JP2005260872A - Image processor and image processing method, and computer-readable recording medium with program for allowing computer to execute image processing method recorded thereon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize coding processing at high speed with a comparatively simple configuration by judging a color of pixels of each color block. <P>SOLUTION: An image processor includes: an image division means (not shown) for dividing generated image data into n×m blocks; two-dimensional DCT processing apparatuses 128, 134, 144 in each color for applying frequency decomposition to generated n×m images; quantization processing apparatuses 129, 135, 141 in each color for coding data after the frequency decomposition; entropy coders 130, 136, 142; single color value judgment means 131, 137, 143 for judging whether level values of color components of the n×m images are all the same; and single color data coders 132, 138, 144 for producing code data of a single color value when the level values of color components of the n×m images are all the same. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus and an image processing method mounted on, for example, a digital copying machine, a digital camera, and a color printer, and a computer-readable recording medium on which a program for causing a computer to execute the image processing method is recorded. is there.

  2. Description of the Related Art Conventionally, a printer draws PDL (page description language) received from a network as multi-value RGB data in band units, encodes it according to a multi-value image compression algorithm (JPEG: Joint Photographic Experts Group, etc.), and the code is stored in memory. After that, at the time of print output, the code data is read from the memory with a delay for each plate. Further, it is decoded into RGB data in accordance with the above compression algorithm, then converted into CMYK data by color conversion processing, converted to binary, quaternary, 8-value, etc. by gradation processing, and C after gradation processing. (Cyan), M (magenta), Y (yellow), K (black) only data corresponding to each plate is transferred to the printer engine, and each plate has a dedicated decoding device and an image processing device dedicated to each plate. The print output was executed.

  As this compression method, there is a method of transforming image data into frequency components by orthogonal transform such as DCT (Discrete Cosine Transform) and quantizing the transform coefficient, and particularly as a method of encoding a multi-value image using DCT. The JPEG method standardized by ITU-T and ISO is known. This JPEG DCT arithmetic expression is shown in Equation 1.

  As another compression method, there is known Wavelet conversion in which image data is divided into a plurality of blocks in the horizontal frequency direction and the vertical frequency direction, and the lower frequency blocks are made finer. The Wavelet transform has recently attracted attention as a method for effectively compressing natural gradation images. Wavelet conversion is known to be suitable for compression of an image having continuous gradation such as a photograph. FIG. 18 shows an example of division and an arithmetic expression thereof.

  The printer image 200 is divided into a graphics image portion 201 and a photographic image portion 202 as shown in FIG. The graphics image portion 201 often has the same color. When the frequency decomposition is performed, only the DC value is present, but the AC value is often “0”. The photographic image portion 202 is suitable for the JPEG system, and a considerable compression rate can be obtained by performing frequency decomposition and quantizing from a high frequency.

  Also, when the input image data is compressed in the copying machine, the input image is divided into blocks of M × N pixels, the colors in the block are checked, and if all the pixels are white, the determination is made. A method is disclosed in which the result is encoded by an arithmetic coding method, and if the result is not white, encoding is performed by a DCT processing method to increase the coding efficiency (see, for example, Patent Document 1).

  In addition, as a decoding apparatus using DCT, the DCT coefficient after Huffman decoding is checked, and the operation of inverse DCT processing of the DCT coefficient part of “0” is omitted, thereby enabling high-speed DCT calculation. (For example, refer to Patent Documents 2 and 3).

Japanese Patent No. 3072776 Japanese Patent No. 2839392 Japanese Patent No. 2858774

  Conventionally, as described above, the graphics image portion and the photographic image portion are divided, and the graphics portion is compressed by a predictive coding method such as DPCM (differential pulse code modulation) or a method such as an arithmetic coding method. However, a high compression rate is demanded by compressing a photographic image by the JPEG method. However, in such a conventional technique, when two different methods are used corresponding to the features of the image, the hardware becomes large and the processing becomes complicated. was there.

  The present invention has been made in view of the above, and determines the color of the pixel of each color block, and when it is determined that each block independently has the same color, the one-color data code of a different path from the frequency conversion process An object of the present invention is to realize an encoding process at a high speed and with a relatively simple configuration by using an encoding device.

  In order to solve the above-described problems and achieve the object, an invention according to claim 1 is an image processing apparatus that outputs image data generated by drawing to a printer engine, and outputs the generated image data to n × m. Image dividing means for dividing the image into blocks, frequency decomposition means for frequency-decomposing the n × m image generated by the image dividing means, and frequency-decomposed data encoding means for encoding the data after frequency decomposition One color value determining means for determining whether or not the level values of the color components of the n × m image are all the same, and the level values of the color components of the n × m image are all the same value by the single color value determining means. In this case, a single color value encoding means for generating code data of a single color value is provided.

  According to the first aspect of the present invention, it is determined by the one color value determination means whether the level values of the color components of the n × m image are all the same value, and the level values of the color components of the n × m image are determined. By providing two processing paths, one is a color value encoding means for generating code data of one color value when all are the same value, and the other is a processing path for frequency-decomposing and quantizing the high frequency of other images, For example, a graphics image composed of a single color is processed by a one-color value encoding means, and a mixed color image such as a photograph can be encoded after normal frequency decomposition.

