JP2005157854A - Image processing method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost, fast printer that reduces the amount of data processing when converting print data into image data suitable for printing. <P>SOLUTION: A line tag that represents a color component present on each line is created when a rendering process is implemented. The line tags are refereed to during the second stage of the rendering process so as to reduce the amount of calculations and processing time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  2. Description of the Related Art Conventionally, an image processing apparatus that performs printing by converting print data in a predetermined format and generating image data is known. As such an apparatus, the apparatus as shown in FIG. 9 is generally used. FIG. 9 shows a schematic configuration of a system for creating a document to be printed by the host computer 901 and printing it by a printing apparatus 902 such as a laser beam printer or an inkjet printer.

  In FIG. 9, reference numeral 901 denotes a host computer. An application 903 such as a word processor or DTP software is running on the host computer, and a document to be printed is created using these applications. The created document is converted into print data by the operating system and the printer driver 904 and transmitted to the printing apparatus.

  The print data is configured as a set of command data representing information such as a normal page configuration, graphics to be printed, and characters (hereinafter referred to as objects). These commands are defined as a language system called PDL (page description language). Typical examples of PDL include PostScript (registered trademark), LIPS (registered trademark), and PCL.

  The print data is processed by the PDL parser 905. Specifically, the object information is extracted from the data in the PDL format, and is stored in the work memory as information suitable for the subsequent rasterization process. The rasterizer 906 generates two-dimensional bitmap image data based on the object information configured as described above. Further, the bitmap image is subjected to color gradation conversion processing so as to be adapted to a printing process 908 described later, and final image data is generated. This process is called a so-called halftone process. Image data is temporarily stored in the image memory 907.

  The image data in the image memory is sent to the printing process 908. The printing process 908 includes an image forming unit of an electrophotographic system or an ink jet recording system, and performs print output by forming a visible image on a sheet. The image data in the image memory 907 is transferred in synchronization with a synchronization signal, a clock signal, a transfer request signal, and the like necessary for operating the printing process 908.

  In the above example, the print data has been described as being generated by the host computer 901. However, in some cases, the print data may be generated inside the printing apparatus 902 in order to check the test of the printing apparatus 902 and the device configuration. The page printed in this way is called a test page, and print data is generated in accordance with an instruction from a control panel (not shown) of the printing apparatus (909). The format of the print data generated by the test page generator 909 may be a PDL format or an object information format output by the PDL parser 905.

Also, as in Patent Document 1, rasterized by a host computer, rasterized data is divided into blocks, color information indicating the presence or absence of each component of CMYK is generated at the time of rasterization, and the amount of information transferred between the host computer and the printer is reduced. There was also something to do.
Japanese Patent Laid-Open No. 11-196281

  In the conventional example as described above, it has become clear that the following problems occur in a series of processing related to printing processing from the rendering 908 to the printing process 908.

  That is, it is a problem of processing speed for converting print data into image data. In order to improve the printing speed of printing devices, there has been a remarkable increase in the speed of the printing process in recent years, but in order to take advantage of the performance of this printing process, image data is stored in the image memory at a sufficient speed. It must be done.

  On the communication path connecting the host computer 901 and the printing apparatus 902, a method capable of realizing low-speed and high-speed communication such as USB 2.0, IEEE 1394, GigaBit Ethernet (registered trademark) has appeared, which becomes a bottleneck. Things are disappearing. However, in order to improve the processing speed of the PDL parser 905 and the rasterizer 906, it is necessary to install a CPU capable of high-speed processing in the printing apparatus 902 when these functions are realized by software. When these functions are realized by dedicated hardware such as so-called ASIC, the ASIC must be driven at a high frequency. In any case, the manufacturing cost of the printing apparatus 902 is soared, which is one obstacle to realizing a low-cost and high-speed printing apparatus.

  The present invention has been made in view of the above-described problems, and reduces the amount of data processing and realizes a high-speed image data generation method for a process for generating image data, thereby realizing a low-cost and high-speed printing apparatus. The purpose is to help realize

In order to achieve the above object, a first invention according to the present application is an image processing method for generating image data composed of at least two primary colors,
A rendering step for rendering one line based on input object data;
A line tag generation step of generating additional information indicating the presence or absence of color information of each primary color in the image data of one line generated by the rendering step;
A data conversion step of converting one line of image data generated by the rendering step into image data that can be processed by an image output unit;
A selection step of selecting processing contents of the data conversion step based on line tag information generated by the line tag generation step.

As explained above, according to the first invention of the present application,
In data processing to convert print data into image data, the amount of computation can be reduced,
There is an effect that a high-speed printing apparatus can be realized at low cost without using special hardware.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 2 is a schematic configuration diagram of a printing apparatus according to an embodiment of the present invention.

