JP4345485B2 - Installation of color conversion lookup table for printer - Google Patents

Description

  The present invention relates to a technique for installing a color conversion lookup table for a printer in a computer.

  In a printer driver that creates print data for a printer, various color conversion profiles are used for color conversion (see Patent Document 1).

JP 2003-271327 A

  As the color conversion profile, an ICC profile in accordance with the ICC (International Color Consortium) standard is often used. As the ICC profile, two types of profiles, ie, a source profile and a destination profile are usually used. As is well known, a source profile is for converting a color space (input color space) of an input device (digital camera or scanner) into a profile connection space (Profile Connection Space). The destination profile converts the profile connection space into a color space (output color space) of an output device (for example, a printer or a monitor). The ICC profile can take one of two data formats: a lookup table and a conversion matrix.

  Conventionally, a color conversion lookup table for a printer in which a source profile and a destination profile are synthesized in advance is created and installed in a computer. This color conversion lookup table converts a color space (for example, sRGB color space) of the input device into an ink amount color space (for example, CMYK color space) of the printer. Such a color conversion look-up table for a printer is created that is suitable for the print mode at the time of printing. However, since the pre-synthesized color conversion lookup table for printers was mounted on a CD-ROM, etc., the capacity of the printer driver in the CD-ROM was enlarged, putting pressure on other areas. Furthermore, when this synthesis process is performed at the time of printing, there is a problem that the processing time is reduced.

  An object of the present invention is to provide a technique for preventing an excessive printing time due to a reduction in printer driver capacity before installation and a time required for composition of a color conversion profile.

In order to achieve the above object, an installation method according to the present invention is a method for installing a color conversion lookup table for a specific printer in a computer from a recording medium inserted in the computer or a printer driver providing server .
(A) From the profile data file that includes a plurality of types of color conversion profiles for each type , the computer sets one type of color conversion profile according to the parameters that define the printing mode of the specific printer. Selecting each one , and
(B) the computer creating a color conversion lookup table for the specific printer by combining the plurality of selected color conversion profiles and installing the color conversion lookup table on the computer;
With
The step (b)
The computer, see contains a step of synthesizing all of the plurality of color conversion lookup table used in a plurality of print modes to be used in the specific printer during the installation,
The plurality of print modes are defined by a plurality of parameters including an input color space, a print medium, and a print resolution.
The plurality of types of color conversion profiles are:
A plurality of first type color conversion profiles, one selected according to the input color space;
A plurality of second type color conversion profiles, one selected according to the print medium;
A plurality of third type color conversion profiles, one selected according to the combination of the print medium and the print resolution;
Including

According to this method, since all the color conversion lookup tables are combined at the time of installation, it is possible to prevent an excessive printing time due to the time required for combining the color conversion profiles. In addition, since it is not necessary to store all color conversion lookup tables in the installer before installation, the data capacity before installation can be reduced. Furthermore, it is possible to create an appropriate color conversion lookup table corresponding to the combination of the input color space, the print medium, and the print resolution.

The first type color conversion profile has a function of converting a first RGB color space as the input color space into a predetermined profile connection space;
The second type color conversion profile has a function of converting the profile connection space to a second RGB color space,
The third type color conversion profile may have a function of converting the second RGB color space into an ink amount space related to a plurality of inks used in the specific printer.

  According to this configuration, a color conversion lookup table for converting the input color space into the ink amount space of a specific printer can be created by synthesizing three types of color conversion profiles.

  Note that the present invention can be realized in various forms, for example, to realize a color conversion lookup table or printer driver installation method and apparatus, a printing method and a printing apparatus, and functions of those methods or apparatuses. Computer program, a recording medium storing the computer program, a data signal including the computer program and embodied in a carrier wave, and the like.

  FIG. 1 is an explanatory diagram showing the overall configuration of a network system as an embodiment of the present invention. This system includes a support center 100 and a client computer 200 connected via the Internet. The client computer 200 is connected to the color printer 300.

  The support center 100 includes a printer driver providing server 110 and a Web server 120. These two servers 110 and 120 may be realized on separate computer hardware, or may be realized on the same computer hardware. Further, the service by the two servers 110 and 120 may be provided by one server.

  The two servers 110 and 120 store various files and program modules in order to provide a printer driver via the Internet. For example, the web server 120 stores various web pages including a printer support home page and a printer driver providing page. The printer driver providing server 110 stores installation programs for various printer printer drivers.

  The client computer 200 has a data processing unit 210 and a disk drive 220. The data processing unit 210 includes a CPU and a memory, and can implement various functions by executing a computer program. In the example of FIG. 1, the data processing unit 210 has functions of a browser 212 and a printer driver installer 214. The printer driver installer 214 is provided from the recording medium disk DC inserted into the disk drive 220 or from the printer driver providing server 110.

