JP4427011B2 - Color matching device or color matching method - Google Patents

Description

  The present invention relates to a color matching device that matches the output characteristics of a correction target output device with the output characteristics of a target output device.

Conventionally, when receiving an order for printing in the printing industry, in order to confirm the color of a printed matter, a customer has been shown the color calibration output in advance by a color proofing printer and the customer is informed. However, the color of the output (printing) result is often different between the color proofing printer and the printing machine. For example, it is assumed that common image data is input to both the printing machine and the color proofing printer and output (printed). However, in many cases, the hues of the output (printed) by the printing press and the output (printed) by the color proofing printer do not match. Therefore, so-called “color matching” is performed to match the color characteristics between the output devices of the color proofing printer and the printing press.
JP 2003-274205 A

  As the method, for example, a target printing device (printing machine) uses a color (device dependent color) dependent on the target printing device (printing machine) and a color independent of the target printing device (printing machine) (device independent). Similarly, a look-up table (LUT) that is a color correspondence table with a color) is created, and in the same manner, a correction target printing apparatus (color proofing printer) that should match the color characteristics of the target printing apparatus also has the same look as above. The color characteristics are matched between the output devices by creating an up-table and performing conversion with device-specific color data via the LUT describing the device-specific color characteristics.

  In addition, when there are a plurality of correction target printing apparatuses to be matched with the color characteristics of the target printing apparatus, an LUT is created for each printing apparatus, and the color matching process is performed for each of them. In spite of aiming at the characteristics, there is a problem that a difference in color matching results occurs between the respective correction target printing apparatuses due to the difference in the color reproduction characteristics among the plurality of correction target printing apparatuses. As a method for solving this problem, a method of correcting so as to eliminate a difference in gradation reproduction between a plurality of correction target printing apparatuses before color matching processing is known.

  However, the above-described method is an effective means for correcting a difference between output devices of the same model, but it is difficult to correct a difference between different types of printing devices having different color gamuts and ink hues. That was a problem.

  The present invention has been made in view of such a problem, and provides a color matching device capable of printing in accordance with the color reproduction characteristics of a correction target printing apparatus in accordance with the color reproduction characteristics of a target printing apparatus. Objective.

According to a first aspect of the present invention for solving the above-described problem, a color matching device that matches the output characteristics of a plurality of correction target output devices to the output characteristics of a target output device. Selecting means for selecting an output device; machine difference correcting means for matching the output characteristics of the correction target output device other than the reference output device to the output characteristics of the reference output device;
Color conversion means for adjusting the output characteristics of the output device to be corrected according to the output characteristics of the reference output device by the machine difference correction means and the output characteristics of the reference output device respectively to the output characteristics of the target output device. It is characterized by having.

  According to this, by selecting a reference output device as a reference from among the output devices to be corrected and matching the output characteristics of the output devices other than the reference output device with the output characteristics of the reference output device, The output characteristics of the correction target output device and the target output device can be corrected by matching the output characteristics of the correction target output device after the machine difference correction with the output characteristics of the target output device. The difference in output characteristics can be eliminated, and the output characteristics of the target output device can be output even between different types of output devices.

  According to a second aspect of the present invention for solving the above problem, in the color matching apparatus according to the first aspect, the selection means is an output device having the narrowest color reproduction range among the plurality of correction target output devices. Is selected as a reference output device.

  According to this, when a correction target output device other than the reference output device is matched with the output characteristics of the reference output device, the output device having the narrowest color reproduction range is selected as the reference output device, thereby correcting other than the reference output device. The operation to match the output characteristics of the target output device to the output characteristics of the reference output device can be performed easily and easily, and the output devices of all the target output devices including the reference output device are reliably matched to the output characteristics of the target output device. Can be matched.

  A third aspect of the invention for solving the above-mentioned problem is the color matching apparatus according to the first or second aspect, wherein the output characteristic is a color reproduction characteristic.

  According to this, a difference in color reproduction characteristics between different kinds of printing apparatuses, particularly in color reproduction characteristics among output characteristics, can be eliminated, and the output characteristics of the target output apparatus can be output between different kinds of output apparatuses.

  According to a fourth aspect of the present invention for solving the above problem, in the color matching device according to the third aspect, each of the output devices is a printing device externally connected to the color matching device. The difference correction means includes a reference color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches printed by the reference output device, and the correction target output device other than the reference output device. And a color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches printed by the reference output device and the correction target output device other than the reference output device. A machine difference correction lookup table creating means for creating a machine difference correction lookup table and the reference output based on the machine difference correction lookup table. First conversion means for combining the color reproduction characteristics of the correction target output device other than the device color reproduction characteristics of the reference output device, and having a.

