JP2010141607A - Image processor, and image processing method for same - Google Patents

Abstract

An image processing apparatus and an image processing method for an image processing apparatus are provided that can maintain the shape of a character image included in a resolution-converted image at a high resolution even in an image including halftone dots.
RGB pixel data of a pixel adjacent to a target pixel and indicating that character shape data is a character pixel is determined as RGB pixel data of the character pixel, and the RGB pixel data is RGB pixel data of the character pixel. In addition, when a matching pattern representing the arrangement of pixels indicating that the character shape data is a character pixel is generated, and the generated matching pattern matches a predetermined matching pattern indicating the arrangement of the character-shaped pixels, the predetermined matching pattern In accordance with the arrangement of the character pixels when the enlargement process is performed on the target pixel included in the pixel, the target pixel on which the enlargement process has been performed is interpolated with the RGB pixel data of the character pixel.
[Selection] FIG.

Description

  The present invention relates to an image processing apparatus and an image processing method of the image processing apparatus.

  In laser printers, digital copiers, etc., when printing bitmap image data, jerky correction is generally performed to correct and smooth the stepped portions of the outlines of characters and images. It has become.

  For example, Patent Document 1 proposes an image data processing apparatus that performs correction for reducing toner consumption in addition to jerky correction for smoothing a staircase portion of characters and figures. Specifically, the image data processing device described in Patent Document 1 extracts and samples a predetermined range of dots centered on a target dot of image data developed in a bitmap shape, and based on the sampled dots Recognize the dot of interest and its surrounding information, in particular the characteristics of the line segment shape at the boundary between the black and white dots in the image data, and represent the recognition result as code information in a defined format. Based on this code information It is determined whether the extracted dots need to be corrected, and if it is determined that correction is necessary, the video data for jerky correction is read using this code information as an address, and a bit is stored using a small storage area. Jerky is eliminated by correcting the contour of the image data developed in a map.

Japanese Patent Laid-Open No. 9-168086

  However, the image data processing apparatus described in Patent Document 1 performs jerky correction on the line segment shape at the boundary between black dots and white dots of the image data, and is a halftone with dithering or the like. There is a problem that jerky correction cannot be performed on dots, and jerky correction can be performed only on monochrome image data that does not include halftone dots.

  The present invention has been made in view of the above, and an image processing apparatus capable of maintaining the shape of a character image included in a resolution-converted image at a high resolution even in an image including halftone dots, and An object is to provide an image processing method of an image processing apparatus.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is a color pixel data of each pixel in an image including a character image and whether each pixel is a character pixel included in the character image. Rendering means for generating character shape data indicating whether or not, enlargement means for executing enlargement processing on the color pixel data of each pixel generated, and enlargement processing based on the generated character shape data and color pixel data The color pixel data of a pixel that is adjacent to the target pixel that has executed and indicates that the character shape data is the character pixel is determined as the color pixel data of the character pixel, and the color pixel data is the color of the character pixel. Determination means for generating a matching pattern that is pixel data and that indicates an arrangement of pixels indicating that the character shape data is the character pixel; and the character included in the character image Generation that generates arrangement data representing the arrangement of the character pixels when the predetermined matching pattern representing the arrangement of the prime matches the generated matching pattern when the pixel is subjected to enlargement processing on the predetermined matching pattern And interpolation means for interpolating the pixel of interest subjected to enlargement processing with color pixel data of the character pixel according to the arrangement of the character pixel represented by the generated arrangement data.

  According to a second aspect of the present invention, in the first aspect of the invention according to the first aspect, the first storage means for storing the character shape data for the first number of lines among the generated character shape data, and the first storage. First cutout means for cutting out the character shape data in the first pixel range from the means, wherein the determination means is such that the color pixel data is color pixel data of the character pixel and the character shape data is the character shape data. The matching pattern of the first pixel range indicating the arrangement of pixels indicating character pixels is generated.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein, when the pixel of interest for which the enlargement processing has been performed is a background, the interpolation unit determines the pixel of interest for which the enlargement processing has been performed, Interpolation is performed using color pixel data of the character pixels.

  The invention according to claim 4 is the invention according to claim 3, wherein the interpolation means recognizes a pixel in which the color pixel data indicates white as a background.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, a second storage unit that stores the color pixel data for the second number of lines among the generated color pixel data. And second cutout means for cutting out the color pixel data of the second pixel range from the second storage means, and the determination means includes the generated character shape data and the color of the second pixel range. Based on pixel data, the color pixel data of a pixel adjacent to the target pixel and indicating that the character shape data is the character pixel is determined as the color pixel data of the character pixel.

  The invention according to claim 6 is the invention according to claim 5, wherein the second pixel range is narrower than the first pixel range.

  According to a seventh aspect of the present invention, the drawing means includes color pixel data of each pixel in an image including a character image and character shape data indicating whether each pixel is a character pixel included in the character image. A drawing step to be generated, an enlargement step in which the enlargement unit executes an enlargement process on the color pixel data of each pixel generated, and an enlargement process based on the character shape data and the color pixel data generated by the determination unit The color pixel data of a pixel that is adjacent to the target pixel that has executed and indicates that the character shape data is the character pixel is determined as the color pixel data of the character pixel, and the color pixel data is the color of the character pixel. The character image includes a determination step for generating a matching pattern representing pixel arrangement indicating pixel data and the character shape data indicating the character pixel, and a generation unit. When the predetermined matching pattern representing the arrangement of the character pixels matches the generated matching pattern, the arrangement data representing the arrangement of the character pixels when the pixel is enlarged according to the predetermined matching pattern is generated. And an interpolation step in which the interpolation means interpolates the pixel of interest that has been subjected to the enlargement process with the color pixel data of the character pixel according to the arrangement of the character pixel represented by the generated arrangement data. It is characterized by.

