JP2007300201A - Method of adjusting color tone, image processing unit, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately correct color tone rolling occurring when performing gray scale print in a color printer. <P>SOLUTION: Processing content for converting the gray component of an input image to the color tone is decided. Color tone conversion processing based on the processing content is performed to the gray scale prepared in advance. The gray scale is outputted from the printer. The range of the color tone rolling and the color information are inputted into an image processing unit. A plurality of test gray scales, where the color tone rolling portion is changed in steps, are outputted to the printer. The test gray scale having the minimum color tone rolling is selected from the plurality of test gray scales. The color tone rolling correction content corresponding to the input of the selected test gray scale is decided. Color tone adjustment processing is decided based on the decided color tone conversion processing and the color tone rolling correction processing. The color tone adjustment processing is performed to an image outputted by the printer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a color tone adjustment method, an image processing apparatus, and a program for adjusting a loss of gray balance of an image printed in gray scale by a color printing apparatus such as a color printer.

  When gray scale printing is performed in a color printing apparatus such as a color printer, gray balance is often lost due to variations in ink ejection due to individual model differences or changes over time. In particular, in an inkjet printer, when gray scale printing is performed using only a K (black) color material, there is a problem that gradation is low and graininess is deteriorated. Therefore, an ink jet printing a color image with four colors of C (cyan), M (magenta), Y (yellow), K (black) or six colors including Lc (light cyan) and Lm (light magenta). There is also a printer. However, when gray is created by mixing color inks, there is a problem that the gray line is tinted. Therefore, various gray balance adjustment methods have been proposed in order to solve such problems and adjust the reproducibility of gray.

  For example, US Pat. No. 6,088,907 (Patent Document 1) discloses the following gray balance adjustment method. That is, a color patch representing a halftone gray color tone and a color test pattern with a changed color tone are printed, visually compared with a reference gray having a flat spectral sensitivity characteristic, a correction value is determined from the patch selection, and the printer color conversion is performed. Apply.

  Japanese Patent No. 3552874 (Patent Document 2) discloses a configuration for performing the following gray balance adjustment. In other words, the strength of the element colors is determined by visual selection of the color bias patch, and the gray scale pattern in which the element color that needs to be adjusted is emphasized and corrected using the tone curve is printed. Perform color correction corresponding to the input.

Furthermore, Japanese Unexamined Patent Publication No. 2003-234913 (Patent Document 3) discloses the following gray balance adjustment method. That is, a pattern sheet having a patch in which the amount of each element color is changed in a plurality of gradations is printed, and a gray balance adjustment correction curve is generated based on the amount of change in the element color of the selected patch.
U.S. Patent No. 6008907 Japanese Patent No. 3552874 JP 2003-234913 A

  However, the conventional adjustment method as described above is a form in which the gray at a specific portion of the gray line is picked up and adjusted by selecting a color patch or the like, and the entire gray line is corrected based on the adjustment value. For this reason, it has not been possible to appropriately correct the color shift that occurs locally in a specific gradation portion of the gray line.

  In addition, in the adjustment of the gray balance performed only by visual observation, more accurate adjustment can be performed by preparing a reference gray that serves as an index for comparing colors. However, there is a problem that it cannot be applied to cases where it is difficult to prepare a reference gray, such as color tone shift correction for gray to which an arbitrary color tone such as black tone, cold black tone, or sepia tone is added.

  That is, in a color image output apparatus such as an ink jet printer that performs printing with four colors of C, M, Y, and K, or six colors obtained by adding Lc and Lm to these, the following processing is performed. First, a gray printed with only K is used as a reference gray, and visually compared with a sheet printed with a patch having a density that can be selected by a printer whose gray balance is to be adjusted. The gray balance is adjusted by determining the correction amount of the element color according to the selection of the patch. Therefore, there is a problem that it is difficult to adjust the gray balance with respect to gray to which an arbitrary color tone such as warm black tone, cold black tone, and sepia tone is added.