  In FIG. 2, a color laser printer 200 is a printing apparatus according to an embodiment of the present invention. The color laser printer 200 includes a printer controller 201, a laser beam printer engine 202, and a video interface 203 that connects the two. A host computer 204 transmits print data. Reference numeral 205 denotes an interface for connecting the host computer 201 and the color laser printer 200. Specifically, a USB (Universal Serial Bus), a parallel interface, a serial interface, an IEEE 1394 interface, an Ethernet (registered trademark) interface, or the like is used.

  The host computer 204 is a personal computer on which an operating system such as Windows (registered trademark) is operating. When application software such as a word processor requests printing, print data suitable for the color laser printer 200 is printed in the printer driver software. Is transferred to the color laser printer 200 via the interface 203.

  The print data transferred from the host computer 204 is subjected to predetermined image processing such as rasterization and halftone processing by the printer controller 201 and converted into image data. The generated image data is transmitted to the print engine 202 via the video interface 203, and the print engine 202 drives the electrophotographic process to print the received image data on a sheet as a recording medium. The laser beam printer engine of this printing apparatus is a printer engine that forms a color image with four color toners of C (cyan), M (magenta), Y (yellow), and K (black).

  FIG. 3 is a block diagram for explaining the color laser printer 200 in detail.

  The color laser printer 200 includes a printer controller 201, a laser beam printer engine 203, and a user interface 307.

  The printer controller 201 is composed of units 301 to 305, which will be described later, and controls the overall operation of the printer, such as processing the print data received from the host computer 204 into image data and sending it to the LBP engine together with various synchronization signals.

  The laser beam printer engine 203 is composed of a paper feed mechanism, an electrophotographic process, and the like. The laser beam printer engine 203 drives the paper feed mechanism in accordance with a command signal from the printer controller 201 to perform a paper feeding operation, and receives a video signal received from the printer controller 201 A laser driver is operated in accordance with the synchronization signal, and an image is formed on a medium such as paper supplied from a paper feeding mechanism using an electrophotographic process.

  The user interface 307 includes various buttons (not shown), LEDs, and a liquid crystal panel. The user inputs a request to the color laser printer 200 using the buttons, such as online / offline switching, test print execution, and print cancel. The user interface 307 notifies the input request to the printer controller 201, and the printer controller 201 notifies the user interface 307 of the state of the color laser printer 200 and displays it on the liquid crystal panel or the like.

  A CPU 301 is a processor for controlling the entire controller, and operates according to a program stored in a RAM 302 or a ROM 303 described later.

  The RAM 302 is a RAM for storing various data. An I / O buffer for storing data transmitted to and received from the host computer, an image memory for storing image data to be output by the printer engine 203, and a program executed by the CPU 301 are used as a working space for storing data.

  A ROM 303 is a ROM that stores a program of the CPU 301 and fixed data. When the power of the color laser printer 200 is turned on, the CPU 301 reads a program from the ROM 303 and starts controlling the color laser printer 200.

  The engine interface unit 304 is a unit for communicating with the laser beam printer engine 203. The engine interface unit 304 has a function of sending image data stored in the image memory of the RAM 302 to the laser beam printer engine 203, and a function of sending a command signal instructed by the CPU 301 and receiving a status signal.

  The I / O unit 305 is a unit for communicating with the host computer 204. Specifically, it comprises an IC called a USB controller, an Ethernet (registered trademark) controller, a parallel controller, or the like corresponding to the type of the interface 205 to be used. The I / O unit 305 stores the data transmitted from the host computer 204 in an I / O buffer in the RAM 302.

  Reference numeral 306 denotes a system bus.

  1 and 4 are flowcharts for explaining the image processing method of the present invention.

  In step S 101, as described in the conventional example, when processing the print data transmitted from the host computer 204, the CPU 301 analyzes the PDL data received from the I / O unit and stores information on the object to be drawn in the RAM 303. Convert and store in a data format that is easy to process. On the other hand, when a test print is instructed from the user interface 306, the CPU 301 collects information necessary for the test print and stores object information corresponding to the test print layout in the RAM 303. A set of object information generated in this way is called an object list.

  For example, in the example of the print data in which the rectangle 601, the rectangle 602, and the character string 603 are arranged on the canvas 600 as shown in FIG. 6, an object list as shown by 700 in FIG.

  The object list 700 in FIG. 7 includes object information 701 corresponding to the rectangle 601 in FIG. 6, object information 702 corresponding to the rectangle 602, and object information 703 corresponding to the character string 603. Each object information includes information useful for subsequent processing, as well as information for uniquely determining an object such as color, position, and size. For example, in this example, information indicating from what line to what line each object is drawn is added (704 and 705 in FIG. 7).

