JP2005268917A - Image forming support apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming support apparatus wherein image data for the CTP can be used by on-demand print and the sharpness of characters and line drawings in the case of gradation conversion can be maintained. <P>SOLUTION: A flowchart denoting one example of processing flows executed by a video interface includes: steps 102, 104 for applying edge discrimination to image data with high gradation and high resolution generated for the CTP by N×M blocks each; a step 108 of applying binary processing to edge parts so as to keep 0 and 255 as they are; a step 106 of applying de-screening to other parts than the edge parts by using a low pass filter; a step 110 of applying black letter discrimination to the edge parts; a step 112 of resetting CMY data as to black letter parts; and a step 116 of composing the respective images to convert the resolution and generating image data so as to convert the image data with high resolution and low gradation into image data with low resolution and high gradation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming support apparatus, and more particularly to an image forming support apparatus that outputs data to an image forming apparatus having a so-called printing function for forming an image on a recording medium, such as a color copying machine, a facsimile, or a printer.

  In conventional printing (for example, offset printing), intermediate products such as paper printing (printing paper) such as photosetting, block printing, net negative, net positive, PS plate (printing plate) are generated, and these intermediate products are used as the original. Printing and bookbinding. In recent years, “direct printing” or “on-demand printing” in which printing is performed directly from DTP data is known with the spread of DTP (DeskTop Publishing / Prepress). In DTP, printing data obtained by processing a page layout on a computer is formed on photographic paper or a plate-making film, and a printing plate is created and printed based on the printing data. In addition, CTP (Computer To Plate) that directly forms a printing plate with electronic data without generating an intermediate product is also attracting attention. As an apparatus that can be used for such a printing process, an image forming apparatus having a printing function such as a printer or a copying machine is known. Image forming apparatuses in recent years have been improved in color with improved image quality. For example, a color printer using an electrophotographic process (xerography) can form high-quality and high-speed images. In this image forming apparatus, print data can be output without receiving print data and generating a printing plate or the like.

  FIG. 10 is a configuration diagram of a conventional image forming system. As shown in FIG. 10A, the image forming system includes an image forming apparatus 11 and a DFE (Digital Front End Processor) apparatus that passes print data to the image forming apparatus 11 and gives a print instruction. ing. FIG. 10B shows a data flow.

  The DFE device has a drawing function and a printer controller (print control device) function. For example, the DFE device sequentially receives print data described in a page description language (PDL) from a client terminal, and the print data is rasterized. The image data is converted into an image (RIP process: Raster image process), and the RIP-processed image data and print control information (job ticket) such as the number of printed sheets and paper size are sent to the image forming apparatus 11, and the print engine of the image forming apparatus 11 And the paper conveyance system is controlled to cause the image forming apparatus 11 to execute the printing process. That is, the printing operation of the image forming apparatus 11 is controlled by a printer controller by the DFE apparatus. The print data includes four colors (YMCK) of three basic colors for color printing, ie, yellow (Y), cyan (C), and magenta (M), and black (K). Sent to.

  The image forming apparatus 11 records an image on printing paper using an electrophotographic process. The image output terminal (IOT) module 12 and a feed module (FM: Feeder Module) connected to the IOT module 12 are used. 5) A user interface device 18 for supporting the input of various data including an output module 17 and a touch panel. The IOT module 12 includes a toner supply unit 22 on which YMCK toner cartridges 24 are mounted, and an IOT core unit 20. The IOT core unit 20 has a so-called tandem configuration in which print engines (printing units) 30 having an optical scanning device, a photosensitive drum, and the like are arranged in a line for each color and in the belt rotation direction, and controls the print engine 30. An electric system control storage unit 39 for storing an electric circuit or the like is provided. In the IOT core unit 20, the toner image on the photosensitive drum is transferred (primary transfer) to the intermediate transfer belt 43, and then the toner image is transferred to the printing paper (secondary transfer). Multiple transfer is performed on the intermediate transfer belt 43. The image (toner image) transferred onto the intermediate transfer belt 43 is transferred onto the printing paper conveyed from the feed module 15 at a predetermined timing, and the toner image is melted and fixed onto the paper by a fixing device (Fuser) 70. Is done. Thereafter, the paper is discharged out of the apparatus via the paper discharge processing device 72. Further, during double-sided printing, a sheet of paper that has already been printed on one side is temporarily held on a paper discharge tray (stacker) 74, pulled out from the paper discharge tray 74, reversed through a reverse conveyance path 49, and again IOT core unit 20 Passed to.

  On the other hand, in CTP, the RIP processing as described above is performed by the DFE device. At this time, since CTP generally uses a large-sized plate of about 1 m as a printing plate, imposition is performed to generate image data imposing a plurality of images. Then, a printing plate is formed from the generated image data, printing is performed, and post-processing such as cutting is performed.

  By the way, when the image data created for CTP is to be printed by the image forming system as described above, the image data created for CTP has high resolution and low gradation (for example, 2400 dpi, 1 bit). Since the above-described image forming system has low resolution and high gradation (for example, 600 dpi, 8 bits), it is necessary to perform resolution and gradation conversion (hereinafter referred to as descreening processing).

  As the descreening process, a method has been proposed in which 1-bit is descreened, converted into multiple values, and output to an inkjet printer or the like.