  According to the present invention, even if the character image is expressed in halftone, the stepped portion of the contour portion of the character image can be interpolated, so even in an image including halftone dots, the resolution There is an effect that the shape of the character image included in the converted image can be maintained at a high resolution.

  Exemplary embodiments of an image processing apparatus and an image processing method of the image processing apparatus according to the present invention are explained in detail below with reference to the accompanying drawings. In the present embodiment, an example in which the image processing apparatus according to the present invention and the image processing method of the image processing apparatus are applied to a multicolor image forming apparatus that is a printer will be described. However, the present invention is not limited to this. For example, the present invention can be applied to an image processing apparatus such as a copying machine, a facsimile machine, and a multifunction machine.

  FIG. 1 is a block diagram showing a configuration of a multicolor image forming apparatus according to the present embodiment. In the multicolor image forming apparatus according to the present embodiment, reference numeral 1 denotes a belt-like photoconductor that is an image carrier, and the photoconductor 1 is rotatably supported by rotating rollers 2 and 3, and each rotation thereof. The rollers 2 and 3 are driven to rotate in the direction of arrow A. On the outer periphery of the photoreceptor 1, a charging device 4 as a charging unit, a static elimination lamp L, and a cleaning blade 15 </ b> A for the photoreceptor 1 are arranged. At the downstream position of the charging device 4, there is an optical writing unit that is irradiated with laser light emitted from a laser writing unit 5 that is optical writing means.

  A multi-color developing device 6 in which a plurality of developing units (developing means) are supported in a switchable manner is disposed downstream of the optical writing unit. The multicolor developing device 6 includes a yellow developing unit, a magenta developing unit, and a cyan developing unit for each color of toner to be accommodated. A black developing unit 7 containing black toner is provided at the top of the multicolor developing device 6.

  Any one of these development units moves to a developable position in synchronization with the development timing of the corresponding color. The multicolor developing device 6 has a function of selecting any developing unit by rotating 120 degrees on the circumference. When these developing units operate, the black developing unit 7 moves to a position separated from the photoreceptor 1. The movement is performed by the rotation of the cam 45.

  The laser writing unit 5 sequentially generates laser light according to image forming signals (writing information) of a plurality of colors from a laser light source (not shown), and periodically uses the polygon mirror 5B rotated by the polygon motor 5A. Then, the surface of the charged photoreceptor 1 is scanned through the fθ lens 5C and the mirror 5D, and an electrostatic latent image is formed on the surface.

  The electrostatic latent image formed on the surface of the photoreceptor 1 is developed with toner from the corresponding developing unit, and a toner image is formed and held. The intermediate transfer belt 10 is adjacent to the photoreceptor 1 and is supported by rotating rollers 11 and 12 so as to be rotatable in the direction indicated by the arrow B. The toner image on the photoreceptor 1 is transferred onto the surface of the intermediate transfer belt 10 by a transfer brush (first transfer means) 13 on the back side of the intermediate transfer belt 10.

  The surface of the photoreceptor 1 is cleaned for each color by the cleaning blade 15A, and a toner image of a predetermined color is formed on the surface. Each time the intermediate transfer belt 10 is rotated, the toner image on the photosensitive member 1 is transferred to the same position on the surface, and a plurality of color toner images are superimposed and held on the intermediate transfer belt 10. The Thereafter, the toner image is transferred to a recording medium such as paper or plastic.

  At the time of transfer onto the paper, the paper stored in the paper feeding device (paper feeding cassette) 17 is fed out by the paper feeding roller 18 and transported by the transporting roller 19, and is temporarily applied to the registration roller pair 20. After being stopped, the toner image is transferred to the nip between the intermediate transfer belt 10 and the transfer roller (second transfer means) 14 at a timing so that the transfer position of the toner image becomes normal. Then, after the toner images of a plurality of colors on the intermediate transfer belt 10 are collectively transferred by the action of the transfer roller 14, the sheet is sent to the fixing device 50, where the toner image is fixed, and then the paper discharge roller pair 51. As a result, the paper is discharged to the paper discharge stack 52 at the top of the main body frame 9.

  The intermediate transfer belt 10 is provided with a cleaning device 16 for the intermediate transfer belt 10 at a portion of the rotation roller 11 so that the cleaning blade 16A can be contacted and separated via a cleaning blade contacting / separating arm 16C. In the process of receiving the toner image from the photoreceptor 1, the cleaning blade 16A is separated from the intermediate transfer belt 10 and comes into contact after the toner image is transferred from the intermediate transfer belt 10 to the paper. The residual toner after the toner is transferred is scraped off. As already described, there are cleaning blades for the photoreceptor 1 and the intermediate transfer belt 10. Waste toner scraped by these blades is stored in a collection container 15. The collection container 15 is replaced as appropriate. An auger 16B provided inside the cleaning device 16 for the intermediate transfer belt 10 conveys waste toner scraped off by the cleaning blade 16A and sends it to the collection container 15 by a conveying means (not shown).

  Reference numeral 31 denotes a unitized process cartridge that incorporates the photosensitive member 1, the charging device 4, the intermediate transfer belt 10, the cleaning device 16, a conveyance guide 30 that forms a paper conveyance path, and the like so that they can be replaced when the end of their service life is reached. It is configured. In addition to the replacement of the process cartridge 31, the multi-color developing device 6 and the black developing unit 7 are also replaced at the end of their service life. In order to facilitate the replacement and the handling of jammed paper, a part of the front frame 8 of the main body is replaced. Has a structure that can be opened and closed about the support shaft 9A.

