JP2006203675A - Color gamut compressor, compressing method and compression processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color gamut compressor in which the generation of a false contour line can be suppressed, and stabilized image quality can be attained for an image subjected to color gamut compression without requiring complex operation. <P>SOLUTION: Since the color gamut compressor is arranged to compare a plurality of prestored regions (region A to region D) with an inputted color component distribution and to perform color gamut compression (decompression) based on a compression table or a decompression table corresponding to a region including the color component distribution entirely, the generation of the false contour line can be suppressed as compared with the case that compression is performed by operation for every color component, and the occurrence of an accidental error can be prevented without requiring complex transformation operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color gamut compression device, a color gamut compression method, and a color gamut compression processing program. The present invention relates to a color gamut compression device, a color gamut compression method, and a color gamut compression processing program.

Conventionally, as this type of color gamut compression device, the distribution of color components of input image data is divided into a plurality of areas, and the distance from a predetermined center point is maximized in one area. When the color component is extracted and the same color component is outside the color gamut boundary of the output device, it is compressed to the color gamut boundary of the output device and other color components in the same region at the same compression rate A color gamut compression device that employs a compression method that compresses all of the above is known (for example, see Non-Patent Document 1).
"Adaptive 3D Gamut Mapping Based on Color Distribution of Image". Ryoichi Saito and Hiroaiki Kotera, IS &T's NIP19: 2003 International Conference on Digital Printing Technologies.

However, in the color gamut compression device described in the above-mentioned non-patent document, all colors in the area are based on the compression ratio of the color component that is farthest from the color gamut boundary of the output device in each divided area. Since it is configured to perform color gamut compression of components, depending on the input image data, there is a problem that a brightness jump occurs between adjacent areas and a pseudo contour occurs. .
In addition, every time image data is input, it is necessary to perform a complex conversion operation for all color components, so there is a possibility that an error may occur accidentally. There is also a problem of end.

  In view of such a situation, the present invention can suppress the generation of a pseudo contour when a color component outside the color gamut boundary of the output system device is compressed into the color gamut boundary of the output system device or inside thereof. Another object of the present invention is to provide a color gamut compression device, a color gamut compression method, and a color gamut compression processing program capable of obtaining a stable image quality for an image after color gamut compression without requiring a complicated operation. And

  In order to achieve the above object, the present invention provides a color gamut compression apparatus that compresses a color component outside a color gamut boundary of an output system device into the color gamut boundary or the same color gamut boundary of the output system device. Color component input means for inputting components, compression table storage means for storing a plurality of types of compression tables that define the compression mode of the color components, and distribution of color components input by the color component input means And a selection means for selecting one of the plurality of types of compression tables stored in the compression table storage means, and the compression selected by the selection means. The gist of the invention is that it comprises compression means for compressing the color component input by the color component input means based on the table.

  In such a configuration, the color gamut compression apparatus first compresses a color component outside the color gamut boundary of the output system device into the color gamut boundary of the output system device or within the color gamut boundary of the output system device. The component is input by the color component input means. At this time, it is desirable to input all the color components in the input image data. In addition, the color gamut compression device stores a plurality of types of compression tables that define the compression mode of color components. As this compression table, for example, the mapping relationship between the pre-compression and post-compression coordinates is defined for the coordinates above in a predetermined color space (for example, L * a * b * color space, RGB color space, etc.). Tables to be used can be mentioned. Further, the compression table may be a vector arithmetic expression representing a relationship between a position vector before compression of coordinates in a color space and a position vector after compression. The color gamut compression apparatus of the present invention stores a plurality of types of compression tables that define such color compression modes.

  Then, according to the distribution of the color component input by the color component input means by the selection means, one of the compression tables stored in the compression table storage means is selected from the plurality of types of compression tables. A table is selected, and compression of color components based on the selected compression table is executed by the compression means. With this configuration, an optimum compression table corresponding to the input color component distribution is selected from a plurality of types of compression tables stored in advance, and the selected compression table is selected. Therefore, compared with the case where compression is performed by calculation for each color component of input image data as described in non-patent literature, a pseudo contour is not generated. In addition, since color gamut compression is performed based on a pre-stored compression table, it is not necessary to perform complex conversion operations for all color components, and the image quality is destroyed due to an accidental error. Risk can be reduced.

