JP2007324713A - Color transformation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color transformation system in which even an image printed by a multicolor printer can be reproduced with high precision. <P>SOLUTION: The color transformation system comprises a section for acquiring input image data composed of component data, a section for converting component data representing a color by a first kind of color space into first kind data representing a component by arrangement of pixels, and converting other component data into second kind data representing a component by arrangement of pixels and representing the color of each pixel between common color spaces; and a section performing color transformation for first kind data on the first kind data, and color transformation for second kind data on the second kind data to generate output data where the color of pixel is represented by the output color space. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a color conversion system that converts input image data into output image data in which pixel colors are expressed in an output color space depending on an output device that outputs an image.

  In the field of printing, DTP (Desk Top Publishing) that performs editing using a computer has been widely applied. By applying DTP, the operator can edit characters and images while confirming the image of the printed matter on the display screen of the computer.

  In addition, printing using a color printing machine is a large and costly operation such as preparing a film original plate and further preparing a printing plate. Therefore, conventionally, before printing, use a proofer that is easier than a color printer to create a proof image that resembles the color of the color image printed by that color printer as much as possible. Has been done. By creating a proof image, not only the operator who performs the editing work but also the operator who performs the printing work can check the color and layout of the printed image before printing, greatly reducing the labor and cost of the printing work. Can be suppressed.

  By the way, usually, many color printing machines form images using color materials of C (cyan), M (magenta), Y (yellow), and K (black). In such a color printing machine, An image is output based on the output image data in the CMYK color space. In recent years, proofers that output proof images have been used to express colors using CMYK color materials, as with color printers. However, image data with the same value in the same CMYK color space has been used. Even in such cases, the color expressed by the type of device or machine difference may differ slightly. Therefore, when trying to reproduce a print image with a proofer, it is necessary to convert the image data before the proofer instead of sending the image data for a color printing machine to the proofer as it is. Here, attention is paid to the color of the image, and this conversion of the image data is referred to as color conversion.

  Hereinafter, a flow of a series of processes for performing color conversion processing on image data for a color printing machine and outputting a proof image by a proofer will be described. Here, CTP (Computer To Plate) for generating a printing film plate for each color of CMYK based on image data in the CMYK color space for color printers, and CMYK color space for proofers (colors for color printers) In order to distinguish from a space, in the following, a proofer that generates a proof image based on image data of “′” is attached to the color space for the proofer and is referred to as a C′M′Y′K ′ color space or the like) An image output system configured as described above will be described as an example.

  FIG. 1 is a diagram illustrating an example of an image output system.

  Part (A) of FIG. 1 shows a configuration diagram of the first image output system 1.

  In DTP, when an operator edits a page composed of characters and images using a computer, input image data 1000 representing an image of the edited page is generated. The input image data 1000 is an image of a page expressed by a set of parts such as characters and images constituting the page, and is constituted by a set of part data representing each part. The component data constituting the input image data 1000 includes, for example, component data representing an image read by a scanner and color expressed in an RGB color space depending on the scanner, and an operator using a personal computer. Component data in various input color spaces, such as component data representing colors in the CMYK color space, representing a drawn graphic image are mixed. Input image data 1000 generated by operator editing is sent to the color separation device 1110.

  In the color separation device 1110, component data in various input color spaces included in the input image data 1000 is converted into component data in the CMYK color space depending on the CTP 1170, and a print image that is a collection of component data in the CMYK color space. Data is generated. The generated print image data is first sent to the color conversion device 1140 for the proofers 1180 and 1190 before being output to the CTP 1170.

  In the color conversion device 1140, color conversion processing is performed on each component data in the CMYK color space included in the print image data, and converted into component data in the C′M′Y′K ′ color space suitable for the proofers 1180 and 1190. The proof image data including the component data of the C′M′Y′K ′ color space is generated. The generated proof image data is sent to a RIP (Raster Image Processor) device 1150 for the proofers 1180 and 1190.

  The proofers 1180 and 1190 output a page image for each scanning line that scans the page. The above-described print image data and proof image data are component data representing each component constituting the page. Since it is configured, it cannot be output by the printing press or the proofers 1180 and 1190 as it is. Therefore, in the RIP device 1150, the proof image data is subjected to rasterization processing and converted into raster proof image data suitable for the proofers 1180 and 1190. The converted proof image data is sent to the gradation proofer 1190, and the proof image in which the color density is expressed by the density of the color material itself is output by the gradation proofer 1190, or is sent to the shading apparatus 1160 and shaded. Processing is performed, and a proof image in which the color density is expressed by a halftone dot is generated by a halftone proofer 1180.

  When the operator confirms the color and layout of the print image using the proof image generated as described above and instructs printing using the computer, the print image data generated by the color separation device 1110 is the CTP 1170. To the RIP device 1120 for use.

  The RIP device 1120 performs rasterization processing on the print image data, and the shading device 1130 performs shading processing on the print image data on which the rasterization processing has been performed. The print image data after the halftone process is sent to the CTP 1170, and a printing film plate of C, M, Y, K4 colors is generated. The four-color printing film plates are mounted on a printing machine and applied with ink of each color, and the applied ink is transferred onto printing paper to generate a printed image.

  In the first image output system 1 shown in part (A) of FIG. 1, a color conversion device 1140 that converts print image data into proofer image data is provided in front of the RIP device 1150. An image output system in which the color conversion device is provided at the subsequent stage of the RIP device is also widely used.

  Part (B) of FIG. 1 shows a configuration diagram of the second image output system 2.

  In the second image output system 2, input image data 1000 generated by operator editing is converted into print image data in the CMYK color space by the color separation device 1110, and then the RIP common to the CTP 1170 and the proofers 1180 and 1190. The apparatus 1120 converts the image data into raster format print image data.

  The raster-format print image data is transmitted to the color conversion device 1140 prior to printing, and after color conversion processing is performed by the color conversion device 1140, it is sent to the gradation proofer 1190 or the shading processing by the shading device 1160. After being applied, it is sent to the halftone proofer 1180.

  When printing is instructed by the operator, the raster-format print image data generated by the RIP device 1120 is transmitted as it is to the shading device 1130 for the CTP 1170, and the print image data subjected to the shading processing is transmitted to the CTP 1170. In CTP 1170, a printing film plate for each color of CMYK is generated.

  In the first image output system 1 shown in part (A) of FIG. 1, color conversion processing is performed on the image of the print image for each part constituting the page, whereas part (B) of FIG. In the second image output system 2 shown in FIG. 2, since a color conversion process is performed on the image of the print image for each scanning line, a processing time is required as compared with the first image output system 1. . However, according to the second image output system 2 shown in part (B) of FIG. 1, the color conversion process is performed on the print image data after the rasterizing process, and therefore the second image output system 2 shown in part (A) of FIG. As compared with the first image output system 1, it is possible to obtain a proof image in which the color of the print image is reproduced with higher accuracy.

  In recent years, in addition to C, M, Y, and K4 color materials, color materials such as G (green) and O (orange) are used to expand the color reproduction range that can be expressed by a color printing machine. Multi-color printers that express colors using, have been used, and image output systems that accurately reproduce the colors of print images printed by the multi-color printers have been proposed ( For example, see Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4.) As the color materials used in color printing machines have become multicolored, the accuracy of color reproduction in the proofer has become more important. Therefore, the image output system 2 shown in Part (B) of FIG. A method of performing multicolor color conversion processing using the method will be described.

  FIG. 2 is a diagram for explaining a series of processes for performing multicolor color conversion processing using the image output system 2 shown in Part (B) of FIG. 1.

