JP2012130066A - Color processing apparatus and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain colorimetric data close to appearance of a color under actual observation conditions.SOLUTION: A light source table holding part 109 holds color temperature information corresponding to the type of a light source. A conversion data holding part 108 holds conversion data for converting colorimetric data related to a spectral reflectance into colorimetric data related to spectral radiance. A UI part 102 inputs a user instruction indicating the type of an observation light source and an input destination of the colorimetric data. A light source information acquisition part 103 acquires the color temperature information of the observation light source from the light source table holding part 109 based on the user instruction. A colorimetric value acquisition part 104 acquires colorimetric data related to the spectral reflectance based on the user instruction. A conversion data acquisition part 105 acquires the conversion data from the conversion data holding part 108 based on the color temperature information of the observation light source. A colorimetric value conversion part 107 converts the colorimetric data using the conversion data.

Description

  The present invention relates to color processing for calculating colorimetric data under an arbitrary viewing condition.

  A color management system (hereinafter referred to as CMS) is known as a technique for centrally managing the color gamut and color reproduction characteristics of different devices and transmitting them correctly. In order to manage the color reproduction characteristics of each device, CMS outputs a color reproduction characteristic data of each device, in the case of a printer, a predetermined color chart, and uses a device profile in which data obtained by measuring the color chart is described. To realize color management. The creation of a device profile requires a color measurement operation using a spectral radiance measuring device or a spectral reflectance measuring device in order to acquire color reproduction characteristic data of each device.

  Here, the characteristics of the colorimetry by the spectral reflectance measuring device and the spectral radiance measuring device will be described.

  FIG. 1 is a diagram schematically showing colorimetry by the spectral reflectance measuring device 15. In the color measurement by the spectral reflectance measuring device 15, light is incident on the sample 11 (for example, a color chart) from a specific direction, and the light reflected in the specific direction is measured. In such color measurement, since the geometric conditions of the light source 13 and the light receiver 12 can be fixed, the light source 13 and the light receiver 12 are accommodated in a relatively small color measurement unit 10, and the color measurement unit 10 is scanned. Many samples 11 can be automatically colorimetrically measured.

  The color measurement by the spectral reflectance measuring instrument 15 is a contact type color measurement and has an advantage that the operation is simple. However, since light is measured under a specific geometric condition, there is a problem that the color appearance of the sample 11 under the actual observation condition of the observer cannot be measured with high accuracy.

  FIG. 2 is a diagram schematically showing the colorimetry by the spectral radiance measuring instrument 14. The color measurement by the spectral radiance measuring instrument 14 can adjust the position of the measuring instrument in accordance with the actual observation conditions (geometric conditions) of the observer. Therefore, while the light from the plurality of light sources 13 is scattered, the light reflected from the sample 11 in the light receiving direction of the observer can be measured. That is, a colorimetric value close to the color appearance of the sample 11 under the actual observation conditions of the observer can be obtained.

  The color measurement by the spectral radiance measuring instrument 14 has an advantage that the color appearance under the observation conditions can be measured with high accuracy. However, the spectral radiance measuring instrument 14 is larger than the spectral reflectance measuring instrument 15, and is not suitable for automatic color measurement, and there is a problem that it takes time for color measurement. Even if there is a device capable of automatic colorimetry, spectral reflection is required because it takes a certain amount of time to integrate the colorimetric light, and it is necessary to position the sample and the device in accordance with the observation conditions (geometric conditions). Compared to the rate measuring device 15, the color measurement work still takes time.

  As described above, the color measurement using the spectral reflectance measuring device has a problem that the color appearance under the actual observation conditions cannot be measured with high accuracy. In addition, the color measurement using the spectral radiance measuring instrument requires time for the color measurement work. That is, it is difficult to measure the color appearance under actual observation conditions with high accuracy, easily and in a short time.

  Patent Document 1 discloses a means for solving this problem. The technique of Patent Document 1 corrects the colorimetric value under the first observation condition to the colorimetric value under the second observation condition. First, the first observation condition and the second observation condition respectively. Measure the color of the white plate. Then, data for correcting the colorimetric value is created from the spectral distribution component that varies depending on the observation conditions. By using this correction data, it is possible to calculate colorimetric data when colorimetry is performed by the spectral radiance measuring instrument in an environment close to actual observation conditions from the colorimetric data of the spectral reflectance measuring instrument. Therefore, the time required for color measurement is reduced, and highly accurate color measurement data close to the state seen under actual observation conditions can be obtained.

