JP2007168129A - Recorder, image formation controller, and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method which enable high-speed and high-quality image formation by generating optimum object attribute data according to a memory capacity and recording conditions. <P>SOLUTION: Rendering is carried out by interpreting PDL image information. Attribute data and raster image data for every object are generated. The recorder which records an image to a recording medium on the basis of these data is configured as follows. That is, the recorder is equipped with a compression means which compresses and encodes each of the attribute data and the raster image data, and a means which sets a target compressibility of the compression encoding by the compression means, for example, according to the memory capacity. Moreover, an attribute number of the attribute data is changed according to the memory capacity, and the attribute data is changed on the basis of the changed number of the attribute data. For achieving the set target compressibility, control is carried out so that the changed attribute data is compressed and encoded by the compression means, and further so that the raster image data is compressed and encoded. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording apparatus, an image formation control apparatus, and a recording method, and more particularly, to a recording apparatus, an image formation control apparatus, and a recording method that perform recording by mounting a recording head according to an ink jet system, for example.

  In recent years, OA equipment such as personal computers (PCs) and copying machines has become widespread, and ink jet recording apparatuses that perform digital image recording are rapidly becoming popular as a kind of recording apparatus for these apparatuses. In particular, colorization has progressed with the enhancement of the functionality of OA equipment, and various color ink jet recording apparatuses have been developed accordingly.

  In general, an ink jet recording apparatus (hereinafter referred to as a recording apparatus) includes a carriage on which a recording head and an ink tank are mounted, a conveying unit that conveys a recording medium such as recording paper, and a control unit that controls them. The recording head for ejecting ink droplets from a plurality of ejection openings scans in the direction (main scanning direction) orthogonal to the recording medium conveyance direction (sub-scanning direction), while recording is performed when non-recording. The recording medium is intermittently conveyed by an amount equal to. Furthermore, in the case of a recording apparatus that supports color recording, a color image is formed by superimposing ink droplets ejected from a recording head that ejects a plurality of colors of ink.

  In this recording apparatus, the following two ink ejection methods are typical.

  One is to provide a heating element (electrothermal energy converter) in the vicinity of the discharge port, and by applying an electrical signal to this heating element, the ink is locally heated to cause a pressure change, and the ink is discharged from the discharge port. This is called the thermal method. The other is called a piezo method in which an electrical pressure converting means such as a piezo element is used to apply a mechanical pressure to ink and eject the ink.

  In general, the former thermal method makes it easy to increase the density of nozzles and allows the recording head to be configured at low cost. However, since heat is used, the ink and the recording head are liable to deteriorate. On the other hand, the latter piezo method is characterized by excellent discharge controllability, high degree of ink freedom, and semi-permanent print head life.

  In any case, the ink jet recording method records characters, figures, and the like by ejecting minute ink droplets onto the recording medium from the ejection port in accordance with a recording signal, and has the following advantages. That is, since it is a non-impact recording method, noise is low, running cost is low, the apparatus is easy to miniaturize, and colorization is easy. For this reason, it is widely used as recording means in recording apparatuses such as copiers, printers, and facsimiles that are used in combination with computers or word processors, or used alone.

  In the conventional ink jet recording method, it is necessary to use a special coated paper having an ink absorbing layer in order to obtain a color image with high color without ink bleeding. However, in recent years, a method has been put to practical use that has the ability to record on plain paper that is used in large quantities in printers, copiers, etc. by improving ink.

  In addition, it is desired to support various recording media such as an OHP sheet, cloth, and plastic sheet. In order to meet these demands, development and commercialization of a recording apparatus capable of performing the best recording regardless of the type of the recording medium when a recording medium having different ink absorption characteristics is selected as necessary has been promoted. Furthermore, regarding the size of the recording medium, a large size has been required for woven fabrics such as posters and clothes for advertising. The demand for such a recording apparatus is increasing in a wide range of fields as an excellent recording means, and it is demanded to provide a higher quality image, and it can be said that the demand for higher speed is further increased.

  In a general color inkjet recording method, color recording is realized using four color inks obtained by adding black (K) to three color inks of cyan (C), magenta (M), and yellow (Y). In such a recording apparatus, unlike a monochrome recording apparatus that records only characters, it is necessary to consider various factors such as ink color development and gradation uniformity when recording a color image.

  Further, in such a recording apparatus, a natural image is formed with higher gradation by further expressing the image, so that conventional cyan (C), magenta (M), yellow (Y), and black (K) are used. In addition to these four colors, another ink is added. That is, the graininess of the highlight portion is reduced by using seven color inks, which are three colors of light cyan (LC), light magenta (LM), and light yellow (LY) having a low ink density.

  Among such recording apparatuses, there is a so-called page printer that analyzes information including color multi-value information of a page description language (PDL) method in page units and prints out in page units. PDL is language information for transferring image information to a printer with a small amount of data by dividing drawing data on a page into drawing elements such as characters, graphics, and images called objects and converting them into object codes.

  When using PDL, first, information to be formed in an image described in PDL is transmitted from the host PC, the received PDL data is interpreted on the printer side, and intermediate data called a display list is generated and held. Next, image information corresponding to the recording resolution is generated from various information by performing rendering (conversion to a raster image) according to the intermediate data. There are two types of PDL, which are characterized by advanced graphics functions such as PostScript (registered trademark), and types that are characterized by high-speed processing functions that can be recorded at high speed, such as LIPS and PCL.