In the present invention, when selecting the compression table by the selection means, each compression table is made to correspond to a plurality of areas in a predetermined color space stored in advance, and an input of these areas is input. It is desirable to perform color gamut compression using a compression table corresponding to a region including all color components. That is, an area storage means for storing a plurality of types of areas in a predetermined color space is provided, and the compression table storage means stores a compression table corresponding to each area stored in the area storage means. Preferably, the selection means is configured to select a compression table corresponding to a region including all color components input by the color component input means. By configuring in this way, it is possible to select the compression table to be used by performing the inside / outside determination of the input color component, so that the processing can be simplified.
As a method for comparing the inclusion relationship between the stored area and the distribution of color components, for example, a table indicating coordinates constituting the outermost shell in the area and the outermost shell in the distribution of color components are used. And a method of comparing with a table indicating coordinates constituting the.

  In addition, when selecting a compression table based on the area inclusion relationship as described above, if there are a plurality of areas including all color components, the smallest area is selected from these areas, and It is desirable for the selection means to select a compression table corresponding to the smallest area. This is because if the compression table corresponding to a region that is much larger than the distribution of the color components is selected, the compression rate increases, and the saturation of the image data after compression decreases.

By the way, the distribution of the color components of the image data input for performing the color gamut compression may be considerably smaller than the color gamut of the output device. In such a case, it is possible to obtain a clearer image than the input image by extending the input color component so as to be substantially the same as the color gamut of the output device. That is, the area storage means stores a specific area included in the color gamut of the output device, and stores an expansion table corresponding to the specific area and defining an expansion mode of the color component. An extended table storage means is provided, and the selecting means selects an extended table corresponding to the specific area when the specific area includes all the color components input by the color component input means. It is desirable that the compression unit expands the color component input by the color component input unit based on the expansion table selected by the selection unit.
However, some users may wish to output an image that is faithful to the original input image. Therefore, when expanding the input color component described above, the user may It is desirable to perform the operation after inputting a predetermined operation for expanding the component.

By the way, the above-described color gamut compression apparatus that compresses a color component outside the color gamut boundary of the output system device to the color gamut boundary of the output system device or inside thereof is a color component outside the color gamut boundary of the output system device. Needless to say, the present invention can also be realized as a color gamut compression method that presents a procedure for compressing the image to the color gamut boundary of the same output system device or inside thereof.
Therefore, a color gamut compression method for compressing a color component outside the color gamut boundary of the output system device into the color gamut boundary or the same color gamut boundary of the output system device, the color component input step for inputting the color component, and One of the compression tables is selected from a plurality of types of compression tables that prescribe the compression modes of the color components stored in advance according to the distribution of the color components input by the color component input means. The invention also includes a selection step of selecting a color and a compression step of compressing the color component input in the color component input step based on the compression table selected in the selection step. To establish.
It is not necessarily limited to the actual color gamut compression device, and there is no difference that it is effective as a color gamut compression method.

  Further, a color gamut compression apparatus and a color gamut compression method for compressing a color component outside the color gamut boundary of the output system device to or within the color gamut boundary of the output system device are realized by the color gamut compression apparatus alone. The idea of the invention includes various aspects such as being used in a state of being incorporated in a certain device, and may be changed as appropriate, such as software or hardware. Is possible. In the case of software that controls the color gamut compression device as an embodiment of the idea of the invention, the invention can be realized as a recording medium for the hardware or software.

As an example thereof, a color gamut compression device that compresses a color component outside the color gamut boundary of the output system device into the color gamut boundary or the same color gamut boundary of the output system device, a color component input means for inputting the color component, Compression table storage means for storing a plurality of types of compression tables that define the compression mode of the color component, and the compression table storage means according to the distribution of the color components input by the color component input means. Selecting means for selecting one of the plurality of types of compression tables stored in the data table, and the color component based on the compression table selected by the selection means A color gamut compression processing program that functions as compression means for compressing color components input by the input means is also included in the present invention.
That is, you may form with the program which makes each means with which a color gamut compression apparatus comprises is realizable. Of course, the software recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium that will be developed in the future.