  According to a second aspect of the present invention, there is provided a previous block encoding flow determination unit that determines whether the previous block used the one-color value encoding unit.

  According to the second aspect of the invention, in the first aspect, by determining whether the previous block used the one-color value encoding means, the difference between the previous DC value and the DC value is determined. An encoding process can be performed and output.

  The invention according to claim 3 predictively encodes a DC value to be encoded using the DC component value of the previous block when the previous block does not use the one-color value encoding means. DC value predictive encoding means is provided.

  According to the invention of claim 3, in claim 1, when the previous block does not use the one-color value encoding means, the DC is encoded using the DC component value of the previous block. By predictively encoding the value, it is possible to perform encoding processing using the previous DC predicted value.

  According to a fourth aspect of the present invention, when the previous block does not use the frequency-decomposed data encoding means, the DC value to be encoded using the DC component value of the previous block is predicted code. DC value predictive encoding means is provided.

  According to the fourth aspect of the present invention, when the previous block does not use the post-frequency decomposition data encoding means, the DC value to be encoded is predicted using the DC component value of the previous block. Encoding makes it possible to perform encoding processing using the previous DC prediction value.

  According to a fifth aspect of the present invention, there is provided an image processing apparatus that outputs image data generated by drawing to a printer engine, image dividing means for dividing the generated image data into n × m blocks, and the image Frequency resolving means for frequency-decomposing the n × m image generated by the dividing means, frequency-decomposed data encoding means for encoding the data after frequency decomposition, and levels of color components of the n × m image When the level values of the color components of the n × m image are all the same by the single color value determining unit that determines whether all the values are the same value, the frequency resolution unit is not used. One-color-value frequency-resolved data generation means for generating a frequency-resolved value based on the level value of the color component.

  According to the fifth aspect of the present invention, when the level values of the color components of the n × m image are all the same value by the single color value determination means, the frequency resolution based on the color component level values is used without using the frequency resolution means. By generating a value, it is possible to efficiently generate a monochromatic frequency decomposition value.

  According to a sixth aspect of the present invention, there is provided an image processing method for outputting drawing-generated image data to a printer engine, an image dividing step for dividing the generated image data into n × m blocks, and the image A frequency decomposition step for frequency-decomposing the n × m image generated by the division step, a frequency-decomposed data encoding step for encoding the data after the frequency decomposition, and a color component level of the n × m image If the color value determination step for determining whether all the values are the same and the level values of the color components of the n × m image are all the same by the one color value determination step, code data for the single color value is generated. And a single color value encoding step.

  According to the sixth aspect of the present invention, it is determined in the one color value determination step whether the level values of the color components of the n × m image are all the same value, and the level values of the color components of the n × m image are determined. By providing two processing paths, one color value encoding process for generating code data of one color value when all are the same value, and a processing path for frequency-decomposing other images and quantizing the high frequency, For example, a graphics image composed of a single color is processed in a single color value encoding step, and a mixed color image such as a photograph can be encoded after normal frequency decomposition.

  According to a seventh aspect of the present invention, there is provided an image processing method for outputting image data generated by drawing to a printer engine, an image dividing step of dividing the generated image data into n × m blocks, and the image A frequency decomposition step for frequency-decomposing the n × m image generated by the division step, a frequency-decomposed data encoding step for encoding the data after the frequency decomposition, and a color component level of the n × m image If the color value determination step for determining whether all the values are the same value and the level values of the color components of the n × m image are all the same by the one color value determination step, the frequency decomposition step is not used. And a one-color-value frequency-resolved data generation step for generating a frequency-resolved value based on the level value of the color component.

  According to the seventh aspect of the present invention, when the level values of the color components of the n × m image are all the same in the one color value determination step, the frequency decomposition based on the color component level value is performed without using the frequency decomposition step. By generating a value, it is possible to efficiently generate a monochromatic frequency decomposition value.

  The invention according to claim 8 is characterized in that a program for causing a computer to execute the image processing method according to claim 6 or 7 is recorded.

  According to the invention according to claim 8, the image processing method according to claim 6 or 7 is recorded on a computer-readable recording medium as a program, whereby the image according to claim 6 or 7 is recorded on a computer. The processing method can be executed.

  The image processing apparatus according to the present invention (Claim 1) determines whether the level values of the color components of the n × m image are all the same value by the one color value determination means, and determines the color component of the n × m image. Two processing paths are provided: one color value encoding means for generating code data of one color value when the level values are all the same, and a processing path for frequency-decomposing the other images and quantizing their high frequencies. Thus, for example, a graphics image composed of a single color can be processed by a single color value encoding means, and a mixed color image such as a photograph can be encoded after normal frequency decomposition, so that comparison can be performed at high speed. The encoding process can be performed with a simple configuration.