For example, in the technique described in Patent Document 1, it is proposed to perform multi-value processing by filtering a binary image (soft filtering). When performing the filtering process, filtering is performed so as to leave a halftone dot structure. That is, in the technique described in Patent Document 1, the parameters of the soft focus filter are finely defined so that the halftone image structure is multivalued while remaining in the multivalued image. Accordingly, if a multi-valued image having a halftone dot image structure remaining is output to an image forming apparatus such as an ink jet printer that performs error diffusion processing, a certain halftone dot structure can be restored.
International Publication No. 02/30103 Pamphlet

  However, when 1-bit is simply subjected to descreening processing by filtering and multi-valued, there is a problem that small point characters are crushed or line drawings are blurred. Furthermore, when a black character or the like has a background color, there is a problem that each color spreads to adjacent pixels and the sharpness of the black character is reduced.

  On the other hand, the technique described in Patent Document 1 has a problem that unless the filter coefficient is changed for each number of lines of halftone dots, it is not possible to deal with character crushing or blurring of line drawings.

  The present invention has been made in consideration of the above facts, and can use image data for CTP in on-demand printing and can maintain sharpness of black characters or the like during gradation conversion. An object is to provide a formation support apparatus.

  In order to achieve the above object, the image formation support apparatus according to the present invention determines the black character portion after converting the gradation of the image data from the low gradation to the high gradation, and determines the image data corresponding to the black character portion. When the image data for CTP is converted to a tone that can be printed by on-demand printing by providing a function that performs image processing so that the ink color becomes black, black characters are also printed in the image data after the tone conversion. Since it can be expressed in one color, CTP image data can be used for on-demand printing, and sharpness of black characters and the like can be maintained during gradation conversion.

  As described above, according to the present invention, CTP image data can be used for on-demand printing, and the sharpness of black characters and the like can be maintained during gradation conversion.

  First, prior to describing embodiments of the present invention, aspects of the present invention will be described. Also, aspects including embodiments of various technical matters will be described together.

  An aspect of the present invention is an image forming support apparatus that processes and transfers image data of each page generated by processing a print job in accordance with an image forming apparatus on an output side, An image storage unit that receives and holds image data, a conversion unit that converts the gradation of the image data stored in the image storage unit from a low gradation to a high gradation, and a high gradation obtained by the conversion of the conversion unit Among the image data, a determination unit that determines a black character portion, and an image processing unit that performs image processing on the image data corresponding to the black character portion so as to be black ink based on the determination result of the determination unit. It is characterized by that.

  According to the aspect of the present invention, the image data created for the printing plate is held in the image storage unit. The image data held in the image storage unit is converted from low gradation to high gradation image data by the conversion means. That is, the image data created for CTP is low gradation image data, but can be converted into high gradation image data used in on-demand printing or the like by the conversion means.

  Further, the determination means determines a black character portion in the high gradation image data obtained by the conversion of the conversion means. Then, in the image processing means, image processing is performed on the image data corresponding to the black character portion so that the ink color is black based on the determination result of the determination means. That is, when the black character portion is determined by the determining means, the image processing means performs image processing on the image data so that the black character portion is black. For example, image processing is performed so that color data other than black is eliminated. As a result, the black character is black, so that the sharpness of the black character after gradation conversion can be maintained.

  Therefore, CTP image data can be used in on-demand printing, and sharpness of black characters or the like can be maintained during gradation conversion.

  For example, the image processing unit may include a reset unit that resets color data other than black in the image data corresponding to the black character portion based on the determination result of the determination unit. In other words, since the color data other than black in the black character portion can be eliminated by the reset means, the sharpness of the black character after gradation conversion can be maintained.

  The image processing means includes a process black determination means for determining whether the image data determined to be a black character by the determination means is black (so-called process black) expressed by color data other than black, and a process black determination means. A prohibition unit that prohibits reset by the reset unit for the portion determined to be process black may be further included. As a result, it is possible to reproduce the process black for the image data after the gradation conversion for those intentionally using the process black.

  The image data stored in the image storage unit further includes a line drawing determination unit that determines a character / line drawing portion, and the conversion unit performs image data from a low gradation to a high gradation based on the determination result of the line drawing determination unit. You may make it perform the conversion process converted into. As a result, different gradation conversions can be performed between the character and line drawing portion and the other portions, and gradation conversion according to each attribute can be performed. Therefore, it is possible to prevent deterioration of the character / line drawing part due to gradation conversion.

  Further, the conversion means may be constituted by a low-pass filter. That is, gradation conversion processing can be performed by using a low-pass filter used for descreening.

  The conversion means includes a first gradation conversion means for performing gradation conversion processing for converting the gradation of the image data from a low gradation to a high gradation when the determination result of the determination means is not a character / line drawing part. When the determination result of the determination unit is a character / line drawing part, the second gradation conversion unit may perform a gradation conversion process different from the first gradation conversion unit. For example, when converting from 1-bit to 8-bit gradation, descreening using a low-pass filter is performed as the first conversion means, and binarized gradation conversion of 0, 255 is used as the second conversion means. You may make it apply the binarization means which performs. That is, by performing gradation conversion by binarization for the character / line drawing part, it is possible to prevent deterioration of the character or line drawing due to gradation conversion.

  Further, the first gradation converting means and the second gradation converting means are constituted by low-pass filters, and the respective filter coefficients of the second gradation converting means are compared with those of the first gradation converting means. You may make it set so that it may become a weak low bass filter. In other words, the character / line drawing portion may be descreened with a weak low-pass filter, and in this way, the low-pass filter weaker than the low-pass filter used other than the character / line drawing portion is used for the character / line drawing portion. As a result, it is possible to prevent the deterioration of the character / line drawing part and to prevent the character / line drawing part from being jagged.

