JP2010147842A - Image processing device, image processing method, and image processing program - Google Patents

Abstract

An image processing apparatus, an image processing method, and an image processing program capable of realizing accurate color reproduction and high-speed processing during printing are provided.
A block setting unit 320 of a printer driver 300 divides an image area constituting print data PD into blocks, and a block determination unit 330 determines whether the set block includes an index designated pixel. To do. For the block including the pixel designated by the index, the first color conversion unit 340 performs color conversion for each pixel individually, thereby realizing color reproduction faithful and accurate to the color designated by the index. On the other hand, for blocks that do not include index-designated pixels, the second color conversion unit 350 performs color conversion processing in units of blocks, thereby speeding up the processing.
[Selection] Figure 2

Description

  The present invention relates to an image processing apparatus, an image processing method, and an image processing program that perform image processing for printing.

  2. Description of the Related Art Conventionally, in ink jet printing that forms dots of color materials such as ink, color conversion is performed for converting print data to be printed into data of color expression corresponding to the color of the color material. For example, the print data is data in the R (red) G (green) B (blue) format, and color using color materials of each color of C (cyan), M (magenta), Y (yellow), and K (black). When printing, RGB format print data is color-converted to CMYK format data. Then, printing is performed by forming dots of each color on the paper surface according to the data after color conversion.

  Further, in order to realize accurate color reproduction by printing, an index corresponding to a combination of color material amounts to be used for reproducing a specified color may be specified for each pixel of print data. When printing, the index is read from the pixels of the print data, and the specified color is accurately reproduced by executing printing using the color material amount corresponding to the index by referring to a predetermined table. Can do. Printing using such an index is mainly used for applications that require strict color reproduction, such as printing of color samples.

  As a technique for speeding up such color conversion processing, Patent Document 1 summarizes an image represented by image data for each block composed of a plurality of pixels, and performs color conversion without distinguishing each pixel in the block. A technique for quickly executing color conversion processing is disclosed.

JP 2002-185810 A

  However, the technique described in Patent Document 1 described above performs color conversion on RGB values designated for each pixel and does not correspond to image data for which an index is designated. For this reason, when printing image data with an index specified in order to achieve strict color reproduction, the color conversion process cannot be accelerated, and printing that combines accurate color reproduction and high processing speed. The image processing for use could not be realized.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 For a plurality of color materials used in printing, color information indicating a first pixel in which an index corresponding to a combination of color material amounts for reproducing a specified color is designated, and a color to be printed A print data acquisition unit that acquires print data for printing an image including a second pixel for which the image is specified, and an image represented by the acquired image data are partitioned to set a pixel group including a plurality of pixels Designated as a pixel group setting unit, a pixel group determination unit for determining whether the set pixel group includes the first pixel, and a pixel group including the first pixel A first color conversion unit that converts the index or the color information into a color material amount of each color material in units of pixels, and color information designated for each pixel of a pixel group that does not include the first pixel, Second color to be converted into color material amount of each color material in group units The image processing apparatus characterized by comprising a section.

  According to this configuration, for the pixel group including the first pixel for which the index is designated, the process of converting the index and color information into the color material amount of each color material is performed in units of pixels. A color material amount that accurately reproduces the specified color is required. For the pixel group that does not include the first pixel, the color information of each pixel is collectively converted into the color material amount of each color material in units of blocks, so that the color material of each color material is compared with the case of conversion in units of pixels. The processing amount for obtaining the color material amount is reduced. Accordingly, it is possible to realize processing that combines accurate color reproduction and high-speed processing during printing.

  Application Example 2 In the image processing apparatus, the second color conversion unit calculates an average gradation value of color information based on color information designated for each pixel of a pixel group not including the first pixel. An image processing apparatus that calculates and obtains a color material amount common to each pixel of the pixel group based on the average gradation value.

  According to this configuration, in the pixel group that does not include the first pixel, since the color material amount common to each pixel of the pixel group is obtained based on the average gradation value in the pixel group, the first pixel Therefore, the amount of processing for a pixel group that does not include the color is reduced, and the speed of color conversion processing can be increased.