  The present invention has been made in consideration of the above circumstances, and a color tone adjustment method, an image processing device, and a color tone adjustment method that can suitably correct a color shift that occurs locally in a gray line when performing grayscale printing with a color printing device, and The purpose is to provide a program.

In order to solve the above problems, the present invention is a color tone adjustment method in an image processing apparatus for adjusting the color tone of an image printed in gray scale by a printing apparatus capable of color printing,
A selection process for selecting a target grayscale color tone;
A first determination step of determining a processing content for converting a gray component of an input image into the color tone;
Applying a tone conversion process based on the processing content determined in the first determination step to a gray scale prepared in advance, and outputting the gray scale from the printing apparatus;
When there is a color shift in the gray scale output by the printing apparatus, an input step for inputting a range of color shift and its color information to the image processing apparatus;
A second output step of causing the printing apparatus to output a plurality of test gray scales in which the color tone transition portion is changed stepwise based on the color tone transition range and color information;
A second determination step of selecting a test gray scale having a minimum color shift from the plurality of test gray scales, and determining a color shift correction content corresponding to an input of the selected test gray scale;
A color tone adjustment process is determined based on a color tone conversion process based on the processing content determined in the first determination step and a color tone shift correction process based on the color shift correction content determined in the second determination step. A third determining step;
And a color tone adjustment processing step for performing the color tone adjustment processing on the image output by the printing apparatus.

In order to solve the above problem, the present invention is an image processing apparatus for adjusting the color tone of an image output in gray scale by a printing apparatus capable of color output,
A selection means for selecting a target grayscale color tone;
First determining means for determining a processing content for converting a gray component of an input image into the color tone;
First output means for applying a tone conversion process based on the processing content determined by the first determination means to a gray scale prepared in advance, and outputting the gray scale to a printing apparatus;
When there is a color shift in the gray scale output from the printing apparatus, input means for inputting a range of color shift and its color information;
Second output means for causing the printing apparatus to output a plurality of test gray scales in which the color tone transition portion is changed stepwise based on the color tone transition range and color information;
A second determination unit that selects a test gray scale having the smallest color shift from the plurality of test gray scales, and determines a color shift correction content corresponding to an input of the selected test gray scale;
A color tone adjustment process is determined based on a color tone conversion process based on the processing content determined by the first determination unit and a color tone shift correction process based on the color shift correction content determined by the second determination unit. A third determining means;
And color tone adjustment processing means for performing the color tone adjustment processing on an image output by the printing apparatus.

Furthermore, in order to solve the above-described problem, a program according to the present invention provides:
A computer for adjusting the color tone of an image printed in grayscale on a printing device capable of color printing.
A selection procedure to select the target grayscale tone,
A first determination procedure for determining a processing content for converting a gray component of an input image into the color tone;
A first output procedure in which a tone conversion process based on the processing content determined by the first determination procedure is applied to a gray scale prepared in advance, and the gray scale is output from the printing apparatus;
When there is a color shift in the gray scale output by the printing apparatus, an input procedure for inputting a range of color shift and its color information to the computer;
A second output procedure for causing the printing apparatus to output a plurality of test gray scales in which the color tone transition portion is changed stepwise based on the color tone transition range and color information;
A second determination procedure for selecting a test gray scale having the smallest color shift from the plurality of test gray scales and determining a color shift correction content corresponding to an input of the selected test gray scale;
A color tone adjustment process is determined based on a color tone conversion process based on the processing content determined by the first determination procedure and a color tone shift correction process based on the color shift correction content determined by the second determination procedure. A third decision procedure;
And a color tone adjustment processing procedure for performing the color tone adjustment processing on an image output by the printing apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, when performing a grayscale printing with a color printing apparatus, the color tone shift which generate | occur | produces locally in a gray line can be corrected suitably. As a result, without using an expensive measuring instrument such as a colorimeter, it is easy to visually compare even if it is not an expert, and there is no local color shift in the gray line in the gray tone desired by the user. A gray image can be easily reproduced.

