JP7119845B2 - Image processing device and program - Google Patents

Description

The present invention relates to an image processing apparatus and program.

At present, in addition to color materials equivalent to process colors such as C (cyan), M (magenta), Y (yellow), and K (black) in image forming apparatuses, clear, fluorescent pink, metallic, etc. 2. Description of the Related Art There is known an image forming apparatus that forms an image on a recording medium by mounting special color materials.

On the other hand, in order to suppress changes in the quality of an image formed on a recording medium due to changes in gradation characteristics over time, the relationship between the factors that change the gradation characteristics and changes in the gradation characteristics are associated in advance, and image formation is performed. There is sometimes a density calibration technique for correcting the density of image data (Patent Document 1).

Conventionally, the gradation characteristics are measured by reading a chart formed on a recording medium with a spectrophotometer and converting the spectral reflectance information obtained as the reading result into a density value.

However, with the conventional density calibration technique, density calibration can be performed for a special color material whose gradation characteristics have been measured in advance, but for a special color color material whose gradation characteristics have not been measured in advance, Proper density calibration cannot be performed.

In addition, unlike CMYK colors, such as fluorescent colors and metallic colors, there are color materials that have a weak causal relationship between changes in density and gradation characteristics due to the effects of fluorescent components and diffuse reflection of light. It is difficult to perform appropriate density calibration with the method of obtaining only the density value from , and performing density calibration.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image processing apparatus and program that enable density calibration for a wide variety of recording media and color materials.

In order to solve the above-described problems and achieve the object, the present invention obtains spectral reflectance information about an image formed on a recording medium using a special color material, and uses the obtained spectral reflectance information as a a calculating unit that calculates a plurality of colorimetric information based on the colorimetric information; a determining unit that determines one colorimetric information from the plurality of colorimetric information calculated by the calculating unit; and the colorimetric information determined by the determining unit. and a parameter generation unit that generates a gradation parameter used when correcting the gradation characteristic of the special color material based on the color information.

According to the present invention, it is possible to perform density calibration for a wide variety of recording media and color materials.

FIG. 1 is a diagram of an example of an image processing system according to an embodiment. FIG. 2 is a diagram showing an example of the hardware configuration of the DFE. FIG. 3 is a block diagram showing functions of the CPU of the DFE. FIG. 4 is a diagram showing functional blocks of a special color colorant gradation parameter generator. FIG. 5 is a diagram showing an example of a dedicated chart for measurement with a spectrophotometer. FIG. 6 is a diagram illustrating details of processing performed by the colorimetric information calculation unit. FIG. 7 is a diagram showing an example of spectral reflectance information. FIG. 8 is a diagram illustrating an example of colorimetric information calculated by the colorimetric information calculator. FIG. 9 is a diagram showing functional blocks of a used colorimetric information determination unit. FIG. 10 is a diagram showing an example of a table of evaluation coefficients for each piece of measurement information. FIG. 11 is a diagram illustrating an example of an evaluation value for each colorimetric information calculated by the usage information determining unit; FIG. 12 is a diagram showing functional blocks included in a correction target generation unit. FIG. 13 is a diagram showing an example of reference target shape information. FIG. 14 is a diagram showing an example of a specific shape indicated by reference target shape information. FIG. 15 is a diagram showing an example of reference target shape information after non-normalization processing. FIG. 16 is a diagram showing an example of a specific shape indicated by reference target shape information after non-normalization processing. FIG. 17 is a diagram illustrating functional blocks included in a correction parameter generation unit; FIG. 18 is a diagram showing an example of gradation correction parameter information generated by the correction parameter generation unit. FIG. 19 is a flowchart showing the flow of processing for generating gradation correction parameter information.

Exemplary embodiments of an image processing apparatus and a program will be described in detail below with reference to the accompanying drawings. An electrophotographic image forming apparatus will be described below as an example of the image forming apparatus, but the image forming apparatus is not limited to this, and may be an inkjet image forming apparatus.

(Embodiment)
[Explanation of configuration of image processing system]
FIG. 1 is a diagram illustrating an example of an image processing system 100 according to an embodiment. As shown in FIG. 1 , the image processing system 100 includes a computer 200 , a DFE (Digital Front End) 300 , an image forming apparatus 400 and a spectrophotometer 500 .

The computer 200 is a device for creating a print job including image data to be executed by the image forming apparatus 400 by the user, and transmits the created print job to the DFE 300 .

