JP4534505B2 - Printing apparatus and raster image processor - Google Patents

Description

The present invention relates to a printing apparatus and a raster image processor .

  In printing at home and office, a relatively small number of many kinds of printed materials are often printed, and the size of the printed materials is limited (for example, A3 or lower), so that the electrophotographic process (xerography) is used as a printing apparatus. A color printer using is suitable. On the other hand, in the printing industry, for the purpose of printing a small number of kinds of printed matter in large quantities, conventionally, in most cases, a block was generated based on print data, and printing was performed using the generated block. Due to changes in the printing process due to the popularization of DTP (DeskTop Publishing / Prepress), the so-called “digital revolution of printing” has led to the adoption of “direct printing” or “on-demand printing” in which printing is performed directly from DTP data. ing. In direct printing (on-demand printing), pre-pressing without producing intermediate products such as paper printing (printing paper) such as photo-setting in traditional printing (for example, offset printing), block printing, net negative, net positive, PS plate, etc. By completely digitizing the process, a plate is directly created from print data (DTP data) by a plate making device (CTP: Computer To Plate), and printing is performed by setting the created plate on a printing press. .

  In addition, the above-described color printer and plate making apparatus can directly perform printing (preparation of a printing plate) from print data. Printing using a color printer and printing using a plate making apparatus (and a printing machine) are not possible. Since they have different characteristics, a printer and a plate making device are provided as printing devices, and these printing devices, terminals, and devices that perform processing such as rasterization (bitmap data) of print data are used as communication lines. And a printing system that allows a user to select whether to perform printing using a printer or a plate making apparatus in units of individual print jobs when a user instructs printing execution via a terminal. Construction is also being considered.

On the other hand, Patent Document 1 examines the size of characters included in a document to be printed, determines whether or not the size of the characters is equal to or greater than a certain level, and performs printing when small characters are crushed and cannot be read during document printing. The technology to be canceled is described.
JP 2003-150339 A

  For printing on a printing press using a printing plate, for example, ultra-thin lines with a thickness of 0.03pr or 0.06pt or small size characters (for example, characters less than 6pt) can be printed with good quality, A color printer using an electrophotographic process has a characteristic that lines and characters disappear, line thickness increases, characters are crushed, etc., when printing fine lines or small-sized characters. . The technique described in Patent Literature 1 avoids inconveniences such as a small size character being crushed by stopping printing when a small size character exists in an image to be printed. Assuming that the above technique is applied to the above-described printing system provided with a printer and a plate making apparatus as printing apparatuses, the print data generated on the assumption that printing is performed using a printing machine (plate making apparatus) is color. When used for printing with a printer, there are cases in which printing cannot be performed depending on the contents of the printing object (whether or not there are extra fine lines or small size characters), and there is a problem that the usability is very poor.

The present invention has been made in consideration of the above facts, and an object of the present invention is to obtain a printing apparatus and a raster image processor capable of printing an image to be printed including fine lines and small size characters with good quality. It is.

  A printing machine that performs printing using a printing plate is a printed matter that expresses a gradation by area gradation (a plurality of dots are assigned to each pixel, and a specific pixel is turned on / off by each of the plurality of dots assigned to the specific pixel. Printed matter). For this reason, when a printing plate is created by the plate making apparatus, the print data representing the image to be printed has pixels that can take binary gradation values (that is, one bit per one pixel color) of dots in the plate making apparatus. It is converted into image data (binary / high resolution image data expressing gradation with area gradation) in a predetermined format arranged at a resolution corresponding to the recording density (for example, about 2400 to 4800 dpi). Using the binary / high resolution image data, a printing plate is created by the plate making apparatus.

  In addition, a printing apparatus such as a color printer is configured to print a printed matter expressing gradation in area gradation as described above, and there is a model capable of recording dots with a recording density comparable to a printing machine (plate making apparatus). Exists. However, since the electrophotographic process employed in a printing apparatus such as a color printer uses static electricity to form an image, for example, the ambient environmental conditions (temperature and humidity), the thickness of the paper on which the image is transferred, the degree of drying, etc. The density of the printed image varies depending on the environmental conditions and the like. For this reason, in a printing apparatus such as a color printer, patches are periodically created to measure density, density fluctuations caused by fluctuations in environmental conditions and the like are detected based on the density measurement results, and image data to be printed Density correction (also referred to as process control) for correcting the detected density fluctuation is performed.

  However, density correction for image data expressing gradation with area gradation is very complicated, and binary / high resolution image data has an enormous amount of data. It becomes necessary to increase the capacity of a memory or HDD (hard disk drive) provided for storing image data. For this reason, when printing is performed by a printing apparatus such as a color printer, the printing data includes pixels (for example, 8 bits per pixel (= 256 gradations)) in which the print data can take multiple gradation values in the printing apparatus. Conversion to image data (multi-valued / low-resolution image data expressing gradation with multiple values) that represents the image to be printed in a format arranged at a resolution lower than the resolution corresponding to the dot recording density (for example, about 600 dpi) Then, density correction is performed using an LUT (look-up table), and subsequently converted into binary / high-resolution image data that expresses a gradation with an area gradation, and then the area gradation image data is used. Thus, printing with the printing apparatus is performed.