  However, the technique of Patent Document 1 needs to create correction data for converting the colorimetric data of the spectral reflectance measuring device into the colorimetric data of the spectral radiance measuring device for each actual observation condition. In other words, the colorimetric data can be converted only under the observation conditions for which the correction data is created. That is, if correction data for a new observation condition is required, a new correction data creation operation (colorimetry operation) is required.

  Even if correction data for various viewing conditions is created and a mechanism for holding the correction data is prepared, depending on the viewing conditions (light source type, geometric conditions, media characteristics, colorant characteristics, etc.) The correction data is different, and it is unrealistic to cover all the observation conditions.

  Of course, an expensive spectral radiance measuring instrument is essential for the creation of correction data, and it can be said that it is impractical to create correction data in a normal user environment.

JP 2006-200960

  An object of the present invention is to obtain colorimetric data close to the appearance of color under actual observation conditions.

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

  The color processing according to the present invention includes a first holding unit that holds conversion data for converting colorimetric data related to spectral reflectance into colorimetric data related to spectral radiance, and inputs a user instruction indicating a medium to be used. The colorimetric data relating to the spectral reflectance is acquired, the conversion data is acquired from the first holding means based on the used media indicated by the user instruction, and the acquired spectral reflection is obtained using the acquired conversion data. The colorimetric data relating to the rate is converted into the colorimetric data relating to the spectral radiance.

  According to the present invention, colorimetric data close to the appearance of color under actual observation conditions can be obtained.

The figure which shows typically the colorimetry by a spectral reflectance measuring device. The figure which shows typically the colorimetry by a spectral radiance measuring device. 1 is a block diagram illustrating a configuration example of a color processing apparatus according to an embodiment. 5 is a flowchart illustrating a processing example of a color processing apparatus. The figure which shows an example of a user interface. The figure which shows the format example of a colorimetric value. The figure which shows the example of conversion data which a conversion data holding part hold | maintains. The flowchart explaining operation | movement of a light source information acquisition part. The figure which shows an example of the light source corresponding | compatible table which a light source table holding | maintenance part hold | maintains. The flowchart explaining operation | movement of the conversion data acquisition part. The flowchart explaining operation | movement of a colorimetric value conversion part. FIG. 3 is a block diagram illustrating a configuration example of a color processing apparatus according to a second embodiment. 5 is a flowchart illustrating a processing example of a color processing apparatus. The figure which shows an example of a user interface. The figure which shows the example of conversion data which a conversion data holding part hold | maintains. The flowchart explaining operation | movement of a glossiness information acquisition part. The figure which shows an example of the correspondence table which a glossy characteristic table holding part hold | maintains. The flowchart explaining operation | movement of the conversion data acquisition part.

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

[Device configuration]
FIG. 3 is a block diagram illustrating a configuration example of the color processing apparatus 101 according to the embodiment.

  A user interface (UI) unit 102 provides a user interface for the user to specify observation conditions, an input file 112, and an output file 113. That is, the UI unit 101 provides a video interface that displays a graphical user interface (GUI) on a monitor (not shown) and an input interface of a pointing device such as a keyboard, mouse, touch panel, and dial (not shown).

  The light source information acquisition unit 103 acquires the color temperature information of the observation light source specified by the user from the light source table holding unit 109. The light source table holding unit 109 holds a table in which correspondence between light source names and color temperature information is described.

  The colorimetric value acquisition unit 104 acquires measurement data (colorimetric values) of the spectral reflectance measuring device from the input file 112 specified by the user.

  The conversion data acquisition unit 105 acquires conversion data corresponding to the observation light source specified by the user from the plurality of conversion data held by the conversion data holding unit 108. The conversion data holding unit 108 holds a plurality of pieces of conversion data corresponding to the reference light source.

  The colorimetric value conversion unit 107 converts the colorimetric value acquired by the colorimetric value acquisition unit 104, that is, the colorimetric data of the spectral reflectance measuring device, using the conversion data acquired by the conversion data acquisition unit 105. The buffer memory 110 is a work memory in the processing of the color processing apparatus 101, and temporarily stores information during processing and calculation results.

