JP2007036881A - Color processing method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the matter that although record management can be introduced in order to restore the operation for adjusting control parameters of mapping transformation and a record of adjusting operations arranged in timer order is obtained, adjusting operation in the past after the moment in time of restoration cannot be restored when an adjusting operation different from before is performed following to restoration of adjusting operation up to an arbitrary moment in time. <P>SOLUTION: An input color gamut is transformed by mapping into an output color gamut and displayed pseudo-three dimensionally (S502-S504). When control parameters of map conversion are altered, its alteration record is managed (S507) and the results of map transformation at an arbitrary moment in time or in an arbitrary period are reproduced, based on that alteration record (S511-S504). Control parameters are altered frequently by reproduction thus enhancing design efficiency of gamut mapping repeating trial and error. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to color processing for adjusting color reproduction of an image.

  With the spread of personal computers and workstations, desktop publishing (DTP) and computer-aided design (CAD) are widely used. Under such circumstances, the importance of a color reproduction technique for matching a color expressed on a monitor by a computer with a color reproduced on an output medium is increasing. For example, at a DTP site, a computer system having a color monitor and a color printer is used to create, edit, and process an image on the monitor, and the image is output by the color printer. The user strongly desires that the color of the display image on the monitor and the output image of the printer are perceptually matched.

  However, the perceptual matching of colors between the monitor display image and the printer output image is difficult for the following reasons.

  A monitor expresses a color using, for example, light of a specific wavelength emitted from a phosphor. On the other hand, the printer expresses a color by the remaining reflected light that has absorbed light of a specific wavelength by a color material such as ink. That is, the color gamuts of the monitor and the printer are greatly different due to their different image forming forms.

  Furthermore, there are monitors that use liquid crystal panels and cathode-ray tubes, or plasma systems, and their color gamuts differ greatly. Printers also have different color gamuts depending on the recording method, the quality of the recording medium (paper quality), the type of color material, and the amount used. Therefore, it is impossible to make the colors completely match between the display image on the monitor and the output image of the printer, or the output image of the printer output to a recording medium of different quality.

  Here, there is a gamut mapping technique for associating one color reproduction area with another color reproduction area in a uniform color system as a color reproduction technique for perceptual matching of colors in recording media and display media having different color reproduction areas. The gamut mapping technique includes a technique for performing a one-dimensional to three-dimensional complex mapping conversion described in Japanese Patent Laid-Open No. 2001-094799 in multiple stages, and a gradation as a color change described in Japanese Patent Laid-Open No. 2002-033929. There is a technology that realizes a gamut mapping by reducing the curve to a curved expression.

  Japanese Patent Laid-Open No. 2002-033931 describes a technique for achieving perceptual matching of output images from a printer without impairing the gradation of the input image. Furthermore, Japanese Patent Laid-Open No. 2003-173437 describes a technique in which a user performs color adjustment, evaluation, and analysis in a uniform color system while maintaining the gradation of an input image.

  However, these techniques require the user to manually adjust a number of mapping parameters when gamut mapping from the color gamut of the monitor to the color gamut of the printer. The optimal combination of mapping parameters also depends on the monitor and printer model. Therefore, the design of a gamut map that determines the mapping parameters requires significant time costs.

  Also, gamut mapping is generally difficult to control because it is composed of multiple levels of mapping. In order to achieve the color reproduction intended by the user, a high level of knowledge about map conversion is required. Of course, some mapping transformations configure the mapping parameters so that the mapping can be easily controlled. However, it is still difficult to understand the effect of adjusting the mapping parameters and the influence on the entire image.

  Further, mapping by higher-order nonlinear transformation requires understanding of the influence of coefficient terms of nonlinear transformation on the mapping, and is more difficult to control. Furthermore, in order to adjust the mapping parameters while visually confirming the color reproduction, it is necessary to repeat mapping and analysis alternately, and the procedure becomes complicated.

  For the above reasons, even if the mapping result being adjusted is not good, it is difficult to redo the mapping parameter retroactively. For this reason, the design efficiency until a preferable mapping parameter is determined is extremely low.

  Of course, history management can also be introduced to restore the mapping parameter adjustment operation. However, it is only possible to obtain a history in which adjustment operations are arranged in chronological order, and after restoring to an adjustment operation at an arbitrary point in time, if an adjustment operation different from the previous one is performed, it is possible to restore past adjustment operations after the restoration point. Can not.

  As described above, the design efficiency of the gamut mapping that frequently changes the mapping parameters and repeats trial and error is extremely low.

Japanese Patent Laid-Open No. 2001-094799 JP2002-033929 JP 2002-033931 JP JP 2003-173437 A

  An object of the present invention is to make it possible to reproduce a conversion result of mapping conversion at an arbitrary time point or period.

  The present invention has the following configuration as one means for achieving the above object.

  The color processing according to the present invention is color processing for adjusting the color reproduction of an image, wherein the input color gamut is converted to an output color gamut, the control parameter of the mapping conversion is changed, and the change history of the control parameter is recorded. And the result of the mapping conversion at an arbitrary time or period is reproduced based on the change history.

  According to the present invention, the conversion result of the mapping conversion at an arbitrary time point or period can be reproduced. Therefore, it is possible to increase the design efficiency of a gamut map that frequently changes the control parameter of the map conversion and repeats trial and error.