  Hereinafter, the configuration and operation of an image forming system in which a configuration for performing a color tone adjustment method according to an embodiment of the present invention is implemented will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration example of an image forming system that performs printing by performing color tone adjustment processing according to an embodiment of the present invention. In the system configuration shown in FIG. 1, reference numeral 1 denotes a host computer, 2 denotes a printer capable of color printing, print data is sent from the host computer 1 to the printer 2, and printing is executed by the printer 2.

  In the host computer 1, there are application software 11, a printer driver 12, and a color tone adjustment process determination program 13 that operate in conjunction with each other. Specifically, when the data created by the application software 11 is printed by the printer 2, the application software 11 sends the data to the printer driver 12.

  The printer driver 12 converts the input data into CMYK, which is the ink color of the printer, performs halftone processing, and sends the data to the printer 2. Then, the printer 2 develops the data after halftone processing received from the host computer 1 on the output paper, and generates a hard copy. In this embodiment, an example in which the printer driver 12 performs color conversion processing and halftone processing will be described. However, the printer 2 may be configured to perform halftone processing and color conversion processing.

  In such a system, when the user desires to print by setting a desired gray color tone, the color tone adjustment process determination program 13 is called from the user interface (not shown) of the printer driver 12.

  FIG. 2 is a diagram for explaining an exemplary color conversion process according to an embodiment of the present invention. Color conversion performed by the printer driver 12 when a color image is formed on a recording medium by an inkjet printer or the like. It is a block diagram for demonstrating a process. In FIG. 2, 201 is a color tone adjustment process by 1DLUT, 202 is a color matching processing unit, 203 is a color separation processing unit, 204 is an output γ processing unit, and 205 is a halftone processing unit.

  The 1DLUT color tone adjustment unit 201 performs color tone adjustment processing on the RGB signal of the image data input by the 1DLUT color tone adjustment unit 201 using a one-dimensional lookup table (1DLUT), and outputs it as color tone adjustment image data R′G′B ′ signal. To do.

  The color matching processing unit 202 uses the R′G′B ′ signal that has been subjected to the color tone adjustment processing by the 1DLUT color tone adjustment unit 201 as input image data, and performs color matching processing for matching with the color of the printer. Conversion to the “B” signal The conversion from the input R′G′B ′ signal to the device R “G” B ”signal is a built-in three-dimensional lookup table (hereinafter referred to as“ 3DLUT ”). Referring to FIG. 5, the three-dimensional interpolation processing such as tetrahedral interpolation processing and cube interpolation processing is executed.

  The color separation processing unit 203 color-separates the input device R "G" B "signal into a CMYK signal (or CMYKLcLm signal) corresponding to the ink of the color printer, and outputs the device R" G "B" signal. Is converted into ink CMYK signals (multi-value data) by 3DLUT, and converted into ink colors of a color printer by three-dimensional interpolation processing such as tetrahedral interpolation processing and cube interpolation processing.

  The output γ correction processing unit 204 performs γ correction processing on the color material color data of the CMYK signal in order to correct the γ characteristic due to the combination of the processing content of the halftone processing unit 205 and the engine unit of the color printer. Specifically, correction processing is executed based on the output γ correction table, and the color material color data of the CMYK signal is converted into multi-value data of the C′M′Y′K ′ signal and output.

  The halftone processing unit 205 binarizes the C′M′Y′K ′ signal (multi-valued data) from the output γ correction processing unit 204 into a gradation number that can be expressed by the engine unit of the color printer. The process is executed for each color. Then, the C "M" Y "K" signal (binary data) after the halftone process is transferred to the color printer (printer 2), and printing is executed.

  Next, a method for determining 1DLUT color adjustment processing in the 1DLUT color tone adjustment unit 201, which is the core of the present invention, will be described in detail.