  The input / output unit 106 acquires a colorimetric value requested by the colorimetric value acquisition unit 104 from the input file 112, and outputs an output file 113 in which the colorimetric values converted by the colorimetric value conversion unit 107 are described in a predetermined format. Output according to user specification. The input / output unit 106 is connected to a serial bus such as USB or IEEE1394 or a network. Therefore, data can be input / output between a computer device, an image input / output device (for example, a digital camera, a scanner, a printer, etc.) that performs color matching processing, or a storage device or server device.

  The above-described components are connected to each other via a system bus 111.

[Device operation]
FIG. 4 is a flowchart showing a processing example of the color processing apparatus 101.

  The UI unit 102 displays on the monitor a user interface for the user to input information necessary for colorimetric value conversion (S11).

  FIG. 5 is a diagram illustrating an example of a user interface. The user interface includes an observation light source setting unit 1001 for inputting or selecting a name or symbol indicating the type of the observation light source. There is also an input file setting unit 1002 for inputting or selecting the file name and path name (input destination) of the input file 112 in which the colorimetric values to be converted are described. Further, there is an output file setting unit 1003 for inputting or setting the file name and path name (output destination) of the output file 113 describing the colorimetric values of the conversion result.

  The user operates a pull-down menu of the observation light source setting unit 1001 or sets file names in the input file setting unit 1002 and the output file setting unit 1003 using a keyboard or a mouse. When a necessary instruction (user instruction) is completed, an OK button 1004 is pressed. The pull-down menu of the observation light source setting unit 1001 includes the light color symbols of typical light sources defined in Japanese Industrial Standards (JIS), A, C, and D light sources defined by the International Commission on Illumination (CIE). Set symbols such as standard illuminant and auxiliary standard illuminant.

  Next, the light source information acquisition unit 103 acquires the color temperature information of the observation light source from the light source table holding unit 109 based on the name and symbol of the observation light source set by the user in the observation light source setting unit 1001, and stores the predetermined information in the buffer memory 110. Store in the area (S12).

  Next, the colorimetric value acquisition unit 104 receives the colorimetric values (calculated from the spectral reflectance by the spectral reflectance measuring instrument from the input file 112 set by the user in the input file setting unit 1002 via the input / output unit 106. CIEXYZ value) is acquired (S13). The acquired colorimetric values are stored in a predetermined area of the buffer memory 110.

  FIG. 6 is a diagram showing a format example of colorimetric values, in which the correspondence between grid points (RGB values) obtained by equally dividing the RGB color space and XYZ values is described. Although FIG. 6 shows an example of a 9-step grid, there are no restrictions on the number of grids and the number of colorimetry.

  Next, the conversion data acquisition unit 105 acquires conversion data from the conversion data holding unit 108 based on the color temperature information acquired by the light source information acquisition unit 103 (S14).

  FIG. 7 is a diagram showing an example of conversion data held by the conversion data holding unit 108, and holds color temperature information and conversion data for each of a plurality of reference light sources. The conversion data is a matrix coefficient for matrix calculation for converting the measurement data of the spectral reflectance measuring instrument into the measurement data of the spectral radiance measuring instrument.

  The processing of the conversion data acquisition unit 105 and the method of creating the conversion data held by the conversion data holding unit 108 will be described later.

  Next, the colorimetric value conversion unit 107 converts the colorimetric values stored in the buffer memory 110 by the colorimetric value acquisition unit 104 using the conversion data acquired by the conversion data acquisition unit 105, as will be described in detail later. (S15). The input / output unit 106 describes the colorimetric value converted by the colorimetric value conversion unit 107 in the output file 113 in a predetermined format, and outputs it according to the setting of the output file setting unit 1003 (S16).

Light Source Information Acquisition Unit FIG. 8 is a flowchart for explaining the operation (S12) of the light source information acquisition unit 103.

  When the OK button 1004 shown in FIG. 5 is pressed, the light source information acquisition unit 103 acquires the name or symbol of the observation light source set in the observation light source setting unit 1001 (S21). Then, the color temperature information corresponding to the name or symbol of the observation light source is acquired from the light source correspondence table held in the light source table holding unit 109 (S22).

  FIG. 9 is a diagram showing an example of a light source correspondence table held by the light source table holding unit 109. As shown in FIG. In the light source correspondence table, color temperature information corresponding to the name and symbol of each light source listed in the pull-down menu of the observation light source setting unit 1001 is described.