  According to this, a machine difference correction lookup table is created by the machine difference correction lookup table creation means, and the color reproduction characteristics of the output device to be corrected are used as a reference by the first conversion means based on the machine difference correction lookup table. Since the color reproduction characteristics of the output device can be matched, the difference in color reproduction characteristics between different types of output devices can be eliminated, and the color reproduction characteristics of the output device to be corrected after machine difference correction can be By matching the color reproduction characteristics, the difference between the color reproduction characteristics of the output device to be corrected and the color reproduction characteristics of the target output device can be eliminated, and printing between the different output devices with the color reproduction characteristics of the target output device. Can do.

  According to a fifth aspect of the present invention for solving the above problem, in the color matching apparatus according to the third or fourth aspect, the color conversion means includes a plurality of patches printed by the target output device. The target color signal of each patch obtained by measuring each patch of the chart and printed by the correction target output device or the reference output device matched with the output characteristics of the reference output device by the machine difference correction unit Based on the reference color signal of each patch acquired by measuring each patch of the chart composed of a plurality of patches, the output characteristics of the reference output device are obtained by the target output device and the machine difference correction unit. Color conversion lookup table creating means for creating a color conversion lookup table for the combined correction target output device or the reference output device, and the color conversion look-up table. Based on the up-table, the color reproduction characteristic of the correction target output device matched with the output characteristic of the reference output device or the color reproduction characteristic of the reference output device matched with the color reproduction characteristic of the target output device by the machine difference correction unit. 2 conversion means.

  According to this, a color conversion lookup table is created by the color conversion lookup table creation means, and the correction target output device or the reference output device after machine difference correction is performed by the second conversion means based on the color conversion lookup table The color reproduction characteristics of the target output device can be matched to the color reproduction characteristics of the target output device, so the difference between the color reproduction characteristics of the target output device and the target output device can be eliminated. Printing can be performed with the color reproduction characteristics of the target output device.

  According to a sixth aspect of the present invention for solving the above-described problem, in the color matching device according to any one of the first to fifth aspects, the color signal is a coordinate value in CIELab space or CIEXYZ space. It is the coordinate value in.

  According to this, by obtaining the component values constituting the color signal by the color signal Lab or CIEXYZ, the target output device and the correction target output device can be used to output a color that depends on the output device and a color that does not depend on the output device, respectively. By creating a look-up table (LUT), which is a color correspondence table, and converting the device-specific color data through the LUT describing the device-specific color characteristics, the color characteristics can be changed between different output devices. It becomes possible to match.

  The invention according to claim 7 for solving the above problem is a color matching method for matching output characteristics of a plurality of correction target output devices with output characteristics of a target output device. A selection step of selecting an output device, a machine difference correction step of matching output characteristics of the correction target output device other than the reference output device with an output characteristic of the reference output device, and a machine difference correction step of the reference output device. And a color conversion step of adjusting the output characteristics of the correction target output device in accordance with the output characteristics and the output characteristics of the reference output device to the output characteristics of the target output device, respectively.

  According to this, by selecting a reference output device as a reference from among the output devices to be corrected, and matching the output characteristics of the output devices to be corrected other than the reference output device with the output characteristics of the reference output device, The output characteristic difference between the correction target output device and the target output device can be eliminated by matching the output characteristic of the correction target output device after the machine difference correction with the output characteristic of the target output device. The difference in output characteristics can be eliminated, and the output characteristics of the target output device can be output even between different types of output devices.

  The invention described in claim 8 for solving the above problem is the color matching method according to claim 7, wherein the selecting step includes an output device having the narrowest color reproduction range among the plurality of correction target output devices. Is selected as a reference output device.

  According to this, when a correction target output device other than the reference output device is matched with the output characteristics of the reference output device, the output device having the narrowest color reproduction range is selected as the reference output device, thereby correcting other than the reference output device. The operation of matching the output characteristics of the target output device with the output characteristics of the reference output device can be easily performed without difficulty.

  A ninth aspect of the invention for solving the above-mentioned problem is the color matching method according to the seventh or eighth aspect, wherein the output characteristic is a color reproduction characteristic.

  According to this, a difference in color reproduction characteristics between different kinds of printing apparatuses, particularly in color reproduction characteristics among output characteristics, can be eliminated, and the output characteristics of the target output apparatus can be output between different kinds of output apparatuses.

  The invention described in claim 10 for solving the above problem is the color matching method according to claim 9, wherein each of the output devices is a printing device externally connected to the color matching method. The difference correction step includes a reference color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches printed by the reference output device, and the correction target output device other than the reference output device. And a color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches printed by the reference output device and the correction target output device other than the reference output device. A machine difference correction lookup table creating step for creating a machine difference correction lookup table, and the reference based on the machine difference correction lookup table And having a first conversion step of bringing the color reproduction characteristics of the correction target output device other than a force device to the color reproduction characteristics of the reference output device.

