention,
The encoding means includes
The image data is subjected to lossy compression,
The separated data is subjected to lossless compression.

An image processing apparatus according to the present invention
Decoding means for decoding the image data and the separated data in units of blocks;
Image processing means for performing different image processing on the character part and the non-character part on the decoded image data;
It is characterized by having.

In the image processing apparatus according to the present invention,
The image processing means includes
Based on the separated data corresponding to the image data, the image data is subjected to different image processing in a character portion and a non-character portion.

In the image processing apparatus according to the present invention,
The decoding means includes
Initialization is performed for each block.

An image processing method according to the present invention includes:
A separation data generation step for generating separation data for determining characters and non-characters based on image data;
A dividing step of dividing the image data and the separated data into blocks;
An encoding step of encoding the image data and the separated data in units of blocks;
Is performed by the image processing apparatus.

An image processing program according to the present invention is
Separation data generation processing for generating separation data for determining characters and non-characters based on image data;
A dividing process for dividing the image data and the separated data into blocks;
An encoding process for encoding the image data and the separated data in units of blocks;
Is executed by the image processing apparatus.

  According to the present invention, it is possible to efficiently perform image data encoding processing.

<Characteristics of image processing apparatus>
First, the features of the image processing apparatus of this embodiment will be described with reference to FIG.

  The image processing apparatus according to the present embodiment includes separation data generation means (corresponding to a separation data generation unit: 102) that generates separation data for determining characters and non-characters based on image data, image data, and separation data. Is divided into block units (corresponding to the dividing unit: 104), and encoding means for encoding image data and separated data in block units (corresponding to the JPEG encoder: 106 and MMR encoder: 105). ). As a result, the image data can be divided and encoded in units of blocks, so that the encoding process can be performed efficiently. Hereinafter, the image processing apparatus of the present embodiment will be described in detail with reference to the accompanying drawings.

<Configuration of image processing apparatus>
First, the configuration of the image processing apparatus of the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating the configuration of the image processing apparatus according to the present embodiment.

  The image processing apparatus according to the present embodiment includes a scanner input unit (101) as an image reading device, and RGB (8 bits each) input image data is read from the scanner input unit (101).

  The input image data includes input image data (201) as shown in FIG. The input image data (201) shown in FIG. 2A is composed of a “photograph part” and a “character part”, and is composed of black achromatic characters. The input image data (201) read from the scanner input unit (101) is input to the separated data generation unit (102).

  The separation data generation unit (102) separates the separation data for specifying whether the pixel of interest is a “character portion” or a “non-character portion” based on the input image data (201) input from the scanner input unit (101). Is generated.

  As a method for generating separated data, a known technique can be applied. For example, a method disclosed in Japanese Patent Laid-Open No. 7-240842 can be applied.

  In the technique disclosed in Japanese Patent Laid-Open No. 7-240842, the input image is binarized from a specific threshold value, and the input image is classified into a black pixel and a white pixel, and each pixel is classified. On the other hand, a technique is disclosed in which 3 × 3 pattern matching processing is performed to obtain determination results of “character part” and “non-character part”.

  The separation data generation unit (102) generates separation data by using the separation data generation method described above. Note that the separation data includes separation data (202) as shown in FIG. The separated data (202) is displayed in 1 bit for each pixel, and one pixel is displayed in black.

  The separation data generation unit (102) outputs, as output results, separation data of RGB image data (one pixel is 24 bits composed of 8 bits for each RGB) and one pixel 1 bit (1: character part, 0: non-character part). And are output.

  The output result of the separated data generation unit (102) is stored in the buffer (103). As a result, it is possible to prevent the input image data input from the scanner input unit (101) from being missed due to a delay in image processing.

  The dividing unit (104) reads the image data stored in the buffer (103) in units of divided blocks, and generates image data in units of divided blocks.

  The separated data in divided block units in the dividing unit (104) is input to an MMR (Modified Modified Read) encoder (105), which performs lossless compression processing in the MMR encoder (105).

  Note that the compression processing for the separated data is performed by a lossless compression method because the separated data is handled as information, not as an image. Note that examples of the lossless compression method include Huffman or run-length encoding.

  In addition, since the effective value of the character color information is present only in the character region, it is possible to obtain a very high compression rate by performing MMR encoding on the separated data.