  Next, the light source information acquisition unit 103 stores the acquired color temperature information of the observation light source in a predetermined area of the buffer memory 110 (S23).

Conversion Data Acquisition Unit Before describing the operation of the conversion data acquisition unit 105, a method for creating conversion data will be described.

The conversion data associates the measurement data of the spectral reflectance measuring instrument (hereinafter referred to as spectral reflectance data) and the measurement data of the spectral radiance measuring instrument (hereinafter referred to as spectral radiance data). Therefore, using the least squares method or the like from the spectral reflectance data and spectral radiance data, which are the measurement results of multiple samples (for example, color charts), the matrix coefficient for matrix calculation (conversion data) shown in Equation (1) )
┌ ┐ ┌ ┐┌ ┐
│Xn│ │m11 m12 m13 m14││Xi│
│Yn│ = │m21 m22 m23 m24││Yi│… (1)
│Zn│ │m31 m32 m33 m34││Zi│
└ ┘ └ ┘│ 1│
└ ┘
Where XnYnZn: Tristimulus values calculated from spectral radiance data
XiYiZi: Tristimulus values calculated from spectral reflectance data

  If the tristimulus values calculated from the spectral reflectance data are converted by the matrix calculation shown in Equation (1), tristimulus values taking into account the geometric conditions during colorimetry by the spectral radiance measuring device can be obtained. Equation (1) shows a 3 × 4 matrix operation, but there is no limit to the number of columns.

  Then, the spectral reflectance data and spectral radiance data of the sample are measured under typical observation conditions as the reference, and conversion data corresponding to each of the reference observation conditions is created, and the created conversion data is converted. The data is held in the data holding unit 108.

  FIG. 10 is a flowchart for explaining the operation (S14) of the conversion data acquisition unit 105.

  The conversion data acquisition unit 105 acquires the color temperature information of the observation light source from the buffer memory 110 (S41). Then, the process branches by comparing the color temperature Tv of the observation light source with the color temperature Tn of the reference light source of the conversion data held by the conversion data holding unit 108 (S42).

  When there is a reference light source having a color temperature that matches the color temperature Tv of the observation light source (when Tv = Tn, and the same color temperature as any of the reference light sources), the conversion data acquisition unit 105 converts the conversion data of the reference light source. The data is stored in a predetermined area of the buffer memory 110 (S43). In the example shown in FIG. 7, if the color temperature Tv of the observation light source is 6500K, conversion data of the reference light source D65 (6500K) is acquired.

  In addition, the conversion data acquisition unit 105 does not have a reference light source having a color temperature that matches the color temperature Tv of the observation light source, but there are two reference light sources having color temperatures Tn1 and Tn2 sandwiching the color temperature Tv. The process proceeds to step S45. That is, in the state of Tn1 <Tv <Tn2, such a state is referred to as “within range”.

  Further, there may be a case where there is neither a reference light source having a color temperature that matches the color temperature Tv of the observation light source nor a reference light source having a color temperature sandwiching the color temperature Tv. That is, in the state of Tv <Tn or Tn <Tv, such a state is referred to as “out of range”. In this case, the conversion data acquisition unit 105 acquires the conversion data of the reference light source having the color temperature closest to the color temperature Tv and stores it in a predetermined area of the buffer memory 110 (S44). In the example shown in FIG. 7, if Tv = 2500K, conversion data of the reference light source A (2556K) is acquired.

When there is a reference light source having the color temperatures Tn1 and Tn2 sandwiching the color temperature Tv, the conversion data acquisition unit 105 represents the equation (2) based on the color temperature Tv of the observation light source and the color temperatures Tn1 and Tn2 of the reference light source. The conversion data is interpolated by a linear sum of color temperatures. Then, the conversion data under the observation light source of the interpolation calculation result is stored in a predetermined area of the buffer memory 110 (S45). In the example shown in FIG. 7, if Tv = 4000K, conversion data of the reference light source D50 (Tn1 = 5000K) and the reference light source A (Tn2 = 2556K) are acquired.
[Ms] = {(Tn1-Tv) / (Tn1-Tn2)} [M2] + {(Tv-Tn2) / (Tn1-Tn2)} [M1]… (2)
Where Ms is the conversion data under the observation light source (Tv)
M1 is the conversion data under the reference light source (Tn1)
M2 is the conversion data under the reference light source (Tn2) where Tn2 <Tv <Tn1

Colorimetric Value Conversion Unit FIG. 11 is a flowchart for explaining the operation (S15) of the colorimetric value conversion unit 107.

