JP2005210621A - Image processing apparatus and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an image processing apparatus available in common for various specifications, while efficiently suppressing density uneveness caused by characteristic variations or the like of recording elements. <P>SOLUTION: There are provided sub-blocks 0 and 1 for performing correction processing of color data, when correcting recording data to be outputted to a print engine which performs color recording using a plurality of color inks, with each of the sub-block including a plurality of tables for defining correction data for one or more pieces of color data. The plurality of colors are divided into two groups, corresponding to the sub-block 0 and the sub-block 1, based on additional information relating to the print engine, and color data belonging to each of the groups are controlled so as to be inputted to a corresponding correction processing block. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus and an image processing method, and more particularly to an image processing apparatus and an image processing method for correcting recording data output to a recording unit that performs color recording using a plurality of color recording agents (inks). Is.

  In recent years, OA equipment such as personal computers (PCs) and copying machines has become widespread, and an apparatus that performs digital image recording by an ink jet method as a kind of image forming (recording) apparatus of these equipment has been rapidly developed and popularized. doing. In particular, colorization has progressed with the enhancement of the functions of office automation equipment, and various color ink jet recording apparatuses have been developed accordingly.

  In general, an ink jet recording apparatus includes a carriage on which a recording head and an ink tank as recording means are mounted, a conveying means for conveying a recording medium, and a control means for controlling these. Recording is performed by scanning (scanning) a recording head that discharges ink droplets from a plurality of ejection openings (nozzles) in the direction (main scanning direction) intersecting the recording paper conveyance direction (sub-scanning direction). Sometimes the recording medium is intermittently conveyed by an amount equal to the recording width of one scan. Further, in the case of an ink jet recording apparatus compatible with color recording, a color image is formed by superimposing ink droplets ejected by a recording head of a plurality of colors.

  As a method of ejecting ink in an ink jet recording apparatus, a heating element (electric / thermal energy converter) is provided in the vicinity of the ejection port, and an electric signal is applied to the heating element to locally heat the ink to change the pressure. Are used, and a thermal method in which ink is ejected and an electrical / pressure converting means such as a piezo element are used to apply a mechanical pressure to the ink to eject the ink.

  In general, the former thermal method makes it easy to increase the density of the nozzles and allows the head to be configured at low cost, but it tends to cause deterioration of the ink and the recording head due to the use of heat generation. On the other hand, the latter piezo method is characterized by excellent discharge controllability, high degree of freedom of ink, and semi-permanent head life.

  The ink jet recording method is to record characters and figures by ejecting ink as fine droplets from a discharge port onto a recording medium according to a recording signal, and is non-impact so that there is little noise. A copier that can be used in combination with a computer, a word processor, or the like because it has advantages such as low running costs, easy miniaturization of the device, and easy colorization. In recording apparatuses such as printers and facsimiles, they are widely used as image forming (recording) means.

  16 and 17 are block diagrams showing schematic configurations of a controller unit and an engine unit of a general ink jet recording apparatus, respectively.

  First, the function and schematic operation of the controller unit will be described with reference to FIG. The CPU 1601 is connected to the host PC 1606 (1607) via the USB interface 1604 or the IEEE 1394 interface 1605. The RAM 1608 for storing the command signal and image information received from the host PC 1606 is accessed, and the recording operation is controlled based on the information stored in these memories.

  Instruction information input from the keys of the operation panel 1612 is transmitted to the CPU 1601 via the operation panel interface 1611. Similarly, in response to a command from the CPU 1601, the LED of the operation panel 1612 is turned on or the LCD panel is turned on via the operation panel interface 1611. The display is controlled. The expansion interface 1615 is an interface for performing function expansion by connecting an expansion card such as a LAN controller or an HDD. Image information is converted into dot data for each color ink by an image data processing block 1613, and output to an engine (FIG. 17) as a recording means. Similarly, various commands and status information are transmitted and received between the controller and the engine via the image data processing block 1613.

  Next, the function and operation outline of the engine unit will be described with reference to FIG. The engine unit is connected to a controller (FIG. 16) via a band memory control block 1712. The CPU 1701 accesses a ROM 1703 that stores control programs, an EEPROM 1704 that stores updatable control programs and processing programs, various constant data, and a RAM 1702 that stores command signals and image information received from the controller (FIG. 16). The recording operation is controlled based on the information stored in these memories.

  In recording, the carriage 1711 is moved by operating the carriage motor 1709 via the output port 1705 and the carriage motor control circuit 1707, and the paper feed paper is sent via the output port 1705 and the paper feed motor control circuit 1706. By operating a feed motor 1708, a paper transport mechanism 1710 such as a transport roller is operated. Further, the CPU 1701 can record a desired image on the recording medium by controlling the band memory control block 1712 and the recording head control block 1714 based on various information stored in the RAM 1702 and driving the recording head 1715. .

  Also, from a power supply circuit (not shown), a logic drive voltage Vcc (for example, 3.3 V) for operating the CPU and various control circuits, various motor drive voltages Vm (for example, 24 V), and a heat voltage for driving the recording head. Vh (for example, 12V) is output.

  In the conventional ink jet recording method, it has been necessary to use a special coated paper having an ink absorbing layer in order to obtain a color image with high color development without ink bleeding. A method of giving recording ability to plain paper used in large quantities in a copying machine or the like has been put into practical use.