The DFE 300 is an example of an image processing apparatus according to the present invention, and is based on a print job received from the computer 200. The DFE 300 generates drawing data (raster data) used when the image forming apparatus 400 forms an image. Image Processor) engine. The DFE 300 transmits the generated drawing data to the image forming apparatus 400 .

The image forming apparatus 400 forms an image on a recording medium based on the drawing data received from the DFE 300 . The image forming apparatus 400 uses C (cyan), M (magenta), Y (yellow), and K (black) color materials corresponding to CMYK process colors, as well as clear, white, fluorescent pink, A special color material such as metallic is mounted, and an image is formed on the recording medium.

The spectrophotometer 500 reads an image formed on a recording medium by the image forming apparatus 400 , acquires spectral reflectance information indicating the spectral reflectance, and transmits the acquired spectral reflectance information to the DFE 300 . Although the spectrophotometer 500 is connected to the DFE 300 in this embodiment, it may be connected to the computer 200 or the image forming apparatus 400 .

Schematically, the image forming apparatus 400 prints a dedicated chart 600 (see FIG. 5) using a special color material, and spectral reflectance information obtained by measuring the dedicated chart 600 on which the DFE 300 is printed. is received from spectrophotometer 500 .

Although the DFE 300 and the image forming apparatus 400 are shown as different apparatuses in this embodiment, the present invention is not limited to this. It may have the functions of the DFE 300 . For example, when the computer 200 has the functions of the DFE 300, a configuration corresponding to the functions of the DFE 300 can be understood as an image processing device. Also, the functions of the DFE 300 may be shared by the computer 200 and the image forming apparatus 400 .

Next, the hardware configuration of the DFE 300 is described.

FIG. 2 is a diagram showing an example of the hardware configuration of the DFE 300. As shown in FIG. As shown in FIG. 2, the DFE 300 includes a CPU (Central Processing Unit) 301 that serves as a control subject. The DFE 300 includes a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, a HDD (Hard Disk Drive) 304, an SSD (Solid State Drive) 305, an I/F 306, a liquid crystal display (LCD) 307, and an operation unit 308. Each part is connected to the CPU 301 via the bus 309 .

The CPU 301 uses the RAM 303 as a work area and executes programs stored in the ROM 302, HDD 304, SSD 305, etc., thereby realizing control and image processing of the image forming apparatus 400. FIG.

The HDD 304 and SSD 305 function as storage units that store print jobs sent from the computer 200 and spectral reflectance information received from the spectrophotometer 500 . Also, the program executed by the CPU 301 may be stored.

The I/F 306 communicably connects the CPU 301, HDD 304, SSD 305, etc. with the LCD 307 and the operation unit 308. FIG.

The LCD 307 is an example of a display that outputs information to the user.

An operation unit 308 is a device such as a touch panel, a keyboard, or a mouse used when the user selects information displayed on the LCD 307 or operates the DFE 300 .

[Explanation of functional configuration of DFE]
Next, functions realized by the CPU 301 of the DFE 300 executing programs stored in the ROM 302, HDD 304, SSD 305, etc. will be described.

FIG. 3 is a block diagram showing functions of the CPU 301 of the DFE 300. As shown in FIG. The DFE 300 includes a print image generation unit 401 , a gradation correction unit 402 , a halftone processing unit 403 , a gradation correction parameter generation unit 404 , a special color material gradation correction parameter generation unit 405 , and a storage unit 406 .

Based on the image data included in the print job sent from the computer 200 , the print image generation unit 401 generates drawing data used when the image forming apparatus 400 performs image formation. The print image generation unit 401 transmits the generated drawing data to the gradation correction unit 402 .

The gradation correction unit 402 generates target gradation characteristics (correction target information) for gradation correction, and corrects the gradation values in the drawing data received from the print image generation unit 401 . By correcting the gradation value, it is possible to correct a change in gradation characteristics caused by a change in the environment in which the image forming apparatus is installed or by using a special color material. When performing tone correction processing, the tone correction unit 402 uses tone correction parameters generated by the tone correction parameter generating unit 404 using a known method for CMYK color materials. The gradation correction unit 402 uses data generated by a special color material gradation correction parameter generation unit 405, which will be described later, for the special color material. The tone correction unit 402 transmits the corrected drawing data to the halftone processing unit 403 .