  FIG. 2 is a block diagram illustrating an example of the configuration of the printer driver 230 installed by the printer driver installer 214. The printer driver 230 includes a resolution conversion unit 232, a color conversion unit 234, a halftone processing unit 236, a data arrangement unit 238, a lookup table selection unit 240, and a plurality of color conversion lookup tables 250. ing. The resolution conversion unit 232 converts the resolution of the input color image data R0, G0, B0 into a resolution suitable for processing after the color conversion unit 234.

  The color conversion unit 234 converts the color image data RGB into ink amount data CMYK using one color conversion lookup table 250. When the printer driver 230 is installed, a plurality of color conversion lookup tables 250 suitable for a plurality of printing modes used in the printer 300 are created. The look-up table selection unit 240 selects one table suitable for the print mode used at the time of actual printing from the plurality of color conversion look-up tables 250, and the color conversion unit 234 selects the selected table. Perform color conversion using a table. In the present embodiment, the color conversion lookup table 250 is selected according to three parameters: the input color space, the print medium, and the print resolution. These parameters will be described later.

  In many cases, the input grid points of the color conversion lookup table 250 do not correspond to all the input RGB values (that is, the input grid points are often set at regular intervals). In this case, the color conversion unit 234 performs an interpolation operation on the ink amount output as necessary.

  The halftone processing unit 236 generates dot formation data Dc, Dm, Dy, and Dk indicating the dot formation state for each print pixel by executing halftone processing for each ink. The data arrangement unit 238 arranges these dot formation data Dc, Dm, Dy, Dk and outputs them as print data PD.

  Normally, the printer driver 230 is implemented as a program stored in a storage unit such as a hard disk in the computer 200. In this case, the print data PD created by the printer driver 230 is supplied to the external printer 300. Alternatively, the printer driver 230 may be mounted in the printer 300. In this case, the print data PD created by the printer driver is supplied to a print execution unit (printing mechanism) inside the printer. Even in the case of a printer driver installed in the computer 200, an external printer can be called a “print execution unit”. Accordingly, the printer driver 230 generally has a function of generating print data to be supplied to the print execution unit based on color image data. Note that the resolution converter 232 and the data array unit 238 may be omitted from the printer driver 230.

  FIG. 3 is an explanatory diagram showing the contents of the process of creating the color conversion lookup table 250 by the printer driver installer 214. The installer 214 has a profile data file 216 that includes three types of color conversion profiles: a source profile 10, a media profile 20, and a base lookup table 30.

  The source profile 10 has a function of converting an input color space into a profile connection space. As the input color space, for example, various RGB color spaces can be used. Typical RGB color spaces include an sRGB color space and an AdobeRGB color space (trademark of Adobe). As the profile connection space, a device independent color space such as an L * a * b * color space or an XYZ color space is used.

  The media profile 20 has a function of converting the profile connection space into a predetermined internal processing color space. Any internal processing color space can be used. In the example of FIG. 3, a specific RGB color space (R′G′B ′ color space) is used. As the R′G′B ′ color space, it is preferable to use a color gamut wider than the sRGB color space (standard color space for monitoring). The media profile 20 of the present embodiment compensates for the difference in color reproducibility depending on the print medium, and realizes color correction that enables substantially the same color reproduction even when different print media are used.

  The base look-up table 30 has a function of converting the output color space (here, R′G′B ′ color space) of the media profile 20 into an ink amount color space for a plurality of inks usable in the printer 300. In this example, it is assumed that the printer 300 uses four types of CMYK inks. Note that any other type of ink used in the printer 300 can be used. The base look-up table 30 of this embodiment is used to determine an appropriate ink amount within various limits relating to ink dot formation conditions such as ink duty limit (allowable ink discharge amount per unit area).

  In the profile data file 216, a plurality of profiles are prepared in advance as these three types of profiles 10, 20, and 30, respectively. When installing the printer driver 230 (FIG. 2), one of the three types of profiles 10, 20, and 30 is selected according to a plurality of parameters (input color space, print medium, and print resolution). The profiles are combined to create a color conversion lookup table 250. At this time, all color conversion look-up tables 250 used in all print modes usable in the printer 300 are combined. The color conversion lookup table 250 converts an input color space (here, RGB color space) into an ink amount color space. The color conversion lookup table 250 can also be considered as a kind of “color conversion profile”.

  FIG. 4 shows the relationship between the four types of color conversion profiles 10, 20, 30, 250 and printing parameters. As the source profile 10, those corresponding to a plurality of input color spaces are prepared in advance. In the example of FIG. 4A, three source profiles SP1 to SP3 corresponding to three input color spaces (sRGB, AdobeRGB, xRGB) are prepared. Note that xRGB means a specific extended RGB color space having a wider gamut than sRGB.