  Hereinafter, color processing according to an embodiment of the present invention will be described in detail with reference to the drawings.

[Device configuration]
FIG. 1 is a block diagram illustrating a configuration example of a color signal conversion apparatus.

  The CPU 101 uses the RAM of the memory 102 as a work memory, and a system bus 114 such as a PCI (Peripheral Component Interconnect) bus according to the operating system (OS) and various programs stored in the ROM of the memory 102 and the hard disk drive (HDD) 105. The respective components are controlled via the above and processing described later is executed.

  The CPU 101 accesses the HDD 105 via the system bus 114 and the serial ATA interface (SATA I / F) 103. Further, a network 113 such as a local area network (LAN) is accessed via the network I / F 104.

  Further, the CPU 101 displays a user interface and processing results of processing to be described later on the monitor 107 via the graphic accelerator 106, and inputs user instructions via the keyboard 111 and mouse 112 connected to the keyboard / mouse controller 110. Enter.

  Further, the CPU 101 outputs image data to a printer 109 via a USB (Universal Serial Bus) controller 108, and prints an image instructed by the user, for example.

[Printer output]
A printer output of a digital image in the color conversion apparatus shown in FIG. 1 will be described.

  When the CPU 101 is instructed to display a digital image by the user, the CPU 101 transfers the digital image data stored in the HDD 105 or a server on the network 113 to the RAM of the memory 102. The server on the network 113 includes a server on a wide area network such as the Internet.

  Next, the CPU 101 sends the digital image data stored in the memory 102 to the graphic accelerator 106 and displays it on the monitor 107.

  Here, when printing of the digital image displayed on the monitor 107 is instructed by the user, the CPU 101 activates the printer driver and executes color conversion processing described later, and the digital image data stored in the memory 102 is transferred to the printer 109. To digital image data corresponding to the device CMYK. Then, the CMYK digital image data is sent to the printer 109 to print the image.

[Color conversion processing]
FIG. 2 is a flowchart for explaining the operation of the printer driver, and shows processing executed by the printer driver activated by the CPU 101.

  First, an area for storing image data and a color correction LUT created by a color correction LUT creation application described later is prepared in the memory 102 (S201), and the color correction LUT is read from the HDD 105 (S202).

  The color correction LUT has a data structure that describes the correspondence between the coordinate values of the grid points in the RGB color space shown in FIG. 3A and the coordinate values of the Lab color space corresponding to the grid points. As shown in Fig. 3B, the R, G, B value step is described at the beginning of the data structure, and the correspondence between the coordinate value of each grid point and the Lab value is then nested in R, G, B. They are described in order. In the following, the color correction LUT may be referred to as color distribution data because the above data structure indicates a color distribution.

  Next, using the color correction LUT stored in the memory 102, RGB 24-bit image data is converted into fixed-point Lab image data and stored in an area prepared in the memory 102 (S203). Subsequently, Lab image data is converted into CMYK 32-bit image data using a predetermined color conversion LUT and stored in an area prepared in the memory 102 (S204). In addition, tetrahedral interpolation etc. are used for these conversions.

  Then, the CPU 101 is notified that the image data to be output to the printer 109 is ready (S205). In response to this notification, the CPU 101 reads out CMYK 32-bit image data from the memory 102 and transmits it to the printer 109 via the USB controller 108.

[Color correction LUT creation application]
Next, a color correction LUT creation application for creating a color correction LUT will be described.

  When the user gives an instruction to start the color correction LUT creation application, the CPU 101 loads the color correction LUT creation application stored in the HDD 105 or the like into the work memory (memory 102) and executes it.

  The activated color correction LUT creation application displays the windows shown in FIGS. 4A and 4B on the monitor 107. Although details will be described later, FIG. 4A shows a pseudo three-dimensional display example in which the Lab value of each grid point described in the color correction LUT is displayed as color distribution information on the Lab color space. FIG. 4B is a menu window for adjusting the color correction LUT.

  The user refers to and uses these windows (FIGS. 4A and 4B) to create a color correction LUT. The created color correction LUT can be saved in the HDD 105 or the like according to a user instruction.

  FIG. 5 is a state transition diagram for explaining the operation of the color correction LUT creation application.

  First, initialization processing is performed (S501). Initialization processing includes securing work heap memory in the memory 102, initialization of mapping control parameters, geometry information and display form information (3D object / line object / plane object, etc.) ) Initialization.

  Next, a color correction LUT equivalent to the color distribution information is created by color gamut mapping processing described later based on the mapping control parameters (S502), and three-dimensional object data is generated based on the color correction LUT and the geometry information (S503). ). Based on the display form information, a three-dimensional object is displayed on the monitor 107 (S504), and a message waiting state is entered (S505). And it transfers to the state according to the received message.

[Generation of pseudo three-dimensional object data (S503) and display (S504)]
When generating 3D object data, a combination of two triangles (triangular patches) is generated in each of the smallest squares formed by each grid point on the surface of the largest grid area in the Lab color space. These are figures which show the mode typically.