The halftone processing unit 403 performs screen processing in a format suitable for the image forming apparatus 400 based on the corrected drawing data received from the tone correction unit 402 . The halftone processing unit 403 transmits the screen-processed rendering data to the image forming apparatus 400 .

Next, with reference to FIG. 4, functions of the special color material gradation correction parameter generation unit 405 will be described.

FIG. 4 is a diagram showing functional blocks of the special color material tone correction parameter generation unit 405. As shown in FIG. The special color colorant gradation correction parameter generation unit 405 includes a colorimetric information calculation unit 501 , a use colorimetric information determination unit 502 , a correction target generation unit 503 , and a correction parameter generation unit 504 .

The colorimetric information calculation unit 501 is an example of a calculation unit, and acquires the gradation characteristics of the special color material in the image forming apparatus 400 . The colorimetric information calculation unit 501 calculates a measurement value for each colorimetric information from the spectral reflectance information received from the spectrophotometer 500 , and transmits the measured value to the colorimetric information determination unit 502 to be used and the correction parameter generation unit 504 . Details of the colorimetric information calculation unit 501 will be described later.

Further, the colorimetric information calculation unit 501 may determine whether or not calibration has been previously performed for the combination of the recording medium and the special color material when the dedicated chart 600 is printed. 200 or an operation unit (not shown) of the image forming apparatus 400 to input whether or not the combination has been previously calibrated.

For example, the storage unit 406 stores in the HDD 304 or the SSD 305 correction target information (target gradation characteristics during gradation correction) generated previously by the gradation correction unit 402 . The colorimetric information calculation unit 501 determines that the combination of the recording medium and the special color material when printing the dedicated chart 600 has been previously calibrated (the colorimetric information has been calculated). In this case, the later-described correction target generation unit 503 can acquire previously generated correction target information by causing the storage unit 406 to read it from the HDD 304 or SSD 305 .

FIG. 5 is a diagram showing an example of a dedicated chart 600 measured by the spectrophotometer 500. As shown in FIG. A chart 600 shown in FIG. 5 is a dedicated chart used for gradation correction of a special color material. In this dedicated chart 600, there are a plurality of patches in which the loading amount of the coloring material on the printing medium ranges from 0% to 100% per unit area for the single color material of the special color. Note that the dedicated chart 600 does not have a specified number or arrangement of patches as long as the characteristics of the intermediate gradation of the special color material can be grasped. It preferably contains a 0% patch with no colorant and a 100% patch with solid colorant. For example, a patch with a color material loading amount of 0% corresponds to a gradation value of "0", and a patch with a loading amount of 100% corresponds to a gradation value of "255". Regarding the spectral reflectance information read from the dedicated chart 600, the greater the difference between the minimum values of the gradation values of the patches on the chart 600, the better the accuracy of the gradation correction in the DFE 300 of the present embodiment. .

In this embodiment, the gradation value is a value from 0 to 255, but is not limited to this, and may be a value from 0 to 1024 as long as it represents the density. In this case, among the values representing the density, the smallest value corresponds to the patch with the loading amount of "0%", and the largest value corresponds to the patch with the loading amount of "100%". Each of the values between the minimum and maximum values may appropriately correspond to patches between 0 and 100%.

Next, functions of the colorimetric information calculation unit 501 will be described.

FIG. 6 is a diagram showing functional blocks included in the colorimetric information calculation unit 501. As shown in FIG. The colorimetric information calculator 501 includes a colorimetric information receiver 601 and a colorimetric information calculator 602 .

The colorimetric information receiving unit 601 receives spectral reflectance information, which is the measurement result of the dedicated chart 600 measured by the spectrophotometer 500 . Alternatively, the user may input measurement data corresponding to spectral reflectance information measured by the spectrophotometer 500 to the DFE 300 using the computer 200 .

FIG. 7 is a diagram showing an example of spectral reflectance information. As shown in FIG. 7, the spectral reflectance for each gradation value differs depending on the wavelength of light when the chart 600 is measured.

The colorimetric information calculation unit 602 calculates a plurality of pieces of colorimetric information based on the spectral reflectance information or measurement data received by the colorimetric information receiving unit 601 and transmits the colorimetric information to the use colorimetric information determination unit 502 .