Embodiment
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

[Image forming system]
FIG. 1 is a diagram showing an overall schematic configuration of an image forming system according to the present embodiment. The image forming system includes a high-speed LAN (Local Area Network) using a general-purpose communication protocol, and a client terminal for inputting, for example, electronic data (print data) described in a page description language (PDL) to the high-speed LAN. 400 and 402 are connected. The client terminals 400 and 402 are computers capable of executing various application programs under different operating systems (OS). A scanner device 410 that reads an image of a document and outputs the image data is also connected to the high-speed LAN. The high-speed LAN includes DFE devices 500, 503, 504, 506, and 508, BEP (Back End Processor) devices 600, 603, and 604 as image forming support devices according to the present invention, the details of which will be described later. A CTP device 702 that directly creates a printing plate with data is connected.

  Printing is performed in the press device 710 using the printing plate created by the CTP device 702. Further, a BEP device 600 is connected to the CTP device 702 in parallel (to a high-speed LAN). A high-speed printer 746 similar to the image forming apparatus 11 is connected to the BEP device 600.

  An output device 730, high-speed printers 740 and 742 having the same configuration, and a CTP device 700 are connected to the output side of the BEP device 604 connected to the high-speed LAN. The output device 730 and the high-speed printers 740 and 742 perform print output, and the CTP device 700 creates a printing plate. The DFE device 503 is connected to printer proofers 720 and 722 having the same configuration via the BEP device 603. The printer proofers 720 and 722 are for confirming output for printing and may function as an example of an image forming apparatus.

  The DFE device 504 is connected to a high-speed printer 744, and the DFE device 504 and the high-speed printer 744 are responsible for a department in charge of on-demand printing processing. The DFE device 506 is connected to the output device 732, and the DFE device 508 is connected to the large output device 750. The configuration including the DFE device 506 and the output device 732 and the configuration including the DFE device 508 and the large output device 750 are the same as the configuration of the conventional image forming apparatus.

  The image forming system according to the present embodiment has a configuration in which CTP and an apparatus having a POD (print on demand) function can be mixed in the same system. This is because the BEP device according to the present embodiment has a function for variously processing the data after the print data from the client is converted into raster data (RIP processing).

[Configuration example]
In the image forming system having the above configuration, in order to simplify the description of the embodiment of the present invention, a representative example of a configuration in which a printing plate is created and printed and a configuration in which printing is performed without creating a printing plate are described as an embodiment. Will be described. That is, the configuration A in the case of forming an image using the client terminal 400, the DFE device 500, the CTP device 700, and the press device 710, the client terminal 400, the DFE device 500, the BEP device 600, and the high-speed printer 746 ( The configuration B in the case of forming an image using the apparatus of the image forming apparatus 11) will be described.

  The DFE apparatus 500 has a function of converting data from the client terminal 400 into raster data (RIP processing) and compressing the converted raster image. In this embodiment, the DFE apparatus 500 includes the image forming apparatus 11. Does not require a printer controller function to perform a dependent print control function. That is, the DFE device 500 may have a configuration mainly having only a function of RIP processing.

  FIG. 2 is a diagram showing an embodiment of an image forming system according to the present invention. In other words, the configuration A in which an image instructed to be printed by the client terminal 400 is RIPed by the DFE device 500 and a printing plate is created by the CTP device 702 and then printed by the press device 710, and the RIP image is sent via the BEP device 600. The configuration B for printing by the high-speed printer 746 (image forming apparatus 11) will be described as an embodiment of the image forming system according to the present invention. FIG. 2A shows an outline of a system configuration including the configuration A and the configuration B in the present embodiment, and FIG.

[Configuration A]
In the configuration A, printing is performed using a CTP device 702 that creates a printing plate, a DFE device 500 that outputs print data to the CTP device 702 and instructs printing plate creation, and a printing plate created by the CTP device 702. The press apparatus 710 constitutes a system.

  Since the configuration A is the same as the conventional print processing, detailed description thereof is omitted. However, the DFE apparatus 500 is configured by a front end processor (FEP) unit or ROP (Raster Operation) processing by a front engine. A function of converting data from the client terminal 400 into raster data (RIP processing) and compressing the converted raster image is provided. The DFE apparatus 500 mainly executes only the RIP process in order to create a printing plate. A plate is created by the CTP device 702 from the raster data of the RIP-processed raster image (compressed). An image is pressed on a printing medium by a press device 710 using the printing plate created by the CTP device 702, and printing is performed.

  In the configuration A, the case where the CTP device 702 is connected to the high-speed LAN and the printing plate is created from the print data from the DFE device 500 has been described. However, the CTP device 702 is connected via the BEP device 600. Alternatively, the BEP device 604 and the CTP device 700 in FIG. 1 may be configured. In this case, as described in the configuration B below, the BEP apparatus 600 performs processing depending on the downstream apparatus such as the image forming apparatus 11 and outputs the data based on the print data from the DFE apparatus 500. When the CTP device 700 is adopted as the downstream device, the BEP device 600 performs processing depending on the CTP device 700 and outputs data.

[Configuration B]
Next, the configuration B includes an image forming apparatus 11, a DFE apparatus 500 that passes print data to the image forming apparatus 11 and gives a print instruction, and a BEP apparatus 600 provided between the image forming apparatus 11 and the DFE apparatus 500. Configure the system.

  The image forming apparatus 11 includes an IOT module (IOT main body) 12, a feed module (FM: Feeder Module) 15, an output module 17, and a user interface device 18 such as a personal computer (PC). The feed module 15 may have a multistage configuration. Moreover, you may provide the connection module which connects between each module as needed. In addition, a finisher module may be connected to the subsequent stage of the output module 17. As the finisher module, for example, there are a stacker for stacking sheets and a stapler for binding one or more places, or a punching mechanism for punching holes.