  The colorimetric value conversion unit 107 acquires conversion data under the observation light source from the buffer memory 110 (S51).

  Next, the colorimetric value conversion unit 107 extracts the CIEXYZ value of one grid point from the colorimetric values stored in the buffer memory 110 (S52), and performs spectral emission by matrix calculation represented by Equation (1) using the converted data. The luminance data is converted into CIEXYZ values (S53). Then, the CIEXYZ value of the conversion result is stored in a predetermined area of the buffer memory 110 in association with the grid point (S54).

  Next, the colorimetric value conversion unit 107 determines whether or not the CIEXYZ values of all grid points have been converted (S55), and performs steps S52 to S54 until the CIEXYZ values of all grid points are processed. repeat.

  In this manner, conversion data for converting the tristimulus values calculated from the spectral reflectance data into the tristimulus values calculated from the spectral radiance data is created in a plurality of reference light sources. Then, the colorimetric data (tristimulus values) of the spectral reflectance measuring device is converted by a matrix operation using the conversion data, so that the colorimetric data (three times) considering the geometric conditions of the colorimetric measurement by the spectral radiance measuring device. (Stimulus value). If there is no reference light source that matches the observation light source, the conversion data of the observation light source is interpolated from the conversion data of the reference light source having a color temperature close to that of the observation light source.

  That is, according to the first embodiment, colorimetric data can be converted in consideration of the observation light source and the geometric condition. Therefore, if the colorimetric data of the spectral reflectance measuring device is prepared as an input file according to the observation conditions such as the characteristics of the media and the characteristics of the color material, high-precision measurement close to the appearance of the colors under the actual observation conditions. Color data can be obtained very easily. As a result, it is possible to greatly reduce the user load related to the creation work of a highly accurate profile.

  The color processing according to the second embodiment of the present invention will be described below. Note that the same reference numerals in the second embodiment denote the same parts as in the first embodiment, and a detailed description thereof will be omitted.

[Device configuration]
FIG. 12 is a block diagram illustrating a configuration example of the color processing apparatus 101 according to the second embodiment. The difference from the first embodiment is that a glossiness information acquisition unit 115 and a gloss characteristic table holding unit 114 are provided instead of the light source information acquisition unit 103 and the light source table holding unit 109.

  The glossiness information acquisition unit 115 acquires the glossiness information of the media designated by the user from the gloss characteristic table holding unit 114. The gloss characteristic table holding unit 114 holds a correspondence table of media name or model number and glossiness information.

[Device operation]
FIG. 13 is a flowchart illustrating a processing example of the color processing apparatus 101.

  The UI unit 102 displays on the monitor a user interface for the user to input information necessary for colorimetric value conversion (S21).

  FIG. 14 is a diagram illustrating an example of a user interface. In the user interface of the second embodiment, instead of the observation light source setting unit 1001 shown in FIG. 5, a media setting unit 1005 for inputting or selecting a name or model number indicating the type of media (used media) used by the user. There is. In the pull-down menu of the media setting unit 1005, a general name of media (glossy paper, plain paper, matte paper, etc.), a recording paper vendor model number, and the like may be set.

  Next, the glossiness information acquisition unit 115 acquires the glossiness information from the gloss characteristic table holding unit 114 based on the name and model number of the medium set by the user in the media setting unit 1005, and stores it in a predetermined area of the buffer memory 110. (S22).

  Next, the colorimetric value acquisition unit 104 receives the colorimetric values (calculated from the spectral reflectance by the spectral reflectance measuring instrument from the input file 112 set by the user in the input file setting unit 1002 via the input / output unit 106. CIEXYZ value) is acquired (S23). The acquired colorimetric values are stored in a predetermined area of the buffer memory 110.

  Next, the conversion data acquisition unit 105 acquires conversion data from the conversion data holding unit 108 based on the glossiness information acquired by the glossiness information acquisition unit 115 (S24).