  In the printing by a printing apparatus such as a color printer, the inventor of the present application converts print data into multi-value / low-resolution image data, and after density correction is performed, converts the data into binary / high-resolution image data. Focusing on the fact that it has undergone two conversions, it is difficult to print very fine lines and small-sized characters with a printing device such as a color printer in high quality. This is because the data of the fine lines and small size characters deteriorates once converted into low resolution image data). For the fine lines and small size characters contained in the image to be printed, By converting directly from data to data used for printing, it is possible to suppress deterioration of the data of extra fine lines and small size characters, and to achieve printing of extra fine lines and small size characters with good quality. Thereby forming the basis of the present invention Te.

請 Motomeko 1 printing apparatus according to the described invention, the printing means and the line drawing or a predetermined size smaller than the predetermined thickness in the image of the print target for printing an image to be printed as a set of dots arranged in a predetermined recording density Determining means based on print data representing the image to be printed, whether or not there is a fine image portion consisting of less than characters , and out of the print data , The data other than the data corresponding to the fine image portion determined to be present in the image is represented by pixels having a resolution lower than the resolution corresponding to the predetermined recording density and having a multi-value gradation value. first converting means for converting the first image data, performs a density correction on the first image data, the first image data after the density correction, resolution corresponding to the predetermined recording density and, Binary floor A second converting means for converting the second image data representing the image in pixels having a value for the data corresponding to the fine image portions of the printing data, lower than the resolution corresponding to the predetermined recording density Without performing conversion to resolution and density correction, the data corresponding to the fine image portion is subjected to screen processing on data corresponding to characters of the data smaller than the predetermined size, and the predetermined recording density corresponds to the resolution, and a third conversion means for converting the third image data representing the fine image portion in a pixel having a tone value of the binary, when printing of the print target image by the printing means, the the fine image portions of the image to be printed, the third converting means obtained density correction by the conversion by the to print using a third image data that has not been made, the print The portion other than the fine image portion of the elephant picture is characterized by comprising a control means for Ru is printed using the second image data that has undergone the density correction.

A raster image processor according to a second aspect of the present invention is a raster image processor for outputting created file data to a printing apparatus that prints an image to be printed as a set of dots arranged at a predetermined recording density. Determining means for determining whether or not there is a fine image portion composed of a line drawing or a character less than a predetermined size in the image based on print data representing the image to be printed; and the print data Data other than the data corresponding to the fine image portion determined to be present in the image to be printed by the determination means, a resolution lower than the resolution corresponding to the predetermined recording density, and First conversion means for converting to first image data representing an image with pixels having multi-value gradation values; and a data corresponding to the fine image portion of the print data. The data corresponding to the fine image portion is equivalent to the characters of the data smaller than the predetermined size without performing conversion to a resolution lower than the resolution corresponding to the predetermined recording density and correcting the density. Third conversion means for converting the data to be processed into third image data representing the fine image portion with pixels having a resolution corresponding to the predetermined recording density and a binary gradation value while performing screen processing And combining means for combining the first image data and the third image data as the file data, and correcting the density of the file data with respect to the first image data by the combining means, Second conversion for converting the corrected first image data into second image data representing an image with a pixel having a resolution corresponding to the predetermined recording density and a binary gradation value At the time of printing the image to be printed, the third image data obtained by converting the fine image portion of the image to be printed by the conversion by the third conversion unit and not subjected to density correction is used. An output unit that outputs to the printing apparatus, and includes a control unit that prints and prints a portion other than the fine image portion of the image to be printed using the second image data that has undergone the density correction. It is characterized by having.

The invention of claim 1, wherein, it is possible to print a printing image including the polar fine lines and small size of the characters in good quality, with a gutter Cormorant effect.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. In addition, although it demonstrates using the numerical value which does not hinder this invention below, this invention is not limited to the numerical value described below.

FIG. 1 shows a printing system 10 according to the present embodiment. The printing system 10 performs printing with an image forming apparatus 12 that functions as a printer that forms a visible color image on a predetermined recording sheet by an electrophotographic process based on input print data, and a printing machine (press apparatus) 14. A plate making apparatus (CTP: Computer To Plate) 16 for directly creating a printing plate for printing from input print data is provided. The image forming apparatus 12 is connected to a BEP (BackEnd Processor) 20 via a communication line. The BEP 20 includes a plate making apparatus 16, a large number of client terminals 22 (only a single client terminal 22 is shown in FIG. 1), a RIP. (Raster Image Processor) 24 and server computer 25 are connected to each other via a communication line 26 (for example, a high-speed wired LAN (Local Area Network) using a general-purpose communication protocol having a communication speed of about 1 Gbps (Giga bit per second)). ing. Note that the printing system 10 can be connected to a scanner device that reads an image of a document and outputs image data, and a printer proofer for confirming print output. Further, in the present embodiment, RIP24, BEP20 and the image forming apparatus 12 corresponds to the printing equipment according to the present invention.

  As shown in FIG. 2, the image forming apparatus 12 includes an IOT (Image Output Terminal) module 60, a feed (paper feed) module (FM: Feeder Module) 64 that supplies recording paper to the IOT module 60, and an IOT module 60. A connection module 66 for connecting the feed module 64 and an output module 66 for discharging recording paper on which an image is formed by the IOT module to the outside of the machine body are provided. The feed module 64 may have a multi-stage configuration. Further, a finisher (post-processing device) module may be further provided in the subsequent stage of the output module 66. Examples of the finisher module include a stacker for recording sheets and a stapler that binds at one or two corners of the corner, and a punching mechanism that punches filing punch holes. is there. It is desirable that the finisher module can be used even in an off-line state in which the image forming apparatus 12 is not connected to another apparatus via a communication line.