  The same is true for the replication stage of the primary replica, secondary replica, etc. without any question. In addition, even if the communication method is used as a supply method, the present invention is not changed, and the same applies even if it is written on a semiconductor chip. Furthermore, even when a part is software and a part is realized by hardware, the idea of the invention is not completely different, and a part is recorded on a recording medium as needed. It may be in the form of being read appropriately.

Hereinafter, embodiments of the present invention will be described in the following order.
(1) Configuration of color gamut compression device:
(2) Processing content of color gamut compression device:
(3) Various modifications:
(4) Summary:

(1) Configuration of color gamut compression device:
FIG. 1 is a block diagram showing the configuration of a computer to which a color gamut compression device according to the present invention is applied.
In the figure, a computer 10 is connected to a CPU 11 via a bus 12 with a ROM 13, a RAM 14, a disk driver 15, a printer driver 16, a serial I / O 17, a scanner driver 18, and a CRT driver 19. Has been. The CPU 11 can communicate with each other via the bus 12. The CPU 11 reads out the control program, operating system program, and application program stored in the ROM 12 and the hard disk 51a connected via the disk driver 15 to the RAM 14 as appropriate, and reads the RAM 14 into the work area. However, by executing each program, the computer 10 can function as a color gamut compression device.

  In addition, a flexible disk drive 15b and a CD-ROM drive 15c are connected to the disk driver 15, through which the programs stored in the flexible disk 15b1 and the CD-ROM 15c1 are read and installed on the hard disk 15a. To do. Further, a color printer 16a is connected to the printer driver 16, and image data generated by reading a document to be scanned by the scanner 18a connected via the scanner driver 18 can be printed. ing. Of course, it is also possible to perform printing based on image data for forming the image while displaying the image on the CRT 19a connected via the CRT driver 19 by an operating system program or an application program. It has become. Here, the color printer 16a may be an ink jet printer that forms a print image by discharging CMYK ink (C: cyan, M: magenta, Y: yellow, K: black) onto a print medium such as paper. A laser printer may be employed. Of course, the ink colors are not limited to the four colors CMYK, and may include lm (light magenta) and lc (light cyan).

  The scanner 18a may be a flat bed type that reads a document placed on a platen while scanning, or may be a compact type that reads a document mounted on a tray while pulling it. As described above, the color gamut compression processing program according to the present invention is stored in the flexible disk 15b1 or the CD-ROM 15c1, and is executed while being read out by the computer 10, so that the computer 10 can perform the color according to the present invention. You may make it function as a region compression apparatus. Further, a network device such as a hub 17a is connected to the serial I / O 17, and the color gamut compression processing program according to the present invention is downloaded to the computer 10 via the Internet or LAN to compress the color gamut. You may make it function as an apparatus.

  FIG. 2 is a functional block configuration diagram showing a configuration in which the above-described computer 10 functions as a color gamut compression device. In the figure, the color gamut compression device 50 includes a compression execution determination unit 51, an expansion unit 52, and a compression unit 54. For example, the color of the color image signal input from the input system device 61 of the scanner 18a. The components are supplied via the control unit 60, and among the color components of the color image signal, for example, color components outside the color gamut boundary of the output system device 62 such as the color printer 16a or the CRT 19a are output. Is converted (compressed) to the color gamut boundary or inside thereof, and the converted color component is output to the converted color component signal holding unit 70.

  Here, the compression execution determination unit 51 determines whether or not to execute the color gamut compression process on the color component of the color image signal supplied from the control unit 60, and executes the color gamut compression process. Outputs the color component of the color image signal to the compression unit 54, and conversely outputs the color component of the color image signal to the expansion unit 52 when executing the process of extending the color gamut. That is, the compression execution determination unit 51 determines whether the color component of the color image signal supplied from the control unit 60 is within or outside the color gamut boundary of the output system device 61 or outside the color gamut boundary. If it is outside the color gamut boundary, it is determined that the color gamut compression processing is executed, and if it is located at or inside the color gamut boundary, it is determined that the color gamut expansion processing is executed. Note that the expansion of the color gamut by the expansion unit 52 is performed after a predetermined operation by the user.