  FIG. 11 is a block diagram showing a schematic configuration of a recording apparatus using PDL corresponding to color image recording. As shown in FIG. 11, the recording apparatus includes an image forming controller 1201 and an image forming engine 1202. The image forming controller 1201 realizes an interface for transmitting / receiving image information and various control information to / from a host such as a PC, and generation of image forming data based on input image information. On the other hand, the image forming engine 1202 controls the conveyance of the recording medium and the carriage driving control and drives the recording head to eject ink onto the recording medium to form an image.

  Next, the data flow in the image forming controller will be described in detail.

  There are two main methods for drawing PDL data.

  One is a method called contone rendering, in which rendering processing is executed with RGB multi-value data (in many cases, 8 bits for each color), and the output data format is similarly RGB multi-value data. The other is a method called halftone rendering. According to this method, a display list obtained by converting RGB multi-value data into a color space obtained by adding black (K) to the desired three color inks of cyan (C), magenta (M), and yellow (Y) is desired. And halftone processing prior to rendering processing. The output data format of the halftone rendering method is KCMY data subjected to gradation conversion. It is also possible to perform halftone processing before the display list.

  FIG. 12 is a diagram showing a flow of data processing in the image forming controller according to the contone rendering method.

  In block 1101, when various PDL data is received from the host PC, the CPU analyzes the PDL data, and in block 1102, converts it into intermediate data (display list (DL)) for high-speed rendering processing. The DL buffer 1103 assigned to the RAM normally stores a display list for one page.

  Subsequently, in block 1104, conversion processing (rendering) into 8-bit raster image data of each color of RGB is performed according to the display list generated and stored. Here, raster image conversion processing for each band is performed in accordance with a display list for each band having a smaller number of lines than one page. Then, the type of each object constituting the raster image data is recognized, attribute data indicating the object type is added, and output to the drawing buffer 1105.

  Raster image data and attribute data, which are rendering processing results, are temporarily stored in the rendering buffer 1105, and then subjected to compression encoding processing using a lossy method and a lossless method in block 1006, and the results are stored in the page buffer 1107. Hold. In block 1108, the compressed data held in the page buffer 1107 is read at the time of image recording, decompressed (decoded), processed, and temporarily stored in the image processing buffer 1109. In block 1110, color conversion and halftone processing are executed with reference to the attribute data for the RGB multi-value data to generate 1-bit data for each color of the KCMY component of the output resolution.

  The generated dot data is transferred to the image forming engine 1202.

  Here, the attribute data indicates the type of object, and is configured to identify, for example, chromatic colors and achromatic colors in addition to characters, fine lines, figures, halftone images, and the like. By performing appropriate color adjustment and halftone processing while referring to the attribute data assigned to each pixel in the subsequent image processing, it is possible to achieve high image quality of the final print output.

  Compression encoding is performed to hold the raster image and attribute data generated as described above in a limited memory in units of pages. In color images, raster images created by rendering are very large, and it is difficult to perform highly efficient data compression at all times with a reversible compression method, so an irreversible compression method (for example, JPEG) is adopted. . In the JPEG method, the code amount and image quality can be controlled by controlling the quantization step when quantizing the DCT transform coefficient. In actual compression rate adjustment, if the expected code amount is exceeded, the compression rate (quantization parameter) is changed and compression encoding is performed again, or the code amount is estimated by pre-scanning in advance and quantized. A method of setting parameters is used.

  On the other hand, since the attribute data is not allowed to deteriorate, reversible compression (for example, pack bits compression) is performed. In a lossless compression method typified by packbits compression or the like, the code amount cannot be adjusted, and the size after compression may become very large depending on the data characteristics.

  If the size of the attribute data after compression is large, the ratio of the attribute data to the whole becomes large. Therefore, the total size must be kept small by increasing the compression rate of the raster image. As a result, the image quality deterioration due to lossy compression exceeds the image quality improvement effect using attribute data, leading to a reduction in image quality of the output image.

Therefore, a method has been proposed in which, when the target compression rate is not reached, a replacement bit is determined from the attribute data, and attribute value replacement processing is performed to reduce the amount of information and increase the compression rate (for example, (See Patent Document 1 and Patent Document 2). Specifically, all the identification information of achromatic characters and chromatic characters is replaced with chromatic characters, or the identification information of characters, line drawings, and halftone pixels is all changed to indicate halftone pixels.
JP 2003-069835 A Japanese Patent Laid-Open No. 2004-214738

  However, the conventional image forming controller has the following problems.

  As described above, compression encoding is performed to hold the generated raster image and attribute data in a limited memory in units of pages. An irreversible compression method is employed for the raster image, and the code amount, that is, the compression rate can be adjusted by selectively controlling parameters such as a quantization table. Control is performed so as to suppress the target code amount by repeating the sequential change from the high image quality / low compression parameter to the low image quality / high compression parameter.

  For attribute data, a reversible compression method is adopted, and the amount of code, that is, the compression rate is adjusted by reducing the amount of attribute information as a source. Using the object attribute type created during rendering as the initial value, fixing specific identification information as necessary reduces the attribute type to reduce the amount of information, and consequently suppresses the amount of code after lossless compression. .

  Here, the retry processing that occurs when the raster image and the attribute data do not satisfy the target compression rate, that is, the image recompression processing and the attribute information reduction processing, only requires a lot of time for the processing itself. But it puts a heavy load on the entire system including the memory. Therefore, when the retry process is repeatedly executed, the throughput may be reduced.

  In creating attribute data at the time of rendering, the processing load increases as the various object attributes are identified, leading to an increase in rendering time. In particular, in the case of software rendering by a CPU employed in an image forming controller of a low-cost recording apparatus, it causes a reduction in recording speed.

