JP5043512B2 - Color processing apparatus and method - Google Patents

Description

  The present invention relates to a device that performs color matching processing.

  In order to make maximum use of the characteristics of input / output devices such as displays and printers, there is a color management system that manages the appearance of colors between devices while taking advantage of the characteristics of the devices. In this color management system, color reproduction range (color gamut information) of input / output devices, primary color information (reference colors) such as Red, Green, Blue, Cyan, Magenta, Yellow, White, Black, device gray characteristic information, etc. Appropriate color gamut conversion processing is performed using this as a clue.

  In such a color management system, a plurality of color gamut conversion processing software modules are prepared, and are configured to be selectable by the user according to usage (for example, photo output, graphics data output, character output). Yes.

  By the way, the color gamut information and the like of a device may be attached to a software module (driver) attached and installed to the device, or may be created by a user using a software application. In short, it is defined outside the color gamut conversion processing software module, and the color gamut conversion processing software module performs the color gamut conversion processing according to the given device color gamut information.

On the other hand, according to Patent Document 1, in order to avoid the inconvenience of color reproduction caused by the shape of the working color space mapped by the color gamut conversion software module, and to enable good color reproduction, By determining the three primary colors (on the chromaticity diagram) so as to include all the colors in the color reproduction range, a sufficiently wide working color space can be defined (on the chromaticity diagram).
JP 2006-303711 A

  The problem here is that the consistency between the color gamut information, reference color, and gray characteristic information of the input / output devices does not always satisfy the consistency expected by the color gamut conversion process. It is in.

  For example, the reference color of the output device may be arranged inside or outside the color gamut of the input device due to some failure. In this case, depending on the color gamut conversion processing algorithm, the mapping result may fail.

  Input device reference colors Red (red), Green (green), Blue (blue), Cyan (cyan), Magenta (magenta), Yellow (yellow), White (white), Black (black) A color gamut conversion algorithm that maps to the colors Red, Green, Blue, Cyan, Magenta, Yellow, White, and Black is known. This algorithm interpolates the mapping result of the reference color for colors other than the reference color. In such an algorithm, if the matching relationship is not satisfied in the reference color, there is a discrepancy between the mapping of the reference color itself and the mapping of the vicinity of the reference color by interpolation calculation, and the mapping fails as a whole. There was a case.

  Furthermore, even in the case of a gamut conversion algorithm that does not map the input device reference color to the output device reference color, if any processing is performed using the device reference color, the mapping result is similarly broken. There was a case.

  On the other hand, the technique disclosed in Japanese Patent Laid-Open No. 2006-303711 is a method of selecting a reference color when the reference color (primary color in the sentence) defines a work color space. Considering the handling of inconsistencies in input / output device characteristic information such as the presence of a reference color outside the device color gamut mapped to a sufficiently wide working color space as in the present application It is not a thing.

In order to solve the above-described problem, the present invention provides an acquisition unit that acquires a reference color in a device, and one or more reference colors acquired by the acquisition unit exist on the surface of the color reproduction range of the device. Determining means based on geometric information representing the surface of the color reproduction range of the device, and when the reference means determines that the reference color does not exist on the surface , the reference Rearrangement means for rearranging colors to colors located on the surface of the color reproduction range of the device.

  According to the present invention, even when the information given by the input / output device color gamut information is not consistent, a preferable color gamut conversion process can be realized or the color gamut conversion process is prevented from failing. can do.

Example 1
Hereinafter, an image processing apparatus as an example of an embodiment will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a system configuration used in this embodiment, which is a system that outputs digital data expressed in an sRGB color space to an output device such as a printer while performing color matching color processing. The system used in this embodiment can be composed of a computer and its peripheral devices.

  The CPU 101 is a central processing unit. The ROM 102 is a read-only memory, and is connected to the CPU 101 via the bus 104 together with the random access memory RAM 103. The CPU 101 can directly execute a program stored in the ROM 102 or the RAM 103. An input interface 105, HDD interface 107, video interface 109, and output interface 111 are also connected to the bus 104. A part or all of the bus 104 may be configured by a high-speed network device such as Ethernet (registered trademark) or a peripheral device interface such as PCI. An input device 106 such as a keyboard, a mouse, a digital camera, or a scanner can read information from the CPU 101 via the input interface 105. At this time, device information unique to the digital camera, such as a digital camera model name and color information, can also be read.