  According to this, a machine difference correction lookup table is created by the machine difference correction lookup table creation means, and the color reproduction characteristics of the output device to be corrected are used as a reference by the first conversion means based on the machine difference correction lookup table. Since the color reproduction characteristics of the output device can be matched, the difference in color reproduction characteristics between different types of output devices can be eliminated, and the color reproduction characteristics of the output device to be corrected after machine difference correction can be By matching the color reproduction characteristics, the difference between the color reproduction characteristics of the output device to be corrected and the color reproduction characteristics of the target output device can be eliminated, and printing between the different output devices with the color reproduction characteristics of the target output device. Can do.

  The invention according to claim 11 for solving the above problem is the color matching method according to claim 9 or 10, wherein the color conversion step includes a plurality of patches printed by the target output device. The target color signal of each patch obtained by measuring each patch of the chart and printed by the correction target output device or the reference output device matched to the output characteristics of the reference output device by the machine difference correction step Based on the reference color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches, the target output device and the output characteristic of the reference output device by the machine difference correction step Color conversion look-up table creation step for creating a color conversion look-up table for the combined correction target output device or the reference output device, and the color conversion Based on the backup table, the color reproduction characteristic of the correction target output device or the color reproduction characteristic of the reference output device matched with the output characteristic of the reference output device is matched with the color reproduction characteristic of the target output device by the machine difference correction step. And a second conversion step.

  According to this, a color conversion lookup table is created by the color conversion lookup table creation means, and the correction target output device or the reference output device after machine difference correction is performed by the second conversion means based on the color conversion lookup table The color reproduction characteristics of the target output device can be matched to the color reproduction characteristics of the target output device, so the difference between the color reproduction characteristics of the target output device and the target output device can be eliminated. Printing can be performed with the color reproduction characteristics of the target output device.

  The invention according to claim 12 for solving the above problem is the color matching method according to any one of claims 7 to 11, wherein the color signal is a coordinate value in CIELab space or CIEXYZ space. It is the coordinate value in.

  According to this, by obtaining the component values constituting the color signal by the color signal Lab or CIEXYZ, the target output device and the correction target output device can be used to output a color that depends on the output device and a color that does not depend on the output device, respectively. By creating a look-up table (LUT), which is a color correspondence table, and converting the device-specific color data through the LUT describing the device-specific color characteristics, the color characteristics can be changed between different output devices. It becomes possible to match.

  According to the present invention, by selecting a reference output device as a reference from among the correction target output devices, and adjusting the output characteristics of the correction target output devices other than the reference output device to the output characteristics of the reference output device, the different output device Output characteristics of the correction target output device and the target output device by matching the output characteristics of the target output device with the output characteristics of the target output device. The difference in the output characteristics can be eliminated, and the output characteristics of the target output device can be output even between different types of output devices.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings.

  The present embodiment shows an example in which the color matching device matches the output characteristics of a plurality of correction target output devices with the output characteristics of the target output device. In the following description, each output device is a printing device externally connected to a color matching device as will be described later, and the output characteristics are color reproduction characteristics.

[Color matching device]
First, the color matching apparatus according to the present embodiment will be conceptually described with reference to FIG. FIG. 1 is a schematic diagram showing a color matching apparatus and printing apparatuses according to the present invention. Note that the correction target printing apparatus 2 in the present embodiment is a different-type printing apparatus having a different color gamut and ink hue.

  As shown in FIG. 1, in the color matching apparatus 1 according to the present embodiment, in order to match the color reproduction characteristics of the plurality of correction target printing apparatuses 2 with the color reproduction characteristics of the target printing apparatus 5, first, the plurality of correction target printing apparatuses 2. The standard printing apparatus 4 is selected from the above. After selecting the reference printing apparatus 4, machine difference correction is performed to match the color reproduction characteristics of a correction target printing apparatus (hereinafter simply referred to as “printing apparatus”) 3 other than the reference printing apparatus 4 with the color reproduction characteristics of the reference printing apparatus 4. Color conversion that matches the color reproduction characteristics of the printing apparatus 3 matched with the color reproduction characteristics of the reference printing apparatus 4 and the color reproduction characteristics of the reference printing apparatus 4 with the color reproduction characteristics of the target printing apparatus 5 by machine difference correction, respectively. Do. As a result, printing can be performed with the same characteristics as the color reproduction characteristics of the target printing apparatus 5, regardless of which correction target printing apparatus 2 is the printing apparatus 3 or the reference output apparatus 4.

[Color matching device structure and function]
Next, the structure and function of each part constituting the color matching apparatus according to the present embodiment will be described with reference to FIGS. FIG. 2 is a block diagram showing a schematic configuration of the color matching apparatus of the present invention.