FIG. 8 is a diagram showing an example of colorimetric information calculated by the colorimetric information calculation unit 602. As shown in FIG. Here, the colorimetric information is an item calculated from spectral reflectance information such as L*a*b* color space, XYZ color space, and spectral reflectance in FIG. The colorimetric information includes density information when reading the chart 600, color space information such as the L*a*b* color space and the XYZ color space, as well as the colors of the recording medium itself (recording medium colors) and the chart 600. contains relative color information such as color difference ΔE and chroma difference ΔC.

Note that a list of a plurality of colorimetric information that can be calculated by the colorimetric information calculation unit 602 may be displayed on the LCD 307 to allow the user to select colorimetric information to be calculated. Alternatively, a list of a plurality of colorimetric information that can be calculated by the colorimetric information calculation unit 602 may be displayed on the LCD 307, and items to be calculated by the user may be deleted. For example, when performing density calibration for fluorescent colors or metallic colors, it is not preferable to use density colorimetric information for density calibration. Therefore, delete the density item in advance, or select an item other than density. You may do so.

Next, the use colorimetric information determination unit 502 will be described.

The used colorimetric information determination unit 502 is an example of a determination unit, and determines the gradation from the combination of the type of recording medium on which the dedicated chart 600 is printed and the special color material used to print the dedicated chart 600 . Determines the colorimetric information to be used for correction. The used colorimetric information determination unit 502 sends the type of printing medium, the special color material, and the determined colorimetric information to the correction target generation unit 503 .

Next, functions provided in the use colorimetric information determination unit 502 will be described.

FIG. 9 is a diagram showing functional blocks of the used colorimetric information determining unit 502. As shown in FIG. The used colorimetric information determination unit 502 includes a dynamic range calculation unit 901 and a used colorimetric information selection unit 902 .

The dynamic range calculation unit 901 calculates the absolute value of the difference between the measured value of the chart with the colorant load amount of 0% and the colorant load amount of 100% for the colorimetric information received from the colorimetric information calculation unit 501. Calculate dynamic range. The dynamic range calculation unit 901 transmits the calculated dynamic range to the colorimetric information selection unit 902 to be used.

The used colorimetric information selection unit 902 calculates an evaluation value for each of the plurality of colorimetric information received from the dynamic range calculation unit 901 .

In the present embodiment, for the sake of explanation, the value calculated from the spectral reflectance information by the colorimetric information calculation unit 501 is also used as the colorimetric information. However, with the above-described evaluation value calculation method, since the numerical scale differs for each colorimetric information, it is not possible to appropriately compare the evaluation values.

Therefore, in order to appropriately compare evaluation values calculated for each colorimetric information, in the present embodiment, an evaluation coefficient N is set for each colorimetric information, and an evaluation value D is calculated by the following equation.

D=|V100−V0|/N (1)
V100: measured value corresponding to a patch with 100% colorant loading
V0: Measured value corresponding to a patch with a colorant loading of 0%
N: Evaluation coefficient

By calculating the evaluation value D using the above formula (1), it is possible to appropriately compare the evaluation values of the colorimetric information having different numerical scales.

FIG. 10 is a diagram showing an example of a table of evaluation coefficients N for each piece of measurement information. In the present embodiment, the maximum dynamic range that can be taken for each colorimetric information is assumed and set. For example, for L*, the theoretical numerical range is 0 to 100, so the evaluation coefficient N is set to 100.

This evaluation coefficient N may be stored in the HDD 304 or SSD 305 as a table. In this case, when calculating the evaluation value, the used colorimetric information selection unit 902 requests the storage unit 406 to transmit the table of FIG. It transmits to the selection unit 902 . The present invention is not limited to this, and the user may input the evaluation coefficient N from a computer, or may input it from an operation unit (not shown) of the image forming apparatus 400 .

FIG. 11 is a diagram showing an example of an evaluation value for each colorimetric information calculated by the used colorimetric information selection unit 902. As shown in FIG. The used colorimetric information selection unit 902 selects colorimetric information with a high evaluation value based on the calculated evaluation values shown in FIG. 11 and transmits the selected colorimetric information to the correction target generation unit 503 . In FIG. 11, colorimetric information with a higher evaluation value indicates a larger change in the measured value, and the larger the change in the measured value, the more appropriately the gradation parameter for density calibration can be calculated. Therefore, in this embodiment, the colorimetric information selection unit 902 selects the colorimetric information with the highest evaluation value. In the case of this embodiment, since the value of a* is the largest, the used colorimetric information selection unit 902 selects a*.