  The IOT module 60 includes an IOT core unit 70 and a toner supply unit 72. The toner supply unit 72 is loaded with a four-color toner cartridge 74 in which black (K) is added to three colors of cyan (C), magenta (M), and yellow (Y), which are basic colors in color printing. The IOT core unit 70 includes four print engines (printing units) 76 corresponding to any one of C, M, Y, and K color components. In the present embodiment, each print engine 76 can record dots at a recording density of 2400 dpi (corresponding to the predetermined recording density described in claim 1), and input printing data (1 bit of 2400 dpi). By turning on / off the recording of individual dots in accordance with (image data), it is possible to print images of different color components among the images to be printed as a set of dots arranged at a recording density of 2400 dpi.

  The print engines 76 are arranged in a line along the rotational movement direction of the endless intermediate transfer belt 88 (so-called tandem type). Each print engine 76 scans on the photosensitive drum 78 a photosensitive drum 78, a charger 80 for charging the photosensitive drum 78, and a light beam modulated according to print data of the corresponding color component. An optical scanning device 82 for forming an electrostatic latent image, a developing device 84 for developing the electrostatic latent image formed on the photosensitive drum 78 to form a toner image, and a toner image formed on the photosensitive drum Are transferred to the intermediate transfer belt 88 (primary transfer), and toner images of the respective color components formed by the individual print engines 76 are superimposed on each other on the intermediate transfer belt 88. As a result, a color toner image is formed on the intermediate transfer belt 88.

  The color toner image formed on the intermediate transfer belt 88 is transferred (secondary transfer) onto the recording paper conveyed from the feed module 64 at a predetermined timing by the secondary transfer device 90. The recording paper on which the color toner image has been transferred is conveyed along a conveyance path 92 to a fixing device (Fuser) 94, and the toner image is melted and fixed by the fixing device 94 and delivered to a paper discharge processing device 96 of the output module 66. (The paper may be temporarily held on a paper discharge tray (stacker) 98 and then delivered to the paper discharge processing device 96). After a predetermined end process is performed as necessary, the paper is discharged out of the machine body. Further, at the time of double-sided printing, the recording paper having a toner image fixed (color image printed) on one side is reversed from the paper discharge tray 98 via the reverse path 100 and the reverse conveyance path 102 of the IOT module 60. In the reversed state, it is sent again to the conveyance path 92. The IOT core unit 70 is also provided with an electric system control storage unit 104 that stores an electric circuit for controlling the operation of each print engine 76, a power supply circuit for each module, and the like.

  Although detailed description of the plate making device 16 is omitted, for example, a sheet-shaped printing plate is wound around and fixed to the outer peripheral surface of a cylindrical rotating drum, the rotating drum is rotated, and an input specific color component is input. After printing an image on the printing plate by irradiating a printing plate that rotates integrally with the rotating drum with a light beam modulated according to the printing data, the printing plate on which the image is recorded is developed to print a specific color component. A configuration for producing a plate (press plate) can be employed. In this case, a printing plate corresponding to each color component can be obtained by repeating the above process for each color component of C, M, Y, and K. The printing plates of the respective color components produced by the plate making device 16 are set in a printing machine and used for printing.

  In the printing system 10 according to the present embodiment, the user can instruct the image forming apparatus 12 and the plate making apparatus 16 to print online from the client terminal 22, and the image forming apparatus 12 is used for printing. It is possible to arbitrarily select whether printing is performed using the plate-making device 16 (whether a printing plate is produced by the plate-making device 16 and the produced printing plate is set in the printing machine 14 to perform printing). ing. Printing using the image forming apparatus 12 does not require operations such as creating a printing plate and setting the created printing plate on a printing machine, and can complete printing in a short time after instructing printing (printing). The speed is about 60 sheets / minute), but the size of printable recording paper is limited (usually A3 size or less). On the other hand, in printing using the plate making apparatus 16, it takes a relatively long time to produce a printing plate by the plate making apparatus 16 (for example, several minutes per printing plate), and time and effort to set the produced printing plate in a printing machine. However, once the setting of the printing plate on the printing press is completed, printing can be performed at high speed (for example, several hundred sheets / minute), and the size limit of the printed material is loose. This is used when printing a small amount of printed matter.

  The client terminal 22 comprises a personal computer (PC), and an arbitrary OS (Operating System) and arbitrary application software are installed. In the present embodiment, the user creates a document to be printed by operating the client terminal 22 and using any application software. This document may be a character document, an image such as a photograph or a chart, or a document in which characters and images are mixed. When the creation of the document to be printed is completed, the user performs an operation for instructing printing of the document to be printed. In this operation, parameters that define the processing conditions of the print job to be executed, such as the type of the apparatus that performs printing (image forming apparatus 12 / plate making apparatus 16), the number of copies, the size of the printed matter, and the paper quality, are also specified. For a print job with a processing time limit, the processing time limit is also specified.

  When the above operation is performed by the user, print data describing a document to be printed in a page description language (PDL) is transmitted from the client terminal 22 to the RIP 24, and processing of a print job set by the user is performed. Based on the conditions, print control information (also called a job ticket) in a predetermined format (for example, JDF: Job Definition Format) in which the processing conditions are set as parameters is generated, and the generated print control information is transmitted from the client terminal 22 to the server. -Sent to computer 25. In the present embodiment, a document to be printed may be brought into the printing system 10 after being created externally (transferred to the client terminal 22). In this case, the printing instruction is performed in the same manner as described above. Is called.

