JP2005064924A - Color adjusting method, program for implementing the same, recording medium storing the program, and image output system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color adjusting method capable of reproducing uneven density generated in the axis direction of an ink roller corresponding to an image to be printed. <P>SOLUTION: The method comprises an analyzing step of analyzing a distribution quantity of parameter values of each of fundamental colors for either of vertical and horizontal directions at the time of outputting image data as an image by a color printer for calibration on the basis of the image data, a first correcting step of correcting the parameter value of each of the fundamental colors on the basis of the distribution quantity of parameter values of each of the fundamental colors according to a position in the analyzing direction for each of the fundamental colors, and a second correction step of further correcting the parameter value of each of the corrected fundamental colors by using a first correcting characteristic for correcting the parameter value of each of the fundamental colors so that colors outputted by a printer are reproduced by the color printer for calibration. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color adjustment method, a program for executing the color adjustment method, a recording medium storing the program, and an image output system, and in particular, performs color adjustment in accordance with the vertical or horizontal position of an output image. About.

  Conventional color printers that output halftone color proofs use CMYK (C is cyan (blue green), M is magenta (red purple), Y is yellow (yellow), and K is black (black)). Since the color of the material is close to the color of the printing ink, correction of the difference in halftone dot thickness (dot gain curve correction) is performed based on the measurement result of the dot area ratio for each color of CMYK. It was possible to match the colors. However, for the secondary colors of red R, green G, and blue B, black by CMY3 colors, black by CMYK4 colors and their neighboring colors, the color appearance differs from that of the printing press, and exact color matching is difficult. there were. Therefore, using gradation correction curves for correcting each of CMY so as to reproduce the values of the L * a * b * color system of gray from low density to high density by the CMY three colors output by the printing press. By adjusting the color, it became possible to match the color of the printing press with high accuracy. Here, the value of the L * a * b * color system is a three-dimensional coordinate space representing color, and hue / saturation is represented by the a * b * plane, and L * is orthogonal to the a * b * plane and lightness. Represents.

For example, in the gradation correction curve as described above, three gray colors (L * a * b * color system values) output by a printing press are obtained, and the color (L * a * b * table) is obtained. The CMY parameter values for outputting the color system values) with the calibration color printer are obtained from the CMY three-color gray output by the calibration color printer and the CMY color images close to the CMY parameter values of the grays. There is something. (For example, Japanese Patent Application No. 2002-090702 (paragraphs [0011]-[0085], FIGS. 1 to 17).)
On the other hand, in an offset printing machine that prints by transferring multiple colors of ink to each ink plate while transferring to each ink roller, when printing an image, the image and density differ depending on the position. Generally, the ink supply amount is adjusted in the axial direction of the ink roller in accordance with the image to be printed.

  However, when the ink supply amount is increased on the printing machine, the halftone dots become thicker, and when the ink supply amount is reduced, the halftone dots become thinner. In the case of printing with a portion, the portion with a large supply amount becomes thicker than the portion with a small supply amount due to the thicker halftone dots of M.

  Therefore, by adjusting the ink supply amount in the axial direction of the ink roller as described above, density unevenness due to the thickening of the halftone dots of each color occurs in the axial direction of the ink roller of the image to be printed.

  In other words, even if a color proof is created by a calibration color printer that performs color adjustment using the gradation correction curve described above, density unevenness due to the difference in ink supply amount is not taken into consideration, so that the color proof differs from the printed matter. It becomes a thing.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to output a color of an image output by a calibration color printer based on image data in a target color, and To provide a color adjustment method capable of performing color adjustment according to the vertical or horizontal position of an image to be output, a program for executing this color adjustment method, a recording medium storing the program, and an image output system. is there.

  To achieve the above object, according to the first aspect of the present invention, there is provided a color matching target for an image color output by a combination of a plurality of basic color parameter values in the first color image output device based on image data. A color adjustment method for adjusting a color of an image output from a second color image output device based on the image data so as to be the target color, the color adjustment method based on the image data An analysis stage for analyzing a distribution amount of parameter values of each basic color in either one of vertical and horizontal directions when the image data is output as an image by the second color image output device, and for each basic color A first correction stage for correcting the parameter value of each basic color based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction; Using the first correction characteristic for correcting the parameter value of each basic color so that the color output by the first color image output device is reproduced by the second color image output device. And a second correction stage for correction.