The colorimetric information selection unit 902 may display a list of evaluation values on the LCD 307 to allow the user to select colorimetric information.

Next, the correction target generation unit 503 will be described.

The correction target generating unit 503 is an example of a target generating unit, and the colorimetric information (a* in the example of this embodiment; hereinafter referred to as a*) received from the use colorimetric information determining unit 502 Based on this, the gradation correction unit 402 generates correction target information that has the target gradation characteristics in the gradation correction. When generating the correction target information, the storage unit 406 reads out the reference target shape information, which is the shape information of the reference target that serves as the reference of the gradation characteristics, stored in the HDD 304 or the SSD 305 . Send. The correction target generation unit 503 uses the reference target information received from the storage unit 406 to generate correction target information. The correction target generation unit 503 transmits the generated correction target information, the type of recording medium, and the type of the special color material to the storage unit 406 and the correction parameter generation unit 504 .

Next, functions of the correction target generation unit 503 will be described.

FIG. 12 is a diagram showing functional blocks included in the correction target generation unit 503. As shown in FIG. The correction target generation section 503 includes a reference target shape acquisition section 1201 and a target correction section 1202 .

The reference target shape acquisition unit 1201 requests the storage unit 406 for reference target shape information corresponding to a*. The storage unit 406 reads the reference target shape information corresponding to the colorimetry information from the HDD 304 or the SSD 305 and transmits it to the reference target shape acquisition unit 1201 .

Here, FIG. 13 is a diagram showing an example of reference target shape information, and FIG. 14 is a diagram showing an example of a specific shape indicated by the reference target shape information. As shown in FIG. 13, the reference target has a numerical value of 0.000 corresponding to a patch with a loading amount of coloring material of 0% and a numerical value of 1.000 corresponding to a patch having a loading amount of coloring material of 100%. , and represents the shape of the halftones in the range of values from 0.000 to 1.000 for other payloads. The reference target shape information is, for example, a "linear shape (shape 1)" such as a straight line connecting patches with a loading amount of coloring material of 0% and 100%. The HDD 304 and the SSD 305 store patterns such as an “upwardly convex shape (shape 2)” with large values, and a “downwardly convex shape” with smaller intermediate gradation values than the linear shape. Color information and reference target shapes are associated.

In this embodiment, by using the shape of the reference target according to the colorimetric information, it is possible to appropriately generate tone parameters, which will be described later. This is because the color reproducibility of intermediate tones differs depending on the colorimetric information.

In this embodiment, the reference target shape acquisition unit 1201 requests the storage unit 406 for the reference target shape information corresponding to the colorimetric information determined by the use colorimetric information determination unit 502, and receives the reference target shape information from the storage unit 406. However, the reference target shape information corresponding to the colorimetric information may be input by the user from the computer 200 or may be input from an operation unit (not shown) of the image forming apparatus 400 .

With respect to the normalized reference target shape information, the target correction unit 1202 obtains the measured value of the patch with a colorant loading amount of 0% per unit area and the colorant loading amount of 100% per unit area for a*. % measurements are used to generate non-normalized reference target shape information (corrected target information) corresponding to a*. In this non-normalization process, the target value of each gradation is calculated by the following formula (2) for each numerical value of the reference target shape information.

Tn=TSn(V100-V0)+V0 (2)
Tn: Numerical value of correction target information for n tone target V100: Colorimetric value when the loading amount of colorant in colorimetric information is 100%
V0: Colorimetric value when the loading amount of coloring material in the colorimetric information is 0% TSn: A numerical value corresponding to n% of the loading amount of coloring material in the reference target shape information

The target correction unit 1202 transmits the numerical value Tn of (correction target information) calculated by the equation (2) to the correction parameter generation unit 504 and the storage unit 406 and transmits a* to the storage unit 406 .

Here, FIG. 15 is a diagram showing an example of reference target shape information (correction target information) after non-normalization processing, and FIG. It is a figure which shows an example of a shape. As shown in FIGS. 15 and 16, the normalized reference target of 0.000 to 1.000 shown in FIG. 13 maintains the shape plotted in FIG. 14 and has the same dynamic range as the colorimetric information. It can be seen that it has been denormalized to the correction target with Further, as the difference between the minimum value and the maximum value of each patch formed on the dedicated chart 600 increases, the number of correction target values that can be calculated increases, and the number of correction parameters calculated later increases. accuracy is improved.