  In FIG. 6, the area surrounded by the thick line is the smallest square formed by each lattice point, and is obtained by dividing the square by a broken line and by dividing it by a two-dot chain line. Generate two combinations of two triangles. Next, the grid point coordinates which are the vertices of these triangles are converted into the corresponding Lab values after color conversion using the color conversion LUT. Then, a combination of triangles after color conversion is selected so that the volume of the three-dimensional object is maximized, and three-dimensional object data is generated from the combination of triangles after color conversion. In other words, the surface information of the three-dimensional object is configured as a set of triangular patches.

  The three-dimensional object generated in this way is displayed on the monitor 107 as shown in FIG. 4A, for example.

[Processing for received messages]
FIG. 7 shows a message map. Hereinafter, the process for the notified message will be described.

● Message DISP_MAPCTRL
When the message DISP_MAPCTRL is received, the sub message added to the message is extracted, a mapping control modeless dialog corresponding to the sub message is displayed (S506), and the process returns to the message waiting state (S505).

● Message CTRL_MAP
When the message CTRL_MAP is received, the mapping control submessage and the additional message added to the message are extracted, and the mapping control parameter is adjusted based on the mapping control submessage and the additional message (S507). Then, the process proceeds to color gamut mapping processing (S502). Then, color gamut mapping processing (S502) using the adjusted mapping control parameters, generation of three-dimensional object data (S503), display of three-dimensional objects (S504) are performed, and the process returns to the message waiting state (S505).

● Message CNT_HIST
When the message CNT_HIST is received, a sub message added to the message is extracted, a history operation described later is performed based on the sub message (S511), and the process proceeds to the color gamut mapping process (S502). Then, color gamut mapping processing (S502), generation of three-dimensional object data (S503), display of a three-dimensional object (S504) are performed, and the process returns to the message waiting state (S505).

● Message CTRL_DISP
When the message CTRL_DISP is received, the display control sub message and the additional message added to the message are extracted. Then, the display control information is updated based on the display control sub message and the additional message (S508), and the process proceeds to display of a three-dimensional object (S504). Then, the display of the three-dimensional object is updated based on the updated display control information (S504), and the process returns to the message waiting state (S505).

● Message GEN_LUT
When the message GEN_LUT is received, a color correction LUT from RGB data to Lab data is generated by referring to the mapping color gamut generated by the method described later and saved in the HDD 105 (S509), and the message waiting state (S505) is entered. Return.

● Message PROCESS_END
When the message PROCESS_END is received, a termination processing operation such as release of heap memory is performed, and the color correction LUT creation application is terminated.

[Menu window]
When the buttons 401 to 404 are pressed in the menu window shown in FIG. 4B, a message DISP_MAPCTRL is generated. Further, the sub message is DISP_CHANGE_BRIGHTNESS for the button 401, DISP_CHANGE_HUE for the button 402, DISP_CHANGE_CHROMA for the button 403, and DISP_CTRL_HISTORY for the button 404. When the button 405 is pressed, a message GEN_LUT is generated, and when the button 406 is pressed, a message PROCESS_END is generated.

[Display modeless dialog for mapping control (S506)]
Next, display of a modeless dialog for mapping control when receiving the message DISP_MAPCTRL (S506) will be described.

● Sub message DISP_CHANGE_BRIGHTNESS
When the sub message DISP_CHANGE_BRIGHTNESS is extracted, the brightness adjustment dialog shown in FIG. 8A is displayed. The user uses the slider 801 to set the overall brightness adjustment amount for color correction. The color correction LUT creation application performs a color gamut mapping process, which will be described later, according to the adjustment amount.

● Sub message DISP_CHANGE_HUE
When the sub message DISP_CHANGE_HUE is extracted, a hue adjustment dialog shown in FIG. 8B is displayed. The user uses the list boxes 802 and 803 to select one of brightness and hue (red, green, blue, cyan, magenta, and yellow), and sets the hue adjustment amount of the color in the selected range using the slider 804. Use to set. The color correction LUT creation application performs a color gamut mapping process, which will be described later, according to the adjustment amount.

● Sub message DISP_CHANGE_CHROMA
When the sub message DISP_CHANGE_CHROMA is extracted, a saturation adjustment dialog shown in FIG. 8C is displayed. The user uses the list box 805 to select a hue to be adjusted, and uses the slider 806 to set the vividness adjustment amount for the selected hue. The color correction LUT creation application performs a color gamut mapping process, which will be described later, according to the adjustment amount.

● Sub message DISP_CTRL_HISTORY
When the sub message DISP_CTRL_HISTORY is extracted, a history management dialog shown in FIG. 8D is displayed. Using this dialog, the user can manipulate the state of the mapping control parameter and go back to the previous state or continuously reproduce a series of operations to confirm the effect of the mapping control parameter. The color correction LUT creation application performs a history operation to be described later in accordance with a user instruction.

[Adjustment of mapping control parameters (S507)]
Next, adjustment of the mapping control parameter (S507) will be described.

● Sub message CHANGE_BRIGHTNESS
In the dialog shown in FIG. 8A, when the user operates the slider 801, a message CTRL_MAP and a sub message CHANGE_BRIGHTNESS are generated, and position information of the slider 801 (for example, an integer value of 0 to 100) is added to the message.

  When the message CTRL_MAP is received and the sub message CHANGE_BRIGHTNESS is extracted, the slider position information added to the message is acquired. Then, based on the acquired position information, the brightness control parameter is generated or modified to update the mapping control parameter (S507). Then, based on the updated mapping control parameter, color gamut mapping processing described later is performed (S502).