  The HDD 108, which is a storage medium such as a hard disk device or an optical disk device, can be read and written via the HDD interface 107. Data stored on the HDD 108 can be expanded on the RAM 103 by using an appropriate means. Similarly, the data developed on the RAM 103 can be stored in the HDD 108 by using an appropriate means. The CPU 101 can also execute the data stored in the HDD 108 expanded on the RAM 103 as described above as a program. The ROM 102, RAM 103, and HDD 108 may be devices shared by a network such as a telephone line or Ethernet (registered trademark). In the present embodiment, they are not particularly distinguished.

  Arbitrary characters or images can be displayed on the monitor 110 by causing the CPU 101 to operate the video interface 109. An output device 112 such as a printer or a plotter can send information via the output interface 111. Similarly to the case of the input device 106, the CPU 101 can also read device information unique to the printer such as the model name and color gamut information of the output device 112 via the output interface 111. Further, the input device 106 and the output device 112 may be shared over a network.

  FIG. 2 is an overall view of this embodiment.

  In FIG. 2, the control unit 201 includes an input conversion unit 203, a forward conversion unit 204, a color gamut conversion unit 205, an inverse conversion unit 206, and an output conversion unit 207 based on various types of information stored in a storage unit 202 described later. By controlling, a series of behaviors of the entire image processing apparatus is determined. In most cases, the control unit 201 takes the form of a software module stored in the ROM 102 or the HDD 108, and performs processing using the RAM 101 as appropriate. No further mention will be made regarding the form. The storage unit 202 is a storage location for the software module and various information stored temporarily or permanently, and the entity is a part or all of the ROM 102, HDD 108, and RAM 101. The various information stored includes at least SRC_RAW_PRIMARIES, DST_RAW_PRIMARIES, SRC_RAW_GBD, DST_RAW_GBD, SRC_GRAY, and DST_GRAY used in the color gamut conversion unit 205 described later.

  The input conversion unit 203 converts the input image data depending on the input device into a device based on the white point reference of the ambient light on the input side in accordance with the parameters from the control unit 201, the white point reference, the input profile, and the like. This is a conversion function for converting into an independent color space (for example, XYZ data). Parameters necessary for processing are passed from the control unit 201 described above.

The forward conversion unit 204 is a color perception model forward conversion unit (CAM) for converting the color information obtained from the input conversion unit 203 into the human color perception space JCh or QMh. Are known. The forward conversion unit 204 has a conversion function similar to the input conversion unit 203, and parameters necessary for the processing are passed from the control unit 201. For details, refer to CIECAM97s, CIECAM02, etc. The color gamut conversion unit 205 is a conversion processing unit that performs color gamut conversion processing on the color information sent from the forward conversion unit 204. Parameters necessary for color gamut conversion processing, such as color gamut information, reference colors, and gray characteristics of input / output devices, are stored in the storage unit 202 and passed from the control unit 201. The color gamut conversion process includes a color gamut conversion process (for example, Perceptual, Relative Colorimetric, and Saturation) suitable for performing in a color perception space relative to the reference white color of ambient light, and an absolute value whose size varies depending on the illuminance level. A color gamut conversion process (for example, Absolute Colorimetric) suitable for performing in the color perception space is included. Details of the operation of the color gamut conversion unit 205 will be described later.

  The inverse conversion unit 206 is a conversion function that performs the reverse conversion of the above-described forward conversion unit 204, and the processing result of the color gamut conversion unit 205 is a color in a color space that does not depend on a device based on the white point criterion of the ambient light on the output side. This is a conversion function for converting to information. The color information that is the processing result of the conversion unit is sent to the output conversion unit 211 described later. Parameters necessary for processing are passed from the control unit 201 described above. For details, refer to CIECAM97s, CIECAM02, etc., like the forward conversion unit 204.

  The output conversion unit 207 transmits the color information on the device-independent color space based on the white point criterion of the ambient light on the output side sent from the inverse conversion unit 206 to the CMYK color space depending on the output device. Convert the color information in the color space using the conversion function. Parameters necessary for processing are passed from the control unit 201 described above.

  The driver 208 is a software module necessary for operating the output device.

  FIG. 3 is a flowchart showing the processing contents of the color gamut conversion unit 205 used in this embodiment.