Next, the correction parameter generator 504 will be described.

The correction parameter generation unit 504 is an example of a parameter generation unit, and based on the colorimetric information (a*) received from the colorimetric information calculation unit 501 and the correction target information received from the correction target generation unit 503, The gradation correction parameter information (gradation parameter) is generated so that the gradation characteristic of the special color material of the image forming apparatus 400 substantially matches the shape of the correction target information. The correction parameter generation unit 504 transmits the generated gradation correction parameter information to the storage unit 406 along with the type of recording medium and the type of special color material.

Next, the correction parameter generator 504 will be described.

FIG. 17 is a diagram showing functional blocks included in the correction parameter generation unit 504. As shown in FIG.

The correction parameter generation unit 504 generates tone correction parameter information from the colorimetric information (a*) and the correction target information Tn received from the correction target generation unit 503 . Specifically, it will be described with reference to FIG. 18 .

FIG. 18 is a diagram for explaining tone correction parameter information.

The graph shown in FIG. 18A is a* determined by the colorimetric information determination unit 502 and correction target information Tn, and the graph on the right is tone correction parameter information finally generated. Arrows in the graph shown in FIG. 18A represent the process of generating tone correction parameter information. is associated with In FIG. 18A, the gradation value of the colorimetric information having the same value as the correction target gradation value "20" is "37". In other words, it can be seen that the image forming apparatus 400 should actually print the input value of "37" in order to realize the numerical value of the gradation value "20" of the correction target information. When this correspondence information is calculated for all tone values, tone correction parameter information as shown in the graph of FIG. 18(b) is obtained.

Note that the correction parameter generation unit 504 stores the colorimetric information, the type of recording medium, and the type of coloring material of the special color in the HDD 304 or SSD 305 in the storage unit 406 if the gradation correction has been performed before. Gradation correction parameter information can be generated by reading the stored correction target information and transmitting it to the correction parameter generation unit 504 . In other words, when the combination of the recording medium and the special color material is new, the special color colorant gradation correction parameter generation unit 405 generates the colorimetric information calculation unit 501, the use colorimetric information determination unit 502, and the correction target generation unit 503. , the function of the correction parameter generation unit 504 is used to generate tone correction parameter information.

As described above, the storage unit 406 reads the reference target shape information stored in the HDD 304 or the SSD 305 and transmits it to the correction target generation unit 503. In addition, the storage unit 406 stores the correction target information received from the correction target generation unit 503 and the recording medium. , the color material type of the special color, and the gradation correction parameter information received from the correction parameter generation unit are associated with each other and stored in the HDD 304 or SSD 305 .

Next, a characteristic process flow among the processes performed by the DFE 300, which is the image processing apparatus according to the present embodiment, will be described. FIG. 19 is a flowchart showing the flow of processing for generating gradation correction parameter information.

As shown in FIG. 19, in S1901, when the user executes the special color material calibration, the colorimetric information calculation unit 501 of the DFE 300 converts the image data of the dedicated chart 600 for measurement shown in FIG. The data is sent to the forming apparatus 400, and the dedicated chart 600 is printed.

In S<b>1902 , the colorimetric information calculation unit 501 of the DFE 300 receives spectral reflectance information, which is the colorimetry result of the spectrophotometer 500 from the user.

In S1903, the colorimetric information calculation unit 501 of the DFE 300 calculates a plurality of pieces of measurement information such as L*a*b* and XYZ based on the received spectral reflectance information.

In S1904, the colorimetric information calculation unit 501 of the DFE 300 determines whether or not calibration has been performed before for the combination of the type of printing medium and the type of special color material when the dedicated chart 600 was printed. to decide. If the colorimetric information calculation unit 501 of the DFE 300 determines that calibration has been performed previously for the combination of the type of printing medium and the type of coloring material of the special color, that is, it determines that the correction target has been created previously. If so (No in S1904), the process proceeds to S1909. On the other hand, if the colorimetric information calculation unit 501 of the DFE 300 determines that calibration has not been executed before, that is, if it determines that a new correction target is created (Yes in S1904), the process advances to S1905. .

In S<b>1905 , the used colorimetric information determining unit 502 of the DFE 300 determines colorimetric information with the largest evaluation value from various colorimetric information calculated by the colorimetric information calculating unit 501 .