  By the way, the print control information according to the present embodiment includes information relating to printed matter production from planning / production to delivery (for example, production specifications of printed matter, processing procedures in each process such as production / printing / post-processing, individual print jobs, The print control information received by the server computer 25 can be referred to and updated by the client terminal 22, the RIP 24, and the BEP 20 of the print system 10 in a comprehensive manner. Stored in the server computer 25. The print control information is browsed via the client terminal 22 by a person other than the user (for example, the person in charge of the company's sales department) who has instructed execution of printing, for example, and necessary. When the information is additionally set, the setting of the print control information for instructing the processing procedure in each process is completed so that a printed matter that matches the user's instruction is manufactured. A setting completion flag is added to the print control information stored in the server computer 25. The initial value of the setting completion flag is 0, and 1 is set when the setting of the print control information is completed.

  Next, the RIP 24 will be described. Unlike the conventional RIP, the RIP 24 according to the present embodiment does not have a printer controller function for controlling printing in the image forming apparatus 12, and prints data to be printed by the image forming apparatus 12 and the plate making apparatus 16. This is different from the conventional RIP in that each print data to be processed is processed.

  That is, the RIP 24 is composed of a computer such as a personal computer (PC), and includes a data storage unit 30, a RIP processing unit 32, a compression processing unit 34, and an interface (I / F) unit 36 as shown in FIG. Yes. The data storage unit 30 sequentially stores print data (print data described in PDL and expressing colors in R, G, and B) received by the RIP 24 from the client terminal 22. The RIP processing unit 32 incorporates a PDL interpretation unit and a decomposer functioning as an imager, a so-called RIP engine. The RIP processing unit 32 refers to the print control information stored in the server computer 25 and is added to the print control information corresponding to the unprocessed print job in which the print data is stored in the data storage unit 30. When the setting completion flag becomes 1, the print data corresponding to the print control information is extracted from the data storage unit 30 and interpreted, and R, G, B → C, M, Y, K color conversion and raster image data (bits) are set. RIP (Raster Image Process) processing for generating print data that can be used for printing in the image forming apparatus 12 or the plate making apparatus 16 is performed in units of pages.

  Note that image data to be input to the image forming apparatus 12 in order to cause the image forming apparatus 12 to perform printing, for example, has a resolution of 600 dpi and expresses gradation with 8 bits for each of C, M, Y, and K per pixel. The image data to be input to the plate making apparatus 16 in order to cause the plate making apparatus 16 to perform printing (preparation of a printing plate) is 1 pixel (1 pixel at a resolution of 2400 dpi or 4800 dpi). This is binary / high-resolution image data of 1 bit for each of C, M, Y, and K per dot (representing gradation by a plurality of dots), and the format of the image data to be input to each device is different. . For this reason, the RIP processing unit 32 recognizes the type of the apparatus (image forming apparatus 12 / plate making apparatus 16) that performs printing by referring to the print control information, and recognizes the recognized type from the print data described in PDL. Generate print data in a format suitable for the device. The RIP process for generating print data to be input to the image forming apparatus 12 will be described in detail later.

  Further, the RIP processing unit 32 refers to the parameters set in the print control information corresponding to the print data extracted from the data storage unit 30, and is executed during printing according to the processing conditions of the print job corresponding to the extracted print data. A process to be performed is determined, and a process related to the RIP process among the determined processes is simultaneously performed. As processing related to the RIP processing, for example, if the device that performs printing is the image forming device 12, for example, rotation (Rotation), page allocation (N-UP) in one sheet, and repeat processing , Paper size adjustment, CMS (Color Management System) processing to correct device differences, resolution conversion, contrast adjustment, compression rate designation (low / medium / high), etc. In the case of the apparatus 16, imposition, screen processing, and the like for allocating images for a plurality of pages on a large-size printing surface corresponding to a large-size recording sheet.

  When the above processing is performed, the RIP processing unit 32 removes parameters related to the executed processing from among various parameters set in the print control information stored in the server computer 25. Update the print control information. As a result, when the apparatus that performs printing is the image forming apparatus 12, the print control information stored in the server computer 25 includes the process to be performed by the BEP 20 as a parameter that defines the process to be performed at the time of printing. Only relevant parameters (for example, if the device that performs printing is the image forming device 12, parameters that specify the number of copies, duplex / single-sided, color / black and white, composite printing, sorting, presence / absence of a stapler, etc.) remain. become.

  Note that the print data that has been subjected to the various processes described above in the RIP processing unit 32 is reprinted using the same print data (for example, in printing by the image forming apparatus 12, a plurality of copies are set by collation setting). Are stored in the data storage unit 30 for a certain period or for a period specified for each print job.

  The compression processing unit 34 compresses the print data generated by the RIP processing unit 32 according to a predetermined format (details will be described later). The I / F unit 36 uses the compressed image file output from the compression processing unit 34 as print file data in a predetermined format (for example, TIFF (Tagged Image File Format) format) according to the type of the device that performs printing. Or it transmits to the plate-making apparatus 16 (for example, file transfer by FTO (Fast Transfer Protocol) etc.). When the apparatus that performs printing is the plate making apparatus 16, the print file data is sequentially transferred from the RIP 24 to the plate making apparatus 16 as print data for creating the printing plate, and is printed by the plate making apparatus 16 (creation of the printing plate). ).