  Furthermore, in situations where high compression of the raster image and attribute data is required, encoding the raster image with high compression as a result of the excessive amount of attribute information is a balanced image quality improvement process. It will also interfere.

  In many cases, the target compression rate in actual page data compression largely fluctuates according to the memory loading amount of the system, the size of the raster image, and the recording conditions such as double-sided or single-sided printing. However, the conventional image forming controller determines (fixes) the number of object attribute types for each pixel to be identified at the rendering stage regardless of the set target compression rate. Therefore, in order to achieve the optimum balance between image quality degradation suppression in lossy compression and image quality improvement by attribute adaptation processing, a large number of retry processes are required, which may cause a decrease in final recording performance. .

  The present invention has been made in view of the above-described conventional example. A recording apparatus and an image formation control apparatus that generate optimal object attribute data according to a memory capacity and recording conditions and enable high-speed and high-quality image formation. And to provide a recording method.

  In order to achieve the above object, the recording apparatus of the present invention has the following configuration.

  In other words, rendering is performed by interpreting PDL image information input from the outside, generating attribute data and raster image data for each object, and recording an image on a recording medium based on the attribute data and raster image data A first compression means for compressing and encoding the attribute data; a second compression means for compressing and encoding the raster image data; resources of the recording apparatus and recording conditions by the recording apparatus; In accordance with at least one of compression ratio setting means for setting a target compression ratio in compression encoding by the first and second compression means according to at least one of the above, resources of the recording apparatus, and recording conditions by the recording apparatus , Based on the number of attribute data changed by the attribute changing means, the number of attribute data changing means for changing the number of attributes of the attribute data, A change means for changing the attribute data, and the first compression means compresses and encodes the attribute data changed by the change means so as to achieve the target compression ratio set by the compression ratio setting means, Compression control means for controlling the raster image data to be compression-encoded by two compression means, storage means for storing code data compression-encoded by the first and second compression means, and storage means Recording means for reading out the stored code data, decompressing it, performing image processing, and recording an image on the recording medium based on the image data subjected to the image processing.

  Here, the resource of the recording apparatus is a memory, and the compression rate setting unit and the attribute number changing unit respectively set the target compression rate and change the attribute number of the attribute data according to the capacity of the memory. Good.

  Further, the recording conditions by the recording apparatus include the size of the recording medium, recording on one side of the recording medium or recording on both sides, and the compression rate setting unit and the attribute number changing unit are respectively It is preferable to set the target compression rate and change the number of attributes of the attribute data.

  The first compression unit performs compression encoding using a reversible compression method such as a Packbits method, and the second compression unit uses an irreversible compression method such as a JPEG method. It is preferable to use compression coding.

  Further, the attribute data preferably includes, for each pixel of the image, information indicating a character, a figure or an image type, a distinction as to whether it is a line, and a distinction between a chromatic color and an achromatic color. In this case, it is preferable that the changing unit changes the attribute data so as not to distinguish at least one of the distinction between the line and the chromatic color or the achromatic color.

  The compression control unit includes a plurality of quantization tables in which quantization parameters used for compression encoding are classified into a plurality of stages from the viewpoint of image quality and compression rate, the first compression unit, and the second compression unit. Comparing means for comparing a code amount obtained by compression encoding executed by at least one of the target coding amount obtained from a target compression rate set by the compression rate setting means, and According to the comparison result by the comparison means, the table used for the compression encoding is switched and selected from the plurality of quantization tables, and the first compression means or the second compression means is selected using the quantization table selected by switching. It is desirable to include repetitive control means for performing control so as to execute compression encoding according to the above.

  Furthermore, it is desirable to include change control means for changing the attribute data so as to change the number of the attribute data by controlling the change means according to the comparison result by the comparison means. Here, the change control means may control the number of attribute data to be relatively small when high compression is required according to the target compression rate.

  The recording means preferably includes an ink jet recording head, and the PDL image information is preferably color image information.

  According to another invention, rendering is performed by interpreting PDL image information input from the outside, generating attribute data and raster image data for each object, and recording media based on the attribute data and raster image data An image formation control apparatus for generating image data for recording an image on the first compression means for compressing and encoding the attribute data; a second compression means for compressing and encoding the raster image data; A compression rate setting means for setting a target compression rate in compression encoding by the first and second compression means according to at least one of a resource of the recording device and a recording condition by the recording device; and a resource of the recording device And attribute number changing means for changing the number of attributes of the attribute data according to at least one of the recording conditions by the recording device, and the attribute change The change means for changing the attribute data based on the number of the attribute data changed by the stage, and the change by the first compression means so as to achieve the target compression ratio set by the compression ratio setting means Compression data encoded by the second compression means, and compression encoded by the first and second compression means. The compression control means controls the raster data to be compressed and encoded by the second compression means. Storage means for storing the encoded data, and transfer means for reading out and decompressing the encoded data stored in the storage means to perform image processing, and transferring the image data subjected to the image processing to a printer engine. An image forming control device is provided.

  According to still another invention, rendering is performed by interpreting PDL image information input from the outside, and attribute data and raster image data for each object are generated and recorded based on the attribute data and raster image data. A recording method for recording an image on a medium, comprising: a first compression step for compressing and encoding the attribute data according to at least one of a resource of the recording device and a recording condition by the recording device; and the raster image data According to at least one of a compression rate setting step for setting a target compression rate in compression encoding in the second compression step for compression encoding, and a resource of the recording device and a recording condition by the recording device, the attribute data An attribute number changing step for changing the number of attributes, and the number of the attribute data changed in the attribute changing step, the attribute The attribute data changed in the changing step in the first compression step so as to achieve the target compression rate set in the compression rate setting step and the changing step for changing the data, and the second A compression control step for controlling the raster image data to be compression-encoded in the compression step, and reading out the code data from a storage medium storing the code data compression-encoded in the first and second compression steps. And a recording step of recording an image on the recording medium based on the image data subjected to the image processing.