As shown in Part (B) of FIG. 1, input image data 1000 edited by an operator is converted into print image data in a CMYKOG color space depending on a multicolor color printer by a color separation device 1110. 2 is converted into raster format print image data by the RIP device 1120 shown in FIG. The raster format print image data is sent to the color conversion device 1140, and the print image data in the CMYKOG color space is transmitted to the CMYKOG / L ^* a ^* b ^* conversion unit 1141, and the print image data in the CMYKOG color space The K component is transmitted to the L ^* a ^* b ^* K / C′M′Y′K′O′G ′ conversion unit 1143, and the CMY component of the print image data in the CMYKOG color space is transmitted to the pure color storage unit 1144. .

The CMYKOG / L ^* a ^* b ^* conversion unit 1141 converts the image data in the CMYKOG color space into image data in the L ^* a ^* b ^* color space, which is a common color space independent of the device, and the converted image data Is transmitted to the mapping unit 1142.

The mapping unit 1142 converts the color represented by the image data in the L ^* a ^* b ^* color space into a color within the color reproduction area of the proofer. The converted image data is transmitted to the L ^* a ^* b ^* K / C′M′Y′K′O′G ′ conversion unit 1143.

In the L ^* a ^* b ^* K / C′M′Y′K′O′G ′ converting unit 1143, the image data in the L ^* a ^* b ^* color space is C′M′Y′K′O′G ′ color. The K component of the image data in the C′M′Y′K′O′G ′ color space is converted into the image data in the space, and the print image data in the CMYKOG color space sent from the RIP device 1120 is further converted. Replaced with K component (K version storage process). The image data in the C′M′Y′K′O′G ′ color space is further transmitted to the pure color storage unit 1144.

  In the pure color storage unit 1144, when the color represented by the CMY color component of the print image data in the CMYKOG color space sent from the RIP device 1120 is a pure color, C′M′Y′K′O corresponding to the image data. The CMY component of the image data in the 'G' color space is replaced with a pure color component (pure color storage process).

Also in this color conversion apparatus 1140, CMYKOG / L ^* a ^* b ^* profile in which image data in the CMYKOG color space and image data in the L ^* a ^* b ^* color space are associated, and L ^* a ^* b ^* L ^* a ^* b ^* / C′M′Y′K′O′G ′ in which color space image data and C′M′Y′K′O′G ′ color space image data are associated with each other Color space profiles are stored in advance, and the CMYKOG / L ^* a ^* b ^* conversion unit 1141 and the L ^* a ^* b ^* K / C′M′Y′K′O′G ′ conversion unit 1143 Image data is converted at high speed using a profile. The image data in the C′M′Y′K′O′G ′ color space generated by the color conversion device 1140 is transmitted to the halftone dot device 1160 and the gradation proofer 1190 shown in Part (B) of FIG.

As described above, by changing various profiles used in the color separation device 1110 and the color conversion device 1140 shown in FIG. 1 to the profiles for multicolor printing, the image output shown in Part (B) of FIG. The system 2 can be diverted, and the operator can easily obtain a proof image in which the color of the print image output by the multicolor printing machine is accurately reproduced without requiring empirical knowledge. .
JP 2005-123797 A JP 2001-53976 A JP 2001-36760 A JP-A-8-272081

However, according to the above-described technique, for example, when expressing one color in the color density of 33 gradations, CMYKOG ^/ L ^* a * ^b utilized in CMYKOG ^/ L ^* a * ^{b *} conversion unit 1141 of FIG. 2 ^* The profile data size is 33 ⁶ × 3 = about 3.9 GB. It is impractical to store such an enormous size profile in the color conversion device 1140. When the image output system 2 is to be used for multicolor printing, the color density for expressing one color. Therefore, there is a problem that the number of gradations needs to be reduced, and the color reproduction accuracy deteriorates.

  In view of the above circumstances, an object of the present invention is to provide a color conversion system capable of reproducing a print image printed by a multicolor printer with high accuracy.

The color conversion system of the present invention that achieves the above object provides input image data that represents each component constituting an image and represents the image by a set of component data in which the color of each component is represented in each predetermined color space. An image acquisition unit for acquiring
Of the component data constituting the input image data acquired by the image acquisition unit, the component data expressing the color in the predetermined first type color space is used to express the component by the arrangement of the pixels and the first type color space. For the other component data excluding the component data in which the color is expressed in the first type color space among the component data constituting the input image data by converting into the first type data expressing the color of each pixel in A data format conversion unit that expresses a component by an array of pixels and converts it to second type data that expresses the color of each pixel in a common color space independent of the device;
The first type data is subjected to color conversion processing for the first type data, the second type data is subjected to color conversion processing for the second type data, and the first type data and the second type data are output. And a color conversion unit for converting into output data in which pixel colors are expressed in an output color space depending on a device.

  In the color conversion system of the present invention, the color conversion unit is configured to reproduce the color of an image output from a predetermined target device according to image data obtained by converting input image data. In the color conversion process for the first type data and the color conversion process for the second type data, gamut mapping is performed to convert the colors represented by the first type data and the second type data into colors in the color reproduction area in the target device. It is suitable.

  According to the color conversion system of the present invention, after the component data constituting the input image data is converted into the first type data and the second type data representing the component by the arrangement of the pixels, the first type data and the second type data are converted. Since color conversion processing suitable for each of the two types of data is executed, the input image data can be converted with high accuracy into output data representing an image having a desired color.

The color conversion system according to a preferred embodiment of the present invention can be applied to a proof system that reproduces a target image output from a target device based on input image data using an output device. Gamut mapping can be performed with the first type data and the second type data as they are without going through the process of converting the seed data into image data in the target color space depending on the target device. As a result, the multicolor / common color space profile used in the CMYKOG / L ^* a ^* b ^* conversion unit 1141 shown in FIG. 2 becomes unnecessary, and profile data that must be stored in the color conversion system. The amount is greatly reduced, and the target image output in multiple colors can be reproduced without degrading the accuracy of color reproduction.

In the color conversion system of the present invention, the first type color space is a color space having coordinate components corresponding to a plurality of color plates,
The output color space is a color space having coordinate components corresponding to each of a plurality of color plates at least partially common to the plurality of color plates,
It is preferable that the color conversion unit performs color plate storage processing for maintaining specific coordinate component values in the first type color space in the output color space in the color conversion processing for the first type data.

  By performing the color plate storing process, important colors such as K color and pure color in the image represented by the input image data are reliably maintained in the image represented by the output data.

In the color conversion system of the present invention, the first type color space is a color space having coordinate components corresponding to a plurality of color plates,
The output color space is a color space having coordinate components corresponding to each of a plurality of color plates at least partially common to the plurality of color plates,
The color conversion unit generates a flag indicating whether or not the color represented by the first type data includes a specific coordinate component value in the first type color space in the color conversion process for the first type data, Conversion from the first type data to the third type data in the same format as the second type data, the conversion from the third type data to the output data, and a specific coordinate component based on the flag for the output data It is preferable to perform color plate storage processing that maintains values in the output color space.

  By generating a flag based on the first type data in advance, the second type data and the third type data converted from the first type data are converted into output data by the same process, and the flag is used. The color plate storing process can be executed, and an image having a desired color can be acquired efficiently.

  According to the present invention, it is possible to reproduce a print image printed using multicolored color materials with high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 3 is an overall configuration diagram of an image output system in which an embodiment of the present invention is incorporated.

  The image output system shown in FIG. 3 mainly includes a color scanner 10 that reads an original image, a workstation 20 that performs various processing on image data, and C, M, Y, K, O, and G printing films. CTP 30 for creating a plate, printing machine 40 for creating a print image using a printing film plate created by CTP 30, and outputting an image using color materials of each color of C, M, Y, K, O, and G 2 It consists of two proofers 51 and 52. The CTP 30 and the printing press 40 constitute an example of a target device referred to in the present invention, and the proofers 51 and 52 correspond to an example of an output device referred to in the present invention.