  On the left side of FIG. 1, an electrical / control device 60 is housed. Above that, a fan 58 is provided, which exhausts air to prevent the temperature inside the machine from rising excessively. On the right side of the figure, another relatively small paper feeder 59 is provided. In this embodiment, the intermediate transfer belt 10 is used as an intermediate transfer member, but an intermediate transfer drum can also be used.

  FIG. 2 is a diagram illustrating an example of the hardware configuration of the electrical / control apparatus of the multicolor image forming apparatus. 2 has a printer controller board 121 connected to a PC (Personal Computer) 120 via a network, and also connected to a printer engine 122.

  The printer controller board 121 includes a CPU (Central Processing Unit) 115 with a built-in memory controller, an image processing ASIC (Application Specific Integrated Circuit) 117, and a panel control ASIC 118, which are connected via a bus 116. The memory controller built-in CPU 115 is further connected to a main memory 114 and a ROM (Read Only Memory) 113.

  The memory controller built-in CPU 115 includes a CPU 101, a CPU I / F (Interface) 102, a memory arbiter 103, a communication controller 107, a drawing device 105, a memory controller 104, and a bus controller 106.

  The CPU 101 controls the entire apparatus of the multicolor image forming apparatus. The CPU 101 also analyzes a PDL (Page Description Language) transmitted from the PC 120, outputs a drawing command to the drawing apparatus 105, generates an image processing parameter for the image processing ASIC 117, and the like. The CPU I / F 102 is an interface of the CPU 101 and is connected to the main memory 114 and other controllers via the memory arbiter 103.

  The memory arbiter 103 arbitrates access to the main memory 114 by each controller included in the memory controller built-in CPU 115. The memory controller 104 controls the main memory 114. The memory controller 104 is connected to each controller via the memory arbiter 103.

  The bus controller 106 performs arbitration between each controller that inputs and outputs data to the bus and the bus. The communication controller 107 is connected to a network and receives data, commands, and the like transmitted from the PC 120 or the like connected via the network. The communication controller 107 also outputs data received to each controller connected via the memory arbiter 103, and transmits data input from each controller to the PC 120 or the like.

  In accordance with a drawing command input from the CPU 101, the drawing device 105 indicates RGB pixel data of each pixel representing an image including a character image in an RGB space, and whether each pixel is a character pixel included in the character image. Character shape data is generated, and the generated RGB pixel data and character shape data are drawn in the main memory 114. Here, the data generated by the drawing apparatus 105 is band data in “band” units, which is one of the units in which the multicolor image forming apparatus processes an image.

  The ROM 113 stores computer programs executed by the CPU 101, character font information, and the like. The main memory 114 stores RGB pixel data and character shape data generated by the drawing device 105, code data obtained by compressing the data, computer programs executed by the CPU 101, and the like.

  Note that the program executed by the multicolor image forming apparatus of the present embodiment is provided by being incorporated in advance in a ROM or the like. However, a CD-ROM, a flexible disk ( (FD), CD-R, DVD (Digital Versatile Disk), and the like may be recorded and provided on a computer-readable recording medium.

  Furthermore, the program executed by the multicolor image forming apparatus of the present embodiment may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. The program executed by the multicolor image forming apparatus of the present embodiment may be provided or distributed via a network such as the Internet.

  The image processing ASIC 117 includes an image processing device 110, a bus interface I / F (Interface) 108, and an engine controller 109. The image processing apparatus 110 receives the image processing parameter generated by the CPU 101 and performs image processing according to the image processing parameter.

  The bus I / F 108 is an interface when the image processing ASIC 117 is connected to the bus. The engine controller 109 controls the printer engine 122.

  The panel control ASIC 118 is connected to the panel 119 and controls the panel 119 according to a control command from the CPU 101 or the like. The panel control ASIC 118 includes a panel controller 112 and a bus I / F 111. The panel controller 112 performs control of data displayed on the panel 119, acquisition of information input from the panel 119, and the like. The bus I / F 111 is connected to the bus and inputs / outputs data from the CPU 115 with a built-in memory controller.

  The panel 119 displays the state of the multicolor image forming apparatus and accepts instructions from the operator for the multicolor image forming apparatus.

  The printer engine 122 forms an image on a medium under the control of the engine controller 109. The PC 120 creates a PDL of an image to be output to the multicolor image forming apparatus, and outputs the PDL to the multicolor image forming apparatus via a network.

  FIG. 3 is a flowchart showing an outline of processing in the multicolor image forming apparatus. In FIG. 3, the input PDL is analyzed, subjected to image processing, and then output to the printer engine 122. 3 includes a PDL storage step (step S301), a PDL analysis step (step S302), a drawing processing step (step S303), an RGB band image storage step (step S304), a character shape band storage step (step S305), It has an image processing step (step S320), a page image storage step after gradation processing (step S309), and a printout step (step S310), and the processing of each step is executed in the order described above.

  In the PDL storage step (step S301), the main memory 114 stores the PDL input from the PC 120. In the PDL analysis step (step S302), the CPU 101 executes the computer program to output a drawing command generated by analyzing the PDL stored in the main memory 114 to the drawing device 105.

  In the drawing process step (step S303), the drawing device 105 generates RGB pixel data and character shape data in accordance with the drawing command input from the CPU 101, and transfers them to the main memory 114.

  In the RGB band image storage step (step S304) and the character shape band storage step (step S305), the RGB pixel data and the character shape data transferred from the drawing device 105 are stored in the main memory 114 in band units.

  The image processing step (step S320) includes a resolution conversion step (step S306), a color conversion processing step (step S307), and a gradation processing step (step S308). In the resolution conversion step (step S306), RGB pixel data and character shape data are read from the main memory 114, and the resolution of the RGB pixel data is converted (for example, 600 dpi → 1200 dpi).