  FIG. 15 is a diagram illustrating an example of conversion data held by the conversion data holding unit 108, and holds glossiness information and conversion data for each of a plurality of reference media. The conversion data is a matrix coefficient for matrix calculation shown in Expression (1) for converting the measurement data of the spectral reflectance measurement device into the measurement data of the spectral radiance measurement device, as in the first embodiment.

  Next, the colorimetric value conversion unit 107 converts the colorimetric values stored in the buffer memory 110 by the colorimetric value acquisition unit 104 using the conversion data acquired by the conversion data acquisition unit 105, as will be described in detail later. (S25). The input / output unit 106 describes the colorimetric values converted by the colorimetric value conversion unit 107 in the output file 113 in a predetermined format, and outputs them according to the setting of the output file setting unit 1003 (S26).

Glossiness Information Acquisition Unit FIG. 16 is a flowchart for explaining the operation (S22) of the glossiness information acquisition unit 115.

  When the OK button 1004 shown in FIG. 14 is pressed, the glossiness information acquisition unit 115 acquires the media name or model number set in the media setting unit 1005 (S31). Then, glossiness information corresponding to the media name or model number is acquired from the correspondence table held in the gloss characteristic table holding unit 114 (S32).

  FIG. 17 is a diagram illustrating an example of a correspondence table held by the gloss characteristic table holding unit 114. The gloss characteristic correspondence table describes glossiness information corresponding to the name and model number of each medium listed in the pull-down menu of the media setting unit 1005.

  Next, the glossiness information acquisition unit 115 stores the acquired media glossiness information in a predetermined area of the buffer memory 110 (S33).

Conversion Data Acquisition Unit FIG. 18 is a flowchart for explaining the operation (S24) of the conversion data acquisition unit 105.

  The conversion data acquisition unit 105 acquires the glossiness information of the medium from the buffer memory 110 (S51). Then, the processing is branched by comparing the glossiness Lv of the media with the glossiness Ln of the reference media of the conversion data held by the conversion data holding unit 108 (S52).

  When there is a reference medium having a glossiness that matches the glossiness level Lv of the medium (when Lv = Ln, and the same glossiness as any of the reference media), the conversion data acquisition unit 105 converts the conversion data of the reference medium. The data is stored in a predetermined area of the buffer memory 110 (S53). In the example shown in FIG. 15, if the glossiness Lv of the medium is 30, the conversion data of glossy paper 1 is acquired.

  Also, the conversion data acquisition unit 105 performs processing when there is no reference medium having a glossiness matching the glossiness Lv of the medium, but there are two reference media having glossiness Ln1 and Ln2 sandwiching the glossiness Lv. Advances to step S55. That is, in the state of Ln1 <Lv <Ln2, such a state is referred to as “within range”.

  Further, there may be a case where there is neither a reference medium having a glossiness matching the glossiness Lv of the medium nor a reference medium having a glossiness sandwiching the glossiness Lv. That is, in a state where Lv <Ln or Ln <Lv, such a state is referred to as “out of range”. In this case, the conversion data acquisition unit 105 acquires the conversion data of the reference medium having the glossiness closest to the glossiness Lv, and stores it in a predetermined area of the buffer memory 110 (S54). In the example shown in FIG. 15, when Lv = 5, conversion data of matte paper is acquired.

When there is a reference media with glossiness Ln1 and Ln2 across glossiness Lv, the conversion data acquisition unit 105 determines the glossiness expressed by equation (3) based on the media glossiness Lv and the glossiness Ln1 and Ln2 of the reference media. The conversion data is interpolated by a linear sum of degrees. Then, the conversion data of the glossiness Lv of the interpolation calculation result is stored in a predetermined area of the buffer memory 110 (S55). In the example shown in FIG. 15, if Lv = 25, conversion data of glossy paper 1 and glossy paper 2 is acquired.
[Ms] = {(Ln1-Lv) / (Ln1-Ln2)} [M2] + {(Lv-Ln2) / (Ln1-Ln2)} [M1]… (3)
Where Ms is conversion data of glossiness (Lv)
M1 is conversion data of glossiness (Ln1)
M2 is conversion data of glossiness (Ln2) However, Ln2 <Tv <Ln1

Colorimetric Value Conversion Unit This is the same as the operation of the colorimetric value conversion unit 107 of the first embodiment shown in FIG.