  Application Example 3 In the image processing apparatus, the pixel group determination unit determines whether or not the set pixel group includes an edge portion where a gradation difference between adjacent pixels is a predetermined value or more. And an image processing apparatus in which the first color conversion unit performs processing on a pixel group including the edge portion.

  According to this configuration, since a pixel group including an edge is converted into a color material amount set in units of pixels, color conversion that realizes high-quality printing with excellent edge resolution can be performed.

  Application Example 4 In the image processing apparatus, the image processing apparatus further includes a print control unit that controls printing based on the conversion results of the first color conversion unit and the second color conversion unit.

  According to this configuration, printing excellent in color reproduction can be performed at higher speed.

  Application Example 5 For a plurality of color materials used in printing, the first pixel in which an index corresponding to a combination of color material amounts for reproducing the specified color is designated, and color information indicating the color to be printed Acquiring print data for printing an image including a second pixel for which the image data is designated, partitioning an image represented by the acquired image data, and setting a pixel group composed of a plurality of pixels Determining whether or not the set pixel group includes the first pixel, and specifying the index or the color information specified for each pixel of the pixel group including the first pixel for each color A step of converting the color material amount of the material in units of pixels, and a step of converting color information designated for each pixel of the pixel group not including the first pixel into a color material amount of each color material in units of pixel group And having Image processing method for the.

  In this way, it is possible to realize processing that combines accurate color reproduction and high-speed processing during printing.

  Application Example 6 An image processing program for printing using a plurality of color materials, wherein the computer is a first pixel in which an index corresponding to a combination of color material amounts for reproducing a specified color is designated And a print data acquisition unit that acquires print data for printing an image including a second pixel in which color information indicating a color to be printed is specified, and an image represented by the acquired image data is partitioned A pixel group setting unit that sets a pixel group composed of a plurality of pixels, a pixel group determination unit that determines whether or not the set pixel group includes the first pixel, and the first pixel A first color conversion unit that converts the index or the color information specified for each pixel of the pixel group to be included into a color material amount of each color material in units of pixels, and each of the pixel group that does not include the first pixel The color information specified for the pixel The image processing program for causing to function as the second color conversion section, which converts the color material amount of each colorant in pixel group units.

  According to this image processing program, it is possible to realize processing that combines accurate color reproduction and high-speed processing during printing with a computer.

Hereinafter, embodiments of the present invention will be described based on examples.
FIG. 1 shows a hardware configuration of an image processing apparatus according to an embodiment. A computer 10, which is an example of an image processing apparatus, is a control device for printing by a printer 20, and as shown in FIG. / F16, input I / F17, bus 18 and the like. The bus 18 realizes data communication between the elements 11 to 17 constituting the computer 10, and the communication is controlled by a chip set (not shown).

  In addition to the driver program (image processing program) DP for the printer driver, the hard disk drive 14 stores various programs such as an application and an operating system (hereinafter referred to as “OS”). The driver program DP is recorded in the computer 10 in a form recorded on various computer-readable recording media such as a flexible disk, an optical disk such as a CD-ROM or a DVD-ROM, a magneto-optical disk, a memory card, and a portable hard disk. Supplied. The driver program DP recorded on the recording medium is read by a drive device (not shown) provided in the computer 10 and recorded on the hard disk drive 14. However, the recording method to the hard disk drive 14 is not limited to this, and the computer 10 may download the driver program DP from the predetermined server to the hard disk drive 14 via a network such as the Internet.

  The general-purpose I / F 15 provides an interface conforming to the USB standard, for example, and is connected to an external printer 20. An external display 30 is connected to the video I / F 16, and the video I / F 16 provides an interface for displaying an image on the display 30. An external keyboard 40 and a mouse 50 are connected to the input I / F 17, and the input I / F 17 provides an interface for the computer 10 to acquire input signals from the keyboard 40 and the mouse 50.