  Furthermore, it is desired to support various recording media such as OHP sheets, fabrics, and plastic sheets. To meet these requirements, recording media (recording media) with different ink absorption characteristics are selected as necessary. Therefore, development and commercialization of a recording apparatus capable of performing the best recording irrespective of the type of the recording medium are in progress. In addition, as for the size of the recording medium, large-sized woven fabrics such as advertising posters and clothes have been required. As described above, the demand for the ink jet 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 general, the color ink jet recording method uses four color inks obtained by adding black (Bk) ink to three color inks of cyan (Cy), magenta (Mg), and yellow (Ye). To realize. In such a color inkjet recording apparatus, unlike a monochrome inkjet recording apparatus that mainly records characters, various characteristics such as color development, gradation, and uniformity are improved when recording a color image. Is required.

  In addition, in the ink jet recording apparatus, in order to form a natural image with higher gradation and higher quality, in addition to the conventional four colors of cyan (Cy), magenta (Mg), yellow (Ye), and black (Bk). By using 7-color ink with three colors, light cyan (LC), light magenta (LM), and light yellow (LY), which have low ink density, many things with reduced graininess in the highlight area are realized. ing.

  However, the quality of the recorded image largely depends on the performance of the recording head itself. The slight differences between the nozzles that occur in the recording head manufacturing process, such as the shape of the discharge port of the print head and the variation in the electrothermal transducer (discharge heater), are the amount of ink discharged from each nozzle and the direction of the discharge direction. This may cause deterioration in image quality as density unevenness of a finally formed recorded image. As a result, there is a “white” portion that does not periodically satisfy the area factor of 100% in the head main scanning direction, or conversely, dots overlap more than necessary or white streaks occur. It will be. These phenomena are usually perceived as uneven density by the human eye.

  FIG. 15 is a diagram for explaining density unevenness of an image. Here, a state in which an image 1503 is recorded by ejecting ink from all ejection ports (nozzles) in one scan onto a recording medium 1502 such as a sheet by the recording head 1501 and a direction intersecting the scanning direction (Y A graph 1504 of the density change in (direction) is shown. When the ejection direction and the ink ejection amount vary between the ejection ports of the recording head, the density in the Y direction varies, and this is visually recognized as density unevenness.

  Therefore, a so-called multi-pass recording method has been proposed as a countermeasure against such density unevenness. In order to simplify the description, the multi-pass printing method will be described by taking as an example the case of using a single ink color head composed of 8 nozzles.

  First, by adopting a fixed mask method that generates pass data which is data of each scan (pass) by thinning out print data using an even / odd row pattern or a zigzag / reverse zigzag pattern, 2-pass printing is performed. The realization will be described with reference to FIG.

  The staggered pattern is recorded in the first scan (a), the paper is fed by half the recording width (4 dot width), and then the reverse staggered pattern is recorded in the second scan (b) to complete the recording. In other words, as shown in (a), (b), and (c), paper feeding in units of 4 dots and recording in a zigzag / reverse zigzag pattern are alternately performed to complete a recording area in units of 4 dots per scan. I will let you.

  Next, 2-pass printing using a table reference method that generates pass data by thinning out the print data using a random mask pattern in which print dots and non-print dots are randomly arranged is realized. This will be described with reference to FIGS.

  FIG. 12 is a diagram showing an example of a mask table used in recording scanning, and the table areas shown in FIGS. 12A and 12B are complementary mask tables used in the first pass and the second pass, respectively. . Data in the table is represented by 1 bit / dot, 0 indicates a mask target, and 1 indicates a non-mask target. The mask tables of (A) and (B) are tables each having a size corresponding to 12 pixels in the main scanning direction × 4 pixels in the sub-scanning direction, which are repeatedly developed in each direction and used as mask data. The number of nozzles provided in the recording head is 8, and the number of pixels corresponding to the paper conveyance amount in 2-pass recording is 8/2 = 4, which matches the sub-scanning direction size of each table.

  FIG. 13 is a diagram showing a state of recording scanning using the mask table shown in FIG. For 8 lines of data corresponding to 8 nozzles, A and B are applied as mask patterns every 4 lines. Recording scans are performed in the order of (a), (b), and (c) of FIG. 13. In each print scan, mask processing of image data (recording dots are non-recording dots) using a stored mask table. To generate path data. Specifically, by taking the logical product of the image data and the mask data, if the mask data is 1, the image data is output as it is, and if the mask data is 0, the image data is This is realized by replacing with 0. All image areas are always masked in the order of A and B by two scans to generate print data. Here, the ratio of the mask OFF (1) of A and B is equal to about 50%.

  Thus, by recording one line using two different nozzles, it is possible to form a high-quality image with suppressed density unevenness. In addition, since the amount of ink ejected into the unit area in each scan is reduced in the multipass recording method, the effect of suppressing bleeding (bleeding) by recording while drying the ink, Since the number of recording dots for each scan is reduced, the effect of suppressing the temperature rise of the recording head that causes ejection failure can be achieved at the same time. Although the main scanning direction has been described here, it is possible to further improve the image quality by thinning out and recording continuous dots in the sub-scanning direction. Further, when it is desired to realize image formation in the sub-scanning direction at a resolution higher than the nozzle resolution, the thinning recording in the sub-scanning direction is an essential process.

  As described above, the pass data for each scan is generated by thinning out the print data using a random mask pattern in which print dots and non-print dots are randomly arranged as described above. In addition to the method of generating the data (referred to as the table reference method), the method of generating the pass data by thinning out the recording data using the even / odd column pattern or the zigzag / reverse zigzag pattern (referred to as the fixed mask method) In addition, a method of generating pass data by performing a thinning process while paying attention to recording dots (referred to as a data mask method) or a method using these in combination is known.