In S1906, the correction target generation unit 503 of the DFE 300 generates correction target information used for calibration based on the colorimetric information determined in S1905. The generated correction parameter information is stored in HDD 304 or SSD 305 by storage means 406 of DFE 300 .

In S1907, the correction parameter generation unit 504 of the DFE 300 generates tone correction parameter information based on the correction target information.

In S<b>1908 , the generated gradation correction parameter information is stored in the HDD 304 or SSD 305 by the storage unit 406 of the DFE 300 .

On the other hand, in S1909, the storage unit 406 of the DFE 300 reads out previously generated correction target information from the HDD 304 or SSD 305 based on the type of recording medium on which the dedicated chart 600 is printed and the type of special color material, The data is transmitted to the generation unit 504, and the process proceeds to S1907.

As described above, according to the present embodiment, appropriate colorimetric information to be used for density calibration is determined from spectral reflectance information for a particular color material or recording medium whose gradation characteristics have not been measured in advance. Therefore, appropriate density calibration can be performed.

The functions of each embodiment of the present invention can be realized by a computer-executable program written in a legacy programming language such as assembler, C, C++, C#, Java (registered trademark), or an object-oriented programming language. , programs for executing the functions of each embodiment can be distributed through telecommunication lines.

Programs for executing the functions of each embodiment of the present invention include ROM, EEPROM (Electrically Erasable Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), flash memory, flexible disk, CD ( Compact Disc)-ROM, CD-RW (Re-Writable), DVD-ROM, DVD-RAM, DVD-RW, Blu-ray disc, SD card, MO (Magneto-Optical disc), etc. You can also distribute

Furthermore, part or all of the functions of each embodiment of the present invention can be implemented on a programmable device (PD) such as an FPGA (Field Programmable Gate Array), or can be implemented as an ASIC. , circuit configuration data (bit stream data) downloaded to the PD to realize the functions of each embodiment on the PD, HDL (Hardware Description Language) for generating circuit configuration data, VHDL (Very High Speed Integrated Circuits (Hardware Description Language), Verilog-HDL, etc., and can be distributed on a recording medium.

Although the embodiments according to the present invention have been described above, the present invention is not limited to the above-described embodiments as they are. can. Also, various inventions can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiments.

300 image processing device 307 display unit 501 calculation unit 502 determination unit 504 parameter generation unit

JP 2017-138518 A

Claims (7)

a calculation unit that acquires spectral reflectance information related to an image formed on a recording medium using a special colorant, and calculates a plurality of pieces of colorimetric information based on the acquired spectral reflectance information;
a determination unit that determines one piece of colorimetric information from the plurality of pieces of colorimetric information calculated by the calculation unit;
a parameter generation unit that generates a gradation parameter used when correcting the gradation characteristics of the special color material based on the colorimetric information determined by the determination unit;
An image processing device comprising: each of the plurality of colorimetric information calculated by the calculation has a plurality of values;
The determining unit calculates an evaluation value based on the minimum value and the maximum value of the colorimetric information for each of the plurality of colorimetric information calculated by the calculating unit, and calculates one evaluation value based on the calculated evaluation value. determine the colorimetric information,
2. The image processing apparatus according to claim 1, wherein: The determining unit calculates an evaluation value using a coefficient set for each of the plurality of colorimetric information calculated by the calculating unit.
3. The image processing apparatus according to claim 2, wherein: wherein the plurality of colorimetric information calculated by the calculating unit includes at least one of L*a*b* color space, XYZ color space, and spectral reflectance;
4. The image processing apparatus according to any one of claims 1 to 3, characterized by: a display unit for displaying a list of the plurality of colorimetric information that can be calculated by the calculation unit, and displaying the list of the plurality of colorimetric information displayed on the display unit to the calculation unit to select the colorimetric information calculated by
2. The image processing apparatus according to claim 1 , wherein: the colorimetric information selected by the user from a list of the plurality of colorimetric information that can be calculated by the calculation unit does not include density;
6. The image processing apparatus according to claim 5, characterized by: In the computer that controls the image processing device,
a calculation function of obtaining spectral reflectance information relating to an image formed on a recording medium using a special colorant, and calculating a plurality of pieces of colorimetric information based on the obtained spectral reflectance information;
a determining function for determining one piece of colorimetric information from the plurality of pieces of colorimetric information calculated by the calculating function;
a generation function for generating a gradation parameter to be used when performing gradation correction of a special color material based on the colorimetric information determined by the determination function;
program to realize

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