  Therefore, according to the present invention, it is possible to adjust the number of attribute data of each object in accordance with a target compression rate in compression encoding determined according to a memory capacity to be mounted, a recording size, and the like.

  Accordingly, it is possible to suppress the total processing load related to image formation by suppressing the attribute data amount, and as a result, high-speed image formation can be performed.

  For example, when the memory capacity is relatively large, or when recording in a small size or single-sided recording, it is possible to realize a high image quality process that reflects various subdivided object attributes. On the other hand, when the installed memory capacity is relatively small, or when recording in large size or double-sided, it is possible to achieve high-speed recording by reducing the object attributes while suppressing image quality degradation. It becomes. In this way, high-speed and high-quality image formation can be realized.

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

  FIG. 1 is a diagram showing a schematic configuration of an ink jet recording apparatus (hereinafter referred to as a recording apparatus) which is a typical embodiment of the present invention.

  In FIG. 1, reference numeral 601 denotes a head cartridge, which is an independent ink tank corresponding to each of four color inks of black (K), cyan (C), magenta (M), and yellow (Y). It is composed of a multi-head composed of four recording heads. Each recording head has 1280 nozzles. Reference numeral 602 denotes a carriage that supports the head cartridge 601 and moves them together with recording. The carriage 602 is at the home position (HP) shown in the drawing during standby such as a non-recording state. Reference numeral 603 denotes a conveyance roller, which rotates while holding the recording paper 605 together with an auxiliary roller (not shown), and conveys the recording paper 605 in the Y direction as needed. Reference numeral 604 denotes a paper feed roller that feeds the recording paper 605 and plays a role of suppressing the recording paper 605 in the same manner as the transport roller 603 and the auxiliary roller.

  Each of the four recording heads has 1280 nozzles arranged in the transport direction.

  A basic bidirectional recording operation in the above configuration will be described with reference to FIG.

  During standby, the carriage 602 at the home position (HP) performs recording by ejecting ink onto the recording paper 605 according to the recording data by a plurality of nozzles of the recording head while moving in the X direction by a recording start command. This carriage movement direction is called the main scanning direction. When the recording is completed to the end of the recording paper 605, the recording paper 605 is conveyed by a predetermined width in the Y direction by the rotation of the conveying roller 604. This recording paper conveyance direction is referred to as the sub-scanning direction. Subsequently, the carriage 602 performs recording by discharging ink while moving the X direction in the reverse direction, and the carriage 602 returns to the home position (HP). Image recording is realized by repeating the carriage scanning operation and the recording paper transport operation.

  The recording apparatus basically includes an image forming controller and an image forming engine as shown in FIG.

  Four pl ink droplets are ejected by one ejection operation from four recording heads each having 1280 nozzles used in the recording apparatus of this embodiment. Further, 1280 nozzle rows are arranged in order as nozzle rows for ejecting K, C, M, and Y inks in the main scanning direction. Further, the nozzle resolution of the recording head is 1200 dpi.

  Then, bidirectional recording is performed as described above, and dot formation with a resolution of 1200 dpi × 1200 dpi is performed in one pass.

  FIG. 2 is a diagram illustrating a recording scan state of the recording head in bidirectional recording.

  As shown in FIG. 2, the recording paper equivalent to 1280 lines is first formed after the image formation of 1280 lines in the forward scan, and then the recording paper equivalent to 1280 lines is formed after the image formation of 1280 lines in the backward scan. I do. By repeating this, bidirectional recording is realized.

  3 is a block diagram showing a schematic configuration of the image forming controller.

  The CPU 501 is connected to the host PC 503 via the communication interface 502. The CPU 501 accesses a ROM 505 that stores control programs, an EEPROM 506 that stores updatable control programs and processing programs, various constant data, and the like, and a RAM 504 that stores command signals and image information received from the host PC 503. The recording operation is controlled based on the information stored in these memories.

  The RAM 504 is configured so that the memory capacity can be expanded by using an expansion port. Instruction information key-inputted from the operation panel 508 is transmitted to the CPU 501 via the operation panel interface 507, and the LED lighting and LCD display of the operation panel 508 are similarly controlled via the operation panel interface 507 according to instructions from the CPU 501. The An expansion interface 509 is an interface for performing function expansion by connecting an expansion card 510 such as an HDD.

  The rendering unit 511 interprets the intermediate data (display list (DL)) generated by the CPU 501 and generates a raster image and attribute bits corresponding to each pixel. The irreversible compression unit 514 encodes the raster image in an irreversible manner, and the irreversible decompression unit 515 decodes the raster image that has been compression-encoded in the irreversible manner. The lossless compression unit 512 encodes the attribute bits using a lossless method, and the lossless decompression unit 513 decodes the attribute bits that have been compression encoded using the lossless method. The image processing unit 516 generates and outputs image formation data of each color ink that conforms to the engine specifications by performing optimal image processing according to the object type such as characters and graphics based on the attribute bits. The image forming data is sent to the image forming engine 518 via the engine interface 517.

  Note that the RAM 504 can be expanded in memory, and by adding 128 Mbytes of expansion memory to 128 Mbytes of standard installed memory, a RAM having a total capacity of 256 Mbytes can be provided.