  FIG. 3 is a flowchart for explaining a processing procedure for determining 1DLUT color adjustment processing by the 1DLUT color tone adjustment unit 201 of the printer driver 12 according to the embodiment of the present invention.

  The 1DLUT color tone adjustment unit 201 first selects a desired color tone when it is desired to change the color tone of the entire gray scale to an arbitrary color tone (step S101). FIG. 4 is a diagram showing an example of a gray color selection dialog displayed on a display device (not shown) of the host computer 1 for receiving an input of a gray color desired by the user. In FIG. 4, reference numeral 33 denotes a slider to be searched for selecting a color tone. When the user moves the slider 32 to the left or right within the range of the slide bar 33 with a pointing device such as a mouse, the gray color tone from warm color (warm) to cold color (cool) can be designated continuously.

  The color tone selected by the slider 32 is simply reproduced by the color tone confirmation unit 31. The user can select a desired color tone because halftone grays having different color tones from warm colors to cold colors are displayed on the color tone confirmation unit 31 in conjunction with the movement of the slider 32. Then, after adjusting to a desired color tone by operating the slider 32, the user presses the OK button 34, whereby the gray color tone selection is completed.

  In this embodiment, the gray color tone is designated by the slide bar displayed on the dialog, but a desired halftone gray may be displayed by numerical designation.

  Next, in step S102, gray tone conversion process generation is executed. When the input data is RGB, the gray tone conversion process can be defined by the following γ conversion formula, for example.

R1 = R0 ^ (1.0-0.1 * L)
G1 = G0
B1 = B0 ^ (1.0 + 0.3 * L)
Here, “^” represents a power. (R0, G0, B0) is an input value normalized to 0.0 to 1.0, (R1, G1, B1) is an output value normalized to 0.0 to 1.0, and L is a color tone selection. This is a setting value linked to the slider 32 of the dialog 3. The standard state is L = 0.0, the warmest color is L = −1.0, and the coldest color is L = 1.0.

In the standard state (L = 0.0)
R1 = R0
G1 = G0
B1 = B0
The gray tone conversion characteristics are linear and virtually no conversion.

On the other hand, in the most cold state (L = -1.0),
R1 = R0 ^ 1.1
G1 = G0
B1 = B0 ^ 0.7
Thus, the input / output characteristics as shown in FIG. 5 are shown. That is, FIG. 5 is a diagram illustrating an example of a 1DLUT that is converted into a cold color tone. When so-called gray data is input, in which R0, G0, and B0 are all equal, the B component becomes stronger and the R component becomes weaker, so that the entire color is converted to a cold tone.

In the state where the color is most warm (L = -1.0),
R1 = R0 ^ 0.9
G1 = G0
B1 = B0 ^ 1.3
Thus, the input / output characteristics as shown in FIG. 6 are shown. That is, FIG. 6 is a diagram illustrating an example of a 1DLUT that is converted into a warm color tone. When so-called gray data is input, in which R0, G0, and B0 are all equal, the R component becomes stronger and the B component becomes weaker, so that the entire color is converted to a warm tone.

  In the present embodiment, the G component does not contribute much to the warm and cold colors, so G1 = G0 is always set. Further, the change rate of R and the change rate of B are changed in consideration of visual characteristics.

  The conversion characteristics generated by the above conversion formula are determined as gray tone conversion processing. The determined gray tone conversion processing may be stored in the state of a calculation formula, or may be held as three 1DLUTs (for RGB).

  When the generation of the gray tone conversion process is completed in step S102, the process proceeds to step S103. In step S103, the gray color chart generated in step S102 is applied to the gray scale chart prepared in advance, and the color conversion process and the halftone process to the ink color are applied to the gray scale after the color conversion. Then, printing is performed by the printer 2.