  As shown in FIG. 2, the color matching device 1 includes a storage unit 11, a display unit 12, an external device connection unit 13, and a control unit 14, and these components are mutually connected via a bus 15. It is connected.

  The storage unit 11 includes a device signal Dd (coordinate values in the CMYK color space unique to the device) of each device (correction target printing apparatus 2 and target printing apparatus 5) and a color signal Dc (to the device) that can reproduce the device signal Dd. The coordinate values in the independent color space) are stored in association with each other as a lookup table. In the present embodiment, as shown in FIG. 3, the correction target printing device 2 and the target printing device 5 as devices print (output) color charts respectively, and the color charts are applied to a spectral colorimetry device (not shown). The color signals Dc corresponding to the respective device signals Dd constituting the color chart are obtained by measurement, and the reference printing device lookup table (see FIG. 3A) and the target printing device 5 lookup are obtained. Each table (see FIG. 3B) is created and stored in the storage unit 11.

  This color chart is a color chart composed of CMYK such as IT 8.7 / 3 standardized by ISO (International Organization for Standardization) 12642, which is connected via the external device connection unit 13. Each printing device outputs (prints), measures each patch with a spectroscopic instrument, etc., acquires a color signal corresponding to the data signal of each patch, and creates each lookup table.

  Further, color chart data indicating a color chart for creating each of the lookup tables is stored.

  The display unit 12 includes, for example, an operation input unit configured by a mouse or the like that is not illustrated by the user among the color signals Dc included in the lookup table of the correction target printing device 2 and the lookup table of the target printing device 5. When a color signal desired to be displayed is selected by operation, a color based on the selected color signal is displayed. Further, based on the various processing signals from the control unit 14, the display instructed by the processing signals is performed.

  The external device connection unit 13 is for connecting to the correction target printing device 2, the target printing device 5, and the like.

  The control unit 14 includes a CPU (Central Processing Unit) (not shown), a working RAM (Random Access Memory), various control programs including the color matching program of the present invention, a ROM (Read Only Memory) that stores data, an oscillation circuit, and the like Control information for controlling each of the constituent members to realize an operation corresponding to the operation information included in the operation signal based on an operation signal from an operation unit (not shown). The control information is generated and output to the corresponding constituent member via the bus 15 to control the operation of each constituent member. Further, the control unit 14 executes various control programs stored in a ROM or the like, so that the selection unit, the machine difference correction unit, the color conversion unit, the machine difference correction lookup table creation unit of the present invention together with the above-described members, It functions as first conversion means, second conversion means, and color conversion lookup table creation means.

  The specific processing in the control unit 14 will be described in detail in the following description of the lookup table creation processing.

[Lookup table creation process]
Next, a specific method of table creation processing will be described with reference to FIGS. FIG. 6 is a flowchart showing the lookup table creation process. The process shown in the flowchart is controlled by the control unit 14 based on a color chart program stored in advance in a ROM (not shown) in the control unit 14. It is executed based on.

  First, a lookup table creation process is started by instructing creation of a lookup table (LUT). When the process is started, a lookup table for a plurality of correction target printing apparatuses 2 and target printing apparatuses 5 is created (step S11).

  Specifically, first, a color chart is printed (output) by the color chart data stored in the storage unit 11 in each of the correction target printing apparatuses 2 of the plurality of correction target printing apparatuses 2 shown in FIG. Are measured using a spectral colorimeter or the like (not shown), whereby C (cyan), M (magenta), Y (yellow), and K (black) values (hereinafter, “ Color signals Dc {(L1 *, a1 *, b1 *)... (Lm *, am *, bm *)} as reference color signals corresponding to the data signal Dd of each patch) are corrected. Obtained for each printing apparatus 2 (see FIG. 3A).

  Next, in the same manner as the creation of the lookup table of the correction target printing apparatus 2, the target printing apparatus 5 prints the color chart data using the color chart data stored in the storage unit 11, and each patch constituting the color chart is printed. Is measured using a spectrocolorimeter (not shown) or the like to obtain a target color signal corresponding to the Cz, Mz, Yz, and Kz values of each patch (hereinafter referred to as “data signal Dd of each patch”). As the color signal Dc {(Lz1 *, az1 *, bz1 *)... (Lzm *, azm *, bzm *)} is acquired (see FIG. 3B).

  As a result, the color signal Dc (correction target printing apparatus and target printing apparatus) that is the coordinate value in the device-independent color space corresponding to the device-dependent (in the device-specific CMYK space) coordinate value can be acquired. .

  Next, the reference printing device 4 is selected from the plurality of correction target output devices 2 (step S12).