  In this color gamut conversion function, if the input from the forward conversion unit 204 is the reference color of the input device, whether or not the input is the reference color of the input device in order to map to the reference color corresponding to the output device without fail. There is a case. This is one of the ideas for avoiding the case where the reference color of the input device is not mapped to the corresponding reference color of the output device due to accumulation of calculation errors.

  In S301, SRC_RAW_PRIMARIES, DST_RAW_PRIMARIES, SRC_RAW_GBD, DST_RAW_GBD, SRC_GRAY, and DST_GRAY are read from the storage unit 202 and acquired.

  FIG. 4 shows an example of the input device reference color information SRC_RAW_PRIMARIES and the output device reference color information DST_RAW_PRIMARIES.

  SRC_RAW_PRIMARIES and SRC_RAW_PRIMARIES in this embodiment are arrays in which the reference colors of the respective devices are stored in the order of Red, Yellow, Green, Cyan, Blue, Magenta, White, and Black. It is assumed that each color information is described in a three-dimensional orthogonal coordinate system including one lightness value (J) and two chromaticity values (a, b).

  FIG. 5 shows an example of input device color gamut information SRC_RAW_GBD and output device color gamut information DST_RAW_GBD.

  SRC_RAW_GBD and DST_RAW_GBD are collections of color information constituting the surface of the color gamut of the device. In this embodiment, as shown in FIG. 5, similarly, a closed space composed of triangular plane segments is formed. Recognize.

  FIG. 6 shows an example of input device gray characteristic information SRC_GRAY and output device gray characteristic information DST_GRAY.

  SRC_GRAY and DST_GRAY are information describing the gray characteristics of a device with two or more colors on the gray axis, as shown in FIG.

  In S302, an achromatic color axis conversion process by SRC_GRAY of SRC_RAW_PRIMARIES and DST_RAW_PRIMARIES and an achromatic color axis conversion process by DST_GRAY of DST_RAW_GBD and DST_RAW_GBD are performed. Details of the achromatic color axis conversion process will be described later.

  In S303, SRC_PRIMARIES, DST_PRIMARIES, SRC_GBD, and DST_GBD are converted from the orthogonal coordinate system (J, a, b) to the polar coordinate system (J, C, h). The conversion formula is, for example, the formula shown in FIG.

  In S304, reference color rearrangement processing is performed for rearranging SRC_PRIMARIES and DST_PRIMARIES. Details will be described later.

  In S305, brightness range information SRC_RANGE is calculated from SRC_PRIMARIES, and brightness range information DST_RANGE is calculated from DST_PRIMARIES. In this color gamut conversion process, the lightness range is composed of the minimum lightness and the maximum lightness for each of the input and output, and the maximum lightness and the minimum lightness of SRC_GRAY and DST_GRAY are respectively substituted.

  In step S306, the system waits for a color to be input, and stores it in pIn as soon as it is input, and proceeds to step S307. In this embodiment, pIn is composed of a lightness value J and two chromaticity values a and b.

  In step S307, with respect to pIn, an achromatic color axis conversion process using SRC_GRAY of pIn is performed in the same manner as in S302, and the result is stored in p1.

  In S308, p1 is converted into a polar coordinate system and stored in p2. The conversion formula is as shown in FIG.

  In S309, when a color equal to p2 exists on SRC_PRIMARIES, the index is stored in pCurrent, and then the process proceeds to S315. Otherwise, the process proceeds to S310.

In S309, if a color equal to p2 does not exist on SRC_PRIMARIES, in S310, pPrev and pNext aligned in SRC_PRIMARIES [pPrev], p2, SRC_PRIMARIES [pNext] are searched and determined. Then, the hue difference between SRC_PRIMARIES [pPrev] and p1 is calculated, and the hue difference between p1 and SRC_PRIMARIES [pNext] is calculated and stored in dNext.
In S311, a hue angle that is between DST_PRIMARIES [pPrev] and DST_PRIMARIES [pNext] and stores the ratio of dPrev and dNext is obtained in a clockwise direction, and p3. Store in h.