  Next, PDL processing and image processing will be described in detail.

  The basic data flow of these processes is as already described in the background art with reference to FIG. In summary, first, conversion to a raster image is performed according to a display list (DL), which is intermediate data interpreted and generated from PDL data received from the host PC, and in a format suitable for image formation by the image forming engine. Conversion to dot data is performed. Note that the PDL data is image data in which drawing contents are described, and is divided into font data representing characters and numbers, vector data representing geometric line drawings, various bitmap image data such as natural images, and the like.

  FIG. 4 is a diagram showing the contents of attribute data generated together with the raster image at the time of rendering.

  In this embodiment, the attribute data generated together with the raster image at the time of rendering is 4 bits per pixel. As shown in FIG. 4, bits 3 to 2 indicate that “01” is a character, “10” is a figure, “11” is a halftone image, and “00” does not constitute an object. Bit 1 indicates a thin line when “1”. Bit 0 represents an achromatic color when “1”, and a chromatic color when “0”. For example, if bits 3 to 0 are “0101”, it means an achromatic character, and “1010” means a chromatic thin line.

  Here, the raster image is 8-bit data for each color in the RGB format, and the JPEG method is used as the lossy compression method. In this embodiment, an 8-level quantization table (QTABLE # 0 to # 7) is provided.

  FIG. 5 shows an 8-level quantization table.

  As shown in FIG. 5, in this embodiment, a table from the table (QTABLE # 0) representing the highest image quality / low compression parameter to the parameter (QTABLE # 7) representing the lowest image quality / high compression parameter is appropriately selected. Therefore, compression encoding can be performed with as high image quality as possible.

  As described above, the attribute data is composed of 4 bits per pixel, and in this embodiment, pack bits compression is used as a lossless compression method. In the reversible Packbits method, the capacity of the compression result is fixed and the data amount cannot be adjusted. For this reason, the amount of compression information of attribute data can be reduced by reducing the number of attribute types. Specifically, the attribute type is changed by replacing (replacing) an achromatic color with a chromatic color (bit 0 is fixed to “0”) and a thin line is converted into a figure (common) (bit 1 is fixed to “0”). Reduce. Here, this is handled by converting the identification bit, but it is also possible to reduce the number of bits according to the number of values that can be taken as a result of the reduction.

  Note that a target compression rate is set in the compression encoding process, and the compression process is repeatedly executed by changing parameters (quantization table) as necessary. As described above, in irreversible compression, the raster image is deteriorated with high compression, and the image quality deterioration is visually recognized. Also, although attribute data is highly compressed by bit replacement processing (conversion processing), lost attribute identification information cannot be restored, so that object attribute adaptation processing in subsequent image processing is limited.

  Next, based on the above, the adaptive control processing of the number of object attributes according to the target compression rate designation will be described with reference to a flowchart.

  FIG. 6 is a flowchart showing an adaptive control process for the number of object attributes.

  FIG. 7 is a diagram showing a list of relationships among the RAM memory capacity, the target compression rate, and the number of object identifications.

  As can be seen from this figure, in this embodiment, the number (type) of object attributes identified and generated at the time of rendering is adaptively controlled with respect to fluctuations in the target compression ratio according to the memory capacity of the RAM. When the memory capacity is large, not only can the target compression rate of a raster image or the like be set loosely, but also various buffers can be secured sufficiently large, which contributes to speeding up the overall processing.

  Returning to FIG. 6, the description will be continued. First, in step S101, it is checked whether the memory installed in the recording apparatus is only the standard memory or the memory is added prior to data processing. The target compression rate in the page spool and the number of object attributes that are identified and generated at the time of rendering are controlled according to the state of the mounted memory.

  If it is determined that the installed memory is only the standard memory (that is, the memory capacity is 128 Mbytes), the process proceeds to step S102 and 1/12 is set as the target compression rate (R). In step S103, “8” is set as the object attribute number (N). On the other hand, if it is determined that the installed memory is in the memory expansion state (that is, the memory capacity is 256 Mbytes), the process proceeds to step S104 and 1/8 is set as the target compression ratio (R). To do. In step S105, “16” is set as the object attribute number (N).

  Thereafter, when the PDL data is received in step S106, the process proceeds to step S107, and the CPU 501 interprets the PDL and generates a display list (DL). Further, in step S108, rendering processing is performed according to the generated display list (DL), and attribute data of a type corresponding to the raster image and the amount of installed memory is generated.

  In step S109, the generated raster image and attribute data are compression-encoded and stored in the page buffer (see 1107 in FIG. 11). Here, the compressed page data is completed by repeatedly performing the recompression process until the target compression rate (R) is achieved. This recompression process may involve a re-rendering process. In step S110, optimum image processing is performed to generate desired image formation data of the final image formation engine.

  Here, details of the compression encoding in step S109 will be described.

  FIG. 8 is a flowchart showing detailed processing of compression encoding.

First. In step S201, a table QTABLE # 0 indicating initial parameters is set as a quantization parameter. Next, in step S202, compression encoding of the raster image and attribute data generated by rendering is performed. In step S203, whether or not the compression result fits in the page buffer, that is, whether the code amount fits in the target size. Detect or predict whether or not.

  Here, when it is determined that the code amount obtained by compression encoding exceeds the target code amount, the process proceeds to step S204, and whether or not the currently used quantization table is QTABLE # 4. Check out. If so, the process proceeds to step S208; otherwise, the process proceeds to step S205. In step S205, it is checked whether the quantization table currently in use is QTABLE # 6. If so, the process proceeds to step S209; otherwise, the process proceeds to step S206.