  Here, the reference printing apparatus 4 serves as a reference for adjusting the correction target printing apparatus (printing apparatus) 3 other than the reference printing apparatus 4 to the color reproduction characteristics of the reference printing apparatus 4, and the acquired color signal Dc is used as a reference. Based on this, the correction target printing device having the narrowest color reproduction range is selected as the reference printing device 4 from among the plurality of correction target printing devices 2.

  A method for selecting a correction target printing apparatus having a narrow color reproduction range as the reference printing apparatus 4 will be described in detail. A plurality of different types of correction target printing apparatuses 2 have different color reproduction ranges that can be reproduced. However, the difference in the color reproduction range is, for example, that a certain correction target printing device 2 has a wide color reproduction range that reproduces red, but a narrow color reproduction range that reproduces blue, while another certain correction target printing device. For 2, the color reproduction range that reproduces blue color is wide, but the color reproduction range that reproduces red color is narrow. The features vary depending on each model, and the color reproduction range of all colors (red, blue ...) is comprehensive. Therefore, it is not easy to select the correction target printing apparatus 2 having the narrowest color reproduction range.

  Therefore, in this embodiment, based on the color signal Dc obtained for each correction target printing apparatus 2, the color reproduction area of each correction target printing apparatus 2 is a color space (for example, an international lighting committee) that does not depend on the device. The correction target printing with the narrowest color gamut is achieved by comparing the size of the color space that can be reproduced by each of the correction target printing apparatuses 2 in a three-dimensional manner using the 1976 CIELab space defined by the Society (CIE). The apparatus 2 (the correction target printing apparatus 2 having a color gamut that can be reproduced by another correction target printing apparatus 2) is selected as the reference printing apparatus 4.

  Next, it is determined whether or not the correction target printing apparatus 2 to create the machine difference correction lookup table is the selected reference printing apparatus 4 (step S13). This is because there is no need to perform machine difference correction in the case of the reference printing device 4.

  Next, if it is not the reference printing device 4 (step S13: NO), a machine difference correction lookup table (LUT) is created (step S14).

  Specifically, since the lookup table of each correction target printing device 2 obtained in step S11 is stored in the storage unit 11, the lookup tables of the printing device 3 and the reference printing device 4 are obtained from the lookup table. The color signal Dc (reference output device) shown in the lookup table of the reference printing apparatus 4 shown in FIG. 4A and the lookup table of the printing apparatus 3 shown in FIG. When the color signal Dc of the printing apparatus 3 corresponding to the color signal Dc of the reference printing apparatus 4 is present by comparing with the color signal Dc (printing apparatus) that is present, it corresponds to the color signal Dc of the reference printing apparatus 4 The CxMxYxKx value is associated with the CyMyYyKy value corresponding to the color signal Dc of the printing apparatus 3. On the other hand, when the color signal Dc of the printing apparatus 3 corresponding to the color signal Dc of the reference printing apparatus 4 does not exist, the color signal Dc of the printing apparatus 3 is interpolated and the color signal Dc corresponding to the reference printing apparatus 4 is calculated. Are associated with the CyMyYyKy value corresponding to the color signal Dc of the printing apparatus 3.

  The color signal Dc (reference output device) shown in the lookup table of the reference printing apparatus 4 shown in FIG. 4A and the lookup table of the printing apparatus 3 shown in FIG. 4B are shown. The CxMxYxKx value of the reference printing device 4 and the CyMyYyKy value of the printing device 3 are associated with each other by comparing with the color signal Dc (printing device) that is most approximated (in other words, the color difference ΔE of each color signal is minimized). Also good.

  By associating these, a machine difference correction lookup table (reference printing apparatus 4 → printing apparatus 3) between the reference printing apparatus 4 and the printing apparatus 3 as shown in FIG. 4C can be created. . The created machine difference correction lookup table is stored in the storage unit 11.

  The data signal of each patch is C (cyan: 0 ≦ C ≦ 255), M (magenta: 0 ≦ M ≦ 255), Y (yellow: 0 ≦ Y ≦ 255), K (black: 0 ≦ K ≦ 255). 255). As a color space that does not depend on the device, a 1976 CIELab space defined by the International Commission on Illumination (CIE) is used.

  Since the data signals (C, M, Y, K) of each patch have any value from 0 to 255 as described above, all of these combinations are measured with a spectrocolorimeter or the like. In practice, for example, C (cyan), M (magenta), Y (yellow), and K (black) for each of the six steps (0, 51, 102, 153, 204, and 255). ), A color signal Dc (reference printing apparatus or printing apparatus) corresponding to a total of 1296 patches (that is, the colors of these patches can be reproduced) is acquired. In this case, the obtained patch data signals are interpolated to obtain a desired number of patch data signals and a color signal Dc (reference printing apparatus or printing apparatus) corresponding to the patch data signals. Get it. As the number of combinations of the patch data signal, the color signal Dc (reference printing device), and the color signal Dc (printing device) increases, the machine difference correction lookup table (reference printing device 4 → printing device) shown in FIG. The accuracy of 3) is improved.