  In this embodiment, the printer 20 performs ink jet printing, and in particular, discharges inks (coloring materials) of each color of C (cyan), M (magenta), Y (yellow), and K (black). The following description will be given on the assumption that dots of three types of large, medium, and small dot sizes are selectively formed on the printing paper. Of course, in this embodiment, a case where a CMYK ink set is used will be described as an example. However, the ink set is not limited to this. For example, R (red), B (blue), lc (light cyan) , Lm (light magenta) or the like.

  Next, the software configuration of the computer 10 will be described. FIG. 2 is a diagram illustrating a software configuration of the computer 10. As shown in FIG. 2, the computer 10 has an OS 100, an application 200, a printer driver 300, and a display driver 400 as software configurations. Each of these software configurations functions by the CPU 11 executing a program recorded on the hard disk drive 14. In particular, the printer driver 300 functions by the CPU 11 reading and executing the driver program DP from the hard disk drive 14.

  The OS 100 provides an image device interface (hereinafter referred to as “GDI (Graphical Device Interface)”) 110 and a spooler 120 as one of APIs (Application Programming Interfaces) that can be used by the application 200 and the drivers 300 and 400. ing. The GDI 110 is called in response to a request from the application 200, and the printer driver 300 and the display driver 400 are called in response to a request from the GDI 110. The GDI 110 provides a general-purpose mechanism for the computer 10 to control image output by an image output device such as the printer 20 or the display 30. The printer driver 300 manages processes unique to the model of the printer 20, and the display driver 400 manages processes unique to the model of the display 30. The spooler 120 is interposed between the application 200, the printer driver 300, and the printer 20, and executes job control and the like.

  The application 200 is, for example, a sample printing application for printing a color sample chart, and generates print data PD in accordance with a user operation on the keyboard 40, the mouse 50, or the like. For example, an image of content arbitrarily input by a user, a color sample image registered in advance, or the like is set as print data PD to be printed by the application 200.

  Here, the data structure of the print data PD will be described. The print data PD is bitmap data, and a bitmap image is expressed by a large number of pixels arranged in a matrix. In this embodiment, an information amount of 4 bytes is allocated to one pixel of the print data PD, and each pixel stores pixel data of either RGB value or index. That is, each pixel of the print data PD is designated with a color to be printed by either an RGB value or an index.

  FIG. 3A shows a data format of a pixel for which RGB values are designated. As shown in FIG. 3A, the data type flag F is set to the 0th byte of the pixel data of the pixel for which the RGB value is specified. This data type flag F indicates whether the pixel is an RGB value designated pixel (second pixel) or an index designated pixel (first pixel). The data type flag F is set to “0” in the pixel for which the RGB value is designated. Then, the R value is stored in the subsequent 1 byte, the G value is stored in the 2nd byte, and the B value is stored in the 3rd byte. In other words, in the RGB value designated pixel, 3 bytes out of the 4 bytes described above are used to store the RGB value, and the gradation value of each RGB channel is represented by gradation by 8 bits (256 gradations). .

  FIG. 3B shows the data format of the index designated pixel. As shown in FIG. 3B, “1” is set as the data type flag F in the 0th byte of the pixel data of the pixel designated by the index. Subsequently, the first byte is unused, the upper 8 bits of the index are stored in the second byte, and the lower 8 bits of the index are stored in the third byte. That is, in the pixel designated by the index, 2 bytes out of the 4 bytes described above are used to store the index of a total of 16 bits. Note that the index corresponds in advance to a combination of ink values (hereinafter referred to as “ink amount set”) indicating the amount of each color ink to be used for reproducing a specified color by printing. The index combinations are registered in advance in a one-dimensional color conversion table 341, which will be described later, for example, when the printer manufacturer sets in advance or the user adds a desired combination.

  The print data PD having the above-described configuration is output from the application 200 to the printer driver 300 via the GDI 110 and the spooler 120 provided by the OS 100.