  Next, data processing in the image data processing block 1613 in the controller shown in FIG. 16 will be described with reference to FIG.

  FIG. 14 is a diagram showing the flow of data processing in the image data processing block 1613. The RGB multi-value image data received from the host PC is converted into multi-value image data of ink colors (for example, Cy, Mg, Ye, Bk) by the color conversion process 1401, and then the ink is converted by the quantization process 1402. It is converted into binary data for each color. In this way, the multivalued image data is converted to a level (binary here) that can be output by the engine (recording head).

  As a quantization method used in 1402, an error diffusion method and a dither method are widely known. In the error diffusion method, a diffusion coefficient is assigned to a peripheral pixel for a target pixel, and a quantization error generated in the target pixel is distributed to the peripheral pixels according to the diffusion coefficient. As a result, the density of the entire image is preserved, and a favorable pseudo gradation expression is possible. On the other hand, in the dither method, a dither matrix composed of matrix threshold values is prepared, and one-to-one pixel comparison between each threshold value and each pixel of input data is performed to determine ON / OFF. In general, the dither method tends to lower the image quality as compared with an image to which the error diffusion method is applied. However, the error diffusion method cannot move to the next pixel processing until the error propagates, and high-speed processing is difficult.

  In a high-resolution binary output device such as a recent ink jet recording apparatus, an error diffusion method (multi-value error diffusion method) that expresses each pixel in multiple gradations is used to express a smoother halftone image. Has been. A quantization method combining the multi-value error diffusion method and the density pattern method will be described below with a specific example.

  First, the multi-value image data is subjected to quinary processing by the multi-value error diffusion method. In the quinarization by the multi-value error diffusion method, four threshold values are provided, and output values of 0 to 4 are determined by comparison with pixel values. The error generated there is propagated to surrounding pixel values according to the diffusion matrix in the same manner as in the binarization. Further, the binary data is developed using the density pattern method for the five-value data. More specifically, halftone data is subjected to halftone dot expansion processing in accordance with a 2 × 2 halftone dot matrix. Here, the resolution of multi-value image data (input resolution) is 600 ppi × 600 ppi (ppi represents pixel per inch), and the final recording resolution (output resolution) by the recording head is 1200 dpi × 1200 dpi (dpi is dot per inch). Express). With this method, it is possible to express 5 gradations by expanding each pixel that can be expressed only with 2 gradations of dot ON / OFF, and an error diffusion process that is difficult to increase in speed is 600 ppi lower than the output resolution. By executing the processing at × 600 ppi, the error diffusion processing time can be reduced to ¼.

  In an actual ink jet recording apparatus, the relationship between the input resolution and the output resolution is set in association with the recording mode and the like, and an optimum output gradation number N by the multi-value error diffusion method is set according to the halftone dot matrix size according to this. Some have been proposed that select and execute quantization processing. For example, in the high-speed mode, the input resolution of 300 ppi × 300 ppi is subjected to octarization by the multi-value error diffusion method, and then recording dot data having an output resolution of 1200 dpi × 1200 dpi is generated using a 4 × 4 dot matrix. In the high quality mode, the input resolution of 600 ppi × 600 ppi is quaternized by the multi-valued error diffusion method, and then recording dot data with an output resolution of 1200 dpi × 1200 dpi is generated using a 2 × 2 dot matrix. As a result, it is possible to perform a quantization process with an excellent balance between high-speed processing and high quality according to the purpose.

Also, an ink jet recording apparatus that is configured so that only the Bk ink has a larger ejection amount than other inks and performs image formation at a low resolution only for the Bk data has been put to practical use. In such an apparatus, for example, if the input resolution is 300 ppi × 300 ppi for all color inks, only the Bk ink has an output resolution of 600 dpi × 600 dpi, and the other color inks have an output resolution of 1200 dpi × 1200 dpi, Bk pixel data is quaternized by the multi-value error diffusion method and then developed using a 2 × 2 dot matrix, and other color pixel data is developed by the multi-value error diffusion method. It is necessary to perform processing such as 8-value conversion and development using a 4 × 4 dot matrix.
JP-A-10-000795

  As described above, the discharge direction and the discharge amount vary depending on the shape of the discharge port of the recording head and the variation or change of the electrothermal transducer (discharge heater), resulting in uneven density or white or black in the image. Degradation of image quality such as streaks may occur. These variations in recording characteristics are not limited to those that occur at the time of manufacture, but may also occur due to changes or deterioration in characteristics over a long period of use.

  In order to eliminate such density unevenness, the above-described technique such as multi-pass printing is used. However, appropriate density unevenness correction processing (head shading) is desired in connection with color conversion processing and halftone processing of image information. It is rare. That is, image information corresponding to each nozzle or nozzle group is corrected by multi-value density conversion, and binarization is performed by area gradation processing using the multi-value corrected image information. Thus, density unevenness is avoided and suppressed.

  As a method of acquiring correction information, there are a method of reading an output result of a predetermined image pattern using a sensor mounted on the recording apparatus main body, a method of using characteristic information stored in a recording head in a manufacturing process, and the like.

  The image forming controller includes a plurality of density correction (head shading) tables, and a method for realizing density unevenness correction by selectively using an optimum table based on the acquired correction information is often used.

  In recent years, recording devices have been strongly demanded to improve recording speed. To achieve this, hardware processing by lookup table lookup is required, and the table to be referenced in line units can be changed. Is required. For this reason, a plurality of types of tables are stored in the memory, and the required memory capacity increases remarkably.