  Next, a color conversion lookup table (LUT) is created (step S15).

  Specifically, the color reproduction characteristics of the printing apparatus 3 after the machine difference correction, that is, the color reproduction characteristics of the printing apparatus 3 after matching with the color reproduction characteristics of the reference printing apparatus 4 are changed to the color of the target printing apparatus 5 this time. In order to match the reproduction characteristics, a color conversion lookup table (LUT) is created for the printing apparatus 3 after machine difference correction and the target printing apparatus 5.

  The printing apparatus 3 performs machine difference correction so that the color reproduction characteristic matches that of the reference printing apparatus 4, and each data signal of the printing apparatus 3 is converted to the reference printing apparatus by a machine difference correction lookup table shown in FIG. 4 data signals. Therefore, the color signal corresponding to each data signal of the printing apparatus 3 can be acquired as the color signal Dc of the reference printing apparatus 4 shown in FIG.

  Then, each data signal of the printing apparatus 3 is compared with the color signal Dc of the reference printing apparatus 4 and the color signal Dc by the look-up table of the target printing apparatus 5 shown in FIG. When the color signal Dc of the reference printing apparatus 4 corresponding to the color signal Dc of 5 exists, the CzMzYzKz value corresponding to the color signal Dc of the target printing apparatus 5 and the CxMxYxKx corresponding to the color signal Dc of the reference printing apparatus 4 Associate a value. On the other hand, when the color signal Dc of the reference printing apparatus 4 corresponding to the color signal Dc of the target printing apparatus 5 does not exist, the color signal Dc of the reference printing apparatus 4 is interpolated to calculate the color corresponding to the target printing apparatus 5. The CzMzYzKz value corresponding to the signal Dc and the CxMxYxKx value corresponding to the color signal Dc of the reference printing apparatus 4 are associated with each other.

  By performing this association, a color conversion lookup table (target printing apparatus 5 → correction target printing apparatus 2) of the target printing apparatus 5 and the printing apparatus 3 as the correction target printing apparatus 2 as shown in FIG. 5 is created. Can do. The acquired color conversion lookup table is stored in the storage unit 11.

  On the other hand, if it is determined whether or not the printing apparatus 3 is the reference printing apparatus 4, if the printing apparatus 3 is the reference printing apparatus 4 (step S13: YES), machine difference correction is not performed, and color conversion is performed ( Step S15). Specifically, the color signal Dc of the look-up table of the target printing device 5 and the color signal Dc of the look-up table of the reference printing device 4 described above are compared to correspond to the color signal Dc of the target printing device 5. When the color signal Dc of the reference printing apparatus 4 to be present exists, the CzMzYzKz value corresponding to the color signal Dc of the target printing apparatus 5 and the CxMxYxKx value corresponding to the color signal Dc of the reference printing apparatus 4 are associated with each other. On the other hand, when the color signal Dc of the reference printing apparatus 4 corresponding to the color signal Dc of the target printing apparatus 5 does not exist, the color signal Dc of the reference printing apparatus 4 is interpolated to calculate the color corresponding to the target printing apparatus 5. The CzMzYzKz value corresponding to the signal Dc and the CxMxYxKx value corresponding to the color signal Dc of the reference printing apparatus 4 are associated with each other.

  By performing this association, a color conversion lookup table (target printing device 5 → reference printing device 4) between the target printing device 5 and the reference printing device 4 as shown in FIG. 5 can be created. The acquired color conversion lookup table is stored in the storage unit 11.

[Color matching processing]
Next, the color matching process will be described with reference to FIGS.

  FIG. 7 is a flowchart showing the color matching process, and the process shown by the flowchart is based on the control of the control unit 14 based on a color chart program stored in advance in a ROM or the like (not shown) in the control unit 14. Is executed.

  First, the color matching process is started when either the printing apparatus 3 or the reference printing apparatus 4 gives a print output instruction to perform print output. By starting the processing, it is determined whether or not a print output instruction is given to the reference printing device 4 (step S21).

  Next, when the print output instruction is not issued to the reference printing device 4 (when it is issued to the printing device 3) (step S21: NO), color conversion is performed on the printing device 3. Is performed (step S22).

  More specifically, the color reproduction characteristic of the printing apparatus 3 is matched with the color reproduction characteristic of the target printing apparatus 5 based on the color conversion lookup table of FIG.

  Next, machine difference correction is performed to match the color reproduction characteristics of the printing apparatus 3 with the reference printing apparatus 4 (step S23).