  In the color conversion processing step (step S307), color space conversion processing is performed on the RGB pixel data whose resolution has been converted in step S306, and CMYK pixel data is generated.

  In the gradation processing step S308, halftone processing is performed on the CMYK pixel data subjected to the color space conversion in step S307.

  In the post-gradation processing page image storing step (step S309), the post-halftone processing data obtained by the halftone processing in step S308 is stored in the main memory 114. After the processing in step S309, in the printout step (step S310), the printer engine 122 prints and outputs the data after halftone processing stored in the main memory 114.

  FIG. 4 is a diagram for explaining a storage area of the main memory. FIG. 5 is a diagram illustrating an example of 600 dpi RGB pixel data. FIG. 6 is a diagram illustrating an example of 600 dpi character shape data. Main memory 114 includes PDL storage memory area, program area, RGB band image memory storage area, character shape band image memory storage area, image processing parameter area, post-gradation page memory storage area, enlarged correction memory storage area, and others It has the area of.

  The PDL storage memory area stores the PDL input from the PC 120. The program area stores computer programs executed by the CPU 101. The RGB band image memory storage area stores RGB pixel data (shown in FIG. 5) of the image generated by the drawing device 105 in band units. The character shape band image memory storage area stores character shape data (shown in FIG. 6) generated by the drawing device 105 in band units.

  The image processing parameter area includes a lattice point data storage area, a gamma data storage area, a threshold data storage area, and a DMA (Direct Memory Access) parameter storage area. The grid point data storage area and the gamma data storage area store parameters for performing color space conversion in the color conversion processing step S306.

  The threshold value data storage area stores a threshold value table used when halftone generation processing is performed in the gradation processing step S308. The threshold value table stored in the threshold value data storage area may be provided for each color component constituting the image data to be subjected to halftone processing.

  The DMA parameter storage area stores parameters such as an address used when reading image processing parameters.

  The post-gradation page memory storage area has a C-page memory area, a M-page memory area, a Y-page memory area, and a K-page memory area. Each storage area of the page memory storage area after gradation processing is preferably provided for each color component after halftone processing. For example, in addition to the CMYK color space, each storage area corresponds to each color component in the RGB color space. May be provided.

  The enlargement correction memory storage area stores enlargement correction parameters used for resolution conversion in the resolution conversion step S306.

  FIG. 7 is a flowchart showing the operation processing of the entire image processing according to this embodiment. First, the CPU 101 analyzes the PDL, generates an image processing parameter of the image processing apparatus 110, and stores it in the image processing apparatus parameter area of the main memory 114 (step S701). Subsequently, the image processing apparatus 110 reads image processing parameters from the image processing parameter area of the main memory 114, and further reads enlargement correction parameters from the enlargement correction memory storage area (step S702). The drawing device 105 generates RGB pixel data in accordance with the drawing command input from the CPU 101 and draws it in the RGB band image memory storage area (step S703). At this time, if the RGB pixel data includes a character shape, the drawing device 105 generates character shape data and draws the generated character shape data in the character shape band image memory storage area. The processing in step S703 is repeated until one band is completed (step S704: No). When the processing for one band is completed (step S704: Yes), the image processing apparatus 110 reads RGB pixel data from the RGB band image memory storage area of the main memory 114, and further, character shape data from the character shape band image memory storage area. Is processed, and the image processing result is transferred to the page memory storage area after gradation processing in the main memory 114 (step S705). The process of step S705 is repeatedly executed (step S706: Yes) until the end of one band (step S706: No). As described above, the processes in steps S703 to S706 are executed until one band is finished (step S707: No) (step S707: Yes).

  FIG. 8 is a diagram illustrating the hardware configuration of the image processing apparatus. 8 includes an RGB pixel data address generation device 811, an RGB pixel data reading device 810, a character shape data address generation device 813, a character shape data reading device 812, a resolution conversion device 814, a color conversion processing device 815, Halftone processing device 816, parameter address generation device 803, image processing parameter reading device 802, DMA parameter storage device 804, matching pattern storage device 805, lattice point data storage device 806, gamma table storage device 807, halftone parameter storage device 808 , A threshold matrix storage device 809, an image processing image address generation device 818, an image processing image writing device 819, an image processing image buffer device 817, and a bus arbiter I / F 801.

  The bus arbiter I / F 801 includes an RGB pixel data reading device 810, a character shape data reading device 812, an image processing parameter reading device 802, and an image processing image writing device 819 that are connected to the bus 116 via the bus I / F 108. Mediation is performed when data is input / output.

  The parameter address generation device 803 generates an address of a parameter stored in the image processing parameter area on the main memory 114. The image processing parameter reading device 801 reads the image processing parameters stored in the main memory 114 based on the address generated by the parameter address generation device 803.

  The DMA parameter storage device 804 receives from the image processing parameter reading device 802 and stores parameters such as an address used when the image processing parameter reading device 802 reads the image processing parameters. The parameters stored in the DMA parameter storage device 804 are the multi-value RGB band width which is the band width, the multi-value RGB band height which is the band height, and the RGB band start which is the start address of the band data on the main memory 114. Address, CMYK band width after gradation processing and CMYK band height after gradation processing, which are the width and height of the band after gradation processing, and band data of each color component of C, M, Y, and K Is a start address or the like when the data is stored on the main memory 114.