  Next, BEP20 will be described. The BEP 20 is also composed of a computer such as a PC. As shown in FIG. 3, the BEP 20 includes a data receiving unit 40, an image storage unit 42, an expansion processing unit 44, an image processing unit 46, I / F units 48 and 50, and a print control unit 52. I have. The data receiving unit 40 receives the print file data transmitted from the RIP 24, the image storage unit 42 sequentially stores the print file data received by the data receiving unit 40, and the decompression processing unit 44 stores it in the image storage unit 42. The print file data is read out from the image storage unit 42 in order, a compressed image file is taken out from the read print file data, decompression processing is performed, and tag addition processing described later is performed. The expansion processing unit 44 is connected to the image forming apparatus 12 via the image processing unit 46 and the I / F unit 48, and image data obtained through the expansion processing by the expansion processing unit 44 is input to the image processing unit 46. The

  On the other hand, when the expansion processing unit 44 reads specific print file data from the image storage unit 42, the print control unit 52 print control information corresponding to the specific print file data (print stored in the server computer 25). Control information), the operation of the image processing unit 46 is controlled in accordance with the print job processing conditions defined by the parameters set in the print control information. That is, the image processing unit 46 has a function of performing various processes such as rotation, image position adjustment, enlargement or reduction on the input image data, and the print control unit 52 includes print control information. Sorting pages in ascending / descending order, determining page order for double-sided printing, multi-dimensional look according to the discharge conditions specified by the set parameters and the structure and characteristics of the image forming apparatus 12 that performs printing Page re-arrangement (stapler and / or calibration) such as color conversion, gray balance correction, and color misregistration correction using an uptable (DLUT) The structure of the image forming apparatus 12 such as the securing of the punch hole location, collation (collation), discharge surface (upper and lower) alignment, etc. Various processes processing contents are different depending on sex to perform the image processing unit 46.

  The BEP 20 and the image forming apparatus 12 have a relatively “close” relationship in which communication is performed by a dedicated communication protocol (a communication protocol depending on the print engine 76 of the image forming apparatus 12). The image data subjected to the above process is transferred to the image forming apparatus 12 via the I / F unit 48 and the communication line 18A. Further, at the time of transferring the image data, the print control unit 52 sends various control commands at a timing synchronized with the processing speed of the IOT core unit 70 (each print engine 76 thereof) of the image forming apparatus 12, thereby enabling the print engine. The operation of each part of the image forming apparatus 12 such as 76, the fixing device 94, and the finisher module is controlled, and the image forming apparatus 12 executes a printing process. In addition, the print control unit 52 automatically performs recovery processing at the time of a paper jam in which the processing contents differ depending on the structure and characteristics of the image forming apparatus 12. Thus, the print control unit 52 also functions as a printer controller that controls the operation of the image forming apparatus 12.

  Next, the operation of this embodiment will be described. In the printing system 10 according to the present embodiment, when printing a document to be printed, print data describing the document to be printed in PDL is transmitted from the client terminal 22 to the RIP 24. When a line drawing or character portion and a background or image (for example, a photographic image including a halftone) are mixed in a document to be printed, print data describing the document to be printed in PDL is generally: Data that describes the line drawing / character part (PATH data) and data that describes the background / image part (IMAGE data) are included, and the data that represents whether the next data is PATH data or IMAGE data (MASK) Data) is inserted.

In contrast, in the present embodiment, when print data described in PDL is generated, it is determined whether the thickness of the line drawing included in the document to be printed is less than 0.12 pt, and the document to be printed is also determined. It is determined whether the size (number of points) is less than 6pt for the included characters. Data describing a line drawing or character satisfying the determination is distinguished from PATH data describing a line drawing having a thickness of 0.12 pt or more and a character having a size of 6 pt or more as fine image portion data (PATH 2 data). In addition, the MASK data according to the present embodiment is expanded to indicate whether the next data is PATH data, PATH2 data (fine image portion data), or IMAGE data. By referring to the MASK data in the print data, Of the print data representing the document to be printed, line drawings with a thickness of 0.12 pt or more, line drawing / character data corresponding to characters with a size of 6 pt or more (PATH data), line drawings with a thickness of less than 0.12 pt size that is capable identifying data (iMAGE data) of the data (PATH 2 data) and the background-image part of the fine image portion corresponding to the character of less than 6pt.

Note that “line drawing thickness 0.12pt” and “character size 6pt”, which are the threshold values for discriminating between fine image parts and line drawings / characters, convert the print data into multi-value / low resolution image data and density. When correction is performed and converted into binary / high-resolution image data and printing is performed by the image forming apparatus 12 (details will be described later), line images or characters included in the document to be printed have an appropriate print quality. that is the minimum size to be printed.

  Next, with respect to the RIP processing performed by the RIP 24 when the print data retrieved from the data storage unit 30 is print data in which the image forming apparatus 12 is designated as an apparatus for performing printing, refer to the flowchart of FIG. To explain.