  In S312, the hue angle p2. The maximum saturation point of SRC_GBD at h is calculated and stored in srcCusp, and the hue angle p3. The maximum saturation point of DST_GBD at h is calculated and stored in dstCusp. As a method for obtaining the maximum saturation point, a method is widely used in which an equal hue plane relating to a hue of interest is cut out from device color gamut information such as SRC_GBD and DST_GBD, and the point with the highest saturation is set as the maximum saturation point. The details are not detailed any further.

In S313, the brightness is calculated, and p3. Store in J. For example, do the following calculations:
1) p2. J> srcCusp. In the case of J, p3. J = (DST_RANGE.JMaxdstCusp.J) / (SRC_RANGE.JMaxsrcCusp.J) * (p2.JsrcCusp.J) + DST_RANGE. JMin
2) p2. J == srcCusp. In the case of J, p3. J = dstCasp. J
3) p2. J <srcCusp. In the case of J, p3. J = (dstCusp.JDST_RANGE.JMin) / (srcCusp.JSRC_RANGE.JMin) * (srcCusp.JDST_RANGE.JMin) + DST_RANGE. JMin
In S314, the saturation srcCusp. C, dstCusp. Saturation compression is performed according to the ratio of C, and p3. After storing in C, the process proceeds to S316.

  On the other hand, if a color equal to p2 exists on SRC_PRIMARIES in S310, DST_PRIMARIES [pCurrent] is stored in p3 in S315, and the process proceeds to S316.

  In S316, p3 is converted into an orthogonal coordinate system and stored in p4. The conversion formula is as shown in FIG. 8, for example.

  In S317, reverse achromatic color axis conversion processing by DST_GRAY is performed on p4, and stored in pOut. The contents of the reverse achromatic color axis conversion process will also be described later.

  Finally, after pOut is output in S318, the process returns to S306.

  Next, details of the achromatic color axis conversion process of the color pColor based on the gray characteristic information GRAY performed in S302, S307, and S317 will be described using the flow shown in FIG.

  FIG. 9 is a flowchart illustrating the achromatic color axis conversion process of the color pColor based on the gray characteristic information GRAY referred to in S302 and S306. In the processing according to this flow, it is assumed that pColor has one lightness value J and two chromaticity values a and b.

  In S901, a point on GRAY having the same brightness (pColor.J) as pColor is determined by appropriate interpolation and extrapolation, and stored in pGray. The interpolation / extrapolation means is a widely used technique and will not be discussed further.

  In step S902, the chromaticity (a, b) is subtracted from pColor, the result is stored in pOut, and the achromatic color axis conversion process is terminated.

  Next, details of the reverse achromatic color axis conversion processing of the color pColor based on the gray characteristic information GRAY referred to in S317 will be described using the flow shown in FIG.

  FIG. 10 is a flowchart illustrating the inverse chiropractic achromatic color axis conversion processing of the color pColor based on the gray characteristic information GRAY referred to in S317.

  In S1001, a point on GRAY having the same brightness (pColor.J) as pColor is determined by appropriate interpolation and extrapolation, and stored in pGray.

  In S1002, the chromaticity of pGray is obtained and stored in a and b, respectively.

  In step S1003, the chromaticity (a, b) is added to pColor, the result is stored in pOut, and the inverse achromatic color axis conversion process ends.

  Finally, details of the SRC_PRIMARIES and DST_PRIMARIES rearrangement processing performed in S303 of FIG. 3 will be described using the flow shown in FIG.

  FIG. 11 is a process flow showing an example of the rearrangement process of SRC_PRIMARIES and DST_PRIMARIES referred to in S303.

  In S1101, it is checked whether the processing is finished for RGBCMY on SRC_PRIMARIES excluding W and Bk. If completed, the process proceeds to S1105, and if there is a process remaining, the process proceeds to S1102.

  In S1102, one of RGBCMY reference colors is extracted from SRC_PRIMARIES and read into pColor.

  In S1103, it is checked whether or not pColor exists in the vicinity of the surface of SRC_GBD. If it is near the surface, the process returns to S1101, and if it is not close, the process proceeds to S1104. Here, processing for determining whether a certain color (point) is in or out of the color gamut from geometric information such as SRC_GBD representing the color gamut is widely performed in fields such as three-dimensional graphics. Since it is the same as the existing technology, no further details will be given here.

  In S1104, a point having the maximum saturation value (maximum saturation point) is searched for among the surface colors of SRC_GBD having the same hue as that of pColor, and is set in pColor. Since the process of calculating the maximum saturation point is also widely performed, no further details will be given here.