  If the code amount obtained by compression encoding using the initial parameter (QTABLE # 0) exceeds the target value, the process proceeds to step S206, and the QTABLE number that is the compression parameter of the raster image is set to “+1”. Increment by ". Thereafter, the process proceeds to step S207, and the raster image recompression process is repeated.

  If the compression amount of the raster image is QTABLE # 4 and the code amount obtained by the compression encoding exceeds the target code amount, the process sets the number of object attributes in the attribute data to “ Reduce from 16 ”to“ 8 ”. Thereafter, the process proceeds to step S210, and attribute data recompression processing is performed.

  Further, if the code amount obtained by the compression encoding exceeds the target code amount even if the compression parameter of the raster image is QTABLE # 6, the process proceeds to step S209 where the number of object attributes in the attribute data Is reduced from “8” to “4”. Thereafter, the process proceeds to step S210, and attribute data recompression processing is performed.

  On the other hand, if it is determined in step S203 that the code amount obtained by compression encoding is equal to or less than the target code amount, the process proceeds to step S211. Here, it is checked whether or not the page processing is completed. If it is determined that the processing is not completed, the processing returns to step S202. If it is determined that the processing is completed, the compression encoding processing is terminated.

  In this way, the number of types of object attributes generated for each pixel at the time of rendering is controlled according to the target compression rate determined corresponding to the memory capacity to be mounted. As a result, when the memory is expanded, it is possible to achieve a target compression ratio with a relatively large number of attributes for most image data and realize fine object adaptation processing. On the other hand, in the case of only the standard memory, the adaptive control process for the number of object attributes is started from a small number of attributes, thereby avoiding a decrease in throughput due to repeated execution of the attribute reduction process.

  Now, when the installed memory capacity is small, not only the page buffer but also the allocated capacity of various buffers in the entire system becomes small, and various data processing performance inevitably deteriorates. Especially in rendering processing with heavy processing load, performance degradation is significant when the memory capacity is small. However, the above processing reduces the rendering processing load by reducing the type information amount of the object attribute to be identified and generated, so that a decrease in printing speed can be minimized.

  Therefore, according to the embodiment described above, the number of types of object attributes generated for each pixel at the time of rendering is selected and controlled according to the target compression rate according to the memory mounting amount, and the number of object attributes is relatively set when the memory capacity is small. Set smaller. As a result, deterioration in rendering processing performance due to various buffer shortages is avoided, and repeated execution of compression processing for achieving the target compression rate is suppressed, so that a reduction in throughput can be avoided.

  Also, when the memory capacity is large, optimal image quality improvement processing is performed for each subdivided object attribute, and when the memory capacity is small, the image quality reduction due to compression and the object attribute adaptation processing are balanced. Is possible.

<Other examples>
In the above-described embodiment, the case has been described in which the target compression rate and the number of object attribute identifications are set and controlled in accordance with the increase or decrease in the amount of memory installed in the recording apparatus. In this embodiment, target compression ratio control and object attribute identification number control according to recording conditions such as raster image size, double-sided or single-sided printing will be described.

  The basic configuration of the recording apparatus and the configuration of the image forming controller used in this embodiment are the same as those in the above-described embodiment. The recording apparatus in this embodiment can record various page sizes including A3 and A4. The A4 size also supports double-sided printing. Further, the basic data flow in the image forming controller is as described with reference to FIG.

  Here, the adaptive control of the number of object attributes in accordance with the target compression rate designation characteristic in this embodiment will be described with reference to a flowchart.

  FIG. 9 is a flowchart showing an adaptive control process for the number of object attributes. In FIG. 9, the same processing steps as those already described with reference to FIG. 6 are denoted by the same step reference numerals, and the description thereof is omitted.

  As described above, the image forming controller in this embodiment is capable of printing with various page sizes and duplex printing with some sizes. Therefore, the image forming engine of this embodiment has a mechanism capable of high-speed double-sided printing, and the target compression rate in compression encoding is determined according to the number of pages staying inside the recording apparatus and the page size.

  FIG. 10 is a diagram showing a list of relationships among the recording size, single-sided / double-sided printing, target compression rate, and number of object identifications.

  As shown in FIG. 10, in this embodiment, the target compression rate is 1/8 for single-sided printing in which the recording paper exceeds A4 size, 1/6 for single-sided printing in which the recording paper is A4 size or smaller, and A4 size for the recording paper. In the following double-sided printing, it is assumed to be 1/10.

  Prior to data processing, first, in step S901, it is checked whether the recording page size exceeds the recording paper A4 size. If the size exceeds the A4 size, the process proceeds to step S902. If the size is equal to or smaller than the A4 size, the process proceeds to step S903. Next, in step S902, it is checked whether or not double-sided printing is performed as a recording condition. Here, if it is double-sided printing, the process proceeds to step S907, and if it is single-sided printing, the process proceeds to step S905.

  In step S903, “1/8” is set as the target compression ratio (R) for single-sided printing exceeding A4 size, and “16” is set as the number of object attributes (N) in step S904. Thereafter, the process proceeds to step S106.

  On the other hand, in step S905, “1/6” is set as the target compression ratio (R) for single-sided printing of A4 size or smaller, and in step S906, “16” is set as the number of object attributes (N). To do. Thereafter, the process proceeds to step S106.

  Furthermore, in step S907, “1/10” is set as the target compression ratio (R) for double-sided printing of A4 size or smaller, and in step S908, “8” is set as the number of object attributes (N). Set. Thereafter, the process proceeds to step S106.