  Media profiles 20 corresponding to a plurality of print media are prepared in advance. This is because the media profile 20 is for compensating for the difference in color reproducibility depending on the print medium. In the example of FIG. 4B, three media profiles MP1 to MP3 corresponding to three types of printing media (plain paper, photographic paper, matte paper) are prepared.

  As the base lookup table 30, a table corresponding to a combination of each printing medium and printing resolution is prepared in advance. This is because the base lookup table 30 determines an appropriate amount of ink within various limits related to the ink dot formation conditions. The restrictions on the ink dot formation conditions include the type of print medium and the print resolution. Because it depends on. In the example of FIG. 4C, for plain paper, three types of print resolutions of extremely low resolution R1 (360 × 360 dpi), low resolution R2 (720 × 720 dpi), and medium resolution R3 (1440 × 720 dpi) are used. Three base look-up tables BL1 to BL3 are prepared. For photo paper, three base look-up tables BL4 for three types of printing resolutions of medium resolution R3 (1440 × 720 dpi), high resolution R4 (1440 × 1440 dpi), and extremely high resolution R5 (2880 × 1440 dpi). -BL6 is prepared. Regarding the matte paper, three base look-up tables BL7 to BL9 are prepared for the same three print resolutions R3, R4, and R5 as the photographic paper. As can be understood from this example, the print resolution available in the printer 300 is usually different depending on the print medium. Therefore, as the base lookup table 30, only those suitable for a plurality of printing resolutions determined in advance for each printing medium are prepared in advance.

  The color conversion lookup table 250 synthesizes the combinations corresponding to all the combinations that can be used by the printer 300 among the combinations of the three types of profiles 10, 20, and 30 described above. FIG. 4D illustrates nine look-up tables PM1 to PM9 corresponding to the input color space sRGB. For example, the first color conversion lookup table PM1 is used when the input color space is sRGB, the print medium is plain paper, and the print resolution is extremely low resolution R1. The color conversion lookup table PM1 is a combination of the first source profile SP1, the first media profile MP1, and the first base lookup table BL1. The color conversion lookup table 250 for other input color spaces is synthesized in the same manner, but is not shown in FIG.

  In this specification, a printing method defined by a plurality of parameters for selecting three types of color conversion profiles 10, 20, and 30 is also referred to as a “print mode”. When the printer driver 230 is installed, it is preferable that all the color conversion lookup tables 250 used in all the printing modes available in the printer 300 are combined and stored in the computer 200 as the color conversion lookup table 250. .

  FIG. 5 is an explanatory diagram showing the procedure of the composition process of the color conversion lookup table 250. The source profile 10 and the media profile 20 have 33 × 33 × 33 (variable size) input grid points, and the base lookup table 30 has 32 × 32 × 32 input grid points. Yes. Here, the “input grid point” means a point in a color space defined by an input value (for example, RGB value). The reason why the number of input grid points of the source profile 10 and the media profile 20 is an odd number is to set one of the input grid points to the origin (0, 0, 0) so that black can be reproduced as accurately as possible. is there. In this sense, the number of input grid points of the base lookup table 30 may be set to an odd number.

  The color conversion lookup table 250 has 17 × 17 × 17 input grid points, and the number of input grid points is smaller than any of the three types of color conversion profiles 10, 20, and 30 before synthesis. This is because the data amount of the final color conversion lookup table 250 is reduced. Further, if the color conversion profiles 10, 20, and 30 before synthesis have finer input grid points than the color conversion lookup table 250 after synthesis, errors generated during profile synthesis can be suppressed to a small level. There is an advantage that you can.

  In the synthesis process, first, individual input values RGB corresponding to the input grid points of the color conversion lookup table 250 are given to the source profile 10. For example, it is assumed that three values of RGB are each represented by 8 bits and the color conversion lookup table 250 has 17 × 17 × 17 input grid points. In this case, the input values (R, G, B) are (0, 0, 0), (0, 0, 15), (0, 0, 31), ... (0, 0, 255). ,... (255, 255, 255). Each input value RGB is converted into a Lab value by the source profile 10, and at this time, interpolation is performed as necessary. As this interpolation, for example, tetrahedral interpolation can be used. However, in the example of FIG. 5, since the input grid points of the source profile 10 are 33 × 33 × 33, (0, 0, 0), (0, 0, 7), (0, 0, 15), (0 , 0, 23), (0, 0, 31), ... (0, 0, 255), ... (255, 255, 255), and all the input grid points of the color conversion lookup table 250 are This interpolation is not necessary.

  The output Lab of the source profile 10 is input to the media profile 20 and converted into an R′G′B ′ value. Also in this case, interpolation is performed as necessary (that is, when the input value Lab does not coincide with the input grid point of the media profile 20). Similarly, the output R′G′B ′ of the media profile 20 is input to the base lookup table 30 and converted into ink amounts CMYK, and interpolation is performed as necessary.