  The matching pattern storage device 805 stores matching pattern data necessary for resolution conversion. In the present embodiment, the matching pattern storage device 805 has a predetermined matching pattern representing the arrangement of character pixels included in the character image, and a target pixel included in the predetermined matching pattern, centered on the target pixel on which enlargement processing is performed. Are stored in association with the arrangement data representing the arrangement of the character pixels when the enlargement process is executed.

  FIG. 9 is a diagram illustrating an example of a predetermined matching pattern. FIG. 10 is a diagram illustrating an example of arrangement data. The predetermined matching pattern shown in FIG. 9 is a matching pattern in which a black pixel 902 that is a character pixel, a white pixel 903 other than the character pixel, and a Don't Care indicated by x are arranged around the target pixel 901. is there. The arrangement data shown in FIG. 10 indicates the character pixel (black pixel) 1001 when the enlargement process is executed on the target pixel 901 included in the predetermined matching pattern shown in FIG.

  Furthermore, it is assumed that the matching pattern storage device 805 stores character shape data when the enlargement process is executed on white pixels. FIG. 11 is a diagram illustrating an example of arrangement data when enlargement processing is performed on white pixels. The arrangement data shown in FIG. 11 shows the character shape when the enlargement process is executed on white pixels.

  The RGB pixel data address generation device 811 generates addresses for reading RGB pixel data for each horizontal line from the RGB pixel data stored in the main memory 114.

  The RGB pixel data reading device 810 reads RGB pixel data from the main memory 114 from the RGB band image memory storage area on the main memory 114 using the horizontal line address generated by the RGB pixel data address generating device 811.

  The character shape data address generation device 813 generates an address for reading the character shape data for each horizontal line from the character shape data stored in the main memory 114.

  The character shape data reading device 812 reads character shape data for each horizontal line from the character shape band image memory storage area on the main memory 114 using the address generated by the character shape data address generating device 813.

  The resolution conversion device 814 uses the matching pattern data stored in the matching pattern storage device 805 and the character shape data read by the character shape data reading device 812 to read the RGB pixel data read by the RGB pixel data reading device 810. The resolution is converted into the resolution indicated by the enlargement correction parameter stored in the enlargement correction memory storage area on the main memory 114 (for example, 600 dpi → 1200 dpi).

  The color conversion processing device 815 performs color space conversion processing (BG / UCR processing) on the pixel values of the RGB pixel data input from the resolution conversion device 814. The color conversion processing device 815 converts input RGB pixel data from RGB color space to CMYK pixel data in the CMYK color space.

  The color conversion processing device 815 performs processes such as undercolor removal and color correction in addition to color space conversion. The color conversion processing device 815 acquires parameters used for processing from the lattice point data storage device 806 and the gamma table storage device 807.

  The lattice point data storage device 806 stores lattice point data input from the image processing parameter reading device 802. The gamma table storage device 807 stores a gamma table including parameters for gamma correction input from the image processing parameter reading device 802.

  The halftone processing device 816 performs halftone processing for each color component of CMYK pixel data input from the color conversion processing device 815. The halftone processing device 816 reads parameters necessary for the halftone processing from the halftone parameter storage device 808. The halftone processing device 816 further performs halftone processing for each of the odd and even pixels of the input CMYK pixel data by comparing the values included in the odd threshold matrix and the values included in the even threshold matrix. I do. The halftone processing device 816 outputs the CMYK pixel data after halftone processing as data after halftone processing in units of words in the main memory 114.

  The halftone parameter storage device 808 stores parameters when the halftone processing device 816 read from the main memory 114 performs halftone processing. The threshold value matrix storage device 809 stores a threshold value matrix for halftone processing corresponding to odd-numbered pixels and even-numbered pixels, respectively, based on the position of the horizontal line of CMYK pixel data.

  The post-image processing image buffer device 817 holds CMYK pixel data halftoned by the halftone processing device 816. The post-image processing image buffer device 817 holds the CMYK pixel data having halftoned numbers corresponding to the burst length when the main memory 114 is written.

  The post-image processing image writing device 819 outputs the halftoned CMYK pixel data stored in the post-image processing image buffer device 817 to the main memory 114 via the bus 116. The post-image processing image writing device 819 outputs CMYK pixel data in units of words in the main memory 114.

  The post-image processing image address generation device 818 generates an address when the post-image processing image writing device 819 stores the CMYK pixel data in the main memory 114. The post-image processing image address generation device 818 generates an address on the main memory 114 based on the parameters stored in the DMA parameter storage device 804. More specifically, the horizontal line address of the CMYK pixel data is generated in the same manner as when the RGB pixel data reading device 810 reads the RGB pixel data.

  FIG. 12 is a diagram illustrating the hardware configuration of the resolution conversion apparatus. 12 includes a character shape M line memory 1201, a character shape N * M matrix cutout device 1202, an RGB B line memory 1203, an RGB A * B matrix cutout device 1204, a character color determination device 1205, and a pattern address generation. A device 1206, a delay memory 1207, a 2 * 2 enlargement device 1208, a background recognition device 1209, an RGB line memory controller 1210, and an RGB1 line memory 1211.

  The character shape M line memory 1201 stores character shape data for N lines read by the character shape data reading device 812.

  The character shape N * M matrix cutout device 1202 reads character shape data of an N * M matrix (first pixel range) centered on the pixel of interest from character shape data for N lines stored in the character shape M line memory 1201. Is to cut out. In this embodiment, the character shape data of the N * M matrix centered on the target pixel is cut out. However, the present invention is not limited to this as long as the target pixel is included in the N * M matrix. .

  The RGB B line memory 1203 stores RGB pixel data for B lines read by the RGB pixel data reading device 810.