  In the present embodiment, the printer 2 outputs a gray scale as shown in FIG. 7 for visually confirming whether or not a color shift has occurred. Here, FIG. 7 is a diagram illustrating an example of a gray scale chart. In the gray scale, the RGB values are smoothly changed from 0.0 to 1.0 (in a normalized state), and the gray scale index and scale for inputting the range of color shift are displayed on the gray scale. It is arranged at a predetermined position.

  In the present embodiment, the scale is normalized to 0.0 to 1.0, but values of 0 to 255 may be described on the scale assuming each color 8-bit data.

  In step S104, a color shift correction process is generated. FIG. 8 is a flowchart for explaining the details of the processing procedure of the color tone shift correction processing in step S104 according to the embodiment of the present invention.

  In step S111, the color tone shift correction process is initialized. The color shift correction process is realized by a plurality of 1DLUTs corresponding to the input color, and the input value and the output value are equal in the state after initialization. Next, in step S112, it is confirmed whether or not there is a color shift by visual observation. As a result, when no color shift has occurred (No), it is not necessary to perform the color shift correction process, and thus the color shift correction process ends. On the other hand, if there is a color shift (Yes), the process proceeds to step S113.

  In step S113, color tone shift information is input. FIG. 9 is a diagram showing an example of a color shift information input dialog that is displayed on a display device (not shown) of the host computer 1 according to an embodiment of the present invention and receives input of color shift information. In FIG. 9, reference numeral 41 denotes a gray scale image, and the gray gradation level values at the left end and right end of the color shift are input to the numerical value input interface 42 by an input device such as a keyboard.

  In the example shown in FIG. 7, since color shift has occurred in a range indicated by a rectangle having a gray gradation level of 0.2 to 0.4, 0.2 is set in the leftmost box and 0.4 is set in the rightmost box. input. Further, the user determines the color of the color change. Then, the user selects the color of the color shift from the CMY or RGB hues from the 43 radio buttons.

  In the present embodiment, the gradation level is directly input to the numerical value input box of 42. However, a numerical value may be specified by clicking the gray scale of 41 with the mouse pointer. In the present embodiment, the color of the color change is selected from the radio button. However, an image suggesting the color may be displayed and the color can be selected by clicking with the mouse pointer.

  In step S114, the test gray scale is output from the printer 2. FIG. 10 is a diagram illustrating an example of a test gray scale. In step S <b> 114, a sheet on which a plurality of test gray scales in which the color tone of the color tone transition portion is changed stepwise is generated according to the color tone transition information input in step S <b> 113 and output by the printer 2. In addition, it is preferable that the conversion is smoothly connected to the peripheral portion using a correction curve as shown in FIG. That is, FIG. 11 is a diagram illustrating correction of a color tone shift range using a spline curve.

  For example, an input color tone transition range from the gradation level a1 to the gradation level a2 is set, and the input RGB value is corrected for this range. Here, 0 ≦ a1 and a1 <a2 and a2 ≦ 1. In the example of FIG. 7, a1 = 0.2 and a2 = 0.4. In FIG. 11, correction is performed using a spline curve in which the absolute value of the correction amount is maximized at x satisfying a1 <x <a2. In addition, a curve based on a Gaussian function may be used. At the gradation level x, the correction amounts shown in FIG. 12 are applied to the RGB values of the color tone shift portion according to the color information of the color tone shift.

  FIG. 12 is a diagram illustrating an example of combinations of correction levels in the test gray scale. For example, when the user confirms the presence of cyan (C) tone shift, as shown in the table of C shift in FIG. 12, the gray scale in which GB (C) is decreased step by step, and the respective gray scales , A gray scale in which G and B having a color tone close to C are reduced is created. In the correction, the correction amount of the RGB value is determined so that the brightness is constant.