  For example, if the recording apparatus uses six color inks and the input / output values of the correction table are 10 bits (1024 gradations), the total size of the table is 1024 × 10 bits × 6 colors = 60 Kbits. When four types are prepared, the total size of the table is 240 Kbits, and when 16 types of each color are prepared, the total size of the table is 960 Kbits. When the size of the table becomes large in this way, it is necessary to increase the capacity of the memory mounted on the apparatus, leading to an increase in the cost of the entire recording apparatus.

  On the other hand, if a selectable correction table is shared by all inks in order to reduce the capacity of the correction table, the processing is sequentially performed for each color, which decreases the processing speed and is required as a result. In some cases, the data processing performance cannot be satisfied.

  In recent years, a variety of printing systems have been proposed and commercialized using inkjet printing technology, from personal use to business use, from large format prints such as A0 and B0 sizes to L-size prints for digital photographs. While ink systems and print engines are diversifying, development of an image forming controller that realizes image processing according to a connected print engine is expected.

  In such an image forming controller that is assumed to be connected to a wide variety of print engines, “optimization” according to the characteristics of the print engine is necessary. However, there are many obstacles to achieve this.

  For example, low-cost and high-speed printing is prioritized for a four-color business printer engine, and high-quality printing is most important for a six-color high-quality professional photographic printer engine. In order to satisfy different requirements depending on the engine connected in this way, simply increasing the size of the correction table and the number of parameters to be used causes a significant cost increase, while achieving high speed / high image quality. Cost reduction cannot be realized.

  The present invention has been made in view of the above situation, and is a low-cost image that can be used in common for various specifications while efficiently suppressing density unevenness due to variations in characteristics of recording elements. An object is to provide a processing apparatus.

An image processing apparatus according to an aspect of the present invention that achieves the above object is an image processing apparatus that corrects recording data to be output to a recording unit that performs color recording using recording agents of a plurality of colors.
A plurality of table means each defining correction data for one or more color data, and first and second correction processing blocks for performing correction processing of each color data;
Incidental information receiving means for receiving incidental information related to the recording means;
Based on the auxiliary information, the plurality of colors are divided into two groups corresponding to the first and second correction processing blocks, and color data belonging to each group is input to the corresponding correction processing block. Data control means.

An image processing method as another aspect of the present invention that achieves the above object is an image processing method for correcting recording data to be output to a recording unit that performs color recording using a plurality of color recording agents,
Each includes a plurality of table means for defining correction data for one or more color data, and provided with first and second correction processing blocks for correcting each color data,
An incidental information receiving step of receiving incidental information relating to the recording means;
Based on the auxiliary information, the plurality of colors are divided into two groups corresponding to the first and second correction processing blocks, and color data belonging to each group is input to the corresponding correction processing block. A data control process.

  That is, according to the present invention, in an image processing apparatus that corrects recording data output to a recording unit that performs color recording using recording agents of a plurality of colors, a plurality of data each defining correction data for one or more color data. The first and second correction processing blocks that perform correction processing of each color data are provided, the incidental information about the recording means is received, and the first and second corrections are performed on a plurality of colors based on the incidental information. It is divided into two groups corresponding to the processing blocks, and control is performed so that the color data belonging to each group is input to the corresponding correction processing block.

  In this way, the recording material can be divided into two groups according to the connected recording means (print engine), and each group can be independently processed in parallel.

  Accordingly, it is possible to perform an appropriate correction process according to various print engine specifications (high-speed recording, high image quality, or high-quality recording) without increasing the capacity of the table means.

  When the recording unit is configured to have a plurality of recording heads corresponding to each color, the incidental information may include information regarding the specifications of the recording head.

  In this case, the data control means may divide a plurality of colors into two groups according to the recording resolution of the recording head. For example, when a plurality of colors include black and a plurality of other chromatic colors, and the recording resolution of the black recording head is different from the recording resolution of the recording head of other chromatic colors (cyan, magenta, yellow, etc.) Are divided into two groups of black and other chromatic colors.

  Further, when the recording resolutions of the recording heads of the respective colors are the same, a plurality of colors may be divided into two groups according to the gamma characteristics of the respective colors. For example, when a plurality of colors include black, cyan, magenta, yellow, light cyan, and light magenta, the data control unit divides into two groups of black, cyan, and magenta, and yellow, light cyan, and light magenta. To do.

  The correction processing block may be configured to select a table means used for the correction processing based on the recording characteristics of the recording head of each color.

An image processing apparatus according to another aspect of the present invention that achieves the above object is an image processing apparatus that corrects recording data to be output to a recording unit that performs color recording using a plurality of color recording agents.
Each of which includes a plurality of table means for defining correction data for one or more color data, and a plurality of correction processing blocks for correcting each color data;
Incidental information receiving means for receiving incidental information related to the recording means;
Data control means for controlling to divide into a plurality of groups corresponding to the plurality of correction processing blocks based on the auxiliary information and to input color data belonging to each group to the corresponding correction processing block; Yes.

  The above object can also be achieved by the above image processing apparatus and an ink jet recording apparatus having a recording head that ejects ink from a plurality of nozzles as recording means.

  Furthermore, the above object can also be achieved by a computer program for realizing the above image processing method by a computer apparatus and a storage medium storing the computer program.

  According to the present invention, the recording agent can be divided into two groups according to the connected recording means (print engine), and each group can be independently processed in parallel.