The compression unit 54 inputs all the color components from the compression execution determination unit 51 and compresses the same color components to the color gamut boundary of the output device 62 or inside thereof by a predetermined compression method corresponding to the distribution of the color components. To do.
On the other hand, the expansion unit 52 inputs all the color components from the compression execution determination unit 51, and the distribution of the same color components approaches the color gamut of the output system device 62 by a predetermined expansion method corresponding to the distribution of the color components. Extend as follows.

  The conversion color component holding unit 70 is a conversion color component holding unit that collectively holds the color components of the color image signal supplied from the color gamut compression device 50. The image processing unit 80 is an image processing unit that performs predetermined image processing such as edge processing based on the color components of the color image signal supplied from the converted color component holding unit 70 and outputs the processed image to the control unit 60. The output system device 62 is an output system information device such as a color printer 16 a that visualizes the color components of the color image signal supplied from the control unit 60. The controller 60 is a controller that executes transmission / reception of color image signals between the input system device 61 and the output system device 62.

Next, the processing operation of color gamut compression will be described.
Here, the description will be made assuming that the color space for color gamut compression is the CIE / L * a * b * color space.
First, when the color component of the color image signal is supplied from the input device 61 to the control unit 60, the color image signal is supplied from the control unit 60 to the compression execution determination unit 51 of the color gamut compression device 50. . The color component of the color image signal includes lightness, saturation, and hue information, and is a signal that can be vector-calculated in, for example, the CIE / L * a * b * color space. The compression execution determination unit 51 compares the distribution of all color components of the color image signal supplied from the control unit 60 with the color gamut of the output device 62 stored in advance, and the distribution of all color components is determined. If there is a color component that is larger than the color gamut of the output system device 62, that is, there is a color component outside the color gamut boundary of the output system device 62, all color components are output to the compression unit 54 as executing the color gamut compression processing. On the other hand, if the distribution of all the color components is within the color gamut of the output system device 62, it is assumed that the color gamut expansion processing is executed to bring the distribution area of all the color components closer to the color gamut of the output system device. Is output to the expansion unit 52.
The compression unit 54 that has input all color components of the color image signal performs color gamut compression so that all color components are located at or within the color gamut boundary of the output device 62 based on the compression method described in detail later. Do. Further, the expansion unit 52 that has received all the color components of the color image signal performs the color gamut expansion of all the color components based on the expansion method described in detail later.

  Hereinafter, a method of compression / expansion processing of input color components in the color gamut compression device according to the present embodiment will be described. The ROM 13 of the computer 10 stores a plurality of areas in the L * a * b * color space in advance, and also stores a compression table or an expansion table corresponding to each area. The compression table defines the compression mode of the color component. In the present embodiment, the coordinates of the input color component in the L * a * b * color space and the coordinates of the color component after compression are used. It is stored as a table indicating the relationship. The extended table defines the color component expansion mode. In this embodiment, the coordinates of the input color component in the L * a * b * color space and the coordinates of the expanded color component are used. Is stored as a table indicating the relationship between

  FIG. 3 is a diagram illustrating an example of the area in the L * a * b * color space stored in the ROM 13 of the color gamut compression device according to the present embodiment. In FIG. 3, for convenience of explanation, each region is represented by a two-dimensional plane. However, in this embodiment, the region is a region in an L * a * b * color space, that is, a three-dimensional space. It is an area. In the figure, four regions A, B, C and D (shown by solid lines) in the L * a * b * color space are stored. The ROM 13 also stores a color gamut G (indicated by a broken line) of the output device in advance. Among these areas A to D, the area A and the area B have a size that includes the color gamut G of the output device, and the area A includes the area B. On the other hand, the area C and the area D are included in the color gamut G of the output device, and the area D is included in the area C. In this embodiment, a compression table or an expansion table is selected according to the input color component distribution and the inclusion relationship between the regions A to D, and the color gamut is based on the selected table. Compression or expansion is performed.