  The DFE device 500 has a function of converting data from the client terminal 400 into raster data (RIP processing) and compressing the converted raster image, and mainly performs RIP processing. This data is processed by the BEP device 600 and output to the image forming apparatus 11.

  The BEP device 600 has a process control function depending on the image forming apparatus 11, but this control function may be instructed by the user interface device 18 or may be determined in advance. When instructing by the user interface device 18, the user interface device 18 has an input device such as a keyboard or a GUI (Graphic User Interface) function that accepts an instruction input while presenting an image to the user, and depends on the image forming device 11. What is necessary is just to comprise so that a process may be instruct | indicated.

  The BEP device 600 enables efficient high-speed output by using the RIP processed data stored in the DFE device. That is, the BEP device 600 generates a command code based on the print control information received from the DFE device 500, and controls the processing timing of each unit in the image forming apparatus 11 according to the engine characteristics. In addition, the BEP device 600 completes the spool processing so as to match the engine characteristics of the IOT module 12, the feed module 15, the output module 17, etc., and then passes the image data to the IOT module 12.

  For example, data including a raster base image subjected to RIP processing is sent from the DFE device 500 to the BEP device 600. As this data, in addition to compressed raster-based image file data such as the TIFF (Tagged Image File Format) format, the number of copies, double-sided / single-sided, color / monochrome, composite printing, sort presence, presence / absence of stapler, etc. are printed. Control information and the like are included. The print control information other than the TIFF format raster-based image file data is described in, for example, JDF (Job Definition Format) based on a notation such as XML, and is sent from the DFE device 500 to the BEP device 600 as a job ticket. It is done. The JDF is sent to each process (for example, plate making process, printing process, folding / cutting process, etc.) and used in each process, and the contents described in the JDF describe the contents necessary for the job in each process. Is done. For example, print specifications (configuration, paper quality, size, number of copies, etc.), equipment used in plate making process, plate making process delivery date, printing machine used in printing process, ink used, folding / cutting equipment, delivery date, delivery destination and delivery date, plate making The contents of process imposition specifications, RIP processing procedure for plate making process, output machine setting for plate making process, printer setting for printing process, folding machine setting for folding / cutting, cutting machine procedure, binding procedure, etc. are described.

  Rotation, page allocation (N-UP) within one sheet, repeat processing, paper size adjustment, CMS (Color Management System: color management system) for correcting device differences, resolution conversion, contrast adjustment Processing related to RIP processing such as compression ratio designation (low / medium / high) is processed by the DFE device 500, and the control command is not notified to the BEP device 600 (non-notification).

  In addition, collation (booking), double-sided printing, stamping / punching / stapler finisher devices or paper tray alignment processing, discharge surface (up / down) alignment, calibration processing such as gray balance and color shift correction As for screen designation processing and the like (IOT-dependent processing) that is strongly related to the processing characteristics of the image forming apparatus 11, the BEP device 600 processes the control command through the DFE device 500.

  As described above, the DFE device side of this embodiment transfers one job (JOB) unilaterally to the BEP device side in the order of RIP processing without depending on the engine characteristics, and rearranges pages for printing on the BEP device side. To do.

  FIG. 3 is a conceptual block diagram that focuses on the flow of data when the BEP device 600 is interposed between the DFE device 500 and the image forming device 11.

  The DFE device 500 receives print data (hereinafter referred to as PDL data) described in PDL from the client terminal 400, and temporarily stores the PDL data once, and reads and interprets the PDL data from the data storage unit 502. And RIP processing unit 510 that generates (rasterizes) image data (raster data) in units of pages, and a compression processing unit 530 that compresses the image data generated by RIP processing unit 510 according to a predetermined format. An interface unit 542 is provided following the compression processing unit 530. The RIP processing unit 510 develops PDL data to generate image data. Therefore, the RIP processing unit 510 incorporates a PDL interpretation unit and a decomposer functioning as an imager, a so-called RIP engine. The compression processing unit 530 compresses the image data from the RIP 510 and immediately transfers the compressed image data to the BEP device 600.

  On the other hand, the BEP device 600 receives and holds compressed image data processed by the DFE device 500 regardless of the print job and the processing characteristics of the print engine 30 (for example, processed asynchronously with the processing speed of the print engine 30). The compressed image data is read from the image storage unit 602 and the compressed image data from the image storage unit 602, and the compressed image data on the DFE device 500 side is read out, corresponding to the compression processing of the compression processing unit 530 on the DFE device 500 side. A decompression processing unit 610 is provided that performs decompression processing and sends the decompressed image data to the IOT core unit 20 side. The decompression processing unit 610 has image processing functions such as image rotation, image position adjustment, enlargement or reduction, or electronic cutting on image data read from the image storage unit 602 and decompressed. . A data receiving unit 601 is provided in the previous stage of the image storage unit 602, and an output side interface unit 650 is provided in the subsequent stage of the decompression processing unit 610.

  The BEP device 600 also includes a print control unit 620 that functions as a printer controller that controls each unit of the BEP device 600 and the IOT core unit 20 depending on the processing performance of the IOT core unit 20. The print control unit 620 interprets (decodes) the job ticket from the DFE device 500 or receives a user instruction via the GUI unit 80, and outputs an output form (in accordance with the processing characteristics of the print engine 30, the fixing device 70, or the finisher). An output form specifying unit 622 for specifying the image position in the page or the page discharge order and orientation), and each part such as the print engine 30, the fixing device 70 or the finisher so that the printed matter is output in the specified output form. And a control unit 624 for controlling. The output form specifying unit 622 has a function as an output form information acquiring unit that receives information about an output form desired by the client, and acquires information described in the job ticket and print control information included in the image file data in the TIFF format. By doing so, information on the output form is received.