  Accordingly, it is possible to perform an appropriate correction process according to various print engine specifications (high-speed recording, high image quality, or high-quality recording) without increasing the capacity of the table means.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the components described in the following embodiments are merely examples, and are not intended to limit the scope of the present invention only to them.

  In this specification, “recording” (sometimes referred to as “image formation”) is not only for forming significant information such as characters and figures, but also for human beings visually perceived regardless of significance. Regardless of whether or not it has been manifested, a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or the medium is processed is also expressed.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used for forming a pattern or the like, processing a recording medium, or processing an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port or a liquid channel communicating with the ejection port and an element that generates energy used for ink ejection.

(First embodiment)
FIG. 3 is a diagram showing a schematic configuration of a recording unit of the ink jet recording apparatus as the first embodiment according to the present invention. Here, the recording unit of the six-color print engine will be described.

  A recording head unit 301 contains six color inks of black (Bk), cyan (Cy), magenta (Mg), yellow (Ye), light cyan (LC), and light magenta (LM). The multi-head is composed of six ink tanks and six independent recording heads corresponding to the respective ink tanks. The number of nozzles for each color is 1280 nozzles. Reference numeral 302 denotes a carriage on which the recording head unit 301 is mounted and moves these in the scanning direction (X direction) along the guide shaft 306 when recording is performed. The carriage 302 is at the home position HP shown in the drawing during standby such as a non-recording state.

  Reference numeral 303 denotes a paper feed roller which rotates while suppressing the recording paper 305 as a recording medium together with an auxiliary roller (not shown), and transports the recording paper 305 in the transport direction (Y direction) as needed. Reference numeral 304 denotes a paper feed roller that feeds the recording paper 305 and plays a role of suppressing the recording paper 305 in the same manner as the paper feed roller 303 and the auxiliary roller. Here, the recording heads corresponding to the six colors Bk, Cy, Mg, Ye, LC, and LM of the recording head unit 301 are arranged in a direction (substantially Y direction) crossing the scanning direction (X direction). Each has 1280 nozzles.

  FIG. 4 is a view of the recording head unit 301 as viewed from the recording medium side. Reference numerals 401 to 406 denote recording heads corresponding to six colors of Bk, Cy, Mg, Ye, LC, and LM, respectively. Each recording head has two nozzle rows arranged at a pitch of 600 dpi, and the two nozzle rows are arranged so as to be shifted from each other by half the pitch in the arrangement direction (Y direction). Recording can be performed at a resolution of 1200 dpi in the conveyance direction (Y direction) of the recording medium.

  A basic recording operation in the above configuration will be described.

  While the carriage 302 at the home position HP in the standby state moves in the X direction by a recording start command, ink is ejected from the nozzles of the recording head unit 301 onto the recording paper 305 according to the recording data. When the carriage 302 moves to the end of the recording paper 305 in the X direction and the recording in one scan is completed, the carriage returns to the original home position HP. By rotating the paper feed roller 304, the recording paper 305 is conveyed by a predetermined width in the Y direction, and then ink is ejected while the carriage 302 moves in the X direction again to perform recording. Recording on one sheet of recording paper is performed by alternately repeating such recording scanning and paper feeding operation.

  The ink jet recording apparatus according to the present embodiment has an interface for communicating recording information and various control information with a host device (such as a PC) connected to the apparatus, and input recording information for each ink color. A controller (FIG. 16) configured with an image data processing block for converting the data into ON / OFF data of dots, and an engine (FIG. 17) for controlling the recording unit described above with reference to FIG. 3 to form an image (FIG. 17). ), Etc.

  The controller of this embodiment can be used as a common controller for two inkjet recording apparatuses having different specifications. FIG. 5 is a diagram illustrating an example of an ink jet recording apparatus including two types of print engines different from the common controller of the present embodiment. (A) shows an inkjet recording apparatus A501, which is a low-cost high-speed printer for business, configured by connecting the print engine A521 to the common controller 510, and (b) connecting the print engine B522 to the common controller 510. An inkjet recording apparatus B502, which is a high-quality photographic printer, is shown.

  The print engine A521 of the ink jet recording apparatus A501 shown in FIG. 5A performs image formation using four colors of inks of Bk, Cy, Mg, and Ye, and its specifications are shown in FIG. 6A. Street. That is, the ink discharge amount of each discharge port of the recording head for Cy, Mg, Ye is 8 pl, and the ink discharge amount of each discharge port of the recording head for Bk ink is 20 pl. An image is formed with a resolution of 1200 dpi × 1200 dpi using a recording head for Cy, Mg, Ye, and an image is formed with a resolution of 600 dpi × 600 dpi using a recording head for Bk.

  As described above, the print engine 521 of the ink jet recording apparatus A501 is configured so that only the Bk recording head has a larger ink discharge amount than the other ink recording heads, and an image with a lower resolution is obtained only by the Bk recording head. By performing the formation, a high-speed monochrome image formation is realized. The Cy, Mg, and Ye recording heads can also form images at high speed when forming a color image with a relatively large discharge amount.

  The print engine B522 of the ink jet recording apparatus B502 shown in FIG. 5B performs image formation using six colors of inks of Bk, Cy, Mg, Ye, LC, and LM, and its specifications are shown in FIG. As shown in b). That is, the ink discharge amount of each discharge port of all the recording heads is 2 pl. An image is formed at a resolution of 2400 dpi × 1200 dpi using each recording head.