  This is because the values of the separated data are all 0 except for the character portion.

  On the other hand, the RGB image data in divided block units in the dividing unit (104) is input to a JPEG (Joint Photographic Expert Group) encoder (106), which performs lossy compression processing in the JPEG encoder (106).

  Note that the compression processing for the RGB image data may be performed by deleting information such as noise, so that higher compression efficiency can be obtained by performing the lossy compression method.

  The RGB image data compressed by the JPEG encoder (106) and the separated data compressed by the MMR encoder (105) are passed through an arbitration circuit (107) to a DDR (Double Data Rate) Memory ( 108) temporarily.

  In addition, when accumulating for a long term, it accumulates in HDD (109) via an arbitration circuit (107).

  The RGB image data and the separated data are associated with each other and stored in the DDR Memory (108) or the HDD (109).

  Thereby, input image data is read from the scanner input unit (101), and separation data is generated based on the input image data. Then, the separated data and the RGB image data are respectively compressed for each block unit, and the compressed separated data for each block unit and the RGB image data are stored in the DDR Memory (108) or the HDD (109). It is accumulated in association.

<Ring timing of RGB image data and separated data>
Next, the encoding and decoding timings of RGB image data (one pixel is 24 bits composed of 8 bits for each RGB) and separated data (one pixel is 1 bit) will be described with reference to FIG. In the following description, the timing of encoding and decoding RGB image data will be described. However, the same timing is applied to separated data corresponding to RGB image data.

  First, the dividing unit (104) reads RGB image data (divided block) corresponding to the first block unit of the input image data input from the scanner input unit (101) from the buffer (103) (step S1).

  The divided blocks read from the buffer (103) are input to the JPG encoder (106) and encoded by the JPEG encoder (106) (step S2).

  The divided blocks encoded by the JPEG encoder (106) are written into the DDR Memory (108) via the arbitration circuit (107) (step S3).

  After the writing of the divided block to the DDR Memory (108) is completed, an interrupt is generated to the CPU (115) (step S4), and the divided block encoded by the JPG encoder (106) is the last divided block. Whether or not (step S5).

  If the divided block encoded by the JPG encoder (106) is not the last divided block (step S5 / No), JPEG is initialized (step S6), and the next divided block is read from the buffer (103). This is read (step S7).

  If the divided block encoded by the JPG encoder (106) is the last divided block (step S5 / Yes), the reading of the input image data is terminated (step S8).

  On the other hand, the CUP (115) receiving the interrupt activates the JPEG decoder (110).

  If it is determined that the JPEG decoder (110) is activated (step S11 / Yes), the RGB image data (divided block code) encoded for each divided block is converted to DDR Memory via the arbitration circuit (107). The read divided block code is input to the JPEG decoder (110) via the arbitration circuit (107) (step S12).

  The JPEG decoder (110) decompresses the divided block code read from the DDR Memory (108) and transfers it to the image processing unit 1 (112) (step S13).

  After the expansion of the divided block code is completed (step S14), it is determined whether or not the expanded divided block code is the last divided block code (step S15). If it is not the last divided block code (step S15). / No), JPEG initialization is performed (step S17), and the next activation is waited (step S11).

  If it is the last divided block code (step S15 / Yes), the JPEG decoding process is terminated (step S16).

  Next, an encoding / decoding process for image data in the image processing apparatus of the present embodiment and an encoding / decoding process for image data in a conventional image processing apparatus will be described with reference to FIG.

  As shown in FIG. 4A, the conventional image processing apparatus performs an encoding process on one image data. Then, an interrupt is generated, JPEG decoding is activated, and decoding processing for the encoded data is performed.

  For this reason, in the conventional image processing apparatus, since the encoding / decoding process is performed in units of image data, the encoding / decoding process of the image data is not efficiently performed.

  On the other hand, as shown in FIG. 4B, the image processing apparatus according to the present embodiment divides one image data into a plurality of divided blocks (10 in FIG. 4), and the divided block unit. Perform the encoding process. Then, an interrupt is generated for each encoding process for each divided block, JPEG decoding is activated, and the decoding process is performed for each divided block.