  Next, the printer driver 300 will be described. As shown in FIG. 2, the printer driver 300 includes a print data acquisition unit 310, a block setting unit (pixel group setting unit) 320, a block determination unit (pixel group determination unit) 330, and a first color conversion unit 340. , A second color conversion unit 350, a dot size conversion unit 360, a halftone processing unit 370, and a rasterization processing unit (print control unit) 380.

  The print data acquisition unit 310 acquires print data PD from the application 200. In addition, the print data acquisition unit 310 performs a process of converting the print data PD into data having a resolution corresponding to the print resolution as necessary.

  The block setting unit 320 performs processing for dividing a region of an image represented by the acquired print data PD and setting a pixel group (hereinafter referred to as “block”) including a plurality of pixels.

  The block determination unit 330 performs a process of determining a color conversion unit to be processed for a block from the first color conversion unit 340 and the second color conversion unit 350. Although details of the determination will be described later, the block determination unit 330 selects appropriate color conversion units 340 and 350 for each block based on the presence / absence of an index-designated pixel and the presence / absence of an edge in the block. The edge refers to a boundary portion where the difference in gradation value between adjacent pixels is equal to or greater than a predetermined value in the image of the print data PD.

  The first color conversion unit 340 is a functional unit that performs color conversion (separation) on each pixel included in the block, and converts an index into an ink amount set for each pixel in the block according to the type of pixel. One-dimensional color conversion to be performed and three-dimensional color conversion to color-convert RGB values into ink amount sets are selectively performed. That is, the first color conversion unit 340 performs color conversion for each pixel individually by performing one-dimensional color conversion for the index-designated pixel and three-dimensional color conversion for the RGB value-designated pixel.

  Here, the one-dimensional color conversion is performed according to a one-dimensional color conversion table (hereinafter referred to as “1D-LUT”) 341 in which an index is associated with an ink value of each color. As shown as an example in FIG. 4, in the 1D-LUT 341, an index number is associated with each color ink value of the ink set (C value, M value, Y value, and K value in this embodiment). . The 1D-LUT 341 is stored in advance in the hard disk drive 14 or the like, and the first color conversion unit 340 converts the index specified for the pixel into an ink value of each color ink, that is, an ink amount set according to the 1D-LUT 341.

  The three-dimensional color conversion is performed according to a three-dimensional color conversion table (hereinafter referred to as “3D-LUT”) 342 in which RGB values and ink amount sets are associated with each other. The 3D-LUT 342 is a table describing the correspondence between the RGB values and the ink amount sets of each color with respect to a plurality of representative coordinates in the color space, and characteristics such as color reproducibility, gradation, gamut, and ink duty. Are associated with each other in advance so that the RGB values are generally good. The 3D-LUT 342 is stored in advance in the hard disk drive 14 or the like, and the first color conversion unit 340 converts the RGB value specified for the pixel into an ink amount set according to the 3D-LUT 342. Note that, during the three-dimensional color conversion, the first color conversion unit 340 performs conversion to an ink amount set by performing an interpolation operation on RGB values that are not directly described in the 3D-LUT 342.

  On the other hand, the second color conversion unit 350 is a functional unit that performs color conversion (separation) in which an ink amount set of each pixel in a block is obtained in a block unit. The second color conversion unit 350 calculates the average gradation value of the RGB values of each pixel in the block, performs 3D color conversion on the average gradation value by referring to the 3D-LUT 342, and The ink amount set corresponding to each pixel of the block is obtained by the color conversion of the degree. As described above, since color conversion is performed in units of blocks, the processing time required for the second color conversion unit 350 to perform color conversion is shorter than the color conversion by the first color conversion unit 340 that is performed for each pixel individually. The processing speed can be increased.