● Sub message CHANGE_HUE
In the dialog shown in FIG. 8B, when the user operates the slider 804, a message CTRL_MAP and a sub message CHANGE_HUE are generated. At that time, selection information (for example, list number) of the list boxes 802 and 803 and position information of the slider 804 (for example, an integer value of 0 to 100) are added to the message. The brightness selection list box 802 has 6 lists in 20 increments from brightness 0 to 100, and the hue selection list box 803 has 6 lists corresponding to the above six colors.

  When the message CTRL_MAP is received and the sub message CHANGE_HUE is extracted, the list number added to the message and the position information of the slider are acquired. Then, the brightness value and hue angle value to be adjusted are set based on the acquired list number, and a hue adjustment value that takes an integer value of, for example, −20 to 20 is generated based on the acquired position information. Then, based on the brightness value, hue angle value, and hue adjustment value to be adjusted, the hue control parameter is generated or modified to update the mapping control parameter (S507). Then, based on the updated mapping control parameter, a color gamut mapping process to be described later is performed (S502).

● Sub message CHANGE_CHOROMA
In the dialog shown in FIG. 8C, when the user operates the slider 806, a message CTRL_MAP and a sub message CHANGE_CHROMA are generated. At this time, selection information (for example, list number) in the list box 805 and position information (for example, an integer value from 0 to 100) of the slider 806 are added to the message. The hue selection list box 805 has, for example, 12 lists of yellow, orange, red, magenta, magenta, blue-violet, blue, sky blue, cyan, blue-green, green, and yellow-green.

  When the message CTRL_MAP is received and the sub message CHANGE_CHROMA is extracted, the list number added to the message and the position information of the slider are acquired. Then, a hue angle value to be adjusted is set based on the acquired list number, and a saturation adjustment value that takes a real value of, for example, 0.5 to 2 is generated based on the acquired position information. Then, based on the hue angle value and saturation adjustment value to be adjusted, the saturation control parameter is generated or modified to update the mapping control parameter (S507). Then, based on the updated mapping control parameter, color gamut mapping processing described later is performed (S502).

[History Operation (S511)]
Next, the history operation (S511) will be described.

● Sub message HIST_ADD
In the dialogs shown in FIGS. 8A to 8C, when the user operates the slider, a message CTRL_HIST and a sub message HIST_ADD are generated, and the list number (selected if there is a list box) and slider position information are added to the message.

  When the message CTRL_HIST is received and the sub message HIST_ADD is extracted, the (list number and) position information added to the message is acquired, and the mapping control parameter is generated from the acquired (list number and) position information by the method described above. . Alternatively, the mapping control parameter updated in the mapping control parameter adjustment (S507) is acquired. Then, the current node is acquired from the list corresponding to the node management list 807 shown in FIG. 8D, and a new node with the mapping control parameter added is generated with the current node as the parent node. The node holds parent node information and mapping control parameters.

  For example, when the current node is a node indicated by reference numeral 814 in FIG. 8D, a new node 815 that holds the generated or acquired mapping control parameter and information of the parent node 814 is generated, and the node management list 807 is used as a child node of the node 814. Register to the list corresponding to. As a result, the new node 815 is displayed in a hierarchy (tree display) to the right of the node 814 in the node management list 807, and the current node is updated to the node 815. If a child node already exists in the node 814, the node 815 is displayed at an appropriate position in the hierarchical display (tree display).

● Sub message HIST_UNDO
In the dialog shown in FIG. 8D, when the user presses an Undo button 816, a message CTRL_HIST and a sub message HIST_UNDO are generated, and the parent node acquired from the current node is added to the message.

  When the message CTRL_HIST is received and the sub message HIST_UNDO is extracted, the node information added to the message is acquired. Then, the current node of the node management list 807 is updated to the node indicated by the acquired node information, the mapping control parameter held by the node is acquired, and the color gamut mapping process described later is performed based on the acquired mapping control parameter. (S502).

● Sub message HIST_ANIMATION
In the dialog shown in FIG. 8D, when the user presses the play button 817, a message CTRL_HIST and a sub message HIST_ANIMATION are generated. When the message CTRL_HIST is received and the sub message HIST_ANIMATION is extracted, playback processing is executed.

  FIG. 9 is a flowchart for explaining the reproduction process.

  First, a start point node and an end point node are acquired (S901). In the dialog shown in FIG. 8D, the user can specify a start point node and an end point node by a mouse operation or the like. For example, if a node on the node management list 807 is left-clicked, the start point node is designated, and if a right-click is designated, the end point node is designated.

  Next, it is determined whether or not the parent node is reached in order from the end node to reach the start node (S902). If the start point node cannot be reached (the playback path does not exist), an error message is displayed (S907) and the playback process is terminated.

  If there is a playback path, a playback list indicating the playback order of the nodes is stored in the memory 102 (S903), and mapping control parameters held by the first node of the playback list are acquired (S904). Then, based on the acquired mapping control parameters, a color gamut mapping process (S502) described later, three-dimensional object data generation (S503), and three-dimensional object display (S504) are performed (S905).

  Finally, it is determined whether or not color gamut mapping processing has been performed based on mapping control parameters corresponding to all of the end nodes from the start point node of the reproduction list (S906), and the processing of steps S904 to S906 is repeated until the end point node is reached. .