  In this way, conversion data for converting tristimulus values calculated from the spectral reflectance data into tristimulus values calculated from the spectral radiance data in a plurality of reference media (different glossiness levels) is created. Then, the colorimetric data (tristimulus values) of the spectral reflectance measuring device is converted by a matrix operation using the conversion data, so that the colorimetric data (three times) considering the geometric conditions of the colorimetric measurement by the spectral radiance measuring device. (Stimulus value). That is, the color measurement data measured under the first color measurement geometric condition is converted into the color measurement data measured under the second color measurement geometric condition. If there is no reference medium having a glossiness that matches the medium to be used, the conversion data of the medium to be used is interpolated from the conversion data of the reference medium having a glossiness close to that of the medium to be used.

  That is, according to the second embodiment, colorimetric data can be converted in consideration of the glossiness of the medium and the geometric conditions. Therefore, if you prepare the colorimetric data of the spectral reflectance measuring instrument as an input file according to the observation conditions such as the observation light source and the characteristics of the color material, high-precision colorimetry close to the appearance of the colors under the actual observation conditions Data can be obtained very easily. As a result, it is possible to greatly reduce the user load related to the creation work of a highly accurate profile.

[Modification]
Observation conditions As an example of the observation conditions, the color temperature of the observation light source is used in Example 1, and the glossiness of the medium used is described in Example 2. However, the observation conditions are not limited to these. For example, various observation conditions such as sharpness other than glossiness, image clarity, and the like, the type of color material on which a sample (for example, a color chart) is printed, and geometric conditions at the time of observation can be used. That is, any parameter that causes a variation in the conversion data can be adopted as an observation condition set by the user. Of course, the above information may be combined as an observation condition.

● How to set observation conditions Example 1 shows examples of using light color symbols, standard illuminants, auxiliary standard illuminants, etc. for selection of observation light sources, but it relates to fluorescent lamps stipulated by the International Commission on Illumination (CIE). A standard F number may be used. That is, any name or symbol that can identify the type of light source may be used.

  In the second embodiment, an example is shown in which a user selects a medium to be used from a name indicating the type of the medium. However, a name of a commercially available medium may be registered in advance, and the medium may be selected by the name. In other words, any name, model number, or symbol that can specify the type of media may be used.

  In the above-described embodiment, the example in which the user sets the observation condition has been described. However, the observation conditions may be measured using a measuring instrument. For example, in Example 1, the color temperature of the observation light source may be measured by a sensor, and in Example 2, the glossiness of the medium may be measured by a gloss meter.

● Format of conversion data Equation (1) uses the CIEXYZ value calculated from the spectral radiance and spectral reflectance instead of using the spectral radiance and spectral reflectance as they are. The format of the conversion formula and the conversion data is not limited to Formula (1). For example, using the measurement data of spectral radiance and spectral reflectance of multiple color charts, the coefficient a (λ) and constant b (λ) shown in equation (4) are used for each wavelength by using the least square method. And a conversion formula for predicting the spectral radiance from the spectral reflectance may be used.
S (λ) = a (λ) ・ R (λ) + b (λ) (4)
Where S (λ) is the spectral radiance at wavelength λ
R (λ) is the spectral reflectance at wavelength λ

In addition, Equation (4) converts the spectral reflectance into the spectral radiance by a linear equation, but may be converted by a polynomial as shown in Equation (5), for example.
S (λ) = Σa _i (λ) ・ R _n (λ) (5)
However, the range of Σ operation is from i = 0 to n

  In other words, the type of conversion data is not limited as long as spectral reflectance data can be converted into spectral radiance data with accuracy required by the user.

  Note that, for example, the conversion data under the observation condition in the form of the expression (4) is obtained by performing the above interpolation process from the acquired observation condition information and the coefficient a (λ) and the constant b (λ) of the primary expression of the reference conversion data. Calculate using.

Sample for creating conversion data In the above embodiment, the type of sample for creating conversion data is not particularly limited. For example, when printing a sample using a printer, a part of white, cyan, magenta, yellow, red, green, blue, black, which is a color at the boundary of the color reproduction range (output color gamut) of the printer, or All may be used. Alternatively, a set of gray scale patches with a predetermined lightness interval passing through the hue lines from the white point to the black point of the output color gamut may be used as the sample.