The color scanner 10 reads an original image and generates color separation image data of R, G, and B colors representing the original image. The RGB color separation image data is input to the workstation 20. Although not shown, color-separated image data of C, M, Y, K colors created using a personal computer or the like, or L ^* , a ^* , b ^* 3 obtained by photographing a subject with a digital camera. Color separation image data of colors and the like are also input to the workstation 20. The workstation 20 may receive color separation image data via a connection cable. When the workstation 20 and the color scanner 10 are installed at a remote location, the workstation 20 may, for example, The color separation image data may be received via a computer network or a storage medium such as an MO disk (magneto-optical disk).

  Functionally, the workstation 20 includes an editing device 21, a RIP device 22, a color conversion device 23, a printing screen device 24, and a proofer screen device 25.

In the editing apparatus 21, electronic plate collection based on the input color separation image data is performed by an operator, and page image data representing a page of an image for printing is generated. In this page image data, a page image is represented by a set of parts such as characters and images constituting the page, and is constituted by a set of part data representing each part. For this reason, the page image data includes RGB color space component data input to the editing device 21 and generated by reading the original image with the color scanner 10, or C and M created using a personal computer or the like. , Y, K4 color space component data, and L ^* , a ^* , b ^* color space component data obtained by photographing a subject with a digital camera. The page image data is sent to the RIP device 22.

  In the RIP device 22, rasterization processing is performed on each component data constituting the page image data. The raster component data that has undergone the rasterization process is transmitted to the color conversion device 23.

  In the color conversion device 23, raster component data in various input color spaces is converted into raster component data in a target color space (here, CMYKOG color space) depending on a target device constituted by the CTP 30 and the printing machine 40, The raster part data in the target color space is combined to generate print image data. The generated printing image data is converted into printing image data for plate making representing a halftone image in the printing halftone device 24, and further sent to the CTP 30, where CMYKOG corresponding to the printing image data for plate making is used. A printing film version of each plate is created. The produced printing film plate is mounted on the printing machine 40 and applied with ink, and the applied ink is transferred onto a printing sheet to form a printed image 40a on the sheet.

  A series of operations for creating a printing film plate using the CTP 30 and mounting the printing film plate on the printing machine 40 to perform printing on the paper is a large-scale operation and costs high. Therefore, before the actual printing operation is performed, the proof images 51a and 52a are created by the proofers 51 and 52, and the finished confirmation of the printed image 40a is performed in advance.

  In creating the proof images 51a and 52a, as in the case of printing, the component data included in the page image data created by the editing device 21 is converted into raster format raster component data by the RIP device 22, and further, The color conversion device 23 converts the raster component data in the output color space (here, the C′M′Y′K′O′G color space) depending on the proofers 51 and 52, and the raster component data in these output color spaces. Are combined to generate proof image data. The generated proof image data is sent to the gradation proofer 52, or after being subjected to the shading process by the proofer halftone device 25, is sent to the halftone proofer 51. The halftone proofer 51 generates a proof image 51a in which the color density of the image is expressed by halftone dots, and the gradation proofer 52 generates a proof image 52a in which the color density of the image is expressed by the density of the color material itself. Is done.

  By confirming the proof images 51a and 52a created in this way, the finish of printing can be confirmed in advance.

  Here, the feature of the image output system shown in FIG. 3 as an embodiment of the present invention is the processing content executed in the workstation 20. First, the workstation 20 will be described in detail.

  4 is an external perspective view of the workstation 20 shown in FIG. 3, and FIG. 5 is a hardware configuration diagram of the workstation 20.

  As shown in FIG. 4, the workstation 20 is a large-sized personal computer. As shown in FIG. 4, the exterior device has a main body device 201 and an image display device 202 that displays an image on a display screen 202 a according to an instruction from the main body device 201. By specifying an arbitrary position on the display screen 202a by inputting a keyboard 203 for inputting various information corresponding to key operations to the main unit 201, an instruction corresponding to an icon or the like displayed at the position is input. A mouse 204 is provided. In addition, the main body device 201 has an FD loading port 201a for loading a flexible disk (hereinafter abbreviated as FD) and a CD-ROM loading port 201b for loading a CD-ROM.

  As shown in FIG. 5, the main body device 201 includes a CPU 211 that executes various programs, a main memory 212 that is read out by a program stored in the hard disk device 213 and developed for execution by the CPU 211, and various programs Are connected to the hard disk device 213 storing the data and the like, the FD 100, the FD drive 214 accessing the loaded FD 100, the CD-ROM drive 215 accessing the CD-ROM 110, and the color scanner 10 of FIG. An input interface 216 that receives image data from the color scanner 10 and an output interface 217 that is connected to the CTP 30 and the proofers 51 and 52 in FIG. 3 and sends image data to the CTP 30 and the proofers 51 and 52 are built in. And more The image display device 202 shown in FIG. 4, a keyboard 203, and mouse 204 are connected to each other via a bus 205.

  Here, the RIP program for constructing the RIP device 22 on the workstation 20 and the color conversion program for constructing the color conversion device 23 are stored in each CD-ROM. CD-ROMs 110A and 110B (see FIG. 6) storing these programs are loaded into the CD-ROM drive 215, and the RIP program and the color conversion program stored in the CD-ROMs 110A and 110B are stored in the workstation 20. It is uploaded and stored in the hard disk device 213. Then, the RIP program 22 and the color conversion device 23 constituting the embodiment of the color conversion system of the present invention are constructed in the workstation 20 by starting and executing the RIP program and the color conversion program. .

  In the above, the CD-ROMs 110A and 110B are exemplified as storage media for storing the RIP program and the color conversion program. However, the storage media for storing the RIP program and the color conversion program are not limited to the CD-ROM. Other storage media such as an optical disk, MO, FD, and magnetic tape may be used. Further, the RIP program and the color conversion program may be supplied directly to the workstation 20 via the input interface 216 without going through the storage medium.

  Next, the RIP program and the color conversion program will be described.

  FIG. 6 is a conceptual diagram showing a CD-ROM 110A storing a RIP program and a CD-ROM 110B storing a color conversion program.

  As shown in Part (A) of FIG. 6, the RIP program 310 stored in the CD-ROM 110 </ b> A includes a color space determination unit 311, a CMYK rasterization unit 312, a first common conversion unit 313, and a common rasterization unit 314. As shown in Part (B) of FIG. 6, the color conversion program 320 stored in the CD-ROM 110B includes a color space separation unit 321, a target conversion unit 322, a target output unit 323, a first proof conversion unit 324, A second proof conversion unit 325, a second common conversion unit 326, a pure color storage unit 327, and a proof output unit 328 are included.

  Details of each part of the RIP program 310 and the color conversion program 320 will be described together with the operations of the RIP device 22 and the color conversion device 23.

  FIG. 7 is a functional block diagram of the RIP device 22 and the color conversion device 23.

  The RIP device 22 includes a color space determination unit 411, a CMYK rasterization unit 412, a first common conversion unit 413, a common rasterization unit 414, and an image buffer 415. The color conversion device 23 includes a color space. Separation unit 421, target conversion unit 422, target output unit 423, first proof conversion unit 424, second common conversion unit 425, second proof conversion unit 426, pure color storage unit 427, and proof output unit 428.

  The color space determination unit 411, the CMYK rasterization unit 412, the first common conversion unit 413, and the common rasterization unit 414 that constitute the RIP device 22 are the color space determination unit 311 that constitutes the RIP program 310 shown in FIG. , CMYK rasterization unit 312, first common conversion unit 313, common rasterization unit 314, color space separation unit 421, target conversion unit 422, target output unit 423, The 1 proof conversion unit 424, the second common conversion unit 425, the second proof conversion unit 426, the pure color storage unit 427, and the proof output unit 428 constitute a color conversion program 320 shown in FIG. Unit 321, target conversion unit 322, target output unit 323, first proof conversion unit 324, second common conversion unit 26, the second proof conversion unit 325, the pure color storage unit 327, corresponding to the proof output unit 328.