  According to a second aspect of the present invention, in the first correction step, the parameter value of each basic color is corrected based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction. Including a step of obtaining an amount, wherein the parameter value of each basic color is corrected by the correction amount.

  According to a third aspect of the present invention, the correction amount is a difference between a parameter value distribution amount of each basic color and an average value of the distribution amounts of each basic color according to the position in the analysis direction. It is required to be based on this.

  According to a fourth aspect of the present invention, in the first correction step, the parameter value of each basic color is calculated based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction. The method includes a step of obtaining a second correction characteristic for correcting according to the magnitude of the parameter value, and correcting the parameter value of each basic color using the second correction characteristic.

  According to a fifth aspect of the present invention, the second correction characteristic is the correction of the parameter value of each basic color based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction. An amount is obtained, and the amount is obtained based on the correction amount.

  According to a sixth aspect of the present invention, the second correction characteristic includes a distribution amount of the parameter value of each basic color and an average value of the distribution amount of each basic color according to the position in the analysis direction. It is obtained based on the difference between the two.

  According to a seventh aspect of the present invention, the second correction characteristic includes a distribution amount of the parameter value of each basic color and an average value of the distribution amount of each basic color according to the position in the analysis direction. Based on the difference, a correction amount of the parameter value of each basic color is obtained, and the correction amount is obtained based on the correction amount.

  According to an eighth aspect of the present invention, the first color image output device outputs an image while supplying a plurality of basic color inks to the respective ink rollers. The supply of the ink to the ink is made adjustable at the position in the axial direction, and either one of the vertical and horizontal directions when the image data is output as an image by the second color image output device is the first direction. This is characterized in that the axial direction of the ink roller relative to the image when the image is output by one color image output device.

  The invention according to claim 9 is a program for causing a computer to execute the color adjustment method according to any one of claims 1 and 8.

  The invention described in claim 10 is a recording medium on which the program described in claim 9 is recorded so as to be readable by the computer.

  According to the eleventh aspect of the present invention, the color of an image output by a combination of parameter values of a plurality of basic colors by the first color image output device based on the image data is used as a color matching target, and based on the image data. A second color image output device that outputs an image and adjusts the color of the image output from the second color image output device based on the image data so that the target color is the target color. In the image output system, based on the image data, parameter values of basic colors in one of the vertical and horizontal directions when the image data is output as an image by the second color image output device. Analyzing means for analyzing the distribution amount, and for each basic color, depending on the position in the analysis direction, the parameter of each basic color based on the distribution amount of the parameter value of each basic color A first correction unit for correcting the color, and a parameter value of each basic color corrected by the first correction unit, and a color output by the first color image output device as the second color image output device. A plurality of second correction means for correcting using the first correction characteristics for correcting the parameter values of the respective basic colors so as to reproduce, and a plurality of parameter values corrected by the second correction means. And image output control means for controlling the second color image output device to output an image based on a combination of basic color parameter values.

  According to the color adjustment method of the first aspect, the color to be output can be adjusted in one of the vertical and horizontal directions of the image based on the image data, and further, the adjustment is performed so that the target color is output. Highly accurate color proof can be created.

  According to the color adjustment method of the second aspect, the adjustment of the color to be output performed according to the image in one of the vertical and horizontal directions of the image is performed using the correction amount, so that the correction can be easily performed. it can.

  According to the color adjustment method of the fourth aspect, the adjustment of the color to be output in either one of the vertical and horizontal directions of the image is performed using the density unevenness correction curve (correction characteristic). Adjustments can be made and a more accurate color proof can be created.

  According to the color adjustment method of the fifth aspect, the density unevenness correction curve can be easily obtained using the correction amount.

  According to the color adjustment method of the eighth aspect, it is possible to create a color proof that reproduces the density unevenness that occurs in the axial direction of the ink roller of the printing press.