  FIG. 4 is a diagram showing an example of a compression table and an expansion table stored in the ROM 13 of the color gamut compression device according to this embodiment. In the figure, the coordinates of the input color component in the L * a * b * color space, that is, the coordinates (L, a, b) of the color component before compression (expansion) are shown on the left side of the table. The coordinates (L ′, a ′, b ′) after compression are shown on the right side. Among the input color components, the color components at the coordinates shown in this table are mapped to the coordinates shown on the right side thereof. The compression table defines a mapping relationship in which the color components outside the color gamut G boundary of the output device are compressed so that they are located at or inside the boundary. The extended table defines a mapping relationship in which a color component within the boundary of the color gamut G of the output device is extended so as to be positioned on or near the boundary of the color gamut G.

  As described above, the ROM 13 stores the four areas A to D. Of these areas, the compressed text corresponding to the area A and the area B including the color gamut G of the output system device, respectively. -A table A and a compressed table B are stored. The ROM 13 stores an extended table C and an extended table D corresponding to the area C and the area D included in the color gamut G of the output device. That is, when the distribution of the input color component extends outside the boundary of the color gamut G of the output system device, all the color components are compressed, while the distribution of the input color component is included in the color gamut G of the output system device. If so, it expands all color components.

  FIG. 5 is a diagram illustrating an example of the distribution of the input color component and the compression mode by the compression table of the input color component. In the same figure, the part shown with color shows the distribution of all the input color components. In this case, the input color component distribution H is included in the region A, and partly protrudes from the region B. In this case, the compression table A corresponding to the area A is selected, and color gamut compression based on the selected compression table A is performed. The direction of the arrow shown in the figure indicates the compression direction, and the length of the arrow indicates the size of the compression rate. In the case of FIG. 5, since the distribution of the color component protrudes relatively larger than the color gamut G of the output device, the color gamut compression is performed at a high compression rate. As a result, all input color components are compressed to the color gamut boundary of the output device or inside thereof.

  FIG. 6 is a diagram showing another example of the distribution of the input color components and the compression mode by the compression table of the input color components. In the figure, the input color component distribution H partially protrudes from the color gamut G of the output device and is included in the region A and the region B. In this case, the compression table B corresponding to the region B which is the smallest region among the regions A and B including the input color component distribution H is selected and the selected compression table B is selected. Based on the color gamut compression. In the figure, the arrows indicating the compression direction and the compression rate are shorter than the arrows shown in FIG. 5, and when color gamut compression based on the compression table B is performed, FIG. It is shown that the compression rate is lower than that in the case where the color gamut compression based on the compression table A described above is performed.

  FIG. 7 is a diagram illustrating an example of an extended form by the distribution of the input color component and the extended table of the input color component. In the figure, the input color component distribution H is included in the color gamut G of the output device, and is also included in the region C. Further, the input color component distribution H partially protrudes from the region D. In this case, the extension table C corresponding to the area C including the input color component distribution H is selected, and the color gamut is extended based on the selected extension table C. The direction of the arrow shown in the drawing indicates the expansion direction, and the length of the arrow indicates the size of the expansion rate.

  FIG. 8 is a diagram illustrating another example of an extended form by the distribution of the input color component and the extended table of the input color component. In the figure, the input color component distribution H is included in the color gamut G, region C, and region D of the output device. In this case, the extended table D corresponding to the region D that is the smallest region among the regions C and D including the input color component distribution H is selected, and the selected extended table D is selected. Based on the color gamut compression. In the figure, the arrow indicating the extension direction and the extension rate is longer than the arrow shown in FIG. 7, and when color gamut extension based on the extension table D is performed, FIG. 7 is used. It is shown that the expansion rate is higher than that in the case where the color gamut expansion based on the described expansion table C is performed.