  The RGB A * B matrix cutout device 1204 is the same as the N * M matrix cut out by the character shape N * M matrix cutout device 1202 from the RGB pixel data for B lines stored in the RGB B line memory 1203, or N * RGB pixel data in an A * B matrix (second pixel range) narrower than the M matrix is cut out. In this embodiment, the RGB pixel data of the A * B matrix centered on the target pixel is cut out, but the present invention is not limited to this as long as the target pixel is included in the A * B matrix. .

  The character color determination device 1205 receives the character shape data of the N * M matrix and the RGB pixel data of the A * B matrix from the character shape N * M matrix cutout device 1202 and the RGB A * B matrix cutout device 1204, and sets them as the target pixel. The RGB pixel data of the A * B matrix of a pixel that is adjacent and indicates that the character shape data of the N * M matrix is a character pixel is determined as the RGB pixel data of the character pixel.

  The character color determining device 1205 indicates N pixel arrangement indicating the RGB pixel data of the character pixel in the RGB pixel data of the A * B matrix and the character pixel in the character shape data of the N * M matrix. * Generate a matching pattern for the M matrix.

  FIG. 13 is a diagram illustrating an example of RGB pixel data of an A * B matrix. FIG. 14 is a diagram illustrating an example of character shape data of an N * M matrix. The RGB pixel data of the A * B matrix shown in FIG. 13 is an example in which the upper right two pixels have red (R) pixels 1301 and the pixel range 1303 adjacent to the target pixel 1302 has blue (B) pixels 1304. . In the N * M matrix character shape data shown in FIG. 14, the blue (B) pixel 1304 shown in FIG. 13 is a character pixel (black pixel) 1402, and the red (R) pixel 1301 shown in FIG. This is an example of a pixel (white pixel) 1401) other than the pixel. When the character determination color device 1205 receives the RGB pixel data of the A * B matrix shown in FIG. 13 and the character shape data of the N * M matrix shown in FIG. 14, the blue (B) pixel 1304 is adjacent to the target pixel 1302. In addition, since it indicates that it is a character pixel 1402, blue (B) is determined as RGB pixel data of the character pixel.

  Then, the character color determination device 1205 indicates blue (B) in the RGB pixel data of the A * B matrix shown in FIG. 13, and the character pixel 1402 in the character shape data of the N * M matrix shown in FIG. A matching pattern representing the arrangement of the indicated pixels is generated. When the character color determination device 1205 receives the RGB pixel data of the A * B matrix shown in FIG. 13 and the character shape data of the N * M matrix shown in FIG. 14, the character shape of the N * M matrix shown in FIG. A matching pattern similar to the data is generated.

  FIG. 15 is a diagram illustrating another example of RGB pixel data of an A * B matrix. FIG. 16 is a diagram illustrating another example of character shape data of an N * M matrix. FIG. 17 is a diagram illustrating an example of the generated matching pattern. The RGB pixel data of the A * B matrix shown in FIG. 15 has the same number of red (R) pixels 1501 and blue (B) pixels 1502, and blue (B) in the pixel range 1504 adjacent to the target pixel 1503. This is an example in which the pixel 1502 is dominant. The N * M matrix character shape data shown in FIG. 16 is an example in which the red (R) pixel 1501 and the blue (B) pixel 1502 shown in FIG.

  When the character color determination device 1205 receives the RGB pixel data of the A * B matrix shown in FIG. 15 and the character shape data of the N * M matrix shown in FIG. 16, the red (R) pixel 1501 and the blue ( The pixel 1502 of B) is adjacent to the target pixel 1503, and the red (R) pixel 1501 and the blue (B) pixel 1502 are both character pixels 1601, so that the pixel range 1504 is dominant. The blue (B) indicated by the blue (B) pixel 1502 is determined as the RGB pixel data of the character pixel.

  The character color determination device 1205 indicates blue (B) in the RGB pixel data of the A * B matrix shown in FIG. 15, and indicates that it is a character pixel in the character shape data of the N * M matrix shown in FIG. A matching pattern (shown in FIG. 17) representing the pixel arrangement is generated.

  The pattern address generation device 1206 uses the N * M matrix matching pattern generated by the character color determination device 1205 to find a predetermined matching pattern that matches the N * M matrix from the matching pattern storage device 805. Then, the pattern address generation device 1206 obtains an address on the matching pattern storage device 805 of the arrangement data stored in association with the found predetermined matching pattern, and matches the arrangement data stored in the obtained address. Output from the pattern storage device 805.

  The delay memory 1207 delays the input of RGB pixel data to the 2 * 2 enlargement device 1208 in accordance with the arrangement data output from the matching pattern storage device 805.

  The 2 * 2 enlargement device 1208 multiplies the RGB pixel data of the pixel of interest by 2 * 2 and inputs it to the background recognition device 1209.

  The background recognition device 1209 recognizes whether or not the pixel of interest multiplied by 2 * 2 by the 2 * 2 enlargement device 1208 is the background (whether it is a white pixel). The pixel of interest multiplied by 2 * 2 is interpolated with the RGB pixel data of the character pixel in accordance with the character pixel arrangement represented by the arrangement data output from the storage device 805. In this embodiment, the interpolation is performed only when the target pixel is the background. However, the interpolation is not limited to this, and the interpolation may be performed even when the target pixel is not the background.

  However, when the target pixel is included in a shape other than the character shape, RGB pixel data cannot be converted into a high-resolution image only by interpolation of the target pixel. Also, when there are various colors around the character shape, even if the character has a high resolution, the image quality is not improved and an incorrect image may be generated. Therefore, it is preferable to perform interpolation only when the target pixel is the background.