Conversion Data Interpolation Operation In the above-described embodiment, the example in which the conversion data of the reference light source (media) is interpolated by the linear sum of the color temperature (glossiness) has been described. However, the interpolation calculation is not limited to the linear sum, and for example, the interpolation calculation may be performed based on the ratio of the distances on the CIEXYZ space, the CIExy chromaticity diagram, and the CIEuv chromaticity diagram. Alternatively, an interpolation calculation may be performed using a linear sum of reciprocals of color temperature (glossiness).

Conversion Data In Example 1, the conversion data indicates a matrix coefficient corresponding to the reference light source (standard light source). However, the conversion data is not limited to the standard light source, and conversion data created under a light source other than the standard light source may be used. Further, the number of conversion data is not limited to three types as shown in FIG. 7, for example, and a large number of conversion data can be prepared according to a reference light source (media).

[Other embodiments]
Note that the present invention can be applied to a system composed of a plurality of devices (for example, a computer, an interface device, a reader, a printer, etc.), or a device (for example, a copier, a facsimile machine, a control device) composed of a single device. Etc.).

  Another object of the present invention is to supply a storage medium storing a computer program for realizing the functions of the above-described embodiments to a system or apparatus, and the computer (CPU or MPU) of the system or apparatus executes the computer program. But it is achieved. In this case, the software read from the storage medium itself realizes the functions of the above embodiments, and the computer program and the computer-readable storage medium storing the computer program constitute the present invention. .

  Further, the above functions are not only realized by the execution of the computer program. That is, according to the instruction of the computer program, the operating system (OS) running on the computer and / or the first, second, third,... This includes cases where functions are realized.

  The computer program may be written in a memory of a device such as a function expansion card or unit connected to the computer. That is, the case where the CPU or the like of the first, second, third,... Device performs part or all of the actual processing according to the instruction of the computer program, thereby realizing the above functions.

  When the present invention is applied to the storage medium, the storage medium stores a computer program corresponding to or related to the flowchart described above.

Claims (8)

First holding means for holding conversion data for converting colorimetric data relating to spectral reflectance into colorimetric data relating to spectral radiance;
Input means for inputting user instructions indicating the media used;
A colorimetric value acquisition means for acquiring colorimetric data relating to the spectral reflectance;
Conversion data acquisition means for acquiring conversion data from the first holding means based on the use media indicated by the user instruction;
A color processing apparatus comprising: conversion means for converting the colorimetric data related to the acquired spectral reflectance into the colorimetric data related to the spectral radiance using the acquired conversion data.   2. The color processing apparatus according to claim 1, wherein the first holding unit holds a plurality of conversion data corresponding to a plurality of reference media having different glossiness levels. And second holding means for holding glossiness information corresponding to the type of media;
Glossiness information acquisition means for acquiring glossiness information of the used media from the second holding means based on the user instruction;
3. The conversion data acquisition unit acquires conversion data corresponding to the glossiness of the used media based on the glossiness information of the used media and the glossiness information of the reference media. Color processing device.   When there is no reference medium having a glossiness that matches the glossiness of the used media, the conversion data acquisition means obtains the conversion data from a plurality of reference media having glossiness sandwiching the glossiness of the used media. 4. The color processing apparatus according to claim 3, wherein the conversion data corresponding to the glossiness of the medium used is interpolated.   5. The conversion unit according to claim 1, wherein the conversion unit converts the colorimetric data related to the spectral reflectance into colorimetric data considering a geometric condition in the measurement of the spectral radiance, based on the conversion data. A color processing apparatus according to any one of the above.   5. The user instruction further indicates an input destination of colorimetric data, and the colorimetric value acquisition unit acquires the colorimetric data from an input destination indicated by the user instruction. A color processing apparatus according to any one of the above. Color processing apparatus having holding means for holding conversion data for converting colorimetric data related to spectral reflectance into colorimetric data related to spectral radiance, input means, colorimetric data acquisition means, conversion data acquisition means, and conversion means The color processing method of
The input means inputs a user instruction indicating a medium to be used,
The colorimetric data acquisition means acquires colorimetric data related to the spectral reflectance,
The conversion data acquisition unit acquires the conversion data from the holding unit based on a use medium indicated by the user instruction,
The color processing method characterized in that the conversion means converts the colorimetric data related to the acquired spectral reflectance into colorimetric data related to the spectral radiance using the acquired conversion data.   A program for causing a computer to function as each unit of the color processing device according to any one of claims 1 to 6.

Images