  Returning to FIG. 1, in step S102, the object list stored in the RAM 302 is rendered in a memory area on the RAM 302 called a line buffer.

  FIG. 4 is a flowchart for explaining in detail the processing in step S102 of FIG.

  In step S401, the line buffer is initialized. The line buffer is a memory area for storing image data for one line (FIG. 5). The line buffer includes an image data area (503) in which CMYK data (502) for one pixel can be arranged for one line, and line tag information (501) having the same size as that for one pixel. For example, when one pixel is composed of 8 bits for each of CMYK and one line is composed of 2000 pixels, the line buffer is composed of an image data area of 8000 bytes and a line tag of 4 bytes. The line tag is used to hold color information used in the image data area of the line buffer. In initialization, the image data area and the line tag are cleared to zero.

  In steps S402 to S405, the process is repeatedly applied to each object constituting the object list.

  In step S402, it is determined whether or not the object to be processed intersects the line to be rendered (that is, whether or not rendering is necessary). For example, if the 500th line (line indicated by 800 in FIG. 8) is processed according to the flowchart of FIG. 4 in the print data shown in FIG. 6, the rectangular object 701 has an intersection with the 500th line. The rectangular object 702 and the character string object 703 do not have an intersection. This can be easily determined from the information 704 and 705 added to the object information.

  In step S403, an object that needs to be rendered is rendered. For example, in the example of the processing for the 500th line, the image area corresponding to 400 pixels from the 100th pixel of the line buffer is represented by pixel data (C, M, Y, K) = (0, 0) according to the information of the rectangular object 702. , 0, 192).

In step S404, the line tag information is updated. In updating the line tag information, the C component of the line tag is TagC, the M component is TagM, the Y component is TagY, the K component is TagK, the C component of the pixel data used for filling in step S403 is ObjC, and the M component is ObjM. , Y component is ObjY, K component is TagK,
TagC = TagC | ObjC
TagM = TagM | ObjM
TagY = TagY | ObjY
TagK = TagK | ObjK
It is performed by the operation. Here, “|” is an operation symbol indicating a logical sum (OR) operation.

In the above 500th line example,
TagC = 0 | 0
TagM = 0 | 0
TagY = 0 | 0
TagK = 0 | 192
It becomes. Of course, when the object uses a plurality of colors in bitmap data or the like, the above formula is calculated for all the colors used, and the line tag is updated.

  In step S405, it is confirmed that processing has been performed for all objects, and the one-line rendering processing is completed.

  Returning to FIG. 1 again, from step S103 to step S107, the subsequent processing of rendering (halftone processing in this case) is performed for the C, M, Y, and K components.

  In step S104, the line tag corresponding to the component to be processed is read out. If the read value is 0, it becomes clear from the processing in step S404 described above that the color component is not used in this line, and the process proceeds to step S106. On the other hand, if the read value is not 0, the subsequent process is required, and the process proceeds to step S105.

  In the example of the 500th line, C, M, and Y of the line tags are 0 and K is 192. Accordingly, if the C, M, and Y components are being processed, the process proceeds to step S106, and if the K component is being processed, the process proceeds to step S105.

  In step S <b> 105, halftone processing is performed to reduce the gradation of the image data in the line buffer to a gradation suitable for the print engine 202.

  On the other hand, in step S106, since there is no color component, halftone processing is unnecessary, and only minimum processing necessary for processing of the next line such as various counter updates is performed.

  Comparing the processing of step S105 and step S106, since halftone processing (a kind of digital filter processing) is performed in step S105, the amount of calculation is large, and much processing time is required compared to step S106 that does not require calculation.

  In step S107, it is determined whether or not the processing in steps S104 to S106 has been applied to all the color components C, M, Y, and K. If all the color components have been processed, the process proceeds to step S108. If there is an unprocessed component, the process returns to step S103 to process the next color component.

  In step 108, it is determined whether or not processing has been performed for all lines of the data to be printed. If all the lines have been processed, the process ends. If there are unprocessed lines, the process returns to step S102. The process is performed on the line.

  When the flowcharts of FIGS. 1 and 2 are applied to the print data shown in FIGS. 6 and 7 (the total number of lines is 2000 lines), 1 to 399, 601 to 1199, 1601 to 1649, and 1801 to 2000 lines. Since there is no color component, the skip processing in step S106 can be applied to all components of CMYK. Further, since the CMY component of 400 to 600 lines, the CYK component of 1200 to 1600 lines, and the YK component of 1650 to 1800 lines are also 0, the skip processing in step S106 can be performed. Therefore, it can be understood that the amount of data processing to be processed is greatly reduced and the processing time is shortened as compared with the conventional method of performing halftone processing on all rendered data.