  FIG. 18 is a diagram illustrating an example of RGB pixel data of the A * B matrix after interpolation. When the character color determination device 1205 receives the RGB pixel data shown in FIG. 13 and the character shape data shown in FIG. 14, the background recognition device 1209 outputs the FIG. 10 output from the matching pattern storage device 805 as shown in FIG. 15 is interpolated with the RGB pixel data of the character pixel by 2 * 2 times the pixel of interest 1503 included in the RGB pixel data of the A * B matrix shown in FIG.

  On the other hand, when the character color determination device 1205 receives the RGB pixel data of the A * B matrix shown in FIG. 15 and the character shape data of the N * M matrix shown in FIG. 16, the background recognition device 1209 receives the matching pattern storage device 805. Since the output arrangement data shown in FIG. 11 does not represent a character shape, no interpolation is performed.

  The RGB line memory controller 1210 receives the 2 * 2 pixels interpolated by the background recognition device 1209, stores the received 2 * 2 pixels 2 * 1 in the RGB1 line memory 1211, and performs color conversion on the other 2 * 1 pixels. Transfer to processor 815.

  FIG. 19 is a flowchart showing the procedure of resolution conversion processing. First, the character shape data reading device 812 reads character shape data for N lines in the horizontal line direction from the character shape band image memory storage area on the main memory 114 and writes it to the character shape M line memory 1201 (step S1901). Further, the RGB pixel data reading device 810 reads RGB pixel data for B lines from the RGB band image memory storage area on the main memory 114, and writes it into the RGB B line memory 1203 (step S1902).

  Next, the character shape N * M matrix cutout device 1202 cuts out N * M matrix character shape data centered on the pixel of interest from the character shape data for N lines stored in the character shape M line memory 1201 ( Step S1903). Further, the RGB A * B matrix cutout device 1204 cuts out the RGB pixel data of the A * B matrix centering on the target pixel from the RGB pixel data for B lines stored in the RGB B line memory 1203 (step S1904). .

  The character color determination device 1205 receives the character shape data of the N * M matrix and the RGB pixel data of the A * B matrix, and converts the RGB pixel data of the pixel adjacent to the target pixel and the character shape data to be the character pixel into the character pixel. N * M matrix matching pattern representing the arrangement of pixels that are the same color as the determined RGB pixel data and indicate character pixels is obtained (step S1905).

  The pattern address generation device 1206 uses the generated matching pattern of the N * M matrix to access the matching pattern storage device 805, finds a predetermined matching pattern that matches the matching pattern of the N * M matrix, and The arrangement data when the target pixel included in the matching pattern is multiplied by 2 * 2 is obtained (step S1906).

  The 2 * 2 enlargement device 1208 multiplies the RGB pixel data of the pixel of interest by 2 * 2 and transfers it to the background recognition device 1209 (step S1907).

  The background recognition device 1209 determines whether the RGB pixel data of the pixel of interest 2 * 2 multiplied by the 2 * 2 enlargement device 1208 is white of the background, and if it is white, the pixel of interest 2 × 2 is converted to the RGB of the character pixel. The pixel of interest is interpolated and transferred to the RGB memory controller 1210. If it is not white, the pixel of interest multiplied by 2 * 2 is transferred to the RGB memory controller 1210 as it is (step S1908).

  The RGB memory controller 1210 receives 2 * 2 pixels obtained by multiplying the target pixel by 2 * 2, writes the lower 2 * 1 pixel to the RGB1 line memory 1211, and transfers the upper 2 * 1 pixel to the color conversion processing device 815. (Step S1909).

  The resolution conversion device 814 repeats the above processing until the enlargement processing of each pixel included in the RGB pixel data for one line stored in the RGB band image memory storage area on the main memory 114 is completed (step S1910: No).

  When the enlargement processing of each pixel included in the RGB pixel data for one line is completed (step S1910: Yes), the RGB memory controller 1210 sequentially reads 2 * 1 pixels from the RGB1 line memory 1211, and the color conversion processing device The data is transferred to 815 (step S1911).

  The RGB memory controller 1210 repeats the reading of 2 * 1 pixels from the RGB1 line memory 1211 and the transfer to the color conversion processing device 815 for one line (step S1912: No).

  Then, when the transfer to the color conversion processing device 815 for one line is completed (step S1912: Yes), the resolution conversion device 814 repeats the above processing until the enlargement processing of the RGB pixel data for one band is completed. (Step S1913: No). When the resolution conversion apparatus 814 completes the enlargement process of the RGB pixel data for one band (step S1913: Yes), it repeats the above process until the enlargement process of the RGB pixel data for one page is completed (step S1913). S1914: No). Then, when the enlargement process of the RGB pixel data for one page is finished (step S1914: Yes), the resolution conversion apparatus 814 finishes the enlargement process.

  FIG. 20 is a diagram illustrating an example of RGB pixel data before resolution conversion and RGB pixel data after resolution conversion. According to the resolution conversion apparatus 814 according to the present embodiment, as shown in FIG. 20, even when a character image included in an image before resolution conversion is expressed in halftones other than black and white, resolution conversion is performed. The stepped portion of the character image included in the processed image can be smoothed.

  As described above, according to the multicolor image forming apparatus according to the present embodiment, the RGB pixel data of the pixel adjacent to the target pixel and indicating that the character shape data is the character pixel is determined as the RGB pixel data of the character pixel. Then, a matching pattern representing the pixel arrangement indicating that the RGB pixel data is the RGB pixel data of the character pixel and the character shape data is the character pixel is generated, and the generated matching pattern matches the predetermined matching pattern. In this case, according to the arrangement of the character pixel when the enlargement process is performed on the target pixel included in the predetermined matching pattern, the target pixel that has been subjected to the enlargement process is interpolated with the RGB pixel data of the character pixel, thereby obtaining a character image. Even if the color of the included pixels is halftone, it is possible to interpolate the stepped portion of the outline of the character In, even in an image including a halftone dot, it is possible to keep the character images included in the image in high resolution shape.