In step 120, the print data to be processed is fetched from the data storage unit 30 by the RIP processing unit 32. In the next step 122, all the MASK data inserted in the print data to be processed is extracted by scanning the captured print data to be processed, and the next data is included in the extracted MASK data. By determining whether or not the data indicating that it is PATH2 data (fine image data) is included, the thickness of the print target document represented by the print data to be processed is less than 0.12 pt. Judges whether the line drawing or characters with a size less than 6pt are included. As a document to be printed that includes a line drawing with a thickness of less than 0.12 pt or a character with a size of less than 6 pt, for example, the plate making device 16 finally creates a printing plate (prints with the printing machine 14). An original document prepared on the premise (for example, when printing on the image forming apparatus 12 is instructed for the purpose of checking print data or the like) is printed on the image forming apparatus 12 from the beginning. It may be a manuscript created for the purpose. Step 122 corresponds to the determination means described in claim 1 . If the determination in step 122 is negative, the process proceeds to step 130 without performing any processing.

Although details will be described later, the print data used for printing in the image forming apparatus 12 is normally subjected to density correction (process control) in the image forming apparatus 12 that corrects density fluctuations caused by fluctuations in environmental conditions and the like. the consideration is converted into image data (format resolution 600dpi with 8 bits per pixel one color) multilevel / low resolution RIP24, in the image forming apparatus 12 using a LUT (look-up table) density correction after being made, the binary / high-resolution (resolution 1-bit per pixel one color format of 2400 dpi) are reconverted into image data. However, if the original to be printed contains ultra-thin lines with a thickness of less than 0.12pt or small size characters (fine image part) with a size of less than 6pt, the print data will be fine while undergoing the above two conversions. Deterioration of image data (especially when it is converted to low resolution image data), disappearance of extra fine lines and small size characters, increase in the thickness of extra fine lines, small There is a problem that size characters are crushed.

  For this reason, if the determination in step 122 is affirmed, the process proceeds to step 124 to print a line drawing with a thickness of less than 0.12 pt or a character with a size of less than 6 pt included in the document to be printed with high quality. Therefore, when the RIP processing unit 32 includes characters smaller than 6 pt in the fine image portion, it corresponds to characters having a size of less than 6 pt in the fine image portion data included in the print data to be processed. The data of the fine image portion included in the print data to be processed is converted into binary / high resolution (1 bit per pixel and resolution of 2400 dpi) while performing screen processing by error diffusion method or dither method on the data to be processed RIP processing for conversion to (fine format) fine image data. Step 124 corresponds to the third conversion means described in claim 1, and the fine image portion data corresponds to the third image data. In step 126, the compression processing unit 34 applies a predetermined compression method corresponding to binary lossless compression to data corresponding to characters having a size of less than 6pt among the fine image portion data obtained by the processing in step 124. Compress. In step 128, the data subjected to the compression process in step 126 is filed as a compressed image file of the LW2 layer in the Tiff format, and then the process proceeds to step 130.

  In step 130, the RIP processing unit 32 causes the entire surface of the document to be printed (if the document to be printed includes a fine image portion (if the determination in the previous step 122 is affirmed)) RIP processing for converting print data corresponding to a range excluding the fine image portion) into image data of multi-value / low resolution (format of 8 bits per pixel and resolution of 600 dpi) is performed. Step 130 corresponds to the first conversion means described in claim 1, and the image data corresponds to the first image data. In the next step 132, a line drawing / character portion (a line drawing having a thickness of 0.12 pt or more or a size of 6 pt or more) is included in the range to be processed in step 130 of the document to be printed (excluding the entire original surface or the fine image portion). It is determined whether or not there is a portion corresponding to the character. If the determination is negative, the process proceeds to step 138 without performing any processing. If the determination is affirmative, the process proceeds to step 134, and the compression processing unit 34 converts the image data obtained by the processing in step 130. Among them, data corresponding to the line drawing / character portion (line drawing / character portion data) is compressed by applying a predetermined compression method corresponding to lossless compression. In step 136, the data subjected to the compression process in step 134 is filed as a compressed image file of the LW1 layer in the Tiff format, and then the process proceeds to step 138.

  In step 138, the image data obtained by the processing of step 130 by the compression processing unit 34 (when the line drawing / character portion is included (when the determination in the previous step 132 is affirmed)) The image data in the excluded range, that is, the background / image portion data corresponding to the background / image portion of the document to be printed is compressed by applying a predetermined compression method corresponding to lossy compression. In step 140, the data subjected to the compression processing in step 138 is filed as a compressed image file of the CT layer in the Tiff format. In step 142, the compressed image file of each layer is synthesized as print file data in the Tiff format.

  Subsequently, the print file data obtained by the above RIP process (FIG. 4) is transferred to the BEP 20, and is executed in the BEP 20 when the print file data is temporarily stored in the image storage unit 42 of the BEP 20 and then extracted. The tag addition process will be described with reference to the flowchart of FIG.

  In step 150, the expansion processing unit 44 captures Tiff format print file data from the image storage unit 42. In the next step 152, the compressed image file of each layer included in the captured print file data is converted into a compression method in the RIP 24. Each is expanded by the corresponding expansion method. As a result, the background / image partial data is obtained from the compressed image file of the CT layer, and if the LW1 layer exists, the line drawing / character partial data is obtained from the compressed image file of the LW1 layer, and the LW2 layer exists. In such a case, fine image data can be obtained from the compressed image file of the LW2 layer. In step 154, a screen designation tag that designates the content of the screen processing in units of individual pixel data for the image data obtained by performing the decompression process on the compressed image file of each layer of the print file data. Are added and integrated as a single image data (image data to be printed).