  Therefore, in the DFE device 500, the image data rasterized (drawn and developed) from the page description language by the RIP processing unit 510 is transferred to the BEP device 600 side in the order of pages. The BEP device 600 temporarily stores the image data transferred from the DFE device 500 in the image storage unit 602 that functions as a buffer. The decompression processing unit 610 reads the compressed image data from the image storage unit 602 and decompresses it, and also assembles page data according to a print job designated from the client terminal or the DFE device 500 (relocation of page data or electronic data). Cutting, etc.) and preparing for transfer to the designated print engine. The BEP device 600 sends page data to the IOT core unit 20 in a predetermined order at a speed that maximizes engine productivity while exchanging control commands in synchronization with the processing speed of the print engine 30.

  In this way, the DFE device 500 side only needs to unilaterally transfer one job (JOB) to the BEP device 600 side in the order of RIP processing without depending on the engine characteristics. The BEP device 600 is in charge of processing depending on the print job and the print engine 30 such as rearranging pages for printing.

  In this configuration, processing related to the RIP processing is performed by the DFE device. However, when the RIP processing needs to be performed again, the image is not requested to the DFE device 500 for re-RIP processing (independent of the DFE device 500). The data stored in the storage unit 602 is reused. Thereby, the re-RIP process in the DFE apparatus 500 becomes unnecessary. In addition, the BEP device 600 having a performance adapted to the processing characteristics on the output side such as the print engine can be processed depending on the processing characteristics on the output side in the BEP device 600 connected to the print engine 30 or the like.

  For example, when outputting in the output format desired by the client, an example of requiring processing that depends on processing characteristics on the output side, and reprocessing related to RIP processing is a page within one sheet. There are layout (N-UP), repeat processing, paper size adjustment, CMS (Color Management System) for correcting device differences, resolution conversion, contrast adjustment, compression rate designation (low / medium / high), and the like.

  In addition, as an example of the case where processing dependent on processing characteristics of the image forming apparatus 11 (for example, a print engine) on the output side (dependent processing strongly related to the processing characteristics on the output side) is required, image rotation (Rotation) is required. , Collation, double-sided printing, stamper / punch / stapler finisher devices or paper tray alignment processing (shift: image shift), discharge surface (up / down) alignment, gray balance and color There are calibration processing such as misalignment correction and screen designation processing.

  Incidentally, the image data created for the CTP device 702 is high-resolution and low-gradation image data (for example, 1 bit of 2400 dpi), whereas image data that can be processed by the image forming apparatus 11 is low-resolution and low-resolution. In some cases, the image data is gradation image data (for example, 8 bits of 600 dpi). Therefore, the BEP device 600 according to the present embodiment has a gradation conversion function for converting image data created for CTP into image data that can be processed by the image forming apparatus 11. Here, a detailed configuration of the BEP device 600 based on the gradation conversion function will be described. FIG. 4 is a block diagram showing a detailed configuration of the BEP device 600.

  In the present embodiment, the BEP device 600 is configured by a computer including two CPUs 40A and 40B called so-called dual CPUs. The two CPUs 40 </ b> A and 40 </ b> B are connected to a host bridge 42. A PCI (Peripheral Components Interconnect) bus 44 and a memory 46 are connected to the host bridge 42, and data control between the CPUs 40 </ b> A, 40 </ b> B and the PCI 44 is performed by the host bridge 42.

  Similarly to the host bridge, a south bridge 48 that controls information distribution is connected to the host bridge 42. The south bridge 48 is connected to a USB (Universal Serial) as a data transmission path for connecting peripheral devices. (Bus) 50, a BIOS (Basic Input / Output System) 52 consisting of a program group for controlling peripheral devices, and an ATA IDE Port 54 for connecting a program hard disk are connected.

  The host bridge 42 is connected to a PCI hub (PCI 64 Hub) 56 as an integrated device that integrates the PCI bus 44. That is, a plurality of PCI buses 44 are connected to the PCI hub 56, and a plurality of devices can be connected to the PCI bus 44.

  Two hard disks 60A and 60B for storing image data are connected to the PCI bus 44 via a SCSI (Small Computer System Interface) 58 for connecting peripheral devices. The two hard disks are alternately connected. By using it, it is possible to read and write image data at an apparently double speed. In other words, the RAID (Redundant Arrays of Inexpensive Disks) manages a plurality of hard disks collectively.

  Further, a scanner 410 is connected to the PCI bus 44 via a scan interface board (Scan I / F Board) 62, and a DFE device is connected via an Ethernet (R) 64. (RIP) 500 is connected. That is, the Ethernet (R) 64 corresponds to the above-described interface unit 542 (see FIG. 3).

  Furthermore, video interfaces (Video I / F) 10A, 10B, and 14 corresponding to the above-described interface unit 650 (see FIG. 3) are connected to the PCI bus 44. The video interface (Video I / F (M, K)) 10A is an interface for transmitting image data for magenta (M) and black (K), and is a video interface (Video I / F (Y, C)). Reference numeral 10B denotes an image data interface for yellow (Y) and cyan (C). A video interface (Video I / F (S)) 14 is an auxiliary interface provided for image data for spot colors (for example, for additional colors other than Y, M, C, and K).

  FIG. 5 is a block diagram showing a detailed configuration of the video interfaces 10A and 10B. In FIG. 5, the video interfaces 10 </ b> A and 10 </ b> B have the same configuration and will be described as the video interface 10.

  The video interface 10 is connected via a PCI bridge 25 for relaying data.