  As described above, in this embodiment, when rendering processing is performed, a line tag representing a color component existing in each line is generated, and the amount of calculation is reduced by referring to the line tag in processing subsequent to the rendering processing. And the processing time can be shortened.

(Other embodiments)
In the embodiment, the case where a laser beam printer is used as the printer has been described. However, the present invention is not limited to this, and can be applied to various other printers such as an ink jet printer.

  In the embodiment, the latter process of the rendering process has been described as the halftone process. However, the present invention is not limited to this, and can be applied to a case where the latter process is a density correction process such as gamma correction. It is.

  In the embodiment, the CMYK space has been described as the rendering color space. However, the present invention can also be applied to an RGB space or an expanded CMYK space including color components such as light magenta and light cyan in CMYK. .

It is a flowchart showing the image processing method of this invention. 1 is a configuration diagram illustrating a printing apparatus to which an image processing method of the present invention is applied. 1 is a configuration diagram illustrating details of a printing apparatus to which an image processing method of the present invention is applied. It is a flowchart for demonstrating the rendering process and line tag production | generation process in the image processing method of this invention. It is the figure which represented typically the line buffer used by the rendering process and line tag production | generation process in the image processing method of this invention. It is an example of the print data which the image processing method of this invention processes. It is an example of the object data input into the image processing method of this invention. It is a figure explaining the process example of the rendering process and line tag production | generation process of the image processing method of this invention. It is a figure for demonstrating a prior art example.

Explanation of symbols

200 A color laser printer that is an embodiment of an image processing apparatus of the present invention 201 A printer controller that executes the image processing method of the present invention 202 An image output unit that prints image data 203 A printer controller and an image output unit 204 is an interface for connecting print data 205 is a host computer for transmitting print data to a laser printer 205 is an interface for connecting a host computer and a printer controller

Claims (18)

An image processing method for generating image data composed of at least two primary colors,
A rendering step for rendering one line based on input object data;
A line tag generation step of generating additional information indicating the presence or absence of color information of each primary color in the image data of one line generated by the rendering step;
A data conversion step of converting the image data of one line generated by the rendering step into image data that can be processed by the image output unit;
An image processing method comprising: a selection step of selecting processing contents of the data conversion step based on line tag information generated by the line tag generation step.   2. The image processing method according to claim 1, wherein the image data is composed of CMYK.   2. The image processing method according to claim 1, wherein the image data includes CMYK and one or more color components.   2. The image processing method according to claim 1, wherein the image data is composed of RGB.   5. The image processing method according to claim 1, wherein the object data is a page description language.   6. The image processing apparatus according to claim 1, wherein the data structure of the additional information generated by the line tag generation process is the same as the data structure of one pixel of the image data generated by the rendering process. A featured image processing method.   7. The image processing method according to claim 6, wherein the line tag generation step performs an OR operation on the same color components of each color used in the rendered image data when generating the image data in the rendering step. An image processing apparatus characterized by   8. The image processing method according to claim 1, wherein the data conversion step is halftone processing.   9. The image processing method according to claim 1, wherein the selection step performs the data conversion process only on a color space in which the primary color is present in the additional information generated by the line tag generation step. An image processing method characterized by instructing the data conversion step. An image processing apparatus that generates image data composed of at least two primary colors,
Rendering means for rendering one line based on input object data;
Line tag generation means for generating additional information indicating the presence or absence of color information of each primary color in one line of image data generated by the rendering means;
Data conversion means for converting one line of image data generated by the rendering means into image data that can be processed by an image output unit;
An image processing apparatus comprising: selection means for selecting processing contents of the data conversion means based on line tag information generated by the line tag generation means.   The image processing apparatus according to claim 10, wherein the image data is composed of CMYK.   The image processing apparatus according to claim 10, wherein the image data includes CMYK and one or more color components.   The image processing apparatus according to claim 10, wherein the image data is composed of RGB.   14. The image processing apparatus according to claim 10, wherein the object data is a page description language.   15. The image processing apparatus according to claim 10, wherein the data structure of the additional information generated by the line tag generation unit is the same as the data structure of one pixel of the image data generated by the rendering unit. A featured image processing apparatus.   16. The image processing apparatus according to claim 15, wherein the line tag generation unit performs an OR operation on the same color components of each color used in the rendered image data when the rendering unit generates image data. An image processing apparatus characterized by   17. The image processing apparatus according to claim 10, wherein the data conversion means performs halftone processing. The image processing apparatus according to claim 10, wherein:
The image is characterized in that the selection means instructs the data conversion means to perform data conversion processing only on a color space in which primary colors exist in the additional information generated by the line tag generation means. Processing equipment.

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