  The dot size conversion unit 360 performs a process of converting each ink value of the ink amount set into a dot generation rate indicating the dot generation amount of each dot size. This dot generation rate conversion is performed according to the dot generation rate conversion table 361. FIG. 5 shows an example of the dot generation rate conversion table 361. As shown in the figure, the dot generation rate conversion table 361 associates each ink value of 256 gradations (8 bits) with each dot generation rate of small dots, medium dots, and large dots. This dot generation rate conversion table 361 is set so that image formation with small dots is dominant in a range with a small ink value, and image formation with large dots is dominant in a range with a large ink value. As a result, the graininess generated in the low density image formation can be suppressed, and the high density image formation can be performed with a small number of dots, and high-quality and high-speed printing can be realized. The dot generation rate conversion table 361 is stored in advance in the hard disk drive 14 or the like, and the dot size conversion unit 360 refers to the dot generation rate conversion table 361 and converts each color ink value into a dot generation rate of each dot size. To do.

  The halftone processing unit 370 performs halftone processing on the dot generation rate obtained by the dot size conversion unit 360, and converts each dot size into quantized data corresponding to the presence or absence of dots.

  The rasterization processing unit 380 rasterizes the quantized data and generates print control data CD that can be processed by the printer 20. Then, by outputting the generated print control data CD to the printer 20 via the spooler 120 provided by the OS 100, the operation of the printer 20 based on the print control data CD is controlled, and the sample chart is printed on the printing paper. Let

  Next, a process in which the computer 10 controls printing of the printer 20 will be described with reference to a flowchart. FIG. 6 is a flowchart showing the flow of the print control process. When the process is started and the print data acquisition unit 310 of the printer driver 300 acquires the print data PD from the application 200 (step S100), the color conversion process is then executed (step S110).

  7 and 8 are flowcharts showing the flow of color conversion processing. When the color conversion process is started, the block setting unit 320 sets a block for the area of the image represented by the print data PD (step S200).

  FIG. 9 shows a block setting example. FIG. 9 shows an image of the print data PD. The RGB value designated pixel Pv is indicated by a white background, and the index designated pixel Pi is indicated by oblique lines. As shown in the figure, the image represented by the print data PD is composed of RGB value-designated pixels Pv and index-designated pixels Pi. As shown in FIG. 9, such an image of the print data PD is divided into blocks B occupying an area of 2 pixels × 2 pixels, for example, by the block setting unit 320. In the process of step S200, an area for one block among the undivided areas is sectioned, and one block B is newly set. The size, shape, and arrangement of the blocks are not limited to the example in FIG. For example, a block having a larger size or a diamond shape may be set, or the blocks may be set to be arranged in a staggered pattern.

  Next, the block determination unit 330 reads the data type flag F for each pixel in the block set in step S200 (step S205), and determines whether there is an index-designated pixel Pi in the set block. (Step S210).

  When a pixel whose data type flag F is “1” is included in the block, the block determination unit 330 determines that the index-designated pixel Pi is in the block (step S210: Yes), and the first color The conversion unit 340 individually performs color conversion processing on each pixel in the block including the pixel Pi designated by the index. That is, the first color conversion unit 340 pays attention to the pixel in the block (step S215), and determines whether or not the target pixel is the index designated pixel Pi (step S220). If it is an index designated pixel Pi (step S220: Yes), the index of the pixel of interest is converted into an ink amount set by performing one-dimensional color conversion with reference to the 1D-LUT 341 (step S225).

  On the other hand, if the pixel Pi is not the index designation pixel Pi (step S220: No), the pixel of interest is the RGB value designation pixel Pv. Therefore, the first color conversion unit 340 performs the three-dimensional color conversion with reference to the 3D-LUT 342. By doing so, the RGB value of the pixel of interest is converted into an ink amount set (step S230).

  When the one-dimensional color conversion or the three-dimensional color conversion is performed on the target pixel, the first color conversion unit 340 determines whether or not the color conversion has been completed for all the pixels in the block (step S235). If the process has not been completed for all pixels (step S235: No), the process returns to step S215, focusing on the unprocessed pixels among the pixels in the block, and the processes of steps S215 to S235 are repeated. Thus, as shown in FIG. 10, as an example, for the block B1 including the index designated pixel Pi, the color conversion to the index designated pixel Pi is one-dimensional color conversion, and the color conversion to the RGB value designated pixel Pv is performed. By three-dimensional color conversion, color conversion is performed for each pixel one after another. In this way, when it is confirmed that each pixel in the block has undergone color conversion and color conversion has been performed for all the pixels (step S235: Yes), the process proceeds to step S275.