  The image processing apparatus according to the present invention (Claim 2) is characterized in that, in Claim 1, in order to determine whether the previous block used the one-color value encoding means, the previous DC value and DC There is an effect that an encoding process based on a difference in values can be performed and output.

  The image processing apparatus according to the present invention (Claim 3) uses the DC component value of the preceding block when the preceding block does not use the one-color value encoding means in Claim 1. Therefore, since the DC value to be encoded is predictively encoded, the encoding process using the previous DC predicted value can be performed.

  The image processing apparatus according to the present invention (Claim 4) encodes using the DC component value of the immediately preceding block when the immediately preceding block does not use the frequency-decomposed data encoding means. In order to predictively encode the DC value to be performed, there is an effect that it is possible to perform encoding processing using the previous DC predicted value.

  Further, the image processing apparatus according to the present invention (Claim 5), when the level values of the color components of the n × m image are all the same value by the one color value judging means, the color component is determined without using the frequency resolving means. By generating the frequency resolution value based on the level value, it becomes possible to efficiently generate the frequency resolution value of a single color, so that the encoding process can be performed at a high speed and with a relatively simple configuration.

  In the image processing method according to the present invention (Claim 6), it is determined in the one color value determination step whether or not the level values of the color components of the n × m image are all the same, and the color of the n × m image is determined. There are two processing paths: one color value encoding process for generating code data of one color value when the component level values are all the same, and a processing path for frequency-decomposing other images and quantizing their high frequencies. For example, a graphics image composed of a single color is processed in a single color value encoding process, and a mixed color image such as a photograph can be encoded after normal frequency decomposition, so that it can be performed at high speed. In addition, the encoding process can be performed with a relatively simple configuration.

  Further, according to the image processing method of the present invention (Claim 7), when the level values of the color components of the n × m image are all the same value in the one color value determination step, the color component determination is performed without using the frequency decomposition step. By generating the frequency resolution value based on the level value, there is an effect that it is possible to perform encoding processing with a relatively simple configuration at a high speed that enables efficient generation of a monochrome frequency resolution value.

  A computer-readable recording medium according to the present invention (Claim 8) is a computer-readable recording medium recorded with the image processing method according to Claim 6 or 7 on a computer-readable recording medium as a program. The image processing method according to item 6 or 7 can be executed.

  Exemplary embodiments of an image processing apparatus, an image processing method, and a computer-readable recording medium storing a program for causing a computer to execute the image processing method will be described below in detail with reference to the accompanying drawings. To do.

  The present invention uses YUV (Y: luminance component, U, V: color difference component) when a compression method that performs frequency conversion such as DCT (Discrete Cosine Transform) or Wavelet (Wavelet) is used as a printer image compression method. If the pixel color of each block is determined and the same color is determined independently for each block, it is possible to perform high-speed encoding using a single-color data encoding device in a different path from the frequency conversion processing. It is what. This will be specifically described below.

(Embodiment)
First, the configuration and operation of an image forming apparatus (printer) in which the image processing apparatus according to the present invention is mounted will be described. FIG. 1 is an explanatory diagram illustrating a configuration example of a mechanism unit of an image forming apparatus according to an embodiment of the present invention. Hereinafter, the image forming apparatus of FIG. 1 is described as a color printer. In this embodiment, a laser color printer is taken as an example, but another color printer such as an ink jet printer may be used.

  The color printer 100 shown in FIG. 1 has four colors (Y (yellow), M (magenta), C (cyan)), and K (black)) arranged independently according to the laser beam writing and the electrophotographic process. This is a four-drum tandem engine type image forming apparatus that forms the image forming systems 1Y, 1M, 1C, and 1K, and sequentially superimposes and transfers these four color images on a recording sheet.

  Each of the image forming systems 1Y, 1M, 1C, and 1K includes a photoconductor as an image carrier, for example, small-diameter OPC (organic photoconductor) drums 2Y, 2M, 2C, and 2K, and the OPC drums 2Y, 2M, and 2C. The electrostatic latent images on the charging rollers 3Y, 3M, 3C, and 3K as charging means and the OPC drums 2Y, 2M, 2C, and 2K are developed with a developer from the upstream side of image formation so as to surround 2K. Developing devices 4Y, 4M, 4C, and 4K that generate toner images of Y, M, C, and K colors, cleaning devices 5Y, 5M, 5C, and 5K, and static eliminating devices 6Y, 6M, 6C, and 6K are arranged. .

  Beside each developing device 4Y, 4M, 4C, and 4K, a toner bottle unit 7Y that supplies toner of a predetermined color to the developing devices 4Y, 4M, 4C, and 4K with Y toner, M toner, C toner, and K toner, respectively. , 7M, 7C, 7K are arranged. In addition, each of the image forming systems 1Y, 1M, 1C, and 1K is provided with laser-based optical writing devices 8Y, 8M, 8C, and 8K. The optical writing devices 8Y, 8M, 8C, and 8K are laser light sources. Laser diode (LD) light sources 9Y, 9M, 9C, and 9K, collimating lenses 10Y, 10M, 10C, and 10K, fθ lenses 11Y, 11M, 11C, and 11K, polygon mirrors 12Y as deflection scanning means, 12M, 12C, and 12K, and folding mirrors 13Y, 13M, 13C, 13K, 14Y, 14M, 14C, and 14K.