  The video interface 10 includes a memory controller 27, an SDRAM 26, a 1-bit expander 28, a 0, 255 conversion circuit 31, an N × M block (N × M Block) circuit 29, an edge determination circuit 32, a low-pass filter (Low pass filter). 34, a binarization circuit 36, a black character determination circuit 35, a CMY reset circuit 41, a TRC circuit 37, and a format conversion circuit 38, and is connected to the IOT module 12 through an IOT interface (IOT interface) 16.

  The PCI bridge 25 is connected to a memory controller 27 to which an SDRAM 26 is connected, and reading / writing of image data to / from the SDRAM 26 is controlled by the control of the memory controller 27.

  The image data read from the SDRAM 26 is output to a 1-bit decompressor 28 connected to the memory controller 27, and compressed data such as Jpeg is decompressed by the 1-bit decompressor 28. The 1-bit decompressor 28 is input with image data having a 1-bit gradation at a resolution of 2400 dpi.

  The image data expanded by the 1-bit expander 28 is converted into 0-255 multi-value by the 0-255 conversion circuit 31. At this time, the conversion is performed by replacing 1-bit off with 0 and on with 255. Then, it is input to the N × M blocking circuit 29, for example, a 5 × 5 block is extracted, the edge is determined by the edge determination circuit 32, and the descreening process by the low-pass filter 34 according to the determination result (this embodiment) In the embodiment, 1 bit is converted into 8 bits) or binarization processing (processing for prohibiting descreening processing) by the binarization circuit 36 is performed. That is, a descreening process using a low-pass filter is performed for portions other than the edge portion, and a binarization process by the binarization circuit 36 is performed for the edge portion.

  Here, the tone characteristics of the YMCK data of the image data subjected to the descreening process by the low-pass filter 34 are corrected by the TRC circuit 37 for each color, each recording medium, and each environmental condition.

  The image data binarized by the binarization circuit 36 is determined by the black character determination circuit 35 as black characters, and the CMY reset circuit 41 determines the portion of the color determined as a black character by the CMY reset circuit 41. Data is reset (C = M = Y = 0).

  The edge determination circuit 32 corresponds to the line drawing determination means of the present invention, and the 0, 255 conversion circuit 31, the low-pass filter 34, and the binarization circuit 36 correspond to the conversion means of the present invention. The 0, 255 conversion circuit 31 and the low-pass filter 34 correspond to the first gradation conversion means of the present invention, and the 0, 255 conversion circuit 31 and the binarization circuit 36 correspond to the second gradation conversion means of the present invention. It corresponds to. The black character determination circuit 35 corresponds to the determination unit of the present invention, and the CMY reset circuit 41 corresponds to the image processing unit and the reset unit of the present invention.

  Then, the image data processed by the TRC circuit 37, the binarization circuit 36, or the image data in which the CMY data is reset by the CMY circuit 41 is output to the format conversion circuit 38, and the format conversion according to the IOT module 12 is performed. (For example, processing for combining descreened image data, binarized image data, and CMY-reset image data, processing for converting resolution from 2400 dpi to 600 dpi, etc.) The data is output to the IOT module 12 via the IOT interface 16.

  That is, in the video interface 10, image data for each N × M block is sequentially descreened by the low-pass filter 34 to convert 2400 dpi 1-bit data into 600 dpi 8-bit data. At this time, for the edge portion, the descreening process is prohibited in accordance with the determination result of the edge determination circuit, and processing is performed to hold a binary value (0 or 255). Such processing is performed while shifting one pixel at a time for each N × M block, and the image data that has been subjected to the descreening process and the image data that has been subjected to the binarization process are combined to provide a high-resolution, low-gradation image. The data is converted into low resolution and high gradation image data that can be processed by the IOT module 12.

  Further, in the binarized image data, the black character is determined, and the color color data is reset for the black character portion, so that the color color can be prevented from spreading to the black character, and the sharpness of the black character can be prevented. Can keep you.

  Next, an example of the flow of processing performed in the video interface 10 of the BEP device 600 configured as described above will be described. FIG. 6 is a flowchart showing an example of the flow of processing performed in the video interface 10.

  First, in step 100, 1-bit TIFF format image data is read. That is, the image data stored in the SDRAM 26 is read by the memory controller 27, decompressed by the 1-bit decompressor 28, and the process proceeds to step 101. The 0 and 255 conversion circuit 31 sets 1-bit ON to 255 and OFF to 0. Is converted to multi-value.

  Subsequently, in step 102, the read 1-bit TIFF format image data is read for each N × M block by the N × M blocking circuit 29, the process proceeds to step 104, and the edge determination circuit 32 determines whether the edge is detected. It is determined whether or not. The determination may be made based on the average density of the N × M block and a predetermined threshold value (for example, if the average density is equal to or higher than the threshold value, it may be determined as an edge), or 1 bit (0 of CMYK) In the image of the data converted by the 255 conversion circuit), it may be determined as an edge when consecutive images of the number of runs (for example, 0 or 255) in N × M pixels continue. That is, the edge determination circuit 32 determines whether the character or line drawing is determined by determining the edge.

  Here, if the determination in step 104 is negative, that is, if the image is a picture other than a character or line drawing, the process proceeds to step 106, the descreening process by the low-pass filter 34 is performed, and the process proceeds to step 114. . As a result, the image data is converted from a low gradation of 1 bit to a high gradation of 8 bits. At this time, the tone characteristics of the image data subjected to the descreening process by the low-pass filter 34 are corrected by the TRC circuit 37 for each color, each recording medium, and each environmental condition.

  On the other hand, if the determination in step 104 is affirmative, that is, if it is a character or line drawing, the routine proceeds to step 108.