  On the other hand, when it is determined in step S210 that there is no index-designated pixel Pi in the block (step S210: No), the block determination unit 330 performs edge detection (step S240).

  If there is an edge in the block as a result of the edge detection (step S245: Yes), the first color conversion unit 340 individually performs color conversion processing on each pixel in the block including the edge. That is, the first color conversion unit 340 pays attention to the pixels in the block (step S250), performs three-dimensional color conversion with reference to the 3D-LUT 342, and converts the RGB values into ink amount sets (step S255). . When the three-dimensional color conversion is performed for the target pixel, it is determined whether or not the color conversion has been completed for all the pixels in the block (step S260). If the process has not been completed for all pixels (step S260: No), the process returns to step S250, focusing on the unprocessed pixels among the pixels in the block, and the processes of steps S250 to S260 are repeated. As a result, as shown as an example in FIG. 11, color conversion is performed for each pixel individually in the block B <b> 2 including the edge E without including the index-designated pixel Pi. Then, when the color conversion processing is sequentially performed for the pixels in the block and it is confirmed that the color conversion has been performed for all the pixels (step S260: Yes), the process proceeds to step S275.

  If there is no edge in the block (step S245: No), the set block B does not have a pixel Pi with an index specified to perform strict color reproduction, and has a sharp gradation change in the block. It is judged that there is no. In this case, the second color conversion unit 350 performs color conversion processing. That is, the second color conversion unit 350 calculates an average gradation value in the block (step S265), and performs a three-dimensional color conversion on the average gradation value with reference to the 3D-LUT 342 (step S270). As a result, as shown as an example in FIG. 12, for the block B0 that does not include the index-designated pixel Pi and the edge E, color conversion is performed on a block-by-block basis, and ink values to be applied to the respective pixels are determined in a lump. It is done. In block B0, there is no pixel whose index is designated to perform strict color reproduction, and there is no steep gradation change in the block, so when color conversion is performed collectively using the average gradation value in the block In addition, color reproduction can be realized with sufficient accuracy. Next, the process proceeds to step S275.

  When the process proceeds to step S275, it is determined whether or not the color conversion process is completed. If an unprocessed area remains in the image area of the print data PD (step S275: No), the process returns to step S200 to set the next block for the unprocessed area. The processes of S200 to S270 are repeated. Thus, when color conversion is performed on the entire area of the image of the print data PD (step S275: Yes), the color conversion process is terminated.

  When the color conversion process ends, the process returns to the process of FIG. 6, and the dot size conversion unit 360 converts the ink value of the ink amount set into the dot generation rate of each dot size according to the dot generation rate conversion table 361 (step S120). ).

  Next, the halftone processing unit 370 performs a halftone process such as a dither method or an error diffusion method on the dot generation rate, and converts it into quantized data corresponding to the presence or absence of dots (step S130).

  Next, the rasterization processing unit 380 executes a process of allocating an ejection signal for ejecting ink to each scanning pass and each nozzle of the print head included in the printer 20 according to the quantized data dot-attached pixel. As a result, print control data CD that can be processed by the printer 20 is generated. The generated print control data CD is output to the printer 20 via the spooler 120 with a signal necessary for controlling the printer 20 attached thereto, and printing by the printer 20 is executed (step S140). When printing is executed in this way, the print control process is terminated.