  The image forming systems 1Y, 1M, 1C, and 1K are arranged vertically, and the transfer belt unit 15 is arranged on the right side so as to be in contact with the OPC drums 2Y, 2M, 2C, and 2K. The transfer belt unit 15 is rotationally driven by a drive source (not shown) with the transfer belt 16 stretched around rollers 17 to 20. A paper feed tray 21 storing recording paper as a transfer material is disposed on the lower side of the apparatus, and a fixing device 22 having a heat fixing roller and a pressure roller, a paper discharge roller 23, and a paper discharge tray 24 are arranged at the top of the apparatus. It is installed.

  At the time of image formation, in each image forming system 1Y, 1M, 1C, 1K, the OPC drums 2Y, 2M, 2C, 2K are rotationally driven by a driving source (not shown), and are charged by charging rollers 3Y, 3M, 3C, 3K. The OPC drums 2Y, 2M, 2C, and 2K are uniformly charged, and the optical writing devices 8Y, 8M, 8C, and 8K modulate the laser diode based on the image data of each color, and deflect and scan the laser light to scan the OPC drum 2Y. By performing optical writing on 2M, 2C, and 2K, electrostatic latent images are formed on the OPC drums 2Y, 2M, 2C, and 2K.

  The electrostatic latent images on the OPC drums 2Y, 2M, 2C, and 2K are developed by developing devices 4Y, 4M, 4C, and 4K, respectively, to become toner images of colors Y, M, C, and K, while the paper feed tray 21 Then, the transfer paper is fed in the horizontal direction from the paper feed roller 25 and is conveyed vertically in the image forming systems 1Y, 1M, 1C and 1K by the transport system. This recording paper is electrostatically attracted and held on the transfer belt 16 and conveyed by the transfer belt 16, and a transfer bias is applied by a transfer bias applying means (not shown) so as to be on the OPC drums 2Y, 2M, 2C and 2K. A full color image is formed on the recording paper by sequentially superimposing and transferring the toner images of each color Y, M, C, and K onto the recording paper. The recording paper on which the full-color image is formed is fixed by the fixing device 22 to the full-color toner image by the action of heat and pressure, and is discharged to the discharge tray 24 by the discharge roller 23.

  Next, the configuration and operation of the image processing apparatus in the color printer configured as described above will be described. FIG. 2 is a block diagram showing the configuration of the electrical / control system of the image forming apparatus in FIG. This electrical / control system is a CPU 101 that controls the entire color printer 100, a CPU I / F 102 that is connected to the memory controller 103 and executes interface control between the CPU 101 and the memory controller 103, a main memory 104, and a local bus of the CPU 101. A memory controller 103 that controls transfer between the decoding device, the image processing device, the encoding device, and the main memory is provided.

  Also, a drawing device 105 that receives a drawing command from the CPU 101 and draws a band of the main memory 104, an encoding device 106 that encodes binary band data in the main memory 104, and transfers the code to the main memory 104, an encoding device 106 The decoding device 107, the decoding device 107, which receives the code encoded by, decodes each plate, and transfers it to the C (cyan), M (magenta), Y (yellow), and K (black) plate engine controllers. An engine controller 108 that receives image data from the printer engine 109 and transfers the image data to the printer engine 109 of each plate, and a printer engine 109 (see FIG. 1) that forms images of C, M, Y, and K plates.

  Further, the communication controller 110 connected to the network, receiving various data and commands from the network, and connected to the various controllers via the memory controller 103, stores images to be printed, the control program of the CPU 101, various data, and the like. Controls main memory 104, ROM 112, panel controller 113, etc., CPU 101, local I / F 111 for executing interface control with main memory 104, ROM 112 for storing font information such as characters, control program for CPU 101, and operation panel 114 A panel controller 113 for controlling the user, and an operation panel 114 for notifying the printer of a user input operation.

  FIG. 3 is a block diagram showing the flow of normal image processing for the image data in FIG. In the figure, the CPU 101 analyzes PDL (page description language) and creates a multi-value RGB band memory in the band memory area 104 a of the main memory 101. The main memory 104 stores the band data generated by the CPU 101 in the band memory area 104a. The encoding device 105 reads and encodes the band data in the band memory area 104 a of the main memory 104, and sends the code to the code page memory area 104 b of the main memory 104. The main memory 104 receives the code from the encoding device 105 and stores it.

  Also, the decoding device 106 reads a code for one page made up of the code for each band stored in the code page memory area 104 b of the main memory 104, decodes it, and transfers it to the image processing device 107. The image processing apparatus 107 receives the decoded image data, performs image processing such as color conversion processing and gradation processing, transfers the image processing to the engine controller 108, and the printer engine prints out according to the image data.