  Each element in FIG. 7 is composed of a combination of computer hardware and an OS or application program executed on the computer, whereas each element of the RIP program 310 and the color conversion program 320 shown in FIG. The only difference is that they are configured only by application programs.

Here, the RIP device 22 and the color conversion device 23 shown in FIG. 7 include a device independent color space (L ^* a ^* b ^* color) from the input color space (RGB color space) of the color scanner 10 shown in FIG. First common profile 413a in which coordinate transformation to (space) is defined, device-independent common color space (L ^* a ^* ) from input color space (CMYK color space) depending on the editing program used in the editing apparatus 21 a second common profile 425b in which coordinate transformation to b ^* color space) is defined, coordinate transformation from a device-independent common color space (L ^* a ^* b ^* color space) to a target color space (CMYKOG color space) defined target profile 422a, the coordinate transformation from the common color space ^{(L *} a * ^{b *} color space) to an output color space (C'M'Y'K'O'G' color space) is defined Proof profile 424b, the second proof profile 426a for coordinate transformation from the common color space ^{(L *} a * ^{b *} color space) to an output color space (C'M'Y'K' color space) is defined is prepared in advance Of these various profiles, the profiles other than the second common profile 425b and the first proof profile 424b are provided in advance by a manufacturer or the like that manufactures the color scanner 10, the printer 40, or the proofers 51 and 52. In many cases, the second common profile 425b and the first proof profile 424b are created based on a basic profile provided by a manufacturer or the like. Here, a basic method for creating various profiles will be described.

  FIG. 8 is a conceptual diagram of the target profile 422a.

When the target profile 422a is generated, the editing device 21 shown in FIG. 3 generates color data in which the values of C, M, Y, K, O, and G are sequentially changed as the CMYKOG6 color data. Then, a color patch image based on the color data thus generated is printed using a target device composed of the CTP 30 and the printer 40. Further, each color patch constituting the printed color patch image is measured with a colorimeter, and L ^* , a ^* , b ^* values are obtained, and C, M, Y, K, O, G values, First, simply associate.

Here, in the target profile 422a, color data in one CMYKOG color space needs to be associated with color data in one L ^* a ^* b ^* color space, but the dimension of the CMYKOG color space is L ^*. Since it is larger than the dimension of the a ^* b ^* color space, at this stage, the same L ^* , a ^* , b ^* value is repeatedly acquired for a plurality of C, M, Y, K, O, G values. ing. In addition, since the L ^* a ^* b ^* color space as a whole includes colors that cannot be expressed by the target device, it is simply associated with C, M, Y, K, O, and G values at this stage. The L ^* , a ^* , and b ^* values that do not cover the L ^* , a ^* , and b ^* values that are assumed to be input to the target conversion unit 422 are insufficient.

FIG. 9 shows the color reproduction region of the color scanner 10 in the L ^* a ^* b ^* color space, and the color reproduction region of the target device composed of the CTP 30 and the printer 40.

In the present embodiment, the color reproduction region 510 of the target device can be expanded by using the O, G2 color material in addition to the C, M, Y, K4 color materials in the printing machine 40. However, this is insufficient to cover the color reproduction region 520 of the color scanner 10 that expresses an image with light of R, G, and B colors. Therefore, in the simple association step described above, the L ^* , a ^* , b ^* values outside the color reproduction area 510 of the target device are not associated with the C, M, Y, K, O, G values. If the image data generated by the color scanner 10 is not included in the color reproduction area 510 of the target device, the C, M, Y, K, O even if the correspondence obtained at this stage is used. , G value cannot be converted. Therefore, it is assumed that the color data in the L ^* a ^* b ^* color space outside the color reproduction area 510 of the target device is associated with the color data in the CMYKOG color space and input to the target conversion unit 422 ^. It is necessary to cover the color data in the a ^* b ^* color space.

If the color data is to be covered to the minimum, the color reproduction region of the target device with the L ^* , a ^* , and b ^* values already associated with the C, M, Y, K, O, and G values unchanged. Only the L ^* , a ^* , and b ^* values outside 510 need only be newly associated with C, M, Y, K, O, and G values, but L ^* , a ^* , If only the b ^* value is simply mapped, a tone jump or the like occurs near the boundary of the color reproduction area 510. Accordingly, the entire mapping including L ^* , a ^* , b ^* values near the boundary of the color reproduction area 510 is performed, and further, the color data in the same L ^* a ^* b ^* color space is duplicated. One CMYKOG color space is selected for each color data of the L ^* a ^* b ^* color space which is covered without missing by selecting one of the attached CMYKOG color space color data. The target profile 422a is constructed by associating the color data.

  Next, a method for creating the first proof profile 424b and the second proof profile 426a will be described.

  FIG. 10 is a conceptual diagram of the first proof profile 424b and the second proof profile 426a.

The first proof profile 424b includes a mapping profile for mapping color data in the L ^* a ^* b ^* color space to color data in the color reproduction area 510 of the target device, and colors in the L ^* a ^* b ^* color space. A basic proof profile for converting data into color data in the C′M′Y′K′O′G ′ color space is connected.

When generating a mapping profile, first, the editing device 21 shown in FIG. 3 uses color data obtained by sequentially changing the values of L ^* , a ^* , and b ^* as color data in the L ^* a ^* b ^* color space. Generate. Subsequently, the color data in the L ^* a ^* b ^* color space generated by the editing device 21 is converted into color data in the CMYKOG color space according to the target profile 422a shown in FIG. A color patch image based on the data is printed using a target device composed of the CTP 30 and the printer 40. Further, each color patch constituting the printed color patch image is measured with a colorimeter, and the color data L ^* , a ^* , b ^* values generated by the editing device 21 and the color meter are measured. The mapping profile is constructed by associating the L ^* , a ^* , and b ^* values.

Further, when a new basic proof profile is generated, each value of C′M′Y′K′O′G ′ is obtained from the editing device 21 shown in FIG. 3 as in the case of generating the target profile 422a. Sequentially changed color data is generated, and a color patch image based on the color data thus generated is printed out using the proofers 51 and 52. Subsequently, each color patch constituting the printed color patch image is measured with a colorimeter to obtain L ^* , a ^* , b ^* values, and C ′, M ′, Y ′, K ′, O First, the 'and G' values are simply associated with each other. In the present embodiment, since the mapping process for reproducing the color of the image output from the target device is performed using the mapping profile instead of the basic proof profile, in this basic proof profile, L ^* , a ^* , The b ^* value is required to be converted into C ′, M ′, Y ′, K ′, O ′, and G ′ values for faithfully outputting the color represented by the value. Therefore, the mapping process as in the case of generating the target profile 422a described above is not performed, and the C′M′Y′K′O′G ′ color in which the same L ^* , a ^* , b ^* values are acquired in duplicate. After the color data of the space is selected, the color data in one C′M′Y′K′O′G ′ color space is associated with the color data in the L ^* a ^* b ^* color space. Thus, a basic proof profile is constructed.