  In step S22, the color reproduction characteristics of the printing apparatus 3 are regarded as the color reproduction characteristics of the reference printing apparatus 4, and the color reproduction characteristics are matched with the target printing apparatus 5. Therefore, in step S23, the color reproduction characteristics of the printing apparatus 3 are output as a reference. Match the color reproduction characteristics of device 4. Specifically, in order to match the color reproduction characteristics of the printing apparatus 3 with the color reproduction characteristics of the reference printing apparatus 4, based on the machine difference correction lookup table (LUT) of FIG. Then, machine difference correction is performed to match the color reproduction characteristics of the printing apparatus 3 with the color reproduction characteristics of the reference printing apparatus 4.

  Next, print output is performed (step S24).

  By matching the color reproduction characteristics of the printing apparatus 3 with the color reproduction characteristics of the target printing apparatus 5 by the above process, the printed apparatus 3 can obtain a printed matter similar to that printed by the target printing apparatus 5. Become.

  On the other hand, if it is determined in step S21 whether or not it is the reference output device 4, if the print output instruction is given to the reference printing device 4 (step S21: YES), color conversion is performed. Performed (step S25).

  Based on the color conversion lookup table (LUT) of FIG. 5 stored in the storage unit 11 in the same manner as described above, the color reproduction characteristics of the reference printing apparatus 4 are matched with the color reproduction characteristics of the target printing apparatus 5.

  Next, print output is performed (step S24).

  By matching the color reproduction characteristics of the reference printing apparatus 4 with the color reproduction characteristics of the target printing apparatus 5 by the above-described steps, the printed matter similar to that printed by the target printing apparatus 5 can be obtained by the reference printing apparatus 4 as well. It will be.

  The case where printing is performed with the same characteristics as the color reproduction characteristics of the target printing apparatus 5 when printing in the correction target printing apparatus 2 has been described. However, the present invention is not limited to printing, and the color reproduction characteristics of a plurality of monitors are used. A color matching device can also be used for matching with the target color reproduction characteristics of the monitor.

Variant 1
A modification of the lookup table creation process and the color matching process will be described with reference to FIGS. Only parts different from the above-described embodiment will be described.

  FIG. 8 is a flowchart showing lookup table creation processing. As described above, in steps S13 and S15 in the lookup table creation process shown in FIG. 6, it is determined whether or not the printer is the reference printing device (step S13). : YES) and when it is not the reference printing device 4 (step S13: NO), the color conversion lookup table is created (step S15). In step S33: NO), a color conversion lookup table is not created. In that case, color conversion is performed for the case of not the reference printing apparatus 4 by using the color conversion lookup table created in the case of the reference printing apparatus 4 (step S33: YES). Specifically, as shown in FIG. 9, when a print output instruction to perform print output is issued by either the printing apparatus 3 or the reference printing apparatus 4, the color matching process is started, and the print output instruction is the reference. Regardless of whether it is for the printing device 4 or the printing device 3, if it is the reference printing device 4 in step S41 (step S33: YES), the color conversion lookup table created is used to perform color conversion. (Step S41). Thereafter, if it is not the reference printing device 4 (step S42: NO), machine difference correction is performed (step S43), and printing output is performed (step S44).

  In this way, when the print output instruction is not the reference printing apparatus 4, it is possible to omit the creation of the color conversion lookup table after creating the machine difference correction lookup table, and the color matching process can be performed more easily. It can be carried out.

Variant 2
As shown in FIG. 10, when the print output instruction is not issued to the reference printing apparatus 4, the color conversion process and the machine difference correction process can be combined (step S52). In this method, as in the case described above, a lookup table for the printing device 3, the reference printing device 4, and the target printing device 5 is created, and the lookup table for the target printing device → the lookup table for the reference printing device → printing. The lookup tables are combined in the order of the color conversion processing of the lookup table of the apparatus to create a lookup table (target printing apparatus 5 → printing apparatus 3). By using this lookup table (device link profile) and performing color conversion processing, a printed matter similar to that printed by the target printing device 5 can be easily obtained in either the printing device 3 or the reference printing device 4. Will be.

1 is a schematic diagram showing a color matching device and each printing device of the present invention. It is a block diagram which shows schematic structure of the color matching apparatus of this invention. (A) is a lookup table of the correction target printing apparatus, and (B) is a lookup table of the target printing apparatus. (A) is a lookup table of the reference printing apparatus, (B) is a lookup table of the printing apparatus, and (C) is a correction target lookup table. It is a color conversion lookup table. It is a flowchart which shows a look-up table creation process. It is a flowchart which shows a color matching process. It is a flowchart which shows a look-up table creation process. It is a flowchart which shows a color matching process. It is a flowchart which shows a color matching process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Color matching apparatus 2 ... Correction object printing apparatus 3 ... Printing apparatus 4 ... Reference | standard printing apparatus 5 ... Target printing apparatus 11 ... Memory | storage part 12 ... Display part 13 ...・ External device connection unit 14 ... Control unit 15 ... Bus