  It should be noted that a predetermined waiting time may be introduced in the repetition of the above processing in order to make it easier to visually grasp the influence on the color gamut mapping due to the mapping parameter change. The waiting time is preferably set, for example, in the dialog shown in FIG. 8D.

  For example, in the node management list 807 shown in FIG. 8D, when the node 808 is the start point and the node 814 is the end point, the playback path nodes 808, 812, 813, and 814 are in this order. In this case, the color gamut mapping process (S502) based on the mapping control parameter held by the start node 808 is performed, and after a predetermined time has elapsed, the color gamut mapping process (S502) based on the mapping control parameter held by the node 812 is performed. Do. In this way, the color gamut mapping process (S502) based on the mapping control parameter held by the end point node 814 is finally performed, and the reproduction process ends.

● Sub message HIST_COMPARATOR
In the dialog shown in FIG. 8D, when the user presses the comparison button 818, a message CTRL_HIST and a sub message HIST_COMPARATOR are generated. When the message CTRL_HIST is received and the sub message HIST_COMPARATOR is extracted, the comparative reproduction process is executed.

  FIG. 10 is a flowchart for explaining the comparison reproduction process.

  First, the start node and end node of the two playback paths are acquired (S1001). In the dialog shown in FIG. 8D, the user can specify a start point node and an end point node by a mouse operation or the like. For example, if a node on the node management list 807 is left-clicked, the first reproduction path (referred to as reproduction path 1) is designated, such as a start point node and a right-click if it is an end point node. Subsequently, if a node on the node management list 807 is left-clicked, a second playback path (referred to as playback path 2) is designated, such as a start-point node and right-clicking an end-point node.

  Next, for each of the two reproduction paths, it is determined whether or not the parent node is reached in order from the end node to reach the start node (S1002). If any of the playback paths does not reach the starting point node (the playback path does not exist), an error message is displayed (S1008), and the playback process ends.

  If there are two playback paths, a playback list indicating the playback order of the nodes is stored in the memory 102 for each playback path (S1003), and a pseudo three-dimensional display window for playing the playback path 1 and playback path 2 are played back. A pseudo three-dimensional display window is created (S1004).

  Next, obtain the mapping control parameters held by the first node of the two playlists (S1005), color gamut mapping processing for two playback paths (S502), three-dimensional object data generation (S503), three-dimensional An object is displayed (S504) (S1006).

  Finally, it is determined whether or not color gamut mapping processing has been performed based on mapping control parameters corresponding to all of the end nodes from the start point node of the play list (S1007), and the processing of steps S1005 to S1007 is repeated until the end point node is reached. .

  It should be noted that a predetermined waiting time may be introduced in the repetition of the above processing in order to make it easier to visually grasp the influence on the color gamut mapping due to the mapping parameter change. The waiting time is preferably set, for example, in the dialog shown in FIG. 8D. In order to make it easy to compare the reproduction, it is also effective to synchronize the display update timing of the pseudo three-dimensional display window.

  For example, in the node management list 807 shown in FIG. 8D, in the case of the start node 808 and the end node 811 of the playback path 1, the playback list is nodes 808, 809, 810, 811. In the case of the start point node 808 and the end point node 814 of the playback path 2, the playback list is nodes 808, 812, 813, and 814. In this case, color gamut mapping processing is performed based on the mapping control parameter held by the start point node 808, and the mapping result is displayed in two pseudo three-dimensional display windows. Subsequently, color gamut mapping processing is performed based on the mapping control parameters held by the next node 809 of the reproduction path 1 and the next node 812 of the reproduction path 2, and the display of the pseudo three-dimensional display window is updated in synchronization with each other. To do.

  That is, the processing results of the color gamut mapping of a plurality of reproduction paths are reproduced in synchronization in parallel. In this way, the color gamut mapping process is finally performed based on the mapping control parameters held by the end point nodes 811 and 814, and the comparison reproduction process is completed.

[Color Gamut Processing (S502)]
FIG. 11 is a flowchart for explaining the color gamut mapping process (S502).

  First, the color gamut information of the monitor 107 (monitor color gamut) and the color gamut information of the printer 109 (printer color gamut) are acquired from the HDD 105 (S1101), and the mapping becomes the final mapping result of the color gamut boundary of the monitor 107. A color gamut boundary is generated (S1102).

  Next, the brightness and hue of the monitor color gamut are mapped in the uniform color system (S1103). The lightness / hue mapping operation will be described later, but will be briefly described with reference to the schematic diagram shown in FIG.

  In FIG. 12, the alternate long and short dash line indicates the monitor color gamut 1201 in the green hue, the solid line indicates the first intermediate mapping color gamut 1202, and the dotted line indicates the printer color gamut 1203 in the same hue. In step S1103, the brightness component and the chromaticity component are separated for the colors in the monitor color gamut 1201, and the brightness component is mapped nonlinearly. For the chromaticity component, the hue is adjusted so as to be appropriate. With this brightness / chromaticity mapping, the monitor color gamut 1201 is mapped to the first intermediate mapping color gamut 1202.

  Next, the brightness of the boundary of the first intermediate mapping color gamut 1202 is adjusted to generate the boundary of the second intermediate mapping color gamut (S1104). Although this brightness adjustment map will be described later, it will be briefly described with reference to the schematic diagram shown in FIG.