  FIG. 4 is a block diagram showing the concept of image processing according to the embodiment of the present invention. In the figure, the CPU 101 generates multi-value RGB band data in the main memory 104. The main memory 104 stores band data, page codes, programs, various work data, and the like. The encoding device 105 reads and encodes the band into the band memory area 104 a of the main memory 104 and writes the code into the code page memory area 104 b of the main memory 104. The decoding device 106 decodes the code in the code page memory area 104 b of the main memory 104 in synchronization with the printer engine 109 and transfers the code to the image processing device 107. The image processing device 107 receives the image data decoded by the decoding device 106, performs image processing such as color conversion and gradation processing, and transfers the image data to the engine controller 108. The engine controller 108 transfers the image data after gradation processing received from the image processing apparatus 107 to the printer engine 109. The left side of FIG. 4 shows an example of a multilevel band memory format of the band memory area 104a and an example of a code page memory format of the code page memory area 104b.

  FIG. 5 shows the format of the main memory 104. The band storage area 104a stores multi-value RGB band data. The code page memory area 104b is an area for storing a plurality of pages of encoded data of an encoded band for one page. The program area 104p is an area for storing various programs of the CPU 101. The work area 104w is used as a working memory during the control of the CPU 101 and the like.

  FIG. 6 is a block diagram showing an overall flow of image processing according to the embodiment of the present invention. As shown by the arrows in the figure, the CPU generates PDL (page description language) multi-value RGB band data in the main memory. The encoding device 105 reads the completed band data from the main memory 104, performs encoding, and sends the encoded band data to the code page memory area 104b of the main memory 104. The decoding device 106 reads the completed page code data from the main memory 104 and decodes it, and sends the decoded image data to the image processing device 107. The image processing apparatus 107 performs image processing such as color conversion and gradation processing. The engine controller 108 controls the printer engine 109 to perform print output.

  FIG. 7 is a block diagram showing an internal configuration of encoding apparatus 105 in FIG. In the figure, the encoding device 105 includes a memory controller I / F 120, an encoding processing device 121, a write memory address generation device 122, a read memory address generation device 123, and a controller 124.

  The memory controller I / F 120 executes interface control with the memory controller 104. The encoding processor 121 reads the 8 × 8 RGB data from the band memory area 104a of the main memory 104 through the memory controller I / F 120 and encodes it, and passes through the memory controller I / F 120 to the main memory 104. To the code page memory area 104b. The write memory address generation device 122 generates an address of the band memory area 104a of the main memory 104 processed by the encoding processing device 121. The read memory address generation device 123 generates an address of the code page memory area 104b of the main memory 104 that stores the image processed by the encoding processing device 121. The controller 124 controls the entire encoding device 105.

  FIG. 8 is a block diagram showing a configuration of the encoding processing device 121 in FIG. As shown in the figure, the encoding processing device 121 includes an RGB data 8 × 8 storage device 125, an RGB → YUV conversion device 126, a Y data 8 × 8 storage device 127, a Y two-dimensional DCT processing device 128, a Y quantization process. Device 129, Y entropy encoding device 130, Y single color data determination device 131, Y single color data encoding device 132, U data 8 × 8 storage device 133, U two-dimensional DCT processing device 134, U quantization processing device 135, U entropy An encoding device 136, a U single color data determination device 137, a U single color data encoding device 138, a V data 8 × 8 storage device 139, a V2D DCT processing device 140, a V quantization processing device 141, a V entropy encoding device 142, V single color data determination device 143, V single color data encoding device 144, code format generation device 145, controller It has an over La 146.

  The RGB data 8 × 8 storage device 125 temporarily stores RGB 8 × 8 pixel blocks. The RGB → YUV converter 126 converts RGB of 8 × 8 pixels into YUV according to the JPEG standard, converts the Y component (luminance signal) to the Y data 8 × 8 storage device 127, and the U component (color difference signal Cb). The V component (color difference signal Cr) is transferred to the V data 8 × 8 storage device 139 to the U data 8 × 8 storage device 137.

  The Y data 8 × 8 storage device 127 stores the Y value generated by the RGB → YUV conversion device 126 for the 8 × 8 block. The Y two-dimensional DCT processing device 128 performs DCT (discrete cosine transform) processing on the Y component and transfers the Y component to the Y quantization processing device 129. The Y quantization processing device 129 receives and quantizes the data after the DCT processing of the Y component from the Y two-dimensional DCT processing device 128 and transfers the data to the Y entropy encoding device 130. The Y entropy encoding device 130 receives the quantized data of the Y component from the Y quantization processing device 129, encodes it using the Huffman encoding method, and transfers the encoded data to the code format generation device 145. The Y one-color data determination device 131 reads the 8 × 8 Y values stored in the Y data 8 × 8 storage device 127, determines whether all the values are the same, and notifies the controller 146. The Y color data encoding device 132 receives, encodes, and transfers only the Y value when the Y color data determination device 131 determines that the values are the same, and transfers them to the code format generation device 145.