  Hereinafter, as described in the above-described embodiment, the processes of steps S106 to S110 are executed. Note that the detailed processing of compression encoding in step S109 is the same as that in the above-described embodiment.

  As described above, in this embodiment, the type of object attribute generated for each pixel at the time of rendering is controlled according to the target compression rate determined in association with the recording condition. Thus, when the page size is small or single-sided printing, the target compression rate is achieved with a relatively large number of attributes for most image data, and fine object adaptation processing is realized. In contrast, when the page size is large or double-sided printing is started, adaptive control processing for the number of object attributes is started from a small number of attributes, thereby avoiding a decrease in throughput due to repeated execution of attribute reduction processing.

  When the page size to be recorded is large, or when the number of pages to be spooled for double-sided printing is large, restrictions on various buffer capacities of the entire system increase, which inevitably causes various data processing performances to deteriorate. In particular, in rendering processing with heavy processing load, when the memory capacity is small, the performance degradation is significant. However, in this embodiment as well, in this case, the type information amount of the object attribute to be identified and generated is reduced, thereby reducing the rendering processing load and avoiding a decrease in print speed.

  According to the embodiment described above, the number of types of object attribute information generated for each pixel at the time of rendering can be selected and controlled according to the recording conditions.

  For example, when the page size is large or duplex printing, the object attribute number is set relatively small. As a result, it is possible to avoid a decrease in rendering processing performance due to various buffer shortages, and it is possible to avoid a decrease in throughput by suppressing repeated execution of compression processing to achieve the target compression rate. Furthermore, when the page size is small or single-sided printing, it is possible to perform optimum image quality improvement processing for each subdivided object attribute. Thus, when the page size is small or single-sided printing, it is possible to achieve a balance between image deterioration suppression accompanying compression and high image quality by object attribute adaptation processing.

  In the above-described two embodiments, the case where the target compression rate is set according to the installed memory capacity and the recording condition has been described. However, the present invention is not limited to this. For example, the control may be performed by combining these, or may be determined by combining the priority setting of the print speed and the image quality, the type of medium used, and the like. It is also possible to deal with a target compression ratio that changes based on memory allocation that is dynamically changed according to the internal state of the recording apparatus.

  In the above-described two embodiments, an example is shown in which the deterioration state is determined only from the parameters used in the raster image compression, and the process proceeds to the object attribute identification number reduction process. On the other hand, in the lossy compression such as the JPEG method, deterioration is remarkably recognized with respect to characters. For this reason, it is possible to appropriately determine the deterioration state based on the distribution of the character attributes in the attribute data, the user setting, and the like, and to switch the transition threshold of the object attribute identification number reduction process.

  Furthermore, in the above two embodiments, the ink jet recording apparatus using four color inks of K, C, M, and Y has been described as an example. However, the number of ink colors and color types usable in the recording apparatus are It is not limited to. For example, three color inks except K may be used, light color inks such as light cyan (LC), light magenta (LM), light yellow (LY), and light black (LB), or red (R ), Blue (B) and other special colors may be added. Further, the number of recording heads to be mounted is not limited to one for each ink, and a configuration may be adopted in which a plurality of recording heads are provided for some or all ink colors to achieve high-speed recording.

  Furthermore, the present invention is not limited by the operation principle or configuration of the recording head. For example, the above-described thermal method may be used, or a piezo method may be used.

  Furthermore, in the above-described embodiment, the case where image formation is performed by the ink jet recording apparatus has been described. However, the image forming system applicable to the present invention is not limited to the ink jet system. For example, the present invention can be applied to other serial recording scanning methods such as a thermal transfer method and a thermal method, and an electrophotographic image forming system.

  Further, in the above-described embodiment, the configuration in which the display list (DL) generation process, the rendering process, the image formation data generation process, and the like are all performed inside the image formation system has been described, but the present invention is not limited thereto. For example, it is obvious that some or all of these may be realized by a driver on the host PC side to be connected or other external device.

  Further, the form of the image forming system to which the present invention is applied is not limited to that provided as an integrated or separate image output apparatus for information processing apparatuses such as computers and word processors. For example, the present invention can be applied to a copying machine combined with an image reading apparatus or a facsimile machine having a communication function.

1 is a diagram showing a schematic configuration of a printer equipped with an ink jet recording head that is a typical embodiment of the present invention. FIG. It is a figure explaining the mode of the bidirectional | two-way recording scanning by the printer shown in FIG. FIG. 2 is a block diagram illustrating a schematic control configuration of an image forming controller of the printer illustrated in FIG. 1. It is a figure explaining the example of assignment of an attribute bit. It is a figure which shows 8 types of quantization tables. It is a flowchart which shows the adaptive control process of the number of object attributes. It is a table which shows the target compression rate and the number of identification attributes according to the mounting memory state. It is a flowchart explaining the detail of compression encoding. It is a flowchart which shows the adaptive control process of the object attribute number according to the other Example of this invention. It is a table which shows the target compression rate and the number of identification attributes according to the recording conditions according to the other Example of this invention. 1 is a diagram illustrating a configuration of an image forming system. It is a figure explaining the basic flow of the data processing in an image forming system.