  For this reason, the image processing apparatus according to the present embodiment divides the image data into divided block units and performs the encoding / decoding process. Therefore, the encoding / decoding process can be performed efficiently. Become.

<Printing Process in Image Processing Apparatus of Present Embodiment>
Next, a printing process in the image processing apparatus according to the present embodiment will be described. In the following description, a case where printing is performed by the plotter output unit (116) will be described.

  The separated data and the RGB image data stored in the DDR Memory (108) or the HDD (109) are expanded by the MMR decoder (111) and the JPEG decoder (110), respectively. Become. The separated data is expanded by the MMR decoder (111), and the RGB image data is expanded by the JPEG decoder (110).

  The RGB image data (RGB, 8 bits each) expanded in the JPEG decoder (110) and the separated data (character / non-character determination result: 1 bit) expanded in the MMR decoder (111) are an image processing unit. 1 (112) and image processing is performed.

  Examples of the image processing performed in the image processing unit 1 (112) include processing for emphasizing the “character portion” and performing smooth smoothing processing on the “picture portion”. The processing operation performed in the image processing block 1 (112) will be described below with reference to FIGS.

  The image processing unit 1 (112) refers to the character / non-character determination result of the separated data corresponding to the target pixel of the RGB image data. Emphasis processing is performed by the enhancement filter (502) shown in (b).

  For example, when the determination result of “character part” is obtained based on the separation data corresponding to the target pixel of the RGB image data, the RGB image data shown in FIG. Emphasis processing is performed using an enhancement filter (502) as shown in FIG.

  The enhancement filter (502) shown in FIG. 5B associates the center of the 3 × 3 matrix of the filter with the target pixel for the target pixel, and sets the value of each 3 × 3 pixel to the corresponding filter coefficient. And adding them to obtain a value according to the following equation (1).

  (−1 × 90) + (− 1 × 128) + (− 1 × 90) + (− 1 × 90) + (9 × 128) + (− 1 × 90) + (− 1 × 90) + (− 1 × 128) + (− 1 × 90) = 356 (Expression 1)

  By replacing “356” obtained from the above (Equation 1) with the target pixel value of the RGB image data shown in FIG. 5C, an enhancement processing result as shown in FIG. 5D is obtained. .

  Similarly, when the determination result that the separation data corresponding to the target pixel of the RGB image data is “non-character portion” is obtained, a smoothing filter (501) as shown in FIG. 5A is used. Smoothing processing is performed.

  Note that the image processing unit 1 (112) is configured as shown in FIG. 6, for example.

  The configuration of the image processing unit 1 (112) illustrated in FIG. 6 includes an enhancement filter processing unit (502) that performs processing using the enhancement filter (502) illustrated in FIG. 5B and a smoothing filter illustrated in FIG. A smoothing filter processing unit (501) that performs processing according to (501) and a selector (503), and switches the selector (503) according to the character / non-character determination result of the separated data. The RGB image data is input to the enhancement filter processing unit (502) or the smoothing filter processing unit (501).

  If the character / non-character determination result of the separated data is “character part”, the RGB image data is input to the emphasis filter processing unit (502), and the character / non-character determination result of the separated data is “character part”. In the case of “non-character part”, the RGB image data is input to the smoothing filter processing part (501).

  In this way, the image processing unit 1 (112) performs pixel processing on the RGB image data expanded by the JPEG decoder (110) based on the character / non-character determination result of the separated data corresponding to the RGB image data. The above-described enhancement filter processing (502) and smoothing filter processing (501) are switched by the selector (503) to perform image processing on all pixels.

  Thereby, it becomes possible to perform an emphasis process and a smoothing process with respect to each of the character part and non-character part of RGB image data.

  The color conversion unit (113) converts the RGB image data (8 bits each) subjected to the image processing in the image processing unit 1 (112) to CMYK image data (8 bits each), and the converted CMYK image data. (8 bits each) is input to the image processing unit 2 (114).

  A known technique can be applied to the conversion processing from RGB image data to CMYK image data. For example, a table that can uniquely determine CMYK image data from a combination of 8-bit RGB image data. For example, a method of converting using.

  Next, the image processing unit 2 (114) binarizes (each 1 bit) the CMYK image data (8 bits each).