The correction amount shown in FIG. 12 is displayed as a percentage value. For example, the RGB value at the gradation level x = 0.3 after gray tone conversion processing is
R1 = 0.282
G1 = 0.300
B1 = 0.359
In this case, the correction amount in the gray scale 1Cb is (3, -3, 0). Therefore, the RGB values (R2, G2, B2) at the gradation level x are
R2 = 0.282 * (100 + 3) /100=0.290
G2 = 0.300 * (100-3) /100=0.291
B2 = 0.359
It becomes. At the time of printing, this value is subjected to color conversion to ink color and halftone processing, and output.

  In the above-described example, when the RGB value at the gray scale level x is obtained, the correction processing for each gray scale is performed on the data subjected to the gray tone conversion processing. Here, on the contrary, the gray color tone conversion process may be performed after the correction process for the gray scale color shift range, and substantially the same effect can be obtained.

  In step S115, the user selects a gray scale having a desired color from the test gray scale, and inputs ID information of the selection result to the host computer 1. In step S116, the selection result is applied to the tone correction curve.

For example, in the gray scale 1 Gb, the RGB correction amounts are + 3%, −3%, and 0%, respectively.
R2 = 0.300 * 1.03 = 0.309
G2 = 0.300 * 0.97 = 0.291
B2 = 0.300 * 1.00 = 0.300
A correction curve is generated so that Here, it is preferable that the correction curve is smoothly connected to the periphery using a spline curve or the like.

  When the correction of the specific range is completed for the color shift correction process, the process returns to step S112. In S112, when the color shift is not improved or there are a plurality of color shifts, and there is another region where it is desired to correct the color shift, the sequence proceeds to Step S113 until a satisfactory gray line is obtained. Repeat the process. If a satisfactory gray scale is obtained, the color shift correction table is determined, and the color shift correction process generation is completed.

  When the color tone correction process generation is completed, the process proceeds to step S105 in FIG. In step S105, the content of the color tone adjustment process is determined. The color tone adjustment process is determined as a combination of the content of the gray color tone conversion process generated in step S102 and the content of the color tone shift correction process generated in step S104. Here, the gray color tone conversion process and the color tone shift correction process may be the color tone adjustment process as two consecutive processes, or a 1DLUT obtained by combining the two processing contents may be the color tone adjustment process.

  When the two processes are performed in succession (if the processing content satisfies the monotonous increase), the gray color tone conversion process and the color tone shift correction process match each other regardless of which process is performed first. Therefore, the process of performing the color tone shift correction process after the gray color tone conversion process may be performed as the color tone adjustment process, or conversely, the color tone shift correction process may be performed before the gray color tone conversion process. However, it is preferable that the processing order at the time when the test gray scale is generated in step S104 and the actual processing order are matched because there is no problem. The color tone adjustment process is determined by the above process.

  As described above, in this embodiment, an arbitrary gray color tone is selected, a gray color conversion process is defined, a color shift range in the gray scale of the same color tone is confirmed and corrected, and a color shift correction process is defined. Was applied to the input data as a color tone adjustment process. As a result, the gray portion of the input data (the portion having the same RGB value) is converted into a gray tone desired by the user, and can be output as a gray image that does not have a partial tone shift. Further, in this embodiment, it is not necessary to prepare a colorimeter or the like separately, and it is possible to correct gray color shift easily and inexpensively without taking time. Furthermore, by specifying the color of the color shift and changing the color in a specific direction, it is not necessary to print a large number of patches, and paper can be saved. Furthermore, since correction is performed while checking the entire gray scale, it is possible to create a smoother gray line as compared with adjustment by patch selection.

  Furthermore, in the present embodiment, the processing for RGB image data has been specifically described. However, even when the input data is CMYK, four 1DLUTs are used for correction, and the configuration of the test grayscale is changed to that for CMYK. It can be easily handled.

  Although the embodiment has been described in detail above, the present invention can take an embodiment as a system, apparatus, method, program, storage medium (recording medium), or the like. Specifically, the present invention may be applied to a system composed of a plurality of devices, or may be applied to an apparatus composed of a single device.