  The U data 8 × 8 storage device 133 stores the U value generated by the RGB → YUV conversion device 126 for an 8 × 8 block. The U two-dimensional DCT processing device 134 performs DCT (discrete cosine transform) processing on the U component and transfers the U component to the U quantization processing device 135. The U quantization processing device 135 receives and quantizes the data after DCT processing of the U component from the U two-dimensional DCT processing device 134 and transfers the quantized data to the U entropy coding device 136. The U entropy encoding device 136 receives the quantized data of the U component from the U quantization processing device 135, encodes the data using the Huffman encoding method, and transfers the encoded data to the code format generation device 145. The U one-color data determination device 137 reads 8 × 8 U values stored in the U data 8 × 8 storage device 133, determines whether they are all the same value, and notifies the controller 146. The U color data encoding device 138 receives, encodes, and transfers only the U value to the code format generation device 145 when it is determined by the U color data determination device 137 that the values are the same.

  The V data 8 × 8 storage device 139 stores the V value generated by the RGB → YUV conversion device 126 for an 8 × 8 block. The U two-dimensional DCT processing device 140 performs DCT (discrete cosine transform) processing on the U component and transfers the U component to the V quantization processing device 141. The V quantization processing device 141 receives and quantizes the V-component DCT-processed data from the V2-dimensional DCT processing device 140 and transfers the data to the V entropy coding device 142. The V entropy encoding device 142 receives the quantized data of the V component from the V quantization processing device 144, encodes the data using the Huffman encoding method, and transfers the encoded data to the code format generation device 145. The V single color data determination device 143 reads the 8 × 8 V values stored in the V data 8 × 8 storage device 139, determines whether all the values are the same, and notifies the controller 146 of them. The V single color data encoding device 144 receives only the V value when it is determined as the same value from the V single color data determination device 143, encodes it, and transfers it to the code format generation device 145.

  FIG. 9 is a flowchart showing the processing operation of the encoding processing device 121 configured as shown in FIG. The encoding processing device 121 is executed by the controller 146. In the figure, first, 8 × 8 RGB data is read from the RGB data 8 × 8 storage device 125 (step S1), and the RGB → YUV conversion device 126 converts 8 × 8 block RGB data into 8 × 8 YUV data. (Step S2). Subsequently, it is determined whether or not all the 8 × 8 YUV data are the same (step S3). Here, if all the 8 × 8 YUV data are the same, the Y value is converted into a DC value after DCT (step S4), and whether or not the Y value is the same in the previous block. Is determined (step S5). Here, if the previous block has the same Y value, the difference between the previous DC value of the Y one-color data encoding device 132 and the DC value is obtained, and the DC Huffman table is used to determine the DC Huffman table. The code value and the DC Huffman code length are obtained and transferred to the code format generation device 145 (step S6). On the other hand, if all the Y values are not the same value in the previous block in step S5, the difference between the previous DC value and the DC value of the Y entropy encoding device 130 is obtained, and further the DC Huffman code is obtained from the DC Huffman table. The value and the DC Huffman code length are obtained and transferred to the code format generation device 145 (step S7). After executing Step S6 or Step S7, an AC Huffman code value and an AC Huffman code length with 0 run length when the AC values after DCT conversion are all “0” are obtained and transferred to the code format generation device 145 ( Step S8).

  On the other hand, if the 8 × 8 YUV data are not all the same in step S3, the Y2D DCT processing device 129 DCT-transforms the 8 × 8 Y data (step S10), and further the Y quantization processing device 129 The 8 × 8 DCT coefficients are quantized (step S11). Subsequently, it is determined whether or not the previous block has the same Y value (step S12). Here, if the previous block has the same Y value, the difference between the previous DC value of the Y one-color data encoding device 132 and the DC value is obtained, and the DC Huffman table is used to determine the DC Huffman table. The code value and the DC Huffman code length are obtained and transferred to the code format generation device 145 (step S13). On the other hand, if all the Y values of the previous block in step S12 are not the same value, a difference between the previous DC value and the DC value of the Y entropy encoding device 130 is obtained, and a DC Huffman code is obtained from the DC Huffman table. The value and the DC Huffman code length are obtained and transferred to the code format generation device 145 (step S14). After executing Step S13 or Step S14, an AC Huffman code value and an AC Huffman code length are obtained from the AC Huffman table and transferred to the code format generation device 145 (Step S15).

  Subsequently, when the 8 × 8 YUV data are all the same in step S3, the processing in steps S4 to S8 is performed in the same manner. On the other hand, when the 8 × 8 YUV data is not all the same in step S3. Performs the processing of steps S10 to S15 in the same manner (step S9), and ends this processing.

  FIG. 10 is a block diagram showing an internal configuration of the one-color data encoding device 132 (138, 144) of each color in FIG. Here, the Y one-color data encoding device 132 is taken as an example, but the other U and V one-color data encoding devices 138 and 144 are similarly configured. The Y one-color data encoding device 132 includes a DC value generating device 150, a MAX0 run-length AC value code generating device 151, a DC value encoding device 152, and a code format generating device 153.