  In S1105, pColor is written in SRC_PRIMARIES, and the process returns to S1101.

  If the processing for all RGBCMY on SRC_PRIMARIES has been completed in S1101, the same processing is performed for DST_PRIMARIES in S1106 and thereafter. Specifically, in S1106, it is checked whether the processing has been completed for all RGBCMY except for W and Bk on DST_PRIMARIES. If completed, the process ends. If there is a process remaining, the process proceeds to S1107.

  In S1107, one of RGBCMY reference colors is extracted from SRC_PRIMARIES and read into pColor.

  In S1108, it is checked whether or not pColor exists in the vicinity of the surface of SRC_GBD. If it is near the surface, the process returns to S1106, and if it is not near, the process proceeds to S1109.

  In S1109, a point having the maximum saturation value (maximum saturation point) is searched for among the surface colors of DST_GBD having the same hue as pColor, and is set to pColor.

  In S1110, pColor is written to DST_PRIMARIES and the process returns to S1106.

  12 to 25, when the reference color Blue of the output device is out of the color gamut of the output device, the basic color given as the reference color Blue of the output device is rearranged to thereby determine the reference of the input device. This indicates that no failure occurs between the color Blue and the color gamut conversion result of the neighboring color.

  FIG. 12 shows SRC_RAW_PRIMARIES, DST_RAW_PRIMARIES, SRC_RAW_GBD, DST_RAW_GBD, SRC_GRAY, and DST_GRAY used in the color gamut conversion unit 205, which are prepared on the storage unit 202 to explain the present embodiment.

  FIG. 13 is an outline of color gamut information and the like indicated by the data set shown in FIG. It can be seen that the reference color Blue on DST_PRIMARIES is outside DST_GBD.

  Hereinafter, based on a specific data example, the operation of the color gamut conversion unit 205 will be described focusing on the difference in the processing result depending on the presence or absence of the reference color rearrangement processing in S304.

  The activated color gamut conversion unit 205 reads the information shown in FIG. 12 in S301, performs achromatic color axis conversion processing with SRC_GRAY and DST_GRAY in S302, and further performs polar coordinate conversion in S303, resulting in the state of FIG.

  In FIG. 14, together with the internal state of the color gamut conversion unit 205, the input data to the color gamut conversion unit held by the forward conversion unit 204 located in front and the color gamut conversion unit held by the reverse conversion unit 206 located later. The output data from is also described.

  Here, while the color gamut information SRC_GBD of the input device is defined by all colors on the reference color SRC_PRIMARIES, the color gamut information DST_GBD of the output device is generally composed of colors on the reference color DST_PRIMARIES, but only Blue Note that they are different.

  Furthermore, while DST_PRIMARIES [Blue] and DST_GBD [4] have the same hue, the saturation is clearly smaller in DST_PRIMARIES [Blue]. That is, DST_PRIMARIES [Blue] is clearly located inside DST_GBD.

  First, as reference color rearrangement processing in S304, a case where nothing is performed will be described with reference to FIGS.

  In this case, nothing is performed in the reference color rearrangement process of S304 from the state of FIG. 14, the lightness range is calculated in S305, the state of waiting for input in S306, and the state of FIG. 15 is obtained.

  From the state of FIG. 15, (21, −19, −89), which is the 0th color stored in IN of the forward conversion unit 204 in S306, is given to the color gamut conversion unit 205, and achromatic color axis conversion processing is performed in S307. In step S308, polar coordinate conversion is performed, and the state shown in FIG. 16 is obtained.

  From the state of FIG. 16, in S309, it is checked whether p2 exists on SRC_PRIMARIES. Since this time is equal to SRC_PRIMARIES [Blue], the process proceeds to S315.

  In S315, p2 is mapped to the blue reference color of the output device. Therefore, the value of DST_PRIMARIES [Blue] is stored in p3. In S316, orthogonal coordinate transformation is performed and the result is written to p4. In S317, inverse achromatic color axis transformation processing is performed and stored in pOut. FIG. 17 shows a state in which the conversion result stored in pOut in S318 is output to the inverse conversion unit 206 and the process returns to S306.