  In the present invention, a software program (in the embodiment, a program corresponding to the flowchart shown in the drawing) that realizes the functions of the above-described embodiments is directly or remotely supplied to a system or apparatus. In addition, this includes a case where the system or the computer of the apparatus is also achieved by reading and executing the supplied program code.

  Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. In other words, the present invention includes a computer program itself for realizing the functional processing of the present invention.

  In that case, as long as it has the function of a program, it may be in the form of object code, a program executed by an interpreter, script data supplied to the OS, or the like.

  Examples of the recording medium for supplying the program include the following. Floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card, ROM, DVD (DVD-ROM, DVD-R) .

  As another program supply method, the program can be supplied by downloading it from a homepage on the Internet to a recording medium such as a hard disk using a browser of a client computer. That is, it connects to a homepage and downloads the computer program itself of the present invention or a compressed file including an automatic installation function from the homepage. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the present invention.

  Further, the program of the present invention is encrypted, stored in a storage medium such as a CD-ROM, and distributed to users. Then, the user who has cleared the predetermined condition is allowed to download key information for decryption from the homepage via the Internet. It is also possible to execute the encrypted program by using the key information and install the program on a computer.

  Further, the functions of the above-described embodiments are realized by the computer executing the read program. In addition, the function of the above-described embodiment can be realized by an OS running on the computer based on an instruction of the program and performing part or all of the actual processing.

  Further, the functions of the above-described embodiments are realized even after the program read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. That is, the functions of the above-described embodiments are realized by performing a part or all of the actual processing by the CPU or the like provided in the function expansion board or function expansion unit based on the instructions of the program.

1 is a block diagram illustrating a configuration example of an image forming system that performs printing by performing color tone adjustment processing according to an embodiment of the present invention. FIG. FIG. 4 is a diagram for explaining an exemplary color conversion process according to an embodiment of the present invention, and illustrates a color conversion process performed by the printer driver 12 when a color image is formed on a recording medium by an inkjet printer or the like. It is a block diagram for. 6 is a flowchart for explaining a processing procedure for determining 1DLUT color adjustment processing by the 1DLUT color tone adjustment unit 201 of the printer driver 12 according to the embodiment of the present invention. It is a figure which shows an example of the gray color selection dialog displayed on the display apparatus (not shown) of the host computer 1, and accepting the input of the gray color tone which a user desires. It is a figure which shows an example of 1DLUT converted into a cold color tone. It is a figure which shows an example of 1DLUT converted into a warm color tone. It is a figure which shows an example of a gray scale chart. It is a flowchart for demonstrating the detail of the process sequence of the color tone shift correction process of step S104 which concerns on one Embodiment of this invention. It is a figure which shows an example of the color shift information input dialog which is displayed on the display apparatus (not shown) of the host computer 1 which concerns on one Embodiment of this invention, and receives the input of color shift information. It is a figure which shows an example of a test gray scale. It is a figure which shows the correction | amendment of the color shift range by a spline curve. It is a figure which shows the example of a combination of the correction level in a test gray scale.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Host computer 2 Printer 11 Application software 12 Printer driver 13 Color tone adjustment process determination program 201 1DLUT color correction part 202 Color matching process part 203 Color separation process part 204 Output gamma correction process part 205 Halftone process part

Claims (8)