  The DC value generation device 150 is a DC value generation device that receives one color data from the one color data determination device and generates a DC value as shown in FIG. The MAX0 run-length AC value code generation device 151 does not have frequency components as shown in FIG. 12, and since the AC value values are all “0”, the specific code and its code length are sent to the code format generation device 153. Forward. The DC value encoding device 152 performs predictive encoding from the DC value from the DC value generating device 150 and the DC value of the previous block. The code format generation device 153 receives AC and DC codes from the MAX0 run-length AC value code generation device 151 and the DC value encoding device 152, and connects the codes.

  FIG. 11 is a block diagram showing an internal configuration of DC value encoding apparatus 152 in FIG. The DC value encoding device 152 includes a DC register 155, a previous register 156, a MUX (multiplexer) 157, a subtraction device 158, and a Huffman table (DC) 159.

  The DC register 155 stores the DC value of the current block. The previous register 156 stores the DC value of the previous block. When the previous block is encoded by the one-color data encoding device (132, 138, 144), the MUX 157 changes the value of the previous register 156, if different, the entropy encoding device (130, 136, 142). ) Is transferred to the subtracting device 158. The subtracting device 158 performs a subtraction process with the previous DC value to generate DC difference data. The Huffman table 159 stores the Huffman code of the DC difference data generated by the subtractor 158 and its code length, and outputs it.

  FIG. 14 is a block diagram showing an internal configuration of each color entropy encoding device (103, 136, 142) in FIG. The entropy encoding device includes an 8 × 8 DCT coefficient storage device 160, a DC / AC value clipping device 161, a DC value encoding device 162, an AC value encoding device 163, and a code format generation device 164.

  The 8 × 8 DCT coefficient storage device 160 stores 8 × 8 DCT coefficients after DCT processing. The DC / AC value cutout device 161 cuts out one DC value and 63 AC values from the 8 × 8 DCT coefficient storage device 160, cuts the DC value into the DC value encoding device 162, and outputs the AC value to the DC value encoding device 162. Is transferred to the AC value encoding device 163. The DC value encoding device 162 obtains the DC code and the code length of the DC value received from the DC / AC value clipping device 161 from the DC value Huffman table. The AC value encoding device 163 obtains the AC code and the code length of the AC value received from the DC / AC value clipping device 161 from the AC value Huffman table. The code format processing device 164 combines the DC and AC codes from the DC value encoding device 162 and the AC value encoding device 163 and their code lengths into one code and code length.

  Therefore, as described above, when a compression method that performs frequency conversion such as DCT or Wavelet conversion is used as the compression method of the printer image, the pixel color of each block of YUV is determined, and the same for each block independently. If it is determined as a color, by using a one-color data encoding device of a different path from the frequency conversion processing, for example, a graphics image composed of the same color is processed by the one-color data encoding device, and a photographic image Since two passes for performing quantization processing from a high frequency by frequency decomposition by JPEG are realized, these can be encoded at high speed.

  By the way, the image processing method (operation) described so far can be programmed, recorded on a computer-readable recording medium, and executed on the computer. Further, a part of the image processing method can be provided on a network and realized through a communication line.

  That is, the image processing method described in this embodiment is realized by executing a program prepared in advance on a computer (CPU 30) such as a personal computer or a workstation as shown in FIG. This program is operated by a computer such as a memory 31, a hard disk 34, a flexible disk 37, a CD-ROM (Compact T-Disc Read Only Memory) 36, an MO (Magneto Optical), a DVD (Digital Versatile Disc), etc. The program is recorded on a readable recording medium, read from the recording medium by a computer (CPU 30), and displayed on the display device 33 as necessary. In addition, data of this image processing method can be transmitted and received from the communication device 32 to an external device as necessary.

  In addition, as shown in FIG. 16, this program can be distributed to devices 41 to 43 such as personal computers via a network such as the Internet 30 via the recording medium.

  That is, this program can be provided in a state of being installed in advance on a hard disk as a recording medium built in the computer, for example. The program can be temporarily or permanently stored in a recording medium, and can be provided as packaged software by being incorporated in a computer as a unit or being used as a removable recording medium.

  As the recording medium, for example, a flexible disk, a CD-ROM, an MO disk, a DVD, a magnetic disk, a semiconductor memory, and the like can be used.

  The program can be transferred from a download site to a computer wired or wirelessly via a network such as a LAN (Local Area Network) or the Internet, and downloaded to a storage device such as a built-in hard disk in the computer. .

  As described above, the image processing apparatus and the image processing method according to the present invention, and the computer-readable recording medium on which the program for causing the computer to execute the image processing method is recorded include a digital copying machine, a digital camera, and various color printers. In particular, when a compression system that performs frequency conversion, such as DCT or wavelet, is used as the printer image compression method, the pixel color of each block of YUV is determined, and the same color is determined independently for each block. In such a case, it is suitable for a system that performs high-speed encoding processing by using a single-color data encoding device that is different from the frequency conversion processing.