  As described above, in this embodiment, the image represented by the print data PD is divided into blocks B. For the block B1 including the index-designated pixel Pi, color conversion corresponding to the type of pixel is performed for each pixel. It is performed individually (see FIG. 10). For this reason, in the image represented by the print data PD, a one-dimensional color conversion is performed for a portion for which strict color reproduction is required by designating an index, which is accompanied by an interpolation process of the three-dimensional color conversion. A color reproduction faithful to the specified color and accurate can be realized without degrading accuracy due to a conversion error or the like. On the other hand, for the block B0 that does not include the index designated pixel Pi, the pixels in the block are collectively color-converted by the three-dimensional color conversion using the average gradation value in the block (see FIG. 12). The amount of processing required for color conversion is reduced. Therefore, it is possible to reduce the processing time required for color conversion for the entire image while accurately reproducing colors for areas where strict color reproduction is required. Is realized.

  For the block B0 that does not include the index-designated pixel Pi, the pixel resolution is slightly reduced by color conversion performed collectively in units of blocks, but the index-designated pixel Pi is color-converted for each pixel. Therefore, the resolution of the image does not decrease. In actual color sample printing or the like, the index-designated pixel Pi is often designated as a main region such as the color sample itself in the entire image region of the print data PD. It is assumed that RGB values are often specified for. For this reason, according to the above-described embodiment, it is possible to perform high-quality printing with excellent color reproduction and resolution in the main area where high image quality is required, and color reproduction and resolution performance degradation in non-main areas. With some allowance, overall, print control having high image quality and high processing speed is realized.

  In addition, the block B2 including the edge E that does not include the index-designated pixel Pi is subjected to individual color conversion for each pixel, so that the edge resolution does not decrease. For this reason, high-quality printing excellent in edge reproducibility is realized while increasing the processing speed.

  As mentioned above, although one Example of embodiment was described, it is good also as various forms which do not deviate from the meaning, without being restricted to this. Hereinafter, modified examples will be described.

(Modification 1)
In the above embodiment, for blocks that do not include index-designated pixels and edges, the blocks are color-converted collectively by performing three-dimensional color conversion using the average gradation value in the block. The method of color conversion performed collectively is not limited to this. For example, by applying a value converted using the median value or mode value of the gradation values of the pixels in the block to each pixel in the block, the block may be color-converted collectively.

(Modification 2)
In the embodiment described above, color conversion is performed for each pixel on a block including an edge, but processing related to an edge is not essential. That is, the processing method in the block may be changed only by the presence / absence of an index-designated pixel without performing edge detection.

  Also, the dot generation rate conversion process is not essential. That is, in the case of a printer that performs printing by dot formation of a single dot size, the printer driver 300 performs print tone data by performing halftone processing without performing dot generation rate conversion on the ink amount set. A CD can be generated.

(Modification 3)
In the above embodiment, the print data PD received from the application 200 is bitmap data. However, drawing data in which an object, text, or the like of the print content is described in a predetermined language may be received. In this case, the print data acquisition unit 310 can acquire the print data PD by interpreting the language of the received drawing data and performing expansion and indexing on the bitmap image.

(Modification 4)
In the above embodiment, the printer driver 300 performs color conversion processing, dot generation rate conversion processing, halftone processing, and rasterization processing, but some of these processing is performed on the printer side. It is good also as a structure to perform. For example, the computer 10 as an image processing apparatus performs color conversion, dot generation rate conversion, and halftone processing, and outputs quantized data to the printer 20 as print control data. The printer 20 performs rasterization processing. It is good also as a structure to perform. Further, the computer 10 may perform color conversion and dot generation rate conversion processing, output dot generation rate data to the printer 20 as print control data, and the printer 20 may perform halftone and rasterization processing. Good. Further, the computer 10 may be configured to perform color conversion processing and output the color-converted data to a printer. Of course, the printer has an image processing apparatus that performs color conversion processing, dot generation rate conversion processing, and rasterization processing, and all the processing after color conversion including block setting and determination is executed on the printer side. Good.