Was created as described ^above, L ^* a * ^{b *} and mapping profile color data of a color space is converted into color data of ^L * ^a * ^{b *} color ^space, L ^* a * ^{b *} color data in the color space Are connected to the basic common profile for converting the color data into the color data of the C′M′Y′K′O′G ′ color space, thereby constructing the first proof profile 424b shown in Part (A) of FIG. . The first proof profile 424b maps the color data of the L ^* a ^* b ^* color space into the color reproduction area 510 of the target device shown in FIG. 9, and the color space of the color data is L ^* a ^* b. ^{* To} convert from color space to C′M′Y′K′O′G ′ color space. By constructing the first proof profile 424b in advance, the color data of the L ^* a ^* b ^* color space is converted into C′M′Y′K′O′G ′ included in the color reproduction area 510 of the target device. It can be directly converted into color space color data, and the color of the print image output by the target device can be accurately reproduced.

For example, in the case of expressing one color with a color density of 33 gradations, in the second image output system 2 shown in part (B) of FIG. 1 in which a C, M, Y, K4 printing machine is used. The data size of the CMYK / L ^* a ^* b ^* profile used in the color conversion device 1140 is about 33 ⁴ × 4 = about 4.7 MB. However, in order to widen the color reproduction area in the printing press, when using O, G color ink in addition to C, M, Y, K color ink, CMYKOG / L ^* a ^* b ^* conversion in FIG. The data size of the CMYKOG / L ^* a ^* b ^* profile used in the unit 1141 is 33 ⁶ × 3 = about 3.9 GB, and the CMYKOG / L ^* a ^* b ^* conversion unit 1141 and the L ^* a ^* b ^* The data size of the CMYKOG / C′M′Y′K′O′G ′ profile obtained by connecting the profiles used in the K / C′M′Y′K′O′G ′ conversion unit 1143 is 33 ⁶ × 6 = about 7.7 GB. The data size of the first proof profile 424b used in the present embodiment is 33 ³ × 6 = about 0.2 MB, and the data size is greatly suppressed. For this reason, in this embodiment, it is not necessary to reduce the number of gradations of the color density expressing one color, the color of the print image can be reproduced with high accuracy, and the first proof profile 424b is stored in the memory in advance. It can be stored, and high-speed color conversion processing can be executed.

  Moreover, the conceptual diagram of the 2nd proof profile 426a is shown by the part (B) of FIG. The second proof profile 426a is the first proof profile 424b except that the color data generated by the editing device 21 shown in FIG. 3 is color data obtained by sequentially changing the values of C′M′Y′K ′. It is created in the same procedure as the basic proof profile created prior to.

  Next, a method for creating the first common profile 413a and the second common profile 425b will be described.

  FIG. 11 is a conceptual diagram of the first common profile 413a and the second common profile 425b.

  Part (A) of FIG. 11 shows a conceptual diagram of the first common profile 413a.

When generating the first common profile 413a, a color patch image composed of a large number of color patches is prepared, and the color patch image is read by the color scanner 10 shown in FIG. 3, and color data in the RGB color space for each color patch. The color patch image is measured with a colorimeter, and color data representing coordinates in the L ^* a ^* b ^* color space is obtained for each color patch. The first common profile 413a is obtained by associating the color data in the RGB color space with the color data in the L ^* a ^* b ^* color space.

  Part (B) of FIG. 11 shows a conceptual diagram of the second common profile 425b.

The second common profile 425b includes a basic common profile for converting color data in the CMYK color space into color data in the L ^* a ^* b ^* color space, and a first proof profile 424b shown in part (A) of FIG. The mapping profile used at the time of creation is connected.

Conventionally, editing software for editing images using C, M, Y, K colors has been widely used so that it is easy to grasp images of images printed using C, M, Y, K color materials on a printing press. Are known. A basic common profile is created by associating color data in the CMYK color space with color data in the L ^* a ^* b ^* color space in which the color data is converted based on a predetermined formula, and editing software A basic common profile is provided.

Was created as described above, the color data of CMYK color space ^L * ^a * ^{b *} and the basic common profile for converting the color data of a color ^space, L ^* a * ^{b *} color data in the color space ^L * a The second common profile 425b shown in Part (B) of FIG. 11 is constructed by connecting the mapping profile to be converted into the color data of the ^* b ^* color space. The second common profile 425b maps the color data of the CMYK color space into the color reproduction area 510 of the target device shown in FIG. 9, and changes the color data of the color data from the CMYK color space to L ^* a ^* b ^*. This is for conversion to a color space. By connecting the basic common profile and the mapping profile in advance, the color conversion process can be executed at high speed.

  In the RIP device 22 and the color conversion device 23 of the present embodiment, various profiles created as described above or provided by a manufacturer are prepared in advance, and color conversion processing is executed using these profiles.

  FIG. 12 is a flowchart showing a flow of a series of processes for creating a proof image and a print image.

  In the following, according to FIG. 12, various elements constituting the RIP device 22 and the color conversion apparatus 23 of FIG. 7 and processes executed by these various elements will be described in detail.

  When the operator edits the printed material using the editing device 21 of FIG. 3, page image data representing a page of the edited printed material is generated. The generated page image data is acquired by the color space determination unit 411 of the RIP device 22 shown in FIG. 7 (step S101 in FIG. 12). The color space determination unit 411 corresponds to an example of an image acquisition unit according to the present invention.

  As described above, the page image data is a page represented by a set of components, and component data of various input color spaces are mixed.

The color space determination unit 411 transmits the RGB color space component data of the page image data to the first common conversion unit 413, and transmits the L ^* a ^* b ^* color space component data to the common rasterization unit 414 (FIG. 12). In step S102: No), the CMYK color space component data is transmitted to the CMYK rasterization unit 412 (step S102 in FIG. 12: Yes).

The first common conversion unit 413 converts the RGB color space component data into the L ^* a ^* b ^* color space component data using the first common profile 413a shown in part (A) of FIG. 11 (FIG. 12). Step S104). The part data in the L ^* a ^* b ^* color space after conversion is transmitted to the common rasterization unit 414.

Common rasterizing unit 414 has transmitted from the color space determining unit 411 ^L * ^a * ^{b *} color space component data, and the first common conversion unit 413 converts the component data of the RGB color space is the ^L * ^a * b ^* Rasterization processing is performed on the component data in the color space (step S105 in FIG. 12). The raster component data in the L ^* a ^* b ^* color space that has undergone the rasterization process is temporarily stored in the image buffer 415 (step S106 in FIG. 12).

Also, the CMYK rasterization unit 412 performs rasterization processing on the component data in the CMYK color space transmitted from the color space determination unit 411 (step S103 in FIG. 12). Rasterized raster component data in the CMYK color space is also temporarily stored in the image buffer 415 (step S106 in FIG. 12). The CMYK color space is an example of the first type of color space according to the present invention, and the component data of the CMYK color space is an example of the first type of data according to the present invention. The L ^* a ^* b ^* color space and the RGB color The space component data corresponds to an example of the second type data referred to in the present invention. A combination of the first common conversion unit 413, the common rasterization unit 414, and the CMYK rasterization unit 412 corresponds to an example of the data format conversion unit referred to in the present invention.

In RIP apparatus 22 of the present embodiment, component data of RGB color space, and ^L * ^a * ^{b *} color space rasterization process is performed after the aligned to the component data of the ^L * ^a * ^{b *} color space However, the component data in the CMYK color space is not converted into the component data in the L ^* a ^* b ^* color space, but is subjected to rasterization processing with the component data in the CMYK color space. In this way, rasterized CMYK color space raster component data is sent to the subsequent color conversion device 23, so that the C, M, Y, and K components necessary for the K plate storage processing and pure color storage processing are color converted. An image having a desired color that is reliably transmitted to the device 23 can be reproduced with high accuracy.

In the image buffer 415, raster component data in the CMYK color space transmitted from the CMYK rasterization unit 412 and raster component data in the L ^* a ^* b ^* color space transmitted from the common rasterization unit 414 are stored. And are transmitted to the color conversion device 23 as raster part data in the CMYK-L ^* a ^* b ^* format.