  In step 108, the descreening process by the low-pass filter 34 is prohibited. In this portion, the binarization circuit 36 holds the data as 0 or 255, and the process proceeds to step 110. That is, it is possible to prevent characters and line drawings from being blurred by the descreening process by the low-pass filter 34. In this embodiment, the binarization process is performed by prohibiting the descreening process by the low-pass filter 34 in step 108. However, after the binarization process is performed, it is used in the descreening process of step 106. You may be made to perform the descreening process using the low-pass filter in which the filter coefficient used as a low-pass filter weaker than a low-pass filter was set. That is, a smooth character or line drawing can be obtained by performing a descreening process to such an extent that the unevenness of the character or line drawing is suppressed. The low-pass filter whose coefficient is set so as to be weaker than the low-pass filter 34 at this time corresponds to the second gradation converting means of the present invention.

  In step 110, the black character determination circuit 35 determines whether the character is a black character. The determination is made by referring to the C, M, and Y data to determine whether any of the colors is on (255). If the determination is negative, the step is continued. If the result is affirmative, the process proceeds to step 112.

  In addition, the black character determination by the black character determination circuit 35 is determined such that, after performing edge determination as in the edge determination in step 104, the edge and the image data is only black (K) is determined as a black character. Alternatively, the image data of each color of YMCK may be converted into Lab color space data to determine whether the converted Lab space image data is within a predetermined window comparator. For example, if the image data subjected to Lab conversion enters a window comparator in which a * and b * are each ± 20 or less and L * is 10 or less, it is determined as a black character.

  In step 112, the CMY reset circuit 41 converts C = M = Y = 0 (reset CMY), and the process proceeds to step 114. That is, since the color data of the black character portion is reset, the low gradation image data can be converted into the high gradation image data while maintaining the sharpness of the black character.

  Next, in step 114, it is determined whether or not the above-described processing has been completed for all image data. If the determination is negative, the process proceeds to step 118, the target pixel is moved by one pixel, and the above-described processing is performed. Returning to step 102, the above-described processing is repeated until the determination in step 114 is affirmed. When the determination in step 114 is affirmed, the process proceeds to step 116.

  In step 116, the image data descreened by the low-pass filter 34, the image data held by the binarization process, and the CMY-reset image data are synthesized by the format conversion circuit 38, and a series of processes is performed. finish. When the image data is synthesized, the format conversion circuit 38 converts the image data to the resolution corresponding to the IOT module 12 at the same time. In the present embodiment, conversion from 2400 dpi to 600 dpi is performed. As a result, the image data created for CTP can be used in the image forming apparatus 11, and CTP and on-demand printing can be shared.

  In this embodiment, when the processing of steps 102 to 112 is completed for all pixels, the image data descreened by the low-pass filter 34, the image data held by the binarization process, and the CMY reset are performed. The image data and the image data are combined. However, the processing in steps 102 to 112 may be performed on each pixel to sequentially combine the image data.

  In the present embodiment, when the resolution gradation conversion is performed, in detail, a tag (tag) representing the result of the edge determination in step 104 is generated, and descreening and binarization processing by the low-pass filter 34 are performed according to the tag. It comes to use properly. For example, 0 and 1 tags are used to indicate that 0 is not an edge and 1 is an edge. When the tag is 0, a descreening process by the low-pass filter 34 is performed. In the case of 1, binarization processing by the binarization circuit 36 is performed.

  That is, if all images obtained from the 1-bit TIFF format are descreened by the low-pass filter 34, they can be converted into multi-valued images and output to the image forming apparatus 11 as shown in FIG. Or it will fade. Therefore, in the video interface 10 of the BEP device according to the present embodiment, as described above, all of the 1-bit information is not subjected to the descreening process by the low-pass filter, and the characters and line drawings are held with the information of 0, 255, Only halftones are descreened by a low-pass filter. Thereby, it is possible to prevent deterioration of characters and line drawings due to resolution gradation conversion. 7 shows an example of an image represented by 1 bit on the left side, and an example of an image in the case where the center is subjected to gradation conversion from 1 bit on the left side to 8 bits.

  Further, similarly to the edge determination described above, a tag (tag) representing the result of black character determination in step 110 is generated, and CMY reset is performed according to the tag. For example, as a tag representing the result of black character determination, 0 and 1 tags are used, 0 is not a black character, 1 is a black character, and if the tag is 0, it is binarized. If the tag is 1, the CMY data is reset.

  That is, if the CMY color color is left as it is for the character / line drawing detected by edge determination, the color color may spread to black characters (including black line drawing) (mixed with other colors in black). However, this can be prevented by resetting the CMY data for the black character portion, and the sharpness of the black character can be maintained.

  Then, the modification of said embodiment is demonstrated.

  In the above embodiment, when the black character is determined by the black character determination circuit 35, the CMY data is reset. However, in the modified example, even when the black character is determined, the process black (when the CMY data is equal) In the above, CMY reset is prohibited.

  The configuration of the BEP device 600 is basically the same, and the black character determination circuit 35 of the video interface 10 determines whether it is process black in addition to the black character determination, and is determined to be process black. In this case, the CMY reset is only prohibited. That is, the black character determination circuit corresponds to the determination unit and the prohibition unit of the present invention. Note that whether or not the process black is determined is determined by determining whether or not C = M = Y.

  FIG. 8 is a flowchart showing a flow of processing performed by the video interface according to the modification. In addition, in the modified example, only the step 111 is added between the step 110 and the step 112 with respect to the process performed in the above embodiment (the flowchart in FIG. 6), and the other processes are the same. 111 migration will be described, and description of other processing will be omitted.