  In FIG. 13, the one-dot chain line indicates the first intermediate mapping color gamut 1301 in the green hue, the solid line indicates the second intermediate mapping color gamut 1302, and the dotted line indicates the printer color gamut 1303 in the same hue. In step S1104, the brightness component and the chromaticity component are separated from the colors in the first intermediate mapping color gamut 1301, and only the brightness component is non-linearly mapped while the chromaticity component is constant. The lightness input / output function for realizing the mapping differs depending on the chromaticity. By this operation, the first intermediate mapping color gamut 1301 is mapped to the second intermediate mapping color gamut 1302.

  Next, with reference to the information on the intermediate mapping color gamut and the mapping color gamut, the second intermediate mapping color gamut is subjected to saturation adjustment mapping to the mapping color gamut (S1105). Although this saturation adjustment map will be described later, it will be briefly described with reference to the schematic diagram shown in FIG.

  In FIG. 14, the alternate long and short dash line indicates the second intermediate mapping color gamut 1401 in the green hue, the solid line indicates the mapping color gamut 1402, and the dotted line indicates the printer color gamut 1403. In step S1105, the lightness component and the chromaticity component are separated from the colors in the second intermediate mapping color gamut 1401, and the chromaticity component in the chromaticity component is non-linearly mapped while the lightness component is constant. By this operation, the second intermediate mapping color gamut 1401 is mapped to the mapping color gamut 1402.

[Brightness / Hue Map (S1103)]
FIG. 15 is a flowchart for explaining brightness / hue mapping (S1103).

  First, based on the hue control parameter, the hue input / output functions h0 (・), h20 (・), h40 (・), h60 (・), h80 are applied to six lightness values in increments of 20 from lightness 0 to 100. (•), h100 (•) is generated. The hue control parameter is a hue adjustment amount corresponding to each of the six brightness values in the six hues of red R, green G, blue B, cyan C, magenta M, and yellow Y. Here, the hue input / output function is calculated as a function obtained by connecting hue adjustment values of R / G / B / C / M / Y hue for each lightness with a primary spline, that is, a straight line.

  For example, when the hue angle in the two hues R and Y is moved slightly to the plus side with respect to the lightness value 80, and moved to the minus side in the hue of B, the hue input / output function h80 (•) shown in FIG. Get. Note that FIG. 16 represents the hue angle in radians notation where the positive direction of the b-axis in the ab chromaticity coordinate system is the hue angle 0 rad and the counterclockwise direction is positive.

Next, the color M to be mapped is acquired (S1502), and the hue input / output function h (・) for the color M is set to h0 (・), h20 (・), h40 (・), h60 (・), h80 (・) And h100 (•) are used to calculate the hue input / output function h (•) for the color M (S1503).
h (・) = {h _Lw (・) × (Up-x) + h _Up (・) × (x-Lw)} / 20… (1)
Here, h _Up (·) is input and output functions of the lightness Up immediately above with respect to the brightness x of the color M
h _Lw (・) is the input / output function of the lightness Lw directly below the lightness x of the color M

For example, when the lightness x of the color M is 70, the input / output function of the lightness Lw directly below is h60 (•), and the input / output function of the lightness Up directly above is h80 (•). ) Is as follows.
h (・) = {h60 (・) × (80-70) + h80 (・) × (70-60)} / 20
= {h60 (・) + h80 (・)} / 2

Next, the hue of the color M is mapped using the hue input / output function h (•) (S1504).
Hue _m Mapped = h (Hue _m )… (2)
Where Hue _m is the hue of color M
Hue _m mapped is the hue after mapping

Next, the lightness component of the color M is mapped (S1505). Specifically, the mapping of the lightness component is calculated using an input / output function λ (Lin) independent of chromaticity. The mapping function λ (·) is calculated as follows based on the overall brightness control parameter x.
x ≧ 50: λ (•) = {λ50 (•) × (100-x) + λ100 (•) × (x-50)} / 50
x <50: λ (•) = (λ0 (•) × (50-x) + λ50 (•) × x) / 50… (3)
Here, λ0 (·), λ50 (·), and λ100 (·) are predetermined functions.
λ0 (・) is the mapping function when the control value x = 0
λ50 (・) is the mapping function when control value x = 50
λ100 (・) is the mapping function when control value x = 100

  17A to 17C are diagrams showing examples of mapping functions λ0 (•), λ50 (•), and λ100 (•). As is clear from these figures, the control value x = 0 is generally dark, the control value x = 100 is generally bright, and the control value x = 50 is moderately bright. Be controlled.

  It is determined whether or not the above brightness / hue mapping has been performed on all grid points of the color correction LUT (S1506), and the processing of steps S1502 to S1506 is repeated until mapping processing is performed on all grid points.

  Through the above processing, the monitor color gamut 1201 shown in FIG. 12 is mapped to the first intermediate mapping color gamut 1202.

[Brightness adjustment map (S1104)]
FIG. 18 is a flowchart for explaining the brightness adjustment map (S1104).

  First, the color M to be mapped is acquired from the first intermediate mapping color gamut 1202 which is the result of the brightness / hue mapping (S1103) (S1801). Note that the color M does not represent the color of the monitor color gamut 1201.