The raster component data in the CMYK-L ^* a ^* b ^* format transmitted from the RIP device 22 is acquired by the color space separation unit 421 of the color conversion device 23. Color space separation unit 421, ^{CMYK-L *} a * ^{b *} format raster component data, raster component data and ^L * ^a * ^{b *} color space of CMYK color space sent a set from the RIP unit 22 together To separate raster part data.

Here, normally, proof images 51a and 52a for prior confirmation are created in the proofers 51 and 52 before actual printing is performed. When the operator operates the keyboard or mouse of the workstation 20 to instruct generation of a proof image (step S107 in FIG. 12: Yes), the color space separation unit 421 receives the CMYK sent from the RIP device 22. The raster part data in the L ^* a ^* b ^* color space among the raster part data in the L ^* a ^* b ^* format is transmitted to the first proof conversion unit 424 (step S108 in FIG. 12: Yes), and the raster in the CMYK color space The component data is transmitted to the second common conversion unit 425, the K component of the raster component data in the CMYK color space is transmitted to the second proof conversion unit 426, and the CMY component of the raster component data in the CMYK color space is transmitted to the pure color storage unit 427 ( Step S108 in FIG. 12: No).

When the raster part data of the L ^* a ^* b ^* color space is transmitted from the color space separation unit 421, the first proof conversion unit 424 uses the first proof profile 424b shown in Part (A) of FIG. ^{* A *} b ^* Color space raster component data is mapped into the color reproduction area 510 of the target device shown in FIG. 10 (step S109 in FIG. 12), and the C′M′Y′K′O′G ′ color space is mapped. To proof component data (step S110 in FIG. 12). In the present embodiment, the processes of step S109 and step S110 are simultaneously performed by the first proof profile 424b. The converted proof component data is transmitted to the proof output unit 428.

Further, the second common conversion unit 425 uses the second common profile 425b shown in part (B) of FIG. 11 to convert the raster component data in the CMYK color space transmitted from the color space separation unit 421 to L ^* a ^*. b ^* is converted into raster part data in a color space (step S111 in FIG. 12), and is mapped in the color reproduction region 510 of the target device shown in FIG. 10 (step S112 in FIG. 12). Note that these steps S111 and S112 are also performed simultaneously by the second common profile 425b. The raster part data in the L ^* a ^* b ^* color space after conversion is transmitted to the second proof conversion unit 426.

The second proof conversion unit 426 is supplied with raster component data in the L ^* a ^* b ^* color space from the second common conversion unit 425, and the K component of the raster component data in the CMYK color space is transmitted from the color space separation unit 421. Reportedly. The second proof conversion unit 426 uses the second proof profile 426a shown in part (B) of FIG. 10 to convert raster part data in the L ^* a ^* b ^* color space into the C′M′Y′K ′ color space. The proof component data is converted (step S113 in FIG. 12), and the K component of the converted proof component data is replaced with the K component of the CMYK color space raster component data transmitted from the color space separation unit 421 (K version). Save processing). As a result, the color output in the K plate in the printed image is reliably output in the K color also in the proof image. The proof component data subjected to the K plate storage process is transmitted to the pure color storage unit 427.

  The pure color storage unit 427 receives the proof component data subjected to the K plate storage process from the second proof conversion unit 426 and the CMY component of the raster component data in the CMYK color space from the color space separation unit 421. The pure color storage unit 427 includes C, M, Y transmitted from the color space separation unit 421 among the color components of the proof component data in the C′M′Y′K ′ color space transmitted from the second proof conversion unit 426. A color component whose component is a pure color (each color is a maximum data value) is replaced with a pure color (maximum data value) (step S114 in FIG. 12). The proof component data subjected to the pure color storage process is transmitted to the proof output unit 428. The C′M′Y′K′O′G ′ color space is an example of an output color space according to the present invention, and the target conversion unit 422 and the first proof conversion unit 424 are an example of a color conversion unit according to the present invention. The combination of the second common conversion unit 425, the second proof conversion unit 426, and the pure color storage unit 427 corresponds to an example of the color conversion unit referred to in the present invention.

  In the present embodiment, since various color conversion processes are executed on the component data after the rasterization process is performed, the color of the print image can be reproduced with high accuracy.

  The proof output unit 428 combines the proof component data in the C′M′Y′K′O′G ′ color space transmitted from the first proof conversion unit 424 and the pure color storage unit 427, and the proof component data is Proof image data representing a page composed of parts to be represented is generated. The generated proof image data is output to the gradation proofer 52 of FIG. 3 and the proofer screen device 25 (step S115 of FIG. 12).

  The gradation proofer 52 outputs a proof image 52a in which the color density is expressed by the density of the color material itself based on the proof image data. Further, in the proofer halftone device 25, the proof image data is subjected to a halftone process, and the proof image data after the halftone is sent to the halftone proofer 51. In the halftone proofer 51, a proof image 51a in which the color density is expressed by halftone dots is generated.

In the color conversion device 23 of the present embodiment, the mapping processing is performed after converting the image data of the input color space into the image data of the CMYKOG color space for the target device as executed by the image output system 2 shown in FIG. Since the mapping process is performed directly when the image data in the input color space is converted into the image data in the C′M′Y′K′O′G ′ color space without going through the process, the number of conversions is reduced. As a result, the processing time can be improved, and deterioration of color reproduction accuracy due to errors included in the conversion can be suppressed. In the present embodiment, image data in the target color space (in this embodiment, CMYKOG color space) is converted into image data in a common color space (in this embodiment, L ^* a ^* b ^* color space). A 6-dimensional × 3-dimensional profile with an enormous data size is unnecessary, and multicolored color materials are used in the printing press, but a proof image can be generated without degrading the reproduction accuracy.

  When the operator confirms the color and layout of the proof images 51a and 52a and operates the keyboard and mouse of the workstation 20 to instruct printing, printing is started (step S107 in FIG. 12: No).

First, raster component data in the CMYK color space and raster component data in the L ^* a ^* b ^* color space stored in the image buffer 415 are sent to the color conversion device 23.

  By transmitting the raster component data after the rasterization process at the time of creating the proof image to the color space separation unit 421, it is possible to save the trouble of repeatedly executing the same process and improve the processing time.

The color space separation unit 421 separates the CMYK color space sent from the RIP device 22 and the raster part data in the L ^* a ^* b ^* color space, and transmits the raster part data in the CMYK color space to the target output unit 423. At the same time (step S116 in FIG. 12: No), the raster part data in the L ^* a ^* b ^* color space is transmitted to the target conversion unit 422 (step S116 in FIG. 12: Yes).

The target conversion unit 422 converts the raster part data in the L ^* a ^* b ^* color space transmitted from the color space separation unit 421 into raster part data in the CMYKOG color space using the target profile 422a shown in FIG. The raster component data in the converted CMYKOG color space is transmitted to the target output unit 423 (step S117 in FIG. 12).

  The target output unit 423 combines the raster component data in the CMYK color space transmitted from the color space separation unit 421 and the raster component data in the CMYKOG color space transmitted from the target conversion unit 422, and represents the raster component data. Print image data representing a page composed of parts is generated. The generated print image data is sent to the printing shading device 24 shown in FIG. 3, subjected to the shading process, and then sent to the CTP 30 (step S118 in FIG. 12). In the CTP 30, C, M, Y, K, O, and G 6 color printing film plates are generated based on the print image data, and these printing film plates are mounted on the printing machine 40. 40a is created.

  As described above, according to the RIP device 22 and the color conversion device 23 of the present embodiment, a print image printed by a multicolor printer can be reproduced with high accuracy.