  That is, when the edge determination circuit 32 determines that an edge is detected and binarization processing is performed (when processing of step 208 is performed), the processing proceeds to step 111.

  In step 111, it is determined whether or not the process black. If the determination is affirmative, the CMY reset circuit 41 does not perform the CMY reset, and the process proceeds to step 114 as it is. If the determination in step 111 is negative, the process proceeds to step 112 and the CMY reset circuit. CMY reset by 41 is performed.

  That is, when the black character is determined to be process black, CMY data may be intentionally used, so CMY reset is prohibited. Thereby, intentional process black can be reproduced. For example, an image such as an ink painting may use process black. However, as described above, since process black is subjected to tone conversion without performing CMY reset, the intentional process black is converted to tone after the tone conversion. Can be reproduced with images.

  In step 114, as in the above embodiment, it is determined whether or not the above-described processing has been completed for all image data. If the determination is negative, the process proceeds to step 118, and the target pixel is determined. After moving one pixel, the process returns to step 102 described above, and the above-described processing is repeated until the determination at step 114 is affirmed. When the determination at step 114 is affirmed, the process proceeds to step 116.

  In step 116, the image data descreened by the low-pass filter 34, the image data held by the binarization process, the image data reset by CMY, and the binarized process black image data are obtained. After being synthesized by the format conversion circuit 38, a series of processing ends. When the image data is synthesized, the format conversion circuit 38 converts the image data to the resolution corresponding to the IOT module 12 at the same time. In the present embodiment, conversion from 2400 dpi to 600 dpi is performed. As a result, the image data created for CTP can be used in the image forming apparatus 11, and CTP and on-demand printing can be shared.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various changes or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such changes or improvements are added are also included in the technical scope of the present invention.

  Further, the above embodiments do not limit the invention according to the claims (claims), and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. Absent. The embodiments described above include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  In the compression / decompression process, image objects (line drawing character object LW (Line Work)) represented mainly by binary such as line drawings and characters, and background portions, photograph portions, etc. are mainly represented by multi-gradations. The processing can be adapted according to characteristics of an image object such as an image object (multi-tone image object CT (Continuous Tone)).

  In this embodiment, the N × M block circuit 29 converts the image data into N × M blocks, performs edge determination, and performs descreening processing according to the determination result. Manual instruction using 600 user interface device 18 (instruction by coordinates of a portion for which descreening processing is prohibited, instruction of descreening processing prohibited area using GUI, instruction by describing descreening prohibited area in JDF, etc. ). For example, as shown in FIG. 9, when the photograph area S and the character area M are known, the character area M is designated by coordinates or the like in advance or by using a GUI or the like, thereby descreening. You may make it set to a prohibition area | region (binarization process area | region).

1 is a schematic diagram illustrating an overall configuration of an image forming system according to an embodiment of the present invention. 1 is a diagram illustrating an embodiment of an image forming system. It is a block diagram which shows one Embodiment of a DFE apparatus and a BEP apparatus. It is a block diagram which shows the detailed structure of the BEP apparatus concerning embodiment of this invention. It is a functional block diagram which shows the detailed structure of the video interface of the BEP apparatus concerning embodiment of this invention. It is a flowchart which shows an example of the flow of the process performed by a video interface. It is a schematic diagram showing a general descreening process. It is a flowchart which shows the modification of the flow of the process performed by a video interface. It is a figure which shows an example of the image data with a character area and a photography area. 1 is a diagram illustrating an outline of a conventional image forming system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Video interface 11 Image forming apparatus 32 Edge determination circuit 34 Low pass filter 35 Black character determination circuit 36 Binarization circuit 38 Format conversion circuit 41 CMY reset circuit 500 DFE apparatus 600 BEP apparatus 601 Data reception part 602 Image storage part 700 CTP apparatus

Claims (7)

An image forming support apparatus that processes and transfers image data of each page generated by processing a print job according to an image forming apparatus on the output side,
An image storage unit for receiving and holding the image data created for the printing plate;
Conversion means for converting the gradation of the image data stored in the image storage unit from a low gradation to a high gradation;
Of the high gradation image data obtained by the conversion of the conversion means, determination means for determining a black character portion;
Based on the determination result of the determination means, image processing means for performing image processing so that the image data corresponding to the black character portion becomes black ink,
An image forming support apparatus comprising:   The image forming support according to claim 1, wherein the image processing unit includes a reset unit that resets color data other than black in image data corresponding to a black character portion based on a determination result of the determination unit. apparatus.   The image processing means includes a process black determination means for determining whether the image data determined to be a black character by the determination means is black represented by color data other than black, and the process black determination means for the color data. The image forming support apparatus according to claim 2, further comprising: a prohibiting unit that prohibits the reset by the reset unit for a portion that is determined to be black.   The image data stored in the image storage unit further includes a line drawing determination unit that determines a character / line drawing part, and the conversion unit changes the low gradation to the high gradation based on the determination result of the line drawing determination unit. The image forming support apparatus according to claim 1, wherein gradation conversion processing is performed to convert the image data into image data.   The image forming support apparatus according to claim 4, wherein the conversion unit includes a low-pass filter.   When the determination result of the determination means is not a character / line drawing part, the conversion means performs a gradation conversion process on the first gradation conversion means, and the determination result of the determination means is a character / line drawing part. 6. The image forming support according to claim 4, further comprising: a second gradation conversion unit that performs the gradation conversion process different from the first gradation conversion unit. apparatus.   The first gradation converting means and the second gradation converting means are low-pass filters, and each of the filter coefficients of the second gradation converting means is the first gradation converting means. The image forming support apparatus according to claim 6, wherein the image forming support apparatus is set to be a weak low-pass filter.

Images