Next, calculate the upper bound B _U and the lower boundary B _L of the first intermediate mapping color gamut 1202 (1301) in the same chromaticity and color M (S1802). Then, the upper boundary B _U mapped and the lower boundary B _L mapped of the second intermediate mapping color gamut 1302 at the same chromaticity as the color M are calculated (S1803). FIG. 19 is a diagram showing the relationship between each color gamut and each boundary in the brightness adjustment map. The solid line indicates the boundary of the first intermediate mapping color gamut 1301, the alternate long and short dashed line indicates the second intermediate mapping color gamut 1302, and the dotted line indicates the printer A color gamut 1303 is shown.

Next, an input / output function p (•) for brightness adjustment mapping is derived from the value calculated above and the brightness adjustment parameter (S1804). The input / output function p (•) is calculated as a C2 continuous cubic spline function that satisfies the following conditions.
The p (•) base is [L _BL , L _BU ]
p (・) monotonically increased on the platform
p (L _BL ) = L _BL m
p (L _BU ) = L _BU m
p (・) is at least C1 continuous
p '(L _BL ) = α
p '(L _BU ) = β
Where L _BL is the brightness of B _L
L _BL m is the brightness of B _L mapped
L _BU is the brightness of B _U
L _BU m is the brightness of B _U mapped
α (> 0), β (> 0) are constants that control compression

  The input / output function p (•) is calculated so as to satisfy the above condition, and is further calculated so that the amount of change in brightness is as small as possible so as to preserve the brightness as much as possible in the middle part of the table.

20A and 20B are diagrams showing an example of the input / output function p (•). In FIG. 20A, the lightness is substantially maintained in the middle part of the table, while it is largely compressed near the low lightness and the high lightness. Incidentally, L _BL = 40, L _BL m = 45, L _BU = 68, and L _BU m = 64.

Further, in FIG. 20B, since the change in brightness is large, the function of saving the brightness works in the middle part of the table, but it is not completely saved. In the vicinity of low lightness, it is greatly expanded, and in the vicinity of high lightness, it is greatly compressed. Incidentally, L _BL = 60, L _BL m = 46, L _BU = 84, and L _BU m = 75.

Next, the lightness L _m mapped after mapping with respect to the lightness Lm before mapping of the color M is obtained as L _m mapped = p (Lm) using the input / output function p (•) (S1805).

  It is determined whether or not the above brightness adjustment map has been applied to all grid points of the color correction LUT (S1806), and steps S1802 to S1806 are repeated until the brightness adjustment map of all grid points is completed.

  Through the above processing, the first intermediate mapping color gamut 1301 shown in FIG. 13 is mapped to the second intermediate mapping color gamut 1302.

[Saturation adjustment map (S1105)]
FIG. 21 is a flowchart for explaining the saturation adjustment map (S1105).

  First, the color M to be mapped is acquired from the second intermediate mapping color gamut 1302 that is the result of the brightness adjustment mapping (S1104) (S2101).

  Next, the boundary Bi of the mapped color gamut 1402 in the same brightness / same hue as the color M is calculated (S2102), and the second intermediate mapped color gamut 1401 (1302) in the same brightness / same hue as the color M is calculated. The boundary Bp is calculated (S2103). FIG. 22 is a diagram showing the relationship between each color gamut and each boundary in the saturation adjustment map. The alternate long and short dash line is the second intermediate mapping color gamut 1401, the solid line is the mapping color gamut 1402, and the dotted line is the printer color gamut 1403.

Next, the input / output function q (•) for saturation adjustment mapping is derived from the values calculated above and the saturation adjustment parameter (S2104). The input / output function q (•) is calculated as a C2 continuous cubic spline function that satisfies the following conditions.
The base of q (•) is [0, ci]
q (0) = 0
q (ci) = cp
q '(0) = g _Lo
q '(ci) = g _Hi
q '(x) ≠ 0 (0 ≤ x ≤ ci)
Where cp is the saturation of the color Bp
ci is the saturation of the color Bi
g _Lo is a value that controls the expansion / compression ratio of saturation from low to medium saturation
g _Hi is a value that controls the expansion / compression rate of saturation correction around the maximum saturation.

FIG. 23A and FIG. 23B are diagrams showing an example of the input / output function q (•). In FIG. 23A, while the expansion operation is performed in the high saturation portion, the saturation adjustment value g _Lo is 0.8, so that the low-to-medium saturation portion operates to suppress the saturation. In FIG. 23B, the compression operation is performed in the high saturation portion, while the saturation adjustment value g _Lo is 1.2, so that the saturation is enhanced in the low to medium saturation portions.

Next, the post-mapping chroma c _mod for the pre-mapping chroma c _org of the color M is calculated as c _mod = q (c _org ) using the input / output function q (•) (S2105).

  It is determined whether or not the above saturation adjustment map has been applied to all grid points of the color correction LUT (S2106), and steps S2102 to S2106 are repeated until the saturation adjustment map of all grid points is completed.

  Through the above processing, the second intermediate mapped color gamut 1401 shown in FIG. 14 is mapped to the mapped color reproduction range 1402.