  From the state of FIG. 17, (21, -18, -88) which is the first color stored in IN of the forward conversion unit 204 in S306 is given to the color gamut conversion unit 205, and achromatic color axis conversion processing is performed in S307. In step S308, polar coordinate conversion is performed, and the state shown in FIG. 18 is obtained.

  From the state of FIG. 18, in S309, it is checked whether p2 exists on SRC_PRIMARIES. Since there is no matching color on SRC_PRIMARIES this time, the process proceeds to S310.

In S310, it can be seen from the hue angle of p2 that pPrev is Blue and pNext is Magenta.
dPrev = 258.7-258.2 = 0.5,
dNext = 330.6-258.7 = 71.9
It turns out that it is.

In S311,
DST_PRIMARIES [Blue] = 291.4,
DST_PRIMARIES [Magenta] = 359.4
So if you calculate the hue to preserve the internal ratio,
p3. h = 291.4 + (359.4-291.4) * 0.5 / (71.9 + 0.5) = 291.9
It becomes.

  In step S312, the hue angle p2. From h = 258.7 degrees and SRC_GBD, the maximum saturation point srcCusp is determined as the hue angle p3. The maximum saturation point dstCusp is obtained from h = 291.9 degrees and DST_GBD.

  In this embodiment, as is clear from FIG. 13, the maximum saturation point of the input device in the hue exists on SRC_GBD [4] to SRC_GBD [5]. Similarly, the maximum saturation point of the output device exists on DST_GBD [4] to DST_GBD [5]. srcCusp can be obtained by linearly interpolating SRC_GBD [4] and SRC_GBD [5] according to the hue angle, while dstCusp can be obtained by linearly interpolating DST_GBD [4] and DST_GBD [5] according to the hue angle. . Therefore, srcCusp = (21.2, 90.8, 258.7) and dstCusp = (13.2, 79.6, 291.9) (both are JCh values). The calculation process is omitted.

In step S313, the brightness values of srcCusp and dstCusp are set to p2. Lightness compression is performed from J. Here, srcCusp. J> p2. From J,
p3. J = (13.2-6) / (21.2-0) * (21-0) + 6 = 13.1
It becomes.

  Subsequently, in S314, srcCusp. C, dstCusp. The saturation is determined using the ratio of C. Specifically, p3. C = p2. C / srcCusp. C * dstCusp. C = 89.5 / 90.8 * 79.6 = 78.5, which is the state shown in FIG.

  From the state of FIG. 19, when p3 is subjected to orthogonal coordinate transformation in S316 and stored in p4, p4 is subjected to inverse chiropractic transformation and written to pOut in S317, and pOut is written to the inverse transformation unit 206 in S318. It becomes.

  On the other hand, the case where the reference color rearrangement is performed in FIGS. 14 to S304 will be described below with reference to FIGS. 14 and 21 to 24. FIG.

  As described above, in FIG. 14, DST_PRIMARIES [Blue] is located inside DST_GBD, and DST_PRIMARIES [Blue] is only lower in saturation than DST_GBD [4], and is equal in terms of brightness and hue.

  The details of the reference color rearrangement process S304 are as defined in the flow shown in FIG. 11 as described above. In the case of SRC_PRIMARIES and DST_PRIMARIES shown in FIG. 14, it is clear that only DST_PRIMARIES [Blue] needs to be relocated, and the relocation destination is equal to DST_GBD [4] (S1108 to S1110).

  As described above, when the reference color rearrangement process is performed in FIG. 14, the value of DST_PRIMARIES [Blue] becomes equal to DST_GBD [4], resulting in the state of FIG.

  From the state of FIG. 21, the 0th color (21, −19, −89) stored in the IN of the forward conversion unit 204 in S306 is given to the color gamut conversion unit 205, and in step S307, the achromatic color axis conversion process is performed. In step S308, polar coordinate conversion is performed, and the state shown in FIG. 22 is obtained.

  From the state of FIG. 22, it is checked in S309 whether p2 exists on SRC_PRIMARIES. Since this time is equal to SRC_PRIMARIES [Blue], the process proceeds to S315.

  In S315, p2 is mapped to the blue reference color of the output device. Therefore, the value of DST_PRIMARIES [Blue] is stored in p3, and then the orthogonal coordinate transformation is performed in S316 and the result is written in p4. In S317, the inverse achromatic color axis transformation process is performed and stored in pOut. FIG. 23 shows a state where the conversion result stored in pOut in S318 is output to the inverse conversion unit 206 and the process returns to S306.