Claims (12)

In the color matching device that matches the output characteristics of the plurality of correction target output devices to the output characteristics of the target output device,
Selecting means for selecting a reference output device from the plurality of correction target output devices;
Machine difference correction means for matching the output characteristics of the correction target output device other than the reference output device to the output characteristics of the reference output device;
Color conversion means for adjusting the output characteristics of the output device to be corrected in accordance with the output characteristics of the reference output device by the machine difference correction means and the output characteristics of the reference output device, respectively, to the output characteristics of the target output device,
A color matching device characterized by comprising: The color matching device according to claim 1,
The color matching device, wherein the selection unit selects an output device having the narrowest color gamut from the plurality of correction target output devices as a reference output device. In the color matching apparatus according to claim 1 or 2,
The color matching apparatus, wherein the output characteristic is a color reproduction characteristic. The color matching device according to claim 3,
Each of the output devices is a printing device externally connected to the color matching device,
The machine difference correcting means is
A reference color signal of each patch obtained by measuring each patch of a chart composed of a plurality of patches printed by the reference output device, and a plurality printed by the correction target output device other than the reference output device Machine difference correction lookup of the reference output device and the correction target output device other than the reference output device based on the color signal of each patch acquired by measuring each patch of the chart of Machine difference correction lookup table creation means for creating a table;
First conversion means for matching the color reproduction characteristics of the correction target output device other than the reference output device with the color reproduction characteristics of the reference output device based on the machine difference correction lookup table;
A color matching device characterized by comprising: In the color matching device according to claim 3 or 4,
The color conversion means includes
The target color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches printed by the target output device, and the output characteristics of the reference output device are matched by the machine difference correction unit. Based on the reference color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches printed by the correction target output device or the reference output device, the target output device, Color conversion lookup table creating means for creating a correction target output device or a color conversion lookup table for the reference output device matched to the output characteristics of the reference output device by machine difference correction means;
Based on the color conversion look-up table, the color reproduction characteristics of the output device to be corrected or the color reproduction characteristics of the reference output device matched with the output characteristics of the reference output device by the machine difference correction unit are reproduced. A second conversion means adapted to the characteristics;
A color matching device characterized by comprising: The color matching device according to any one of claims 1 to 5,
The color matching apparatus, wherein the color signal is a coordinate value in CIELab space or a coordinate value in CIEXYZ space. In a color matching method for matching the output characteristics of a plurality of correction target output devices to the output characteristics of a target output device,
A selection step of selecting a reference output device from the plurality of correction target output devices;
A machine difference correction step for adjusting the output characteristics of the correction target output device other than the reference output device to the output characteristics of the reference output device;
A color conversion step for adjusting the output characteristics of the output device to be corrected according to the output characteristics of the reference output device by the machine difference correction step, and the output characteristics of the reference output device, respectively, to the output characteristics of the target output device;
A color matching method comprising: The color matching method according to claim 7,
In the color matching method, the selecting step selects an output device having the narrowest color gamut from the plurality of correction target output devices as a reference output device. The color matching method according to claim 7 or 8,
The color matching method, wherein the output characteristic is a color reproduction characteristic. The color matching method according to claim 9,
Each of the output devices is a printing device externally connected to the color matching method,
The machine difference correction step includes
A reference color signal of each patch obtained by measuring each patch of a chart composed of a plurality of patches printed by the reference output device, and a plurality printed by the correction target output device other than the reference output device Machine difference correction lookup of the reference output device and the correction target output device other than the reference output device based on the color signal of each patch acquired by measuring each patch of the chart of Machine difference correction lookup table creation process to create a table,
A first conversion step of matching a color reproduction characteristic of the correction target output device other than the reference output device with a color reproduction characteristic of the reference output device based on the machine difference correction lookup table;
A color matching method comprising: In the color matching method according to claim 9 or 10,
The color conversion step includes
The target color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches printed by the target output device, and the output characteristics of the reference output device according to the machine difference correction step Based on the reference color signal of each patch obtained by measuring each patch of the chart composed of a plurality of patches printed by the correction target output device or the reference output device, the target output device, A color conversion lookup table creation step of creating a correction target output device or a color conversion lookup table of the reference output device matched to the output characteristics of the reference output device by a machine difference correction step;
Based on the color conversion look-up table, the color reproduction characteristics of the output device to be corrected or the color reproduction characteristics of the reference output device matched to the output characteristics of the reference output device by the machine difference correction step are reproduced. A second conversion step to match the characteristics;
A color matching method comprising: The color matching method according to any one of claims 7 to 11,
The color matching method, wherein the color signal is a coordinate value in CIELab space or a coordinate value in CIEXYZ space.

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