  Thus, each time the mapping conversion control parameter is changed, a node is generated in the change history, and the parent node information and the control parameter at that time are held. Then, a change history list in which nodes are displayed in a hierarchy (tree display) is displayed on the user interface, and a node for reproducing a conversion result of mapping conversion or a continuous specification of nodes is received from the user. Then, the conversion result of the mapping conversion is reproduced according to the instruction. Thereby, the user can greatly improve the design efficiency until a preferable gamut mapping is determined.

[Other embodiments]
Note that the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer), and a device (for example, a copying machine and a facsimile device) including a single device. You may apply to.

  Another object of the present invention is to supply a storage medium (recording medium) that records software for realizing the functions of the above-described embodiments to a system or apparatus, and a computer (CPU or MPU) of the system or apparatus executes the software. Is also achieved. In this case, the software itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the software constitutes the present invention.

  In addition, the above functions are not only realized by the execution of the software, but an operating system (OS) running on a computer performs part or all of the actual processing according to the instructions of the software, and thereby the above functions This includes the case where is realized.

  In addition, the software is written in a function expansion card or unit memory connected to the computer, and the CPU of the card or unit performs part or all of the actual processing according to instructions of the software, thereby This includes the case where is realized.

  When the present invention is applied to the storage medium, the storage medium stores software corresponding to the flowchart described above.

Block diagram showing a configuration example of a color signal converter, A flowchart for explaining the operation of the printer driver; A diagram schematically showing the data structure of a color correction LUT, The figure explaining the data structure of a color correction LUT, The figure which shows the pseudo | simulation three-dimensional display example which displays on the Lab color space the Lab value of each lattice point described in the color correction LUT as color distribution information. Figure showing a menu window for adjusting the color correction LUT, State transition diagram explaining the operation of the color correction LUT creation application, A diagram schematically showing generation of a triangle for generating three-dimensional object data, Figure showing a message map, The figure which shows the example of the display of the dialog for brightness adjustment, The figure which shows the example of a display of the dialog for hue adjustment, The figure which shows the example of the display of the dialog for saturation adjustment, The figure which shows the example of the display of the dialog for history management, A flowchart for explaining reproduction processing; A flowchart for explaining the comparison reproduction process; A flowchart for explaining color gamut mapping processing; A diagram for explaining a monitor color gamut, a first intermediate mapping color gamut, and a printer color gamut, The figure explaining the 1st intermediate mapping color gamut, the 2nd intermediate mapping color gamut, and the printer color gamut, The figure explaining the 2nd intermediate mapping color gamut, mapping color gamut, and printer color gamut, Flow chart explaining brightness / hue mapping, Figure showing an example of hue input / output function The figure which shows the nonlinear mapping characteristic of the brightness component, The figure which shows the nonlinear mapping characteristic of the brightness component, The figure which shows the nonlinear mapping characteristic of the brightness component, A flowchart for explaining the brightness adjustment map; A diagram showing the relationship between each color gamut and each boundary in the brightness adjustment map, Figure showing an example of the input / output function p ( Figure showing an example of the input / output function p ( A flowchart for explaining the saturation adjustment map; A diagram showing the relationship between each color gamut and each boundary in the saturation adjustment map, A diagram showing an example of the input / output function q ( It is a figure which shows an example of the input-output function q (*).

Claims (11)

A color processing method for adjusting the color reproduction of an image,
A conversion step for mapping the input color gamut to the output color gamut;
A change step for changing the control parameter of the mapping transformation;
A management step for managing a change history of the control parameter;
And a reproduction step of reproducing the result of the mapping conversion at an arbitrary time or period based on the change history.   The management step generates a node of the change history every time the control parameter is changed, and holds the parent node information of the generated node and the control parameter at the time of the node generation in the node. The color processing method according to claim 1. Further, a display step of displaying the change history on a monitor by hierarchical display of the nodes;
3. The color processing method according to claim 2, further comprising an input step of inputting instructions of start and end nodes of the period based on the hierarchy display.   The reproduction step acquires the control parameters in the order of nodes from the start node to the end node, supplies the control parameters to the conversion step, and performs the mapping conversion by a series of changes from the start node to the end node. 4. The color processing method according to claim 3, wherein the result is continuously reproduced.   The input step inputs a plurality of sets of the start and end nodes, and the reproduction step acquires the control parameters in order of nodes from the start node to the end node for each set, 4. The color processing method according to claim 3, wherein the reproduction is performed in parallel by supplying to the conversion step.   6. The color processing method according to claim 1, wherein the control parameter is a value for controlling the mapping conversion of at least one element among brightness, saturation, and hue.   The mapping conversion converts the lightness and hue component of the input color gamut to the first color gamut, converts the lightness component of the first color gamut and maps to the second color gamut, 7. The color processing method according to claim 1, wherein a saturation component of a second color gamut is converted and mapped to the output color gamut.   8. The color processing method according to claim 1, further comprising a color gamut display step of displaying the output color gamut obtained by the mapping conversion in a pseudo three-dimensional manner. A color processing device for adjusting the color reproduction of an image,
Conversion means for mapping the input color gamut to the output color gamut;
Changing means for changing the control parameter of the mapping transformation;
Management means for managing the change history of the control parameters;
A color processing apparatus comprising: reproduction means for reproducing the result of the mapping conversion at an arbitrary time or period based on the change history.   9. A program that controls an image processing device to realize the color processing according to claim 1.   11. A recording medium on which the program according to claim 10 is recorded.

Images