  In addition, as a binarization method, a well-known technique is applicable, for example, the method of binarizing with a predetermined threshold value (for example, 128 in 8 bits) is mentioned.

  The output result of the image processing unit 2 (114) is written again into the DDR Memory (108) via the arbitration circuit (107).

  Thereafter, the signal is transmitted again to the plotter output unit (116) via the arbitration circuit (107), converted into an LD (laser diode) signal, and printed on a recording medium.

  As described above, the image processing apparatus according to the present embodiment can efficiently perform the image data encoding process by dividing the image data into blocks and performing the encoding process in units of blocks.

  In addition, since all the separated data including the color information has an effective value only in the character portion of the image, it is possible to obtain very high performance in the compression efficiency of the separated data.

  Also, even if the image data is irreversibly compressed, it is possible to obtain desired information after decompression, so the image data can be irreversibly compressed. Thereby, it is possible to compress image data with higher efficiency.

  Further, by decoding the accumulated code data in units of blocks, it is possible to refer to image data partially without decoding all image data.

  In addition, by performing decoding processing on encoded data in units of blocks, it is possible to speed up the initial operation.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

  For example, the control operation in the image processing apparatus according to the above-described embodiment can be executed by software such as a computer program instead of a hardware configuration, and the above program is stored in an optical recording medium, a magnetic recording medium, an optical recording medium, or the like. It is also possible to cause the image processing apparatus to execute the control operation described above by recording the program on a magnetic recording medium or a recording medium such as a semiconductor and causing the image processing apparatus to read the program from the recording medium. . In addition, the above-described control operation can be executed in the image processing apparatus by causing the image processing apparatus to read the program from an external device connected via a predetermined network.

  The image processing apparatus, the image processing method, and the image processing program according to the present invention can be applied to a device that compresses image data.

It is a figure which shows the structure of the image processing apparatus of this embodiment. It is a figure for demonstrating input image data (201) and isolation | separation data (202). 3 is a flowchart showing a series of processing operations in the image processing apparatus of the present embodiment. It is a figure for demonstrating the encoding / decoding process (a) in the conventional image processing apparatus, and the encoding / decoding process (b) in the image processing apparatus of this embodiment. It is a figure for demonstrating the processing operation performed in the image process part 1 (112). It is a figure which shows the detailed structure of the image process part 1 (112).

Explanation of symbols

101 Scanner Input Unit 102 Separated Data Generation Unit 103 Buffer 104 Separation Unit 105 MMR Encoder 106 JPEG Encoder 107 Arbitration Circuit 108 DDR Memory
109 HDD
110 JPEG Decoder 111 MMR Decoder 112 Image Processing Unit 1
113 Color conversion unit 114 Image processing unit 2
115 CPU
116 Plotter output unit 117 Scanner transmission unit 501 Enhancement filter processing unit 502 Smoothing filter processing unit 503 Selector

Claims (8)

Separation data generation means for generating separation data for determining characters and non-characters based on image data;
A dividing means for dividing the image data and the separated data into blocks;
Encoding means for encoding the image data and the separated data in units of blocks;
An image processing apparatus comprising: The encoding means includes
The image processing apparatus according to claim 1, wherein initialization is performed for each block. The encoding means includes
The image data is subjected to lossy compression,
The image processing apparatus according to claim 1, wherein the separated data is subjected to lossless compression. Decoding means for decoding the image data and the separated data in units of blocks;
Image processing means for performing different image processing on the character part and the non-character part on the decoded image data;
The image processing apparatus according to claim 1, further comprising: The image processing means includes
The image processing apparatus according to claim 4, wherein different image processing is performed on the image data in a character portion and a non-character portion based on separation data corresponding to the image data. The decoding means includes
5. The image processing apparatus according to claim 4, wherein initialization is performed for each block unit. A separation data generation step for generating separation data for determining characters and non-characters based on image data;
A dividing step of dividing the image data and the separated data into blocks;
An encoding step of encoding the image data and the separated data in units of blocks;
An image processing method characterized in that the image processing apparatus performs the above. Separation data generation processing for generating separation data for determining characters and non-characters based on image data;
A dividing process for dividing the image data and the separated data into blocks;
An encoding process for encoding the image data and the separated data in units of blocks;
An image processing program for causing an image processing apparatus to execute.

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