1 is a diagram showing a hardware configuration of an image processing apparatus according to an embodiment. The figure which shows the software structure of a computer. 4A and 4B are diagrams for explaining print data, in which FIG. 4A is a data format of an RGB value-designated pixel, and FIG. 4B is a diagram showing a data format of an index-designated pixel. The figure which shows an example of 1D-LUT. The figure which shows an example of a dot production rate conversion table. 5 is a flowchart showing a flow of print control processing. 5 is a flowchart showing the flow of color conversion processing. 5 is a flowchart showing the flow of color conversion processing. The figure explaining the example of a setting of a block. The figure explaining the process example with respect to a block. The figure explaining the process example with respect to a block. The figure explaining the process example with respect to a block.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Computer as image processing apparatus, 20 ... Printer, 200 ... Application, 300 ... Printer driver, 310 ... Print data acquisition part, 320 ... Block setting part as pixel group setting part, 330 ... Block as pixel group determination part Determination unit, 340... First color conversion unit, 341... 1D-LUT, 342... 3D-LUT, 350... Second color conversion unit, 360 ... dot size conversion unit, 361 ... dot generation rate conversion table, 370. Processing unit, 380... Rasterization processing unit as print control unit, F... Data type flag, DP... Driver program as image processing program, PD... Print data, CD... Print control data, Pi. Index designated pixel, Pv... RGB value designated pixel as the second pixel.

Claims (6)

For a plurality of color materials used in printing, a first pixel in which an index corresponding to a combination of color material amounts for reproducing a specified color is specified, and color information indicating a color to be printed is specified. A print data acquisition unit that acquires print data for printing an image including two pixels;
A pixel group setting section that partitions an image represented by the acquired image data and sets a pixel group including a plurality of pixels;
A pixel group determination unit that determines whether or not the set pixel group includes the first pixel;
A first color conversion unit that converts the index or the color information designated for each pixel of the pixel group including the first pixel into a color material amount of each color material in units of pixels;
Image processing comprising: a second color conversion unit that converts color information designated for each pixel of a pixel group not including the first pixel into a color material amount of each color material in units of pixel groups. apparatus. The image processing apparatus according to claim 1.
The second color converter is
An average gradation value of color information is calculated based on color information designated for each pixel of the pixel group not including the first pixel, and is common to each pixel of the pixel group based on the average gradation value An image processing apparatus characterized by obtaining an amount of a color material. The image processing apparatus according to claim 1 or 2,
The pixel group determination unit determines whether or not the set pixel group includes an edge portion where a gradation difference between adjacent pixels is equal to or greater than a predetermined value.
The image processing apparatus, wherein the first color conversion unit performs processing on a pixel group including the edge portion. In the image processing device according to any one of claims 1 to 3,
An image processing apparatus, further comprising: a print control unit that controls printing based on the conversion results of the first color conversion unit and the second color conversion unit. For a plurality of color materials used in printing, a first pixel in which an index corresponding to a combination of color material amounts for reproducing a specified color is specified, and color information indicating a color to be printed is specified. Obtaining print data for printing an image including two pixels;
Partitioning an image represented by the acquired image data and setting a pixel group including a plurality of pixels;
Determining whether the set pixel group includes the first pixel;
Converting the index or the color information designated for each pixel of the pixel group including the first pixel into a color material amount of each color material in units of pixels;
Converting the color information designated for each pixel of the pixel group not including the first pixel into a color material amount of each color material in units of pixel group. An image processing program for printing using a plurality of color materials,
Computer
An image including a first pixel in which an index corresponding to a combination of color material amounts for reproducing a specified color and a second pixel in which color information indicating a color to be printed is specified is to be printed. A print data acquisition unit for acquiring print data;
A pixel group setting section that partitions an image represented by the acquired image data and sets a pixel group including a plurality of pixels;
A pixel group determination unit that determines whether or not the set pixel group includes the first pixel;
A first color conversion unit that converts the index or the color information designated for each pixel of the pixel group including the first pixel into a color material amount of each color material in units of pixels;
An image that functions as a second color conversion unit that converts color information designated for each pixel of a pixel group not including the first pixel into a color material amount of each color material in units of pixel groups. Processing program.

Images