  In this way, ink amounts CMYK are obtained for the individual input values RGB corresponding to the input grid points of the color conversion lookup table 250, respectively. Therefore, the color conversion lookup table 250 can be created by configuring the correspondence between the input value RGB and the ink amounts CMYK as a lookup table.

  In this embodiment, when the printer driver 230 is installed, all the color conversion lookup tables 250 used in all the printing modes available in the printer 300 are synthesized. In this way, at the time of actual printing, one color conversion lookup table 250 can be selected according to the print mode and used immediately for color conversion. Therefore, there is an advantage that the time required for the entire printing process can be shortened as compared with the case where the color conversion lookup table 250 is combined at the time of printing.

  The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

(1) In the above-described embodiment, the color conversion look-up table is synthesized by synthesizing three types of color conversion profiles. However, the present invention generally performs color synthesis by synthesizing a plurality of types of color conversion profiles. This can be applied when synthesizing a conversion look-up table. For example, a preliminary synthesis lookup table obtained by synthesizing the media profile 20 and the base lookup table 30 described above is prepared in advance for each combination of the print medium and the print resolution, and the preliminary synthesis lookup table and the source profile 10 are prepared. And may be combined. Various color spaces can be used for the input of the preliminary synthesis look-up table. For example, an L * a * b * color space or various RGB color spaces can be used. At this time, the output color space of the source profile is set in advance to correspond to the input color space of the preliminary synthesis lookup table.

(2) In the above embodiment, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware. Also good.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the whole structure of the network system as one Example of this invention. FIG. 2 is a block diagram illustrating a configuration of a printer driver in the present embodiment. FIG. 3 is an explanatory diagram showing the contents of color conversion lookup table composition processing by a printer driver installer. Explanatory drawing which shows the relationship between four types of color conversion profiles and printing parameters. Explanatory drawing which shows the procedure of the synthesis | combination process of a color conversion lookup table.

Explanation of symbols

10 ... Source profile 20 ... Media profile 30 ... Base lookup table 100 ... Support center 110 ... Printer driver providing server 120 ... Web server 200 ... Client computer 210 ... Data processing unit 212 ... Browser 214 ... Printer driver installer 216 ... Profile data file 220 ... Disk drive 230 ... Printer driver 232 ... Resolution conversion unit 234 ... Color conversion unit 236. .. Halftone processing unit 238 ... Data arrangement unit 240 ... Look-up table selection unit 250 ... Color conversion lookup table 300 ... Color printer

Claims (3)

A method for installing a color conversion lookup table for a specific printer into a computer from a recording medium inserted in the computer or a printer driver providing server ,
(A) From the profile data file that includes a plurality of types of color conversion profiles for each type , the computer sets one type of color conversion profile according to the parameters that define the printing mode of the specific printer. Selecting each one , and
(B) the computer creating a color conversion look-up table for the specific printer by combining the plurality of selected color conversion profiles and installing the color conversion look-up table in the computer;
With
The step (b)
The computer, see contains a step of synthesizing all of the plurality of color conversion lookup table used in a plurality of print modes to be used in the specific printer during the installation,
The plurality of print modes are defined by a plurality of parameters including an input color space, a print medium, and a print resolution.
The plurality of types of color conversion profiles are:
A plurality of first type color conversion profiles, one selected according to the input color space;
A plurality of second type color conversion profiles, one selected according to the print medium;
A plurality of third type color conversion profiles, one selected according to the combination of the print medium and the print resolution;
Including the method. The method of claim 1 , comprising:
The first type color conversion profile has a function of converting a first RGB color space as the input color space into a predetermined profile connection space;
The second type color conversion profile has a function of converting the profile connection space to a second RGB color space,
The third type color conversion profile has a function of converting the second RGB color space into an ink amount space regarding a plurality of inks used in the specific printer. An installation program for installing a color conversion lookup table for a specific printer into the computer from a recording medium inserted in the computer or a printer driver providing server ,
Each type of color conversion profile is selected and selected from a profile data file containing a plurality of types of color conversion profiles for each type according to the parameters defining the printing mode of the specific printer. and a plurality of program der Rutotomoni to perform the functions installed on the computer to the computer to create a color conversion lookup table for the specific printer by combining the color conversion profile,
A program for causing the computer to execute a function of combining all of a plurality of color conversion lookup tables used in a plurality of printing modes used in the specific printer at the time of the installation ;
The plurality of print modes are defined by a plurality of parameters including an input color space, a print medium, and a print resolution.
The plurality of types of color conversion profiles are:
A plurality of first type color conversion profiles, one selected according to the input color space;
A plurality of second type color conversion profiles, one selected according to the print medium;
A plurality of third type color conversion profiles, one selected according to the combination of the print medium and the print resolution;
Including installation program.

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