The screen designation tag can be switched according to whether each pixel belongs to image data obtained from which layer. For example, pixel data belonging to the background / image partial data obtained from the CT layer is a line. A tag (for example, (00) _B ) that specifies screen processing corresponding to several hundred thousand line screens (200R) is added, and pixel data belonging to the line drawing / character portion data obtained from the LW1 layer has a line number of 600. A tag (for example, (01) _B ) for designating screen processing corresponding to the line screen (600) is added, and a tag for designating no screen processing for pixel data belonging to the fine image portion data obtained from the LW2 layer (For example, (10) _B ) can be added. Assuming that the screen designation tag is 2 bits as described above, by the above processing, for each pixel belonging to the background / image portion data or line drawing / character portion data, the screen is a 2-bit screen with 8-bit data per color. A designation tag is added to become 10-bit data, and for each pixel belonging to the fine image portion data, a 2-bit screen designation tag is added to 1-bit data per color to become 3-bit data.

  Next, the image data to be printed with the screen designation tag added for each pixel by the tag addition processing (FIG. 5) is transferred to the image forming apparatus 12, so that the IOT module 60 of the image forming apparatus 12 performs the transfer. The print processing to be executed will be described with reference to the flowchart of FIG.

  In step 160, each screen designation tag added to each pixel of the image data to be printed transferred from the BEP 20 is extracted (by this, the data of each pixel is returned to 8 bits or 1 bit per color) and extracted. The screen designation tag is associated with each pixel on the image data and filed as a single screen designation file. In step 162, single pixel data is extracted from the image data to be printed (image data obtained by extracting the screen designation tag). In step 164, the screen designation file is referred to, and the contents of the screen processing designated for the pixel data are recognized by identifying and referring to the screen designation tag designated for the pixel from which data is extracted in step 162. .

  In the next step 166, it is determined whether or not the content of the screen processing recognized in step 164 is “no screen processing”. When the pixel extracted in step 162 is a pixel belonging to the background / image part data or line drawing / character part data (corresponding to a 200-line screen (200R) or 600 line screen (600)) If the screen processing to be performed is designated), the above determination is denied and the routine proceeds to step 168, where the pixel data extracted at step 162 is subjected to density correction using a one-dimensional LUT (lookup table). The conversion data set in the one-dimensional LUT used for the above-described density correction includes, for example, each color component / each density patch formed on the intermediate transfer belt 88, the density of each patch formed, and the measured density. Can be set so that the detected density fluctuation can be corrected by detecting the density fluctuation caused by fluctuations in the environmental conditions and the like of the image forming apparatus 12. By periodically setting the conversion data, the density can be corrected so that the influence of fluctuations in the environmental conditions of the image forming apparatus 12 is eliminated. Since the pixel data for density correction is data in a multi-value / low resolution format, density correction can be performed by simple processing using a one-dimensional LUT.

  Further, in step 170, screen processing (screen processing corresponding to a 200-line screen (200R) having a line number of 200 or a line screen (600) having a line number of 600) specified for the pixel data subjected to density correction is performed. By doing so, the pixel data is converted into image data of binary / high resolution (format of 1 bit per pixel and resolution of 2400 dpi). When the resolution in the multi-value / low resolution image data before conversion is 600 dpi and the resolution in the binary / high resolution image data after conversion is 2400 dpi, 16 pixels (from the data of a single pixel by the above conversion ( Dot) data is generated. The above steps 168 and 170 correspond to the second conversion means described in claim 1, and the converted image data corresponds to the second image data. In the next step 172, the converted data is stored in the memory as print data.

  On the other hand, when the pixel from which data is extracted in step 162 is a pixel belonging to the fine image portion data (when “no screen processing” is designated), the determination in step 166 is affirmed and the process proceeds to step 172. Then, the pixel data extracted in step 162 is stored in the memory as print data as it is. In the next step 174, it is determined whether or not all pixel data has been extracted from the image data to be printed. If the determination is negative, the process returns to step 162, and steps 162 to 174 are repeated until the determination in step 174 is affirmed. If the determination in step 174 is affirmative, the process proceeds to step 176, and the original to be printed is printed by each print engine 76 based on the print data stored in the memory by the above processing. As described above, the determination at step 132 corresponds to the control means according to claim 1, and the print engine 76 corresponds to the printing means according to claim 1.

  As a result, among the originals to be printed, fine image portions corresponding to extra fine lines with a thickness of less than 0.12 pt or small size characters with a size of less than 6 pt are binary from the beginning in the RIP process (FIG. 4). / Since the fine image portion data generated in the high resolution format is used as it is as printing data without being subjected to processing such as density correction and format re-conversion in the printing process described above, Corresponding to a fine image portion on a printed matter on which a document to be printed is printed with data deterioration due to format re-conversion (conversion to a multi-value / low-resolution format that requires), etc. It is possible to prevent the loss of extra fine lines and small size characters, increase the thickness of extra fine lines, and collapse of small size characters. It can be printed in quality.

  Further, portions other than the above-described fine image portion (line drawing / character portion, background / image portion) of the original to be printed are imaged in a multi-value / low-resolution format in the RIP processing (FIG. 4) in the RIP 24. Since data is generated and density fluctuations due to fluctuations in the environmental conditions of the image forming apparatus 12 are corrected, the data is converted into image data in a binary / high resolution format. The part (particularly the background / image part) can be reproduced on the printed matter on which the document to be printed is printed with an appropriate gradation regardless of variations in the environmental conditions of the image forming apparatus 12.