(2) Processing content of color gamut compression processing:
FIG. 9 is a flowchart showing the outline processing contents of the color gamut compression processing executed in the configuration described above.
In the figure, first, color components of input image data are input (step S100). In step S100, all the color components included in the input image data are input. Next, a process of extracting the outermost shell point is performed in step S200. In this process, a process of extracting the outermost shell point in the L * a * b * color space of all the color components input in step S100 is performed. The curved surface including all the outermost shell points extracted by this processing includes all the color components of the input image data.

  Next, in step S300, a table selection process is executed. In this processing, a table used for color gamut compression or expansion based on the distribution relationship of the color components input in step S100 and the inclusive relations between the areas A to D shown in FIGS. A process of selecting a compression table or an expansion table is performed. The table selection process will be described in detail later with reference to the drawing (FIG. 10). Next, in step S400, color gamut compression (expansion) based on the selected table is performed. In other words, based on the compression table or expansion table selected in step S300, a process for compressing (expanding) all the color components input in step S100 is performed. When the process of step S400 is executed, the color gamut compression process is terminated.

FIG. 10 is a flowchart showing the flow of table selection processing that is called and executed in step S300 of the flowchart shown in FIG. When the table selection process shown in the figure is started, first, it is determined whether or not the outermost shell point is within the region D in step S305. In this process, it is determined whether or not all the outermost shell points extracted in step S200 (FIG. 9) are located in the region D. If it is determined that it is located in the area D, then in step S310, a process for selecting the extended table D that is a table corresponding to the area D is performed, and the table selection process is terminated. .
On the other hand, if it is determined in step S305 that the outermost shell point is not in the region D (outside the region D), it is then determined whether or not the outermost shell is in the region C in step S315. If it is determined that it is located in the area C, in the subsequent step S320, a process of selecting the extended table C that is a table corresponding to the area C is performed, and the table selection process is terminated. Let

On the other hand, if it is determined in step S315 that the outermost shell is not in the region C, it is then determined in step S325 whether or not the outermost shell is in the region B. If it is determined that it is located in the area B, it is next determined in step S330 whether or not it is out of the color gamut of the output device. If it is determined that it is out of the color gamut of the output device, in the subsequent step S335, a process of selecting the compressed table B which is a table corresponding to the area B is performed, and the table selection process is terminated. On the other hand, if it is determined that the output device color gamut boundary is within or within the color gamut boundary of the output device, the input color component distribution is within or within the color gamut boundary of the output device and the color gamut of the output device. Therefore, since it is not necessary to perform color gamut compression and expansion, no table is selected and the table selection process is terminated.
If it is determined in step S325 that the outermost shell is not in the region B, the color component distribution is in the region A. Therefore, in step S340, the compression table A corresponding to the region A is selected. Then, the table selection process is terminated.

(3) Various modifications:
In the present invention, if the selected table is an extended table after the compression table or the extended table is selected, the color gamut based on the extended table is selected. It is desirable to perform the extension of the above after waiting for the input of a predetermined instruction from the user. This is because some users desire to output an image faithful to the original input image.

  FIG. 11 is a flowchart showing another example of color gamut compression processing. In FIG. 11, steps that perform the same processing as the steps in the color gamut compression processing shown in FIG. 9 are given the same reference numerals, and descriptions thereof are omitted. In the color gamut compression process shown in FIG. 11, after the table selection process in step S300 is executed, it is determined in step S350 whether an extended table has been selected. That is, it is determined whether or not the extended table C or the extended table D is selected in the table selection process shown in FIG. If it is determined that the extended table has not been selected (the compressed table has been selected), the process proceeds to step S400 to perform color gamut compression (expansion), while the extended table is selected. If it is determined that the color gamut expansion instruction has been input, it is determined in step S360. In this process, it is determined whether or not the user has input an instruction to permit execution of the color gamut expansion process based on the selected expansion table. If it is determined that there is an instruction input, the process proceeds to step S400 to perform color gamut compression (expansion). If it is determined that there is no instruction input, the process of step S400 is not performed and the color gamut is performed as it is. End the compression process.

(4) Summary:
As described above, in the color gamut compression device according to the embodiment, a plurality of areas (area A to area D) stored in advance are compared with the distribution of the input color components, and the distribution of the color components is determined. Since it is configured to perform color gamut compression (expansion) based on a compression table or an expansion table corresponding to all the included areas, compared with the case where compression is performed by calculation for each color component The generation of pseudo contours can be suppressed, and it is not necessary to perform complicated conversion calculations, and it is possible to prevent an accidental error from occurring.