  As described above, the print engine B522 of the ink jet recording apparatus B502 performs high-quality and low graininess by performing image formation by ejecting minute ink droplets from each recording head corresponding to 6-color ink with light colors. Image formation is realized.

  Next, image data processing focused on the controller of the present embodiment will be described in detail with reference to FIG.

  FIG. 7 is a block diagram showing a schematic configuration of an image data processing block in the controller of the present embodiment. The image data processing block includes a color conversion unit 701 and a quantization unit 702, and sequentially executes color conversion processing and quantization processing. After the image information input by the color conversion unit 701 is converted into multi-value image data for each ink color, the quantization unit 702 performs quantization using the error diffusion method and the density pattern method to thereby obtain dot data for each ink color. Is generated. The generated dot data is output to the engine.

  The color conversion processing in the color conversion unit 701 will be described with reference to FIG. FIG. 8 is a diagram illustrating a processing flow in the color conversion unit 701. The color conversion unit includes an input gamma correction block 801, a color space conversion block 802, and an output gamma / density unevenness correction block 803, and sequentially executes three processes such as input gamma correction, color space conversion, and output gamma / density unevenness correction. To do.

  The input gamma correction block 801 performs input gamma correction processing by a table reference method, and outputs 10-bit data for each RGB color obtained using the input 8-bit data for each RGB color as a table input. The 10-bit RGB color data output from the input gamma correction block 801 is supplied to the color space conversion block 802. A color space conversion block 802 converts the RGB data into 10-bit data for each of the ink colors K, C, M, and Y (and LC and LM) by a tetrahedron interpolation method, and outputs an output gamma / density unevenness correction block 803 at a later stage. Output to. The processing in the output gamma / density unevenness correction block 803 will be described later. The output gamma correction is an output gamma correction process by a table reference method, and data of 10 bits for each color of K, C, M, Y (and LC, LM). Is output.

  The quantization process in the quantization unit 702 will be described with reference to FIG. FIG. 9 is a diagram illustrating a processing flow in the quantization unit 702. The quantization unit includes a multilevel error diffusion block 901 and a halftone dot expansion block 902, and sequentially executes two processes, an error diffusion process and a halftone dot expansion process.

  The error diffusion block 901 performs quantization processing based on the multi-level error diffusion method. The input K, C, M, Y (and LC, LM) data of 10 bits is converted into a level corresponding to the print engine or recording mode. Convert to logarithm. In the halftone dot development block 902 in the latter stage, binary data is obtained by executing a halftone dot development of a matrix size corresponding to the print engine or the recording mode.

  Next, the processing in the output gamma / density unevenness correction block 803 according to the engine specification to be connected, which is characteristic in the present embodiment, will be described in detail. In the present embodiment, the output gamma / density unevenness correction block has a dedicated correction table for each group of inks of up to three colors.

  FIG. 10 is a schematic block diagram showing the configuration of the output gamma / density unevenness correction block 803 of this embodiment. Reference numerals 1001a and 1001b denote correction tables, each of which is composed of a RAM of 80 Kbit capacity including eight types of 1024 word × 10 bit configuration tables. Reference numerals 1002a and 1002b denote data input processing units that perform external data input control. Reference numerals 1003a and 1003b denote address generation units, which input 3-bit (8-value) subaddress information for table selection together with outputs from the data input processing units 1002a and 1002b, and generate addresses of the correction table 1001a or 1001b. . Reference numerals 1004a and 1004b denote data output processing units for supplying the output of the correction table 1001a or 1001b to the outside. A control unit 1005 monitors the state of each unit and controls data input / output, and plays a role of transmitting mode selection information and subaddress information supplied from the outside. A recording mode information input unit 1006 notifies the control unit 1005 of a mode selection instruction based on the input mode information.

  In this way, processing for each color is sequentially performed within a group of up to three colors, but processing in each of the two groups is executed in parallel.

  FIG. 1 is a block diagram illustrating processing in two operation modes of the output gamma / density unevenness correction block 803 in the present embodiment. The correspondence between the components shown in FIG. 1 and the components shown in FIG. 10 will be described. 1001a and 1001b are correction tables a and b shown in FIG. 10, sub-block 0 1101a is a data input processor 1002a, address generator 1003a and The data output processing unit 1004a and the sub-block 1 1101b correspond to the data input processing unit 1002b, the address generation unit 1003b, and the data output processing unit 1004b, respectively.

  FIG. 1A shows processing in the operation mode A to which the print engine A is connected. Data of four colors Bk, Cy, Mg, and Ye is input, and Bk has low resolution and large diameter dots. Performs processing corresponding to high-speed recording. FIG. 1B shows processing in the operation mode B to which the print engine B is connected, and data of six colors Bk, Cy, Mg, Ye, LC, and LM is input, and high image quality and high quality are obtained. Processing corresponding to recording is performed. These two operation modes are switched according to a signal (sub address signal or information included in the sub address signal) output from the control unit 1005 in accordance with a signal from the recording mode information input unit 1006 shown in FIG.

  In operation mode A of FIG. 1A, only Bk data is assigned to sub-block 0 1101a, and data of three colors Cy, Mg, and Ye is assigned to sub-block 1 1101b. As a result, when performing monochrome recording, it is possible to independently perform correction processing suitable for Bk data of low resolution and large-diameter dots and color image data of Cy, Mg, and Ye.