  Above, description of 1st Embodiment of this invention is complete | finished and 2nd Embodiment of this invention is described. In the second embodiment of the present invention, instead of sending CMYK color space raster component data from the RIP device to the color conversion device, process information representing the C, M, Y, and K components of the CMYK color space raster component data is provided. It is different from the first embodiment in that it is sent. In the following, the same elements as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only differences from the first embodiment will be described.

  FIG. 13 is a conceptual diagram showing a CD-ROM 110A ′ storing a RIP program and a CD-ROM 110B ′ storing a color conversion program according to the second embodiment of the present invention.

  The RIP program 310 ′ of the present embodiment has substantially the same configuration as the RIP program 310 of the first embodiment shown in FIG. 6, but the RIP program 310 ′ includes a process information generation unit 315 and a second A common conversion unit 326 is provided.

  Further, the color conversion program 320 ′ of the present embodiment also has substantially the same configuration as the color conversion program 320 of the first embodiment shown in FIG. 6, but the color conversion program 320 ′ is shown in FIG. The color space separation unit 321 and the second common conversion unit 326 are not provided, and a first pure color storage unit 3271 and a second pure color storage unit 3272 are provided instead of the pure color storage unit 327 shown in FIG. Yes.

  FIG. 14 is a functional block diagram of the RIP device 22 ′ and the color conversion device 23 ′ in the second embodiment.

  The RIP device 22 ′ generates process information based on raster component data in the CMYK color space stored in the image buffer 415 in addition to the various elements of the RIP device 22 of the first embodiment shown in FIG. 416, a second common conversion unit 425 provided in the color conversion device 23 shown in FIG. The second common conversion unit 425 includes a second common profile 425b instead of the second common profile 425b having a function of mapping to the color reproduction area 510 of the target device shown in part (B) of FIG. A basic common profile 425a that is generated or provided prior to construction and has no mapping function is provided.

  Further, the color conversion device 23 ′ does not include the second common conversion unit 425 and the second proof conversion unit 426 provided in the color conversion device 23 of the first embodiment shown in FIG. Instead of the pure color storage unit 427, a first pure color storage unit 4271 and a second pure color storage unit 4272 are provided.

  FIG. 15 is a flowchart showing a flow of a series of processes in which a proof image and a print image are created by the RIP device 22 ′ and the color conversion device 23 ′ shown in FIG.

Similar to the first embodiment shown in FIG. 12, the page image data edited by the operator is acquired by the color space determination unit 411 of the RIP device 22 shown in FIG. 15 (step S201 in FIG. 15). The RGB color space component data in the page image data is converted into L ^* a ^* b ^* color space component data by the first common conversion unit 413 (step S202: No, step S204 in FIG. 15), and after conversion. The L ^* a ^* b ^* color space component data and the L ^* a ^* b ^* color space component data of the L ^* a ^* b ^* color space are transmitted to the common rasterization unit 414, and the CMYK color space of the page image data is transmitted. The component data is transmitted to the CMYK rasterization unit 412 (step S202 in FIG. 15: Yes).

In the common rasterization unit 414, rasterization processing is performed on the component data in the L ^* a ^* b ^* color space transmitted from the color space determination unit 411 and the first common conversion unit 413 (step S205 in FIG. 15). Raster component data rasterization process is performed ^L * ^a * ^{b *} color space is stored in the image buffer 415 (step S206 in FIG. 15).

  Further, the CMYK rasterization unit 412 performs rasterization processing on the CMYK color space component data transmitted from the color space determination unit 411 (step S203 in FIG. 15), and rasterized raster component data of the CMYK color space is also obtained. Are stored in the image buffer 415 (step S206 in FIG. 15).

When the raster part data of the L ^* a ^* b ^* color space and the CMYK color space is stored in the image buffer 415, the raster part data is combined into one, and the CMYK-L ^* a ^* b ^* format The data is transmitted to the process information generation unit 416 as raster part data.

The process information generating unit 416 generates process information based on the raster component data in the CMYK-L ^* a ^* b ^* format (step S207 in FIG. 15). This process information includes a first flag indicating whether the color represented by the raster component data is a process color, a second flag indicating whether the C color is a pure color, and whether the M color is a pure color. And a fourth flag indicating whether or not the Y color is a pure color, and each pixel has a total of 4 bits from the first flag to the fourth flag. Is generated.

  Table 1 shows various flags constituting the process information and a determination method for determining each flag.

  In the present embodiment, the process information generation unit 416 sets various flag values as follows.

  First, each value from the first flag to the fourth flag is initialized to “0”.

Subsequently, the L ^* , a ^* , b ^* color components of the raster part data in the CMYK-L ^* a ^* b ^* format are acquired, and all the color components of L ^* , a ^* , b ^* are “0”. If it is determined that the color represented by the raster component data is a process color, the value of the first flag is set to “1”.

Also, all the color components L ^* , a ^* , b ^* of the raster component data in the CMYK-L ^* a ^* b ^* format are “0” and the C component is “0 (minimum value)” or “100 ( In the case of “maximum value)”, it is determined that the C color is a pure color, and the value of the second flag is set to “1”.

Hereinafter, similarly, all the color components L ^* , a ^* , b ^* of the raster component data in the CMYK-L ^* a ^* b ^* format are “0” and the M component is “0” or “100”. If there is, the value of the third flag is set to “1”, and if the Y component is “0” or “100”, the value of the fourth flag is set to “1”.

  The process information generated as described above is transmitted to the first proof conversion unit 424, the first pure color storage unit 4271, and the second pure color storage unit 4272 of the color conversion device 23 ′.

The raster component data in the CMYK color space stored in the image buffer 415 is transmitted to the second common conversion unit 425. The second common conversion unit 425 uses the basic common profile 425a that converts the color data in the CMYK color space to the color data in the L ^* a ^* b ^* color space, so that the raster component data in the CMYK color space is L ^* a ^* b. ^* Converted to color space raster part data (step S208 in FIG. 15). Raster component data after conversion of the ^L * ^a * ^{b *} color space is sent to the color conversion unit 23 'with raster component data of the stored ^L * ^a * ^{b *} color space in the image buffer 415, the image buffer 415 The K component of the stored raster component data in the CMYK color space is also sent to the color conversion device 23 '.

When a proof image is generated (step S209 in FIG. 15: Yes), the raster component data in the L ^* a ^* b ^* color space and the K component of the raster component data in the CMYK color space are sent to the first proof conversion unit 424. Reportedly.

The first proof conversion unit 424 uses the first proof profile 424b shown in Part (A) of FIG. 10 to convert the raster part data in the L ^* a ^* b ^* color space into the color reproduction region of the target device shown in FIG. It is converted into proof component data in the C′M′Y′K′O′G ′ color space mapped in 510 (step S210 in FIG. 15) (step S211 in FIG. 15). Further, the K component of the proof component data after conversion is replaced with the K component of the raster component data in the CMYK color space transmitted from the RIP device 22 ′ (K plate saving process). The proof component data in the C′M′Y′K′O′G ′ color space after the K plate storage process is transmitted to the second pure color storage unit 4272.

  In the second pure color storage unit 4272, process information sent from the RIP device 22 ′ in the proof component data in the C′M′Y′K′O′G ′ color space transmitted from the first proof conversion unit 424. The color corresponding to the flag “1” among the second flag, the third flag, and the fourth flag of the proof component data whose first flag is “1” is replaced with a pure color (FIG. 15 step S212). For example, when process information such as (first flag, second flag, third flag, fourth flag) = (1, 1, 0, 0) is acquired, the second in the process information It is determined that “cyan” corresponding to the flag “1” is a pure color, and when the cyan data value in the proof component data is a value close to “0”, it is replaced with “0”, and “100”. If the value is close to “100”, it is replaced with “100”. The proof component data subjected to the pure color storage process is transmitted to the proof output unit 428.