It is a block diagram of a computer. It is a block diagram of a color gamut compression device. It is a figure which shows an example of the some area | region memorize | stored in ROM. It is a figure which shows an example of a compression table and an expansion table. It is a figure which shows the compression aspect by a compression table. It is a figure which shows the compression aspect by a compression table. It is a figure which shows the expansion aspect by an expansion table. It is a figure which shows the expansion aspect by an expansion table. It is a flowchart showing the outline processing contents of color gamut compression processing. 10 is a flowchart showing the flow of table selection processing that is called and executed in step S300 of the flowchart shown in FIG. 10 is a flowchart showing another example of color gamut compression processing.

Explanation of symbols

10 ... Computer 11 ... CPU
12 ... Bus 13 ... ROM
14 ... RAM
DESCRIPTION OF SYMBOLS 15 ... Disk driver 15a ... Hard disk 15b ... Flexible disk drive 15b1 ... Flexible disk 15c ... CD-ROM drive 15c1 ... CD-ROM
16 ... Printer driver 16a ... Color printer 17 ... Serial IO
18 ... Scanner driver 18a ... Scanner 19 ... CRT driver 19a ... CRT
DESCRIPTION OF SYMBOLS 50 ... Color gamut compression device 51 ... Compression execution determination part 52 ... Expansion part 54 ... Compression part 60 ... Control part 61 ... Input system device 62 ... Output system device 70 ... Conversion color component holding part 80 ... Image processing part

Claims (7)

A color gamut compression device that compresses color components outside the color gamut boundary of the output system device into the color gamut boundary or the same color gamut boundary of the output system device,
Color component input means for inputting the color component;
Compression table storage means for storing a plurality of types of compression tables that define the compression mode of the color components;
According to the distribution of the color components input by the color component input means, one of the compression tables stored in the compression table storage means is selected. Selection means to
A color gamut compression apparatus comprising: compression means for compressing a color component input by the color component input means based on the compression table selected by the selection means. Comprising an area storage means for storing a plurality of types of areas in a predetermined color space;
The compression table storage means stores a compression table corresponding to each area stored in the area storage means,
2. The color gamut compression device according to claim 1, wherein the selection unit selects a compression table corresponding to a region including all color components input by the color component input unit.   The selection means selects a compression table corresponding to a minimum area when there are a plurality of areas including all the color components input by the color component input means. The color gamut compression device described in 1. The area storage means stores a specific area included in the color gamut of the output device,
An extended table storage means for storing an extended table corresponding to the specific area and defining an extended form of the color component;
When the specific area includes all the color components input by the color component input means, the selecting means selects an extended table corresponding to the specific area,
4. The color gamut according to claim 2, wherein the compression unit expands the color component input by the color component input unit based on the extended table selected by the selection unit. Compression device.   5. The color gamut compression device according to claim 4, wherein the color component expansion based on the selected expansion table is performed after a predetermined operation. A color gamut compression method that compresses a color component outside the color gamut boundary of an output device device into the color gamut boundary or the same color gamut boundary of the output device device,
A color component input step for inputting the color component;
According to the distribution of the color components input by the color component input means, any one of the compression tables out of a plurality of types of compression tables prescribing the compression mode of the color components stored in advance. A selection process for selecting
A color gamut compression method comprising: a compression step of compressing the color component input in the color component input step based on the compression table selected in the selection step. A color gamut compression device that compresses color components outside the color gamut boundary of the output system device into the color gamut boundary or the same color gamut boundary of the output system device,
Color component input means for inputting the color component;
Compression table storage means for storing a plurality of types of compression tables for defining the color component compression mode;
According to the distribution of the color components input by the color component input means, one of the compression tables stored in the compression table storage means is selected. Selection means to perform, and
A color gamut compression processing program for causing a color component input by the color component input unit to function as a compression unit based on the compression table selected by the selection unit.