  In the above, on the print data described in PDL, the data describing the line drawing in the document to be printed with a thickness of less than 0.12 pt and characters with a size (number of points) of less than 6 pt is a fine image using MASK data. In the above example, it is distinguished whether or not a fine image portion is present based on MASK data. However, the present invention is not limited to this. For example, PDL If the print data described in (1) is data that includes size information indicating the thickness of individual lines and the size of individual characters included in the document to be printed, the size information included in the print data is referenced one by one. It may be determined whether there is a line or character corresponding to the fine image portion. In this aspect, since it is possible to change the discrimination threshold (thickness of line thickness and character size) between the fine image portion and the normal line drawing / character portion, the performance of the image forming apparatus 12 that performs printing can be changed. -The threshold value can be switched according to the ability.

  In the above description, the example in which the process of generating (converting) binary / high-resolution image data from print data described in PDL is applied only to the fine image portion has been described, but the present invention is limited to this. However, the present invention may be applied to all line drawings / characters in a document to be printed (for example, all line drawings / characters including a line drawing having a thickness of 0.12 pt or more and a character having a size of 6 pt or more).

  In the above description, the printing apparatus according to the present invention is separated into the RIP 24, the BEP 20, and the image forming apparatus 12 (the function as the printing apparatus according to the present invention is realized by the RIP 24, the BEP 20, and the image forming apparatus 12). Although described, the present invention is not limited to this, and it goes without saying that the function as a printing apparatus according to the present invention may be mounted on a single apparatus (for example, the image forming apparatus 12).

  Furthermore, in the above description, the electrophotographic process which is a printing method in the image forming apparatus 12 has been described as an example of the printing method by the printing apparatus according to the present invention, but the present invention is not limited to this, and the surroundings of the printing apparatus The present invention can be applied to any printing method that requires density correction according to changes in the environment or the like.

1 is a schematic diagram of a printing system according to the present embodiment. 1 is a schematic configuration diagram of an image forming apparatus. It is a block diagram which shows schematic structure of RIP and BEP. It is a flowchart which shows the content of the RIP process performed by RIP. It is a flowchart which shows the content of the tag addition process performed by BEP. 6 is a flowchart illustrating the contents of a printing process executed by the image forming apparatus.

Explanation of symbols

10 Printing System 12 Image Forming Apparatus 20 BEP
24 RIP
60 IOT module 76 print engine

Claims (2)

Printing means for printing an image to be printed as a set of dots arranged at a predetermined recording density ;
Determining means for determining whether or not there is a fine image portion composed of a line drawing or a character less than a predetermined size in the image to be printed based on print data representing the image to be printed;
Wherein among the print data, the data other than the data corresponding to the fine image portion is determined to be present in the image of the print target by the determination means, lower than the resolution corresponding to the predetermined recording density First conversion means for converting to first image data representing an image with pixels having resolution and multi-value gradation values ;
Performs density correction on the first image data, the representative of the image of the first image data after the density correction, resolution corresponding to the predetermined recording density, and the pixel having the tone value of the binary Second conversion means for converting the image data into two image data ;
The data corresponding to the fine image portion of the print data is converted to the resolution lower than the resolution corresponding to the predetermined recording density and the density correction is performed without performing density correction on the data corresponding to the fine image portion. The fine image portion is represented by a pixel having a resolution corresponding to the predetermined recording density and a binary gradation value while performing screen processing on data corresponding to characters smaller than the predetermined size among the data. Third conversion means for converting into third image data;
At the time of printing the image to be printed by the printing unit, the fine image portion of the image to be printed is used third image data obtained by conversion by the third conversion unit and not subjected to density correction. to print Te, the portion other than the fine image portion of the printed image, and control means Ru is printed using the second image data that has undergone the density correction,
A printing apparatus comprising: A raster image processor that outputs created file data to a printing apparatus that prints an image to be printed as a set of dots arranged at a predetermined recording density,
Determining means for determining whether or not a fine image portion composed of a line drawing or a character having a size less than a predetermined size exists in the image to be printed based on print data representing the image to be printed;
Of the print data, data other than the data corresponding to the fine image portion determined to be present in the image to be printed by the determination unit is lower than the resolution corresponding to the predetermined recording density. First conversion means for converting to first image data representing an image with pixels having resolution and multi-value gradation values;
The data corresponding to the fine image portion of the print data is converted to the resolution lower than the resolution corresponding to the predetermined recording density and the density correction is performed without performing density correction on the data corresponding to the fine image portion. The fine image portion is represented by a pixel having a resolution corresponding to the predetermined recording density and a binary gradation value while performing screen processing on data corresponding to characters smaller than the predetermined size among the data. Third conversion means for converting into third image data;
Combining means for combining the first image data and the third image data as the file data;
The composition unit corrects the density of the file data with respect to the first image data, and the first image data after the density correction has a resolution corresponding to the predetermined recording density and a binary gradation value. Second conversion means for converting to second image data representing an image with pixels having a pixel, and when printing the image to be printed, the fine image portion of the image to be printed is transferred by the third conversion means. Printing is performed using third image data that has been obtained by conversion and has not been subjected to density correction, and the second image data that has undergone the density correction is applied to a portion other than the fine image portion of the image to be printed. Output means for outputting to the printing apparatus having control means for printing using,
A raster image processor comprising:

Images