3 is an explanatory diagram illustrating a configuration example of a mechanism unit of the image forming apparatus according to the embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of an electrical / control system of the image forming apparatus in FIG. 1. It is a block diagram which shows the flow of the normal image processing with respect to the image data in FIG. It is a block diagram which shows the concept of the image processing concerning embodiment of this invention. It is explanatory drawing which shows the format of the main memory in FIG. It is a block diagram which shows the whole flow of the image processing concerning embodiment of this invention. It is a block diagram which shows the internal structure of the encoding apparatus in FIG. It is a block diagram which shows the structure of the encoding processing apparatus in FIG. It is a flowchart which shows the processing operation of the encoding processing apparatus comprised as FIG. It is a block diagram which shows the internal structure of the one-color data encoding apparatus of each color in FIG. It is a block diagram which shows the internal structure of the DC value encoding apparatus in FIG. It is a matrix figure which shows the procedure of AC encoding. It is a matrix figure which shows DC encoding. It is a block diagram which shows the internal structure of the entropy encoding apparatus of each color in FIG. It is a block diagram which shows the example which makes a computer perform the image processing method concerning embodiment of this invention. It is a block diagram which shows the example which downloads and performs the image processing method concerning embodiment of this invention from a network. It is explanatory drawing which shows the example of a printer image used as the object of an image output process. It is explanatory drawing which shows the mode of the wavelet transformation in the past.

Explanation of symbols

100 color printer 101 CPU
DESCRIPTION OF SYMBOLS 103 Memory controller 104 Main memory 104a Band memory area 104b Code page memory area 106 Decoding apparatus 107 Image processing apparatus 108 Engine controller 109 Printer engine 121 Encoding processing apparatus 125 RGB data 8 × 8 storage apparatus 126 RGB → YUV conversion apparatus 128 Y2 Dimensional DCT processing unit 129 Y quantization processing unit 130 Y entropy encoding unit 131 Y single color data determination unit 132 Y single color data encoding unit 134 U two-dimensional DCT processing unit 135 U quantization processing unit 136 U entropy encoding unit 137 U single color Data determination device 138 U single color data encoding device 140 V2D DCT processing device 141 V quantization processing device 142 V entropy encoding device 143 V single color data determination device 14 4 V single color data encoding device 152 DC value encoding device

Claims (8)

In an image processing apparatus that outputs image data generated by drawing to a printer engine,
Image dividing means for dividing the generated image data into n × m blocks;
Frequency resolving means for frequency resolving an n × m image generated by the image dividing means;
Frequency-decomposed data encoding means for encoding the frequency-decomposed data;
One color value determining means for determining whether or not the level values of the color components of the n × m image are all the same value;
When the level values of the color components of the n × m image are all the same value by the one color value determining means, one color value encoding means for generating one color value code data;
An image processing apparatus comprising:   The image processing apparatus according to claim 1, further comprising a previous block coding flow determination unit that determines whether the previous block uses the one color value encoding unit.   When a previous block does not use the one color value encoding means, a DC value prediction encoding means for predictively encoding a DC value to be encoded using a DC component value of the previous block is provided. The image processing apparatus according to claim 1.   When the previous block does not use the frequency-decomposed data encoding means, a DC value predictive encoding means for predictively encoding a DC value to be encoded using the DC component value of the previous block is provided. The image processing apparatus according to claim 1. In an image processing apparatus that outputs image data generated by drawing to a printer engine,
Image dividing means for dividing the generated image data into n × m blocks;
Frequency resolving means for frequency resolving an n × m image generated by the image dividing means;
Frequency-decomposed data encoding means for encoding the frequency-decomposed data;
One color value determination means for determining whether or not the level values of the color components of the n × m image are all the same value;
When the level values of the color components of the n × m image are all the same value by the single color value determination unit, the single color value frequency decomposition data for generating the frequency decomposition value based on the color component level value without using the frequency decomposition unit Generating means;
An image processing apparatus comprising: In an image processing method for outputting image data generated by drawing to a printer engine,
An image dividing step of dividing the generated image data into n × m blocks;
A frequency decomposition step of frequency-resolving an n × m image generated by the image dividing step;
A frequency-decomposed data encoding step for encoding the frequency-decomposed data;
A color value determination step of determining whether or not the level values of the color components of the n × m image are all the same value;
When the level values of the color components of the n × m image are all the same value in the one color value determination step, a one color value encoding step for generating code data of one color value;
An image processing method comprising: In an image processing method for outputting image data generated by drawing to a printer engine,
An image dividing step of dividing the generated image data into n × m blocks;
A frequency decomposition step of frequency-resolving an n × m image generated by the image dividing step;
A frequency-decomposed data encoding step for encoding the frequency-decomposed data;
A color value determination step of determining whether or not the level values of the color components of the n × m image are all the same value;
If the level values of the color components of the n × m image are all the same in the single color value determination step, the single color value frequency decomposition data for generating the frequency decomposition value based on the color component level value without using the frequency decomposition step Generation process;
An image processing method comprising:   A computer-readable recording medium having recorded thereon a program for causing a computer to execute the image processing method according to claim 6 or 7.

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