Explanation of symbols

501 CPU
502 Communication interface 503 Host PC
504 RAM
505 ROM
506 EEPROM
507 Operation panel interface 508 Operation panel 509 Expansion interface 510 Expansion card 511 Rendering unit 512 Lossless compression unit 513 Lossless decompression unit 514 Lossless compression unit 515 Lossless decompression unit 516 Image processing unit 517 Engine interface 518 Image forming engine 601 Head cartridge 602 Carriage 603 Transport roller 604 Paper feed roller 605 Recording paper

Claims (14)

A recording device that interprets PDL image information input from the outside, performs rendering, generates attribute data and raster image data for each object, and records an image on a recording medium based on the attribute data and raster image data There,
First compression means for compressing and encoding the attribute data;
Second compression means for compressing and encoding the raster image data;
A compression rate setting means for setting a target compression rate in compression encoding by the first and second compression means according to at least one of the resource of the recording device and the recording condition by the recording device;
Attribute number changing means for changing the number of attributes of the attribute data according to at least one of the resource of the recording device and the recording condition by the recording device;
Changing means for changing the attribute data based on the number of the attribute data changed by the attribute changing means;
The attribute data changed by the changing unit is compression-encoded by the first compression unit so as to achieve the target compression rate set by the compression rate setting unit, and the raster image data is converted by the second compression unit. Compression control means for controlling to perform compression encoding;
Storage means for storing code data compression-encoded by the first and second compression means;
And recording means for reading and expanding the code data stored in the storage means, performing image processing, and recording an image on the recording medium based on the image data subjected to the image processing. Recording device. The resource of the recording device is a memory,
2. The recording apparatus according to claim 1, wherein the compression rate setting unit and the attribute number changing unit set the target compression rate and change the number of attributes of the attribute data according to a capacity of the memory, respectively. . The recording conditions by the recording device include the size of the recording medium, recording on one side of the recording medium or recording on both sides,
The compression rate setting means and the attribute number changing means respectively set the target compression rate according to the size of the recording medium and the distinction between recording on one side of the recording medium or recording on both sides, and the attribute data The recording apparatus according to claim 1, wherein the number of attributes is changed. The first compression means performs compression encoding using a reversible compression method,
The recording apparatus according to claim 1, wherein the second compression unit performs compression encoding using an irreversible compression method. The reversible compression method includes a pack bits method,
The recording apparatus according to claim 4, wherein the irreversible compression method includes a JPEG method.   The recording according to claim 1, wherein the attribute data includes, for each pixel of the image, information indicating a character, a figure or an image type, a distinction as to whether it is a line, and a distinction between a chromatic color and an achromatic color. apparatus.   The change means changes the attribute data so as not to distinguish at least one of the distinction between the line and the chromatic color or the achromatic color. The recording device described in 1. The compression control means includes
A plurality of quantization tables classified into a plurality of stages from the viewpoint of image quality and compression rate, quantization parameters used for compression encoding
A target code obtained from a code amount obtained by compression coding executed by at least one of the first compression means and the second compression means and a target compression rate set by the compression rate setting means. A comparison means for comparing the conversion amount;
According to the comparison result by the comparison means, the table used for the compression encoding is switched and selected from the plurality of quantization tables, and the first compression means or the second compression is selected using the quantization table selected by switching. The recording apparatus according to claim 1, further comprising repetitive control means for controlling to execute compression encoding by the means.   The compression control means further includes a change control means for changing the attribute data so as to change the number of the attribute data by controlling the change means according to a comparison result by the comparison means. Item 9. The recording device according to Item 8.   The recording apparatus according to claim 9, wherein the change control unit relatively reduces the number of the attribute data when high compression is required according to the target compression rate.   The recording apparatus according to claim 1, wherein the recording unit includes an ink jet recording head.   The recording apparatus according to claim 1, wherein the PDL image information is color image information. Image for rendering by interpreting PDL image information input from the outside, generating attribute data and raster image data for each object, and recording an image on a recording medium based on the attribute data and raster image data An image formation control device for generating data,
First compression means for compressing and encoding the attribute data;
Second compression means for compressing and encoding the raster image data;
A compression rate setting means for setting a target compression rate in compression encoding by the first and second compression means according to at least one of the resource of the recording device and the recording condition by the recording device;
Attribute number changing means for changing the number of attributes of the attribute data according to at least one of the resource of the recording device and the recording condition by the recording device;
Changing means for changing the attribute data based on the number of the attribute data changed by the attribute changing means;
The attribute data changed by the changing unit is compression-encoded by the first compression unit so as to achieve the target compression rate set by the compression rate setting unit, and the raster image data is converted by the second compression unit. Compression control means for controlling to perform compression encoding;
Storage means for storing code data compression-encoded by the first and second compression means;
An image forming control apparatus comprising: a transfer unit that reads out and decompresses code data stored in the storage unit, performs image processing, and transfers the image data subjected to the image processing to a printer engine. A recording method that interprets PDL image information input from the outside, renders, generates attribute data and raster image data for each object, and records an image on a recording medium based on the attribute data and raster image data. There,
Compression encoding in a first compression step for compressing and encoding the attribute data and a second compression step for compressing and encoding the raster image data according to at least one of resources of the recording device and recording conditions by the recording device A compression rate setting step for setting a target compression rate in
An attribute number changing step of changing the number of attributes of the attribute data according to at least one of the resource of the recording device and the recording condition by the recording device;
A change step of changing the attribute data based on the number of the attribute data changed in the attribute change step;
In order to achieve the target compression rate set in the compression rate setting step, the attribute data changed in the change step in the first compression step is compression-encoded, and the raster image data is converted in the second compression step. A compression control step for controlling the compression encoding;
The code data is read out from the storage medium storing the code data compressed and encoded in the first and second compression steps, is subjected to image processing, and the recording is performed based on the image data subjected to the image processing. And a recording step of recording an image on a medium.

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