  On the other hand, in the operation mode B of FIG. 1B, data of three colors Bk, Cy and Mg are assigned to the sub-block 0 1101a, and data of three colors Ye, LC and LM are assigned to the sub-block 1 1101b. . As a result, the six colors are divided into two groups having similar gamma characteristics, that is, dark colors with high density (Bk, Cy, Mg) and light colors with low density (Ye, LC, LM). More appropriate density correction processing can be performed using the corrected table. In particular, the gamma characteristics of Cy and Mg in dark colors and LC and LM in light colors are very similar.

  FIG. 2 is a diagram showing the state of color data processing in the two operation modes shown in FIG. 2A corresponds to the operation mode A, and FIG. 2B corresponds to the operation mode B. In FIG. 2, the processing cycles of the color data in both modes are represented by the same time for convenience, but in reality, the processing cycle times in each mode are often different.

  In the operation mode A of FIG. 2A, in the sub-block 0, the subsequent two cycles after processing Bk are idle, while in the sub-block 1, the processing is sequentially executed in the order of Cy, Mg, and Ye. These three cycles correspond to processing for one pixel.

  In the operation mode B in FIG. 2B, the sub-block 0 performs processing in the order of Bk, Cy, and Mg, while the sub-block 1 performs processing in the order of Ye, LC, and LM. Also in this case, three cycles correspond to processing for one pixel.

  As described above, in the present embodiment, in the inkjet recording apparatus A that realizes high-speed four-color printing, processing using different correction table groups is performed for Bk of low resolution and large diameter dots, thereby achieving high image quality. In the ink jet recording apparatus B that realizes color printing, it is possible to perform processing using a different correction table group for each group of dark ink and light ink, and the specifications of the connected print engine It is possible to realize optimum data processing according to the situation.

  As described above in detail, according to the present embodiment, the ink color is divided into two groups according to the connected print engine, and each group is independently processed in parallel. For high-speed four-color print engines equipped with Bk heads with different discharge amounts, Bk and Cy, Mg, and Ye are divided into two series, independent parallel processing, and high-definition recording with six-color micro droplets. The print engine that performs the above processing can be divided into two series of dark inks of Bk, Cy, and Mg and light inks of Ye, LC, and LM, and independent parallel processing can be performed.

  Therefore, common image processing that can perform appropriate correction processing according to various print engine specifications (high-speed recording, high image quality, or high-quality recording) without causing an increase in cost due to an increase in table capacity. An apparatus (controller) can be provided.

(Other embodiments)
In the above-described embodiment, for a print engine that performs image formation using four colors of ink, a correction table group that is classified into two groups of Bk, Cy, Mg, and Ye and is independent for each group. For print engines that process images in parallel using 6 colors of ink and categorize them into two groups: Bk, Cy, Mg and Ye, LC, LM. The correction table group has been described as being processed in parallel.

  However, the combination of groups corresponding to the two correction tables used for parallel processing is not limited to this, and can be changed as appropriate according to the characteristics of the connected print engine. Further, the number of groups to be classified is not limited to 2, and may be 3 or more.

  In the above embodiment, the inkjet print engine A that uses four colors of inks Bk, Cy, Mg, Ye, and the inkjet that uses six colors of inks Bk, Cy, Mg, Ye, LC, and LM. The controller that can be selectively connected to the two print engines, the print engine B of the system, has been described as an example. However, the present invention is not limited to this, and the specification of the print engine to be connected (the ink used) The number of colors, color types, recording resolution, etc.) are not limited to these.

  For example, ink using three colors except Bk may be used, or other light colors such as light yellow (LY) and special colors may be added. Also, the configuration of the recording head to be mounted is not limited to one set (one for each color), but can be applied to a print engine that includes a plurality of recording heads (two or more for each color) to realize high-speed printing.

  Further, in the above-described embodiment, the description has been made on the case where an image is finally formed by using single-size dots from binary image data (binary recording), but it differs based on three or more multi-value image data. It may be one that selectively forms dots of a plurality of sizes and completes the image (multi-value recording), or that overprints the same ink.

  In addition, in the above-described embodiment, the case where the present invention is applied to the output gamma / density unevenness correction processing has been described as an example. However, other processing (for example, quantization processing) is possible as long as the processing uses a table. The present invention can also be applied.

  In the above embodiment, the configuration has been described in which the input gamma correction process, the color space conversion process, the quantization process, and the like are performed inside the inkjet recording apparatus (or controller) in addition to the output gamma / density unevenness correction process. It is obvious that a part or all of these may be realized by a driver on the host PC side to be connected or other external device.

  Furthermore, there is no particular limitation on the operation principle and configuration of the recording head that can be used in the present invention. That is, the recording head is provided with a heating element (electrical / thermal energy conversion element) in the vicinity of the discharge port, and by applying an electric signal to the heating element, the ink is locally heated to cause a pressure change, and the ink is discharged. A thermal system that ejects ink from an ejection port may be used, or a piezoelectric system that ejects ink by applying mechanical pressure to the ink using an electrical / pressure converting means such as a piezoelectric element.

  In the above-described embodiment, the inkjet recording apparatus or the image forming system has been described as an example. However, the present invention is not limited to the inkjet system, and individual characteristics change due to various factors. As long as the recording is performed by a recording head having a plurality of possible recording elements, it can be applied to a melt type thermal transfer system, a laser system, or the like.

  The form of the recording apparatus and the image forming system according to the present invention is not limited to one provided as an image output apparatus of an information processing apparatus such as a computer or a word processor, or a copying apparatus combined with a reading apparatus. Or a facsimile machine having a communication function.

  In the present invention, a software program that realizes the functions of the above-described embodiments is directly or remotely supplied to a system or apparatus, and the computer of the system or apparatus reads and executes the supplied program code. Including the case where it is also achieved by. In that case, as long as it has the function of a program, the form does not need to be a program.

  Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. That is, the claims of the present invention include the computer program itself for realizing the functional processing of the present invention.

  In this case, the program may be in any form as long as it has a program function, such as an object code, a program executed by an interpreter, or script data supplied to the OS.

  As a recording medium for supplying the program, for example, floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card ROM, DVD (DVD-ROM, DVD-R) and the like.

  As another program supply method, a client computer browser is used to connect to an Internet homepage, and the computer program of the present invention itself or a compressed file including an automatic installation function is downloaded from the homepage to a recording medium such as a hard disk. Can also be supplied. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the claims of the present invention.

  In addition, the program of the present invention is encrypted, stored in a storage medium such as a CD-ROM, distributed to users, and key information for decryption is downloaded from a homepage via the Internet to users who have cleared predetermined conditions. It is also possible to execute the encrypted program by using the key information and install the program on a computer.

  In addition to the functions of the above-described embodiments being realized by the computer executing the read program, the OS running on the computer based on the instructions of the program is a part of the actual processing. Alternatively, the functions of the above-described embodiment can be realized by performing all of them and performing the processing.

  Furthermore, after the program read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion board or The CPU or the like provided in the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

It is a schematic block diagram explaining the process in two operation modes of the gamma correction / density unevenness correction block of the embodiment of the present invention. It is a figure explaining the mode of the sequential processing of the color in two operation modes of the gamma correction / density unevenness correction block of embodiment of this invention. It is the schematic which shows the structure of the recording part of embodiment of this invention. FIG. 4 is a schematic diagram illustrating a nozzle arrangement of the recording head in FIG. 3. FIG. 2 is a diagram illustrating a schematic configuration of two recording apparatuses according to an embodiment of the invention. It is a figure which shows the specification of the print engine in embodiment of this invention. It is a block diagram which shows schematic structure of the image data processing block of embodiment of this invention. It is a block diagram which shows schematic structure of the color conversion block of embodiment of this invention. It is a block diagram which shows schematic structure of the quantization block of embodiment of this invention. It is a schematic block diagram which shows the structure of the gamma correction / density unevenness correction block of embodiment of this invention. It is a figure explaining the mode of the multipass recording using a zigzag / reverse zigzag pattern. It is a figure which shows an example of the mask table for path | pass data generation. It is a figure explaining the mode of multipass printing using a mask table. It is a figure explaining the data processing flow in a controller. It is a figure explaining the density nonuniformity resulting from the dispersion | variation in discharge characteristics. It is a block diagram which shows schematic structure of the controller part in an inkjet recording device. It is a block diagram which shows schematic structure of the engine part in an inkjet recording device.

Claims (11)

An image processing apparatus that corrects recording data to be output to a recording unit that performs color recording using recording agents of a plurality of colors,
A plurality of table means each defining correction data for one or more color data, and first and second correction processing blocks for performing correction processing of each color data;
Incidental information receiving means for receiving incidental information related to the recording means;
Based on the auxiliary information, the plurality of colors are divided into two groups corresponding to the first and second correction processing blocks, and color data belonging to each group is input to the corresponding correction processing block. An image processing apparatus comprising: a data control unit. The recording means has a plurality of recording heads corresponding to each color;
The image processing apparatus according to claim 1, wherein the incidental information includes information related to specifications of the recording head.   The image processing apparatus according to claim 2, wherein the data control unit divides the plurality of colors into two groups according to a recording resolution of the recording head. The plurality of colors includes black and other chromatic colors;
4. The image processing apparatus according to claim 3, wherein the recording resolution of the black recording head is different from the recording resolution of the other chromatic recording head.   The image processing apparatus according to claim 4, wherein the other chromatic colors include cyan, magenta, and yellow.   3. The data control unit according to claim 2, wherein the data control unit divides the plurality of colors into two groups according to gamma characteristics of the respective colors when the recording resolutions of the recording heads of the respective colors are the same. Image processing device.   The plurality of colors include black, cyan, magenta, yellow, light cyan, and light magenta, and the data control unit divides into two groups of black, cyan, and magenta, and yellow, light cyan, and light magenta. The image processing apparatus according to claim 6.   8. The image processing apparatus according to claim 2, wherein the correction processing block selects table means used for correction processing based on the recording characteristics of the recording heads for the respective colors.   9. An ink jet recording apparatus comprising: the image processing apparatus according to claim 1; and a recording head that ejects ink from a plurality of nozzles using ink as the recording agent. An image processing apparatus that corrects recording data to be output to a recording unit that performs color recording using recording agents of a plurality of colors,
Each of which includes a plurality of table means for defining correction data for one or more color data, and a plurality of correction processing blocks for correcting each color data;
Incidental information receiving means for receiving incidental information related to the recording means;
A data control unit configured to divide into a plurality of groups corresponding to the plurality of correction processing blocks based on the auxiliary information, and to input color data belonging to each group to the corresponding correction processing block; An image processing apparatus. An image processing method for correcting recording data to be output to a recording unit that performs color recording using recording agents of a plurality of colors,
Each includes a plurality of table means for defining correction data for one or more color data, and provided with first and second correction processing blocks for correcting each color data,
An incidental information receiving step of receiving incidental information relating to the recording means;
Based on the auxiliary information, the plurality of colors are divided into two groups corresponding to the first and second correction processing blocks, and color data belonging to each group is input to the corresponding correction processing block. And a data control step.

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