  In the proof output unit 428, the proof component data subjected to the pure color storage process is synthesized to generate proof image data, and the proof image data is output to the gradation proofer 52 and the proofer shading device 25 in FIG. (Step S213 in FIG. 15), proof images 51a and 52a are created.

Also, when the printing is performed (step of FIG. 15 S209: No), the raster component data sent from the RIP unit 22' ^{L * a} * ^b * color space is acquired by the target conversion unit 422, the process The information and the K color component are transmitted to the first pure color storage unit 4271.

In the target conversion unit 422, raster part data in the L ^* a ^* b ^* color space is converted into raster part data in the CMYKOG color space using the target profile 422a shown in FIG. 8, and the raster part in the CMYKOG color space after conversion is converted. The data is transmitted to the first pure color storage unit 4271 (step S214 in FIG. 15).

  In the first pure color storage unit 4271, similarly to step S 212, the K plate storage process and the pure color storage process are performed on the raster component data in the CMYKOG color space (step S 215 in FIG. 15). The raster component data in the CMYKOG color space that has been subjected to the K plate storage process and the pure color storage process is transmitted to the target output unit 423.

  In the target output unit 423, the transmitted raster component data of the CMYKOG color space is combined to generate target image data, and the generated target image data is sent to the printing shading device 24 shown in FIG. It is sent to the CTP 30 (step S216 in FIG. 15). In the CTP 30, C, M, Y, K, O, and G 6 color printing film plates are generated based on the print image data, and these printing film plates are mounted on the printing machine 40. 40a is created.

In this way, by generating process information in advance, raster component data in the CMYK color space is also converted into raster component data in the L ^* a ^* b ^* color space, and then processed together by the color conversion device 23 ′. And an image having a desired color can be obtained efficiently. In this embodiment, the RIP device 22 and the color conversion device 23 are constructed on the same workstation 20, but the RIP device and the color conversion device are often constructed on separate personal computers. . In an image output system in which a RIP device and a color conversion device are constructed on separate machines and connected via a network, process information is transmitted from the RIP device to the color conversion device instead of image data in the CMYK color space. As a result, the amount of communication data can be reduced and the processing speed can be improved.

  Here, the example in which the proofer is applied as the output device has been described above. However, the output device according to the present invention may be an electrophotographic or ink-jet color printer, a printing machine, or a display screen. It may be an image display device such as a CRT display device or a plasma display device that displays an image.

In the above description, the C′M′Y′K′O′G ′ color space is applied as the output color space, the L ^* a ^* b ^* color space is applied as the common color space, and the CMYKOG color space is used as the target color space. However, the output color space, common color space, and target color space referred to in the present invention are not limited to these color spaces. For example, the RGB color space is applied as the output color space, and the common color The Luv color space may be applied as the space, and the CMYK color space may be applied as the target color space.

  In the above description, the example in which the print image data and the proof image data are generated in one color conversion device has been described. However, these pieces of data may be generated by separate devices.

It is a figure which shows an example of an image output system. It is a figure for demonstrating a series of processes which perform a multicolor color conversion process using the image output system shown to the part (B) of FIG. 1 is an overall configuration diagram of an image output system in which an embodiment of the present invention is incorporated. It is an external appearance perspective view of a workstation. It is a hardware block diagram of a workstation. It is a conceptual diagram which shows CD-ROM in which the RIP program and the color conversion program were memorize | stored. It is a functional block diagram of a RIP device and a color conversion device. It is a conceptual diagram of a target profile. It is a figure which shows the color reproduction area | region of the color scanner 0 in L ^* a ^* b ^* space, and the color reproduction area | region of a target device. It is a conceptual diagram of a 1st proof profile and a 2nd proof profile. It is a conceptual diagram of a 1st common profile and a 2nd common profile. It is a flowchart figure which shows the flow of a series of processes in which a proof image and a printing image are produced. It is a conceptual diagram which shows CD-ROM in which the RIP program in 2nd Embodiment and the color conversion program were memorize | stored. It is a functional block diagram of the RIP apparatus and color conversion apparatus in 2nd Embodiment. FIG. 10 is a flowchart showing a flow of a series of processes for creating a proof image and a print image in the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Color scanner 20 Workstation 21 Editing apparatus 22 RIP apparatus 23 Color conversion apparatus 24 Screening device for printing 25 Screening device for proofer 30 CTP
DESCRIPTION OF SYMBOLS 40 Printing machine 40a Print image 51 Halftone proofer 51a Proof image 52 Gradation proofer 52a Proof image 201 Main body apparatus 201a FD loading port 201b CD-ROM loading port 202a Display screen 202 Image display device 203 Keyboard 204 Mouse 205 Bus 211 CPU
212 Main memory 213 Hard disk device 214 FD drive 215 CD-ROM drive 216 Input interface 217 Output interface 30 Color printer 100 FD
110, 110A, 110B CD-ROM
310 RIP program 311 Color space determination unit 312 CMYK rasterization unit 313 First common conversion unit 314 Common rasterization unit 315 Process information generation unit 320 Color conversion program 321 Color space separation unit 322 Target conversion unit 323 Target output unit 324 First proof conversion unit 325 Second proof conversion unit 326 Second common conversion unit 327 Pure color storage unit 3271 First pure color storage unit 3272 Third pure color storage unit 328 Proof output unit 411 Color space determination unit 412 CMYK rasterization unit 413 First common conversion unit 414 Common rasterization Unit 415 image buffer 416 process information generation unit 421 color space separation unit 422 target conversion unit 423 target output unit 424 first proof conversion unit 425 second common conversion unit 426 second proof conversion 427 pure color storage unit 4271 first solid color storage unit 4272 second pure color storage unit 428 Proof Output unit

Claims (4)

An image acquisition unit that represents each component constituting an image, and acquires input image data representing the image by a set of component data in which the color of each component is expressed in each predetermined color space;
Among the component data constituting the input image data acquired by the image acquisition unit, the component data expressing the color in the predetermined first type color space is expressed by the pixel arrangement and the first type Other parts excluding the part data in which the color is expressed in the first type color space among the part data constituting the input image data by converting into the first type data expressing the color of each pixel in the color space For data, a data format conversion unit that expresses parts by an array of pixels and converts them into second type data that expresses the color of each pixel in a common color space independent of the device;
The first type data is subjected to color conversion processing for the first type data, and the second type data is subjected to color conversion processing for the second type data, so that the first type data and the second type data are processed. A color conversion system comprising: a color conversion unit that converts data into output data in which pixel colors are expressed in an output color space that depends on the output device.   The color conversion unit performs color conversion processing for the first type data so that the color of an image output by a predetermined target device is reproduced by the output device in accordance with image data obtained by converting the input image data In the color conversion process for the second type data, gamut mapping is performed to convert the colors represented by the first type data and the second type data into colors in the color reproduction area of the target device. The color conversion system according to claim 1. The first type color space is a color space having coordinate components corresponding to each of a plurality of color plates,
The output color space is a color space having a coordinate component corresponding to each of a plurality of color plates at least partially common to the plurality of color plates;
The color conversion unit is a color conversion process for the first type data, and performs a color plate storing process for maintaining a specific coordinate component value in the first type color space in the output color space. The color conversion system according to claim 1, wherein: The first type color space is a color space having coordinate components corresponding to each of a plurality of color plates,
The output color space is a color space having a coordinate component corresponding to each of a plurality of color plates at least partially common to the plurality of color plates;
A flag indicating whether the color represented by the first type data includes a specific coordinate component value in the first type color space in the color conversion process for the first type data; In the flag for the generation, the conversion from the first type data to the third type data in the same format as the second type data, the conversion from the third type data to the output data, and the output data 2. The color conversion system according to claim 1, wherein a color plate storing process for maintaining the specific coordinate component value based on the output color space is performed.

Images