  23, the first color (21, −18, −88) stored in IN of the forward conversion unit 204 in S306 is given to the color gamut conversion unit 205, resulting in the state of FIG. .

  Details of the processing when the input is (21, -18, -88) do not change depending on the presence or absence of the reference color rearrangement processing, and thus will not be repeated here.

  FIG. 25 is a table summarizing the data extracted from FIGS.

  From FIG. 25, it can be seen that the gradation gradation inversion that occurs when the reference color rearrangement process S304 is not performed does not occur when the reference color rearrangement process S304 is performed.

  In this embodiment, attention is paid particularly to RGBCMY which is a chromatic color among the reference colors. However, when the achromatic color such as the gray axis and Bk and W of the reference colors cannot be matched, that is, on the gray axis. When the reference colors Bk and W are not located, the gradation sometimes fails near Bk and W.

  In this case, the brightest part of the gray axis is matched with W (replaced with the reference color W), the darkest part is matched with Bk (replaced with the reference color Bk), or the reference colors Bk and W are placed on the gray axis. The failure can be prevented by performing the matching process such as moving.

  In addition, in the reference color rearrangement process, the color space was not changed and converted from CIECAM02 and performed in another color space, but another color space (for example, the Munsell color specification) The same effect is obtained when the rearranged result is converted back to CIECAM02 again.

It is a figure which shows an example of a system configuration. It is a conceptual diagram of the whole structure. 5 is a flow showing processing contents of a color gamut conversion unit 205. It is an example of input device reference color information SRC_RAW_PRIMARIES and output device reference color information DST_RAW_PRIMARIES. It is an example of input device color gamut information SRC_RAW_GBD and output device color gamut information DST_RAW_GBD. It is an example of input device gray characteristic information SRC_GRAY and output device gray characteristic information DST_GRAY. This is an expression for converting the orthogonal coordinate system (J, a, b) to the polar coordinate system (J, C, h). This is an expression for converting the polar coordinate system (J, C, h) to the orthogonal coordinate system (J, a, b). It is a flow of an achromatic color axis conversion process of the color pColor based on the gray characteristic information GRAY. It is the flow of the reverse achromatic color axis conversion process of the color pColor by the gray characteristic information GRAY. It is a processing flow which shows an example of the rearrangement process of SRC_PRIMARIES and DST_PRIMARIES. This is an example of SRC_RAW_PRIMARIES, DST_RAW_PRIMARIES, SRC_RAW_GBD, DST_RAW_GBD, SRC_GRAY, DST_GRAY. 13 is an outline of color gamut information and the like indicated by the data set shown in FIG. 12. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. 3 is a diagram illustrating an example of an internal state of a color gamut conversion unit 205. FIG. It is the table | surface which extracted and summarized the data from FIGS.

Claims (6)

An acquisition means for acquiring a reference color in the device;
A determination unit that determines whether one or more reference colors acquired by the acquisition unit exist on the surface of the color reproduction range of the device based on geometric information representing the surface of the color reproduction range of the device. When,
By the determination unit, when the reference color is determined not to be present in the surface, to have a relocation means for relocating the reference color to a color that are located on the surface of the color reproduction range of the device A color processing apparatus.   2. The color processing apparatus according to claim 1, wherein the reference color includes a part or all of red, green, blue, cyan, magenta, yellow, white, and black. The rearrangement unit, when the reference color is a chromatic color, the color having the characteristic color in the same hue, in any one of claims 1 or claim 2, characterized in that repositioning said reference color The color processing apparatus as described. The color processing apparatus according to claim 3 , wherein the rearrangement unit rearranges the reference color to the color of the maximum saturation point in the hue of the color reproduction range. One of the color processing apparatus according to claim 1 to 4 in order to realize using a computer, program the computer is stored in capable storage medium read. Get the reference color on the device
Determining whether one or more reference colors acquired by the acquisition means are present on the surface of the color reproduction range of the device based on geometric information representing the surface of the color reproduction range of the device ;
When the determination unit determines that the reference color does not exist on the surface , the reference color is rearranged to a color located on the surface of the color reproduction range of the device, Color processing method.

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