A color tone adjustment method in an image processing apparatus that adjusts the color tone of an image printed in gray scale by a printing apparatus capable of color printing,
A selection process for selecting a target grayscale color tone;
A first determination step of determining a processing content for converting a gray component of an input image into the color tone;
Applying a tone conversion process based on the processing content determined in the first determination step to a gray scale prepared in advance, and outputting the gray scale from the printing apparatus;
When there is a color shift in the gray scale output by the printing apparatus, an input step for inputting a range of color shift and its color information to the image processing apparatus;
A second output step of causing the printing apparatus to output a plurality of test gray scales in which the color tone transition portion is changed stepwise based on the color tone transition range and color information;
A second determination step of selecting a test gray scale having a minimum color shift from the plurality of test gray scales, and determining a color shift correction content corresponding to an input of the selected test gray scale;
A color tone adjustment process is determined based on a color tone conversion process based on the processing content determined in the first determination step and a color tone shift correction process based on the color shift correction content determined in the second determination step. A third determining step;
And a color tone adjustment processing step of performing the color tone adjustment processing on the image output by the printing apparatus.   The third determining step includes a color tone conversion process based on the processing content determined in the first determining step and a color tone shift correcting process based on the color shift correction content determined in the second determining step. The color tone adjustment method according to claim 1, wherein the color tone adjustment processing is determined by synthesis.   The first output step is characterized in that the printing apparatus outputs an image in which an index and a scale indicating a gradation level of tone shift are arranged at a specific position of the gray scale. 2. The color tone adjustment method according to 2.   The second output step is characterized in that the printing apparatus outputs an image in which an index and a scale indicating the gradation level of color shift are arranged at specific positions of the plurality of test gray scales. Item 3. The color tone adjustment method according to Item 1 or 2.   The second output step outputs, by the printing apparatus, an image in which numbers or symbols serving as indices are arranged as identification IDs at specific positions of the plurality of test gray scales. The color tone adjusting method according to 1 or 2. In the input step, a color shift range is input as the color shift information,
In the second output step, an image in which an index indicating the color tone shift range input in the input step is arranged at a specific position of the plurality of test gray scales in the color tone shift range of each test gray scale. The color tone adjustment method according to claim 1, wherein the color tone is output by the printing apparatus. An image processing apparatus for adjusting the color tone of an image output in gray scale by a printing apparatus capable of color output,
A selection means for selecting a target grayscale color tone;
First determining means for determining a processing content for converting a gray component of an input image into the color tone;
First output means for applying a tone conversion process based on the processing content determined by the first determination means to a gray scale prepared in advance, and outputting the gray scale to a printing apparatus;
When there is a color shift in the gray scale output from the printing apparatus, input means for inputting a range of color shift and its color information;
Second output means for causing the printing apparatus to output a plurality of test gray scales in which the color tone transition portion is changed stepwise based on the color tone transition range and color information;
A second determination unit that selects a test gray scale having the smallest color shift from the plurality of test gray scales, and determines a color shift correction content corresponding to an input of the selected test gray scale;
A color tone adjustment process is determined based on a color tone conversion process based on the processing content determined by the first determination unit and a color tone shift correction process based on the color shift correction content determined by the second determination unit. A third determining means;
An image processing apparatus comprising: color tone adjustment processing means for performing the color tone adjustment processing on an image output by the printing apparatus. A computer for adjusting the color tone of an image printed in grayscale on a printing device capable of color printing.
A selection procedure to select the target grayscale tone,
A first determination procedure for determining a processing content for converting a gray component of an input image into the color tone;
A first output procedure in which a tone conversion process based on the processing content determined by the first determination procedure is applied to a gray scale prepared in advance, and the gray scale is output from the printing apparatus;
When there is a color shift in the gray scale output by the printing apparatus, an input procedure for inputting a range of color shift and its color information to the computer;
A second output procedure for causing the printing apparatus to output a plurality of test gray scales in which the color tone transition portion is changed stepwise based on the color tone transition range and color information;
A second determination procedure for selecting a test gray scale having the smallest color shift from the plurality of test gray scales and determining a color shift correction content corresponding to an input of the selected test gray scale;
A color tone adjustment process is determined based on a color tone conversion process based on the processing content determined by the first determination procedure and a color tone shift correction process based on the color shift correction content determined by the second determination procedure. A third decision procedure;
A program for executing a color tone adjustment processing procedure for performing the color tone adjustment processing on an image output by the printing apparatus.

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