  In this embodiment, an example in which image processing is performed on RGB pixel data has been described. However, the present invention is not limited to this as long as it is multi-valued image data, and image processing can be similarly performed. it can. For example, multi-value image data expressed in CMY, CMYK, L * a * b *, etc., multi-value image data expressed in one version, such as only CMY C version, RGB only R Image processing can be similarly performed on value image data and the like.

1 is a block diagram showing a configuration of a multicolor image forming apparatus according to an embodiment. It is a figure which shows the example of the hardware constitutions of the electrical equipment and control apparatus of a multicolor image forming apparatus. It is a flowchart which shows the outline of the process in a multicolor image forming apparatus. It is a figure explaining the storage area of a main memory. It is a figure which shows an example of RGB pixel data of 600 dpi. It is a figure which shows an example of the character shape data of 600 dpi. It is a flowchart which shows the operation | movement process of the whole image processing concerning this Embodiment. It is a figure explaining the hardware constitutions of an image processing apparatus. It is a figure which shows an example of a predetermined matching pattern. It is a figure which shows an example of arrangement | positioning data. It is a figure which shows an example of arrangement | positioning data at the time of performing an expansion process to a white pixel. It is a figure explaining the hardware constitutions of the resolution converter. It is a figure which shows an example of the RGB pixel data of an A * B matrix. It is a figure which shows an example of the character shape data of a N * M matrix. It is a figure which shows the other example of the RGB pixel data of an A * B matrix. It is a figure which shows the other example of the character shape data of a N * M matrix. It is a figure which shows an example of the produced | generated matching pattern. It is a figure which shows an example of the RGB pixel data of the A * B matrix after interpolation. It is a flowchart which shows the procedure of the resolution conversion process. It is a figure which shows an example of RGB pixel data before resolution conversion, and RGB pixel data after resolution conversion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 105 Drawing apparatus 110 Image processing apparatus 814 Resolution conversion apparatus 1201 Character shape M line memory 1202 Character shape N * M matrix extraction apparatus 1203 RGB B line memory 1204 RGB A * B matrix extraction apparatus 1205 Character color determination apparatus 1206 Pattern address generation apparatus 1208 2 * 2 enlargement device 1209 Ground recognition device

Claims (7)

Drawing means for generating color pixel data of each pixel in an image including a character image and character shape data indicating whether each pixel is a character pixel included in the character image;
Enlargement means for executing enlargement processing on the color pixel data of each pixel generated;
Based on the generated character shape data and the color pixel data, the color pixel data of a pixel adjacent to the target pixel on which the enlargement process has been performed and indicating that the character shape data is the character pixel Determining means for determining color pixel data, and generating a matching pattern representing an arrangement of pixels indicating that the color pixel data is color pixel data of the character pixel and the character shape data is the character pixel;
When the predetermined matching pattern representing the arrangement of the character pixels included in the character image matches the generated matching pattern, the arrangement of the character pixels when the pixel is enlarged to the predetermined matching pattern Generating means for generating arrangement data representing
Interpolating means for interpolating the pixel of interest subjected to the enlargement processing with the color pixel data of the character pixel according to the arrangement of the character pixel represented by the generated arrangement data;
An image processing apparatus comprising: Of the generated character shape data, first storage means for storing the character shape data for the first number of lines;
First cutout means for cutting out the character shape data in the first pixel range from the first storage means,
The determination unit generates the matching pattern in the first pixel range indicating an arrangement of pixels indicating that the color pixel data is color pixel data of the character pixel and the character shape data is the character pixel. The image processing apparatus according to claim 1.   The interpolating unit interpolates the target pixel on which the enlargement process has been performed with color pixel data of the character pixel when the target pixel on which the enlargement process has been performed is a background. The image processing apparatus according to 1.   The image processing apparatus according to claim 3, wherein the interpolation unit recognizes a pixel whose color pixel data indicates white as a background. Second storage means for storing the color pixel data for the second number of lines among the generated color pixel data;
A second cutout unit that cuts out the color pixel data in the second pixel range from the second storage unit;
The determination unit is configured to determine the color of a pixel adjacent to the target pixel and indicating that the character shape data is the character pixel based on the generated character shape data and the color pixel data of the second pixel range. The image processing apparatus according to claim 1, wherein pixel data is determined as color pixel data of the character pixel.   The image processing apparatus according to claim 5, wherein the second pixel range is narrower than the first pixel range. A drawing step in which drawing means generates color pixel data of each pixel in an image including a character image and character shape data indicating whether each pixel is a character pixel included in the character image;
An enlarging step in which an enlarging unit executes an enlarging process on the color pixel data of each pixel generated
Based on the character shape data and the color pixel data generated by the determination unit, the color pixel data of a pixel adjacent to the target pixel on which the enlargement process has been performed and indicating that the character shape data is the character pixel is obtained. Determination to determine color pixel data of the character pixel, and to generate a matching pattern indicating an arrangement of pixels indicating that the color pixel data is the color pixel data of the character pixel and the character shape data is the character pixel Process,
When the predetermined matching pattern representing the arrangement of the character pixels included in the character image matches the generated matching pattern, the generation unit performs the enlargement process on the pixel according to the predetermined matching pattern. A generation step of generating arrangement data representing the arrangement of character pixels;
An interpolation step in which the interpolation means interpolates the pixel of interest subjected to the enlargement process with the color pixel data of the character pixel according to the arrangement of the character pixel represented by the generated arrangement data;
An image processing method for an image processing apparatus, comprising:

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