[First Embodiment]
The present invention targets, for example, the color of an image based on image data output from a printing press (first color image output device), and outputs the image using a calibration color printer (second color image output device). Sometimes, the color adjustment is performed using the tone correction curve for correcting the parameter values of the four basic colors (C, M, Y, K) of the image data so that the target color is output. In addition, the supply amount of ink is adjusted in the axial direction of the ink roller according to the image on the printing machine that performs printing by transferring to each color plate while supplying multiple colors of ink to each ink roller. This is to reproduce the density unevenness generated by the operation.

  Here, the four basic colors (C, M, Y, K) are C for cyan (blue green), M for magenta (red purple), Y for yellow (yellow), and K for black (black). is there. The parameters are so-called gradations, halftone dot area ratios, and the like. In the following embodiments, the parameter values are represented by halftone dot area ratios where the minimum value is 0 (%) and the maximum value is 100 (%). Represent. 0 represents white, 100 represents solid, and for example, “CMYK combination”, “K”, and the like shown below are “CMYK dot area ratio (parameter value) combinations” “K halftone dot area ratio (parameter value)”.

  Hereinafter, an embodiment of an image forming system according to the present invention will be specifically described with reference to the drawings.

(Control configuration)
First, the control configuration of the first embodiment according to the present invention will be described with reference to FIG. FIG. 1 is a functional block diagram of the image output system of the present invention. As shown in FIG. 1, the image output system includes a calibration color printer 2 that outputs a color image based on image data, and a control device 1 that performs control related to image formation control of the color printer 2.

  The control device 1 is a so-called computer, and functions as a controller that performs control related to image formation control of the calibration color printer 2. As shown in FIG. 1, as shown in FIG. The storage unit 10 comprising a hard disk drive) corrects the CMYK halftone dot area ratio of the image data so that the color printer 2 for calibration outputs an image in the color output from the target printing machine (not shown). A control unit 11 having a function of performing color adjustment and controlling the calibration color printer 2 so as to form an image is provided. Further, although not shown, an input means for inputting various data (image data and measurement result data) is provided. In addition, a display such as a CRT, a mouse, a keyboard, and the like may be provided.

  The storage unit 10 is an image data storage unit 101 that stores image data transmitted from a work terminal (not shown) and input via an input unit (not shown), and C, M, Y so as to reproduce colors output by the printing press. , K, a LUT (lookup table) storage unit 102 for storing a reference gradation correction curve (first correction characteristic), a program for controlling the entire control device 1, and CMYK based on image data A program for correcting the halftone dot area ratio and adjusting the color, a program for controlling image formation in the proofreading color printer 2, and the like are stored in a specific directory.

  Further, a color adjustment method program for performing color adjustment by correcting the halftone dot area ratio of CMYK based on the image data, such as a floppy (registered trademark) disk, a CD-ROM, a magnetic recording tape or the like, is carried out. You may store in a recording medium etc. Further, when the program software is executed by a computer, the program software can be read from the recording medium by a reading device attached to the computer.

  The control unit 11 includes a CPU and performs various types of control based on a program stored in the storage unit 11. The control unit 11 controls the entire control device 1 and controls image formation control of the calibration color printer 2. And a function as image output control means. Further, a distribution amount relating to an image in either one of the vertical and horizontal directions when the image data is output by the calibration color printer 2 for each of C, M, Y, and K based on the image data (details will be described later). Based on the analysis result by the analysis means 111 and the analysis result by the analysis means 111, each dot area ratio is determined for each C, M, Y, K of the combination of CMYK of the image data according to the position in the direction of analysis. Color correction by correcting the corrected C, M, Y, and K using the correction unit 112 (first correction unit) that corrects the above and the reference tone correction curve stored in the LUT storage unit 102 Color adjusting means (second correcting means) 113 is provided.

  The calibration color printer 2 is connected to the control device 1 and forms a color image by a combination of CMYK based on the image data corrected and converted by the control unit. The calibration color printer 2 may be configured to have the functions of the storage unit 10 and the control unit 11.

(Color adjustment method)
Next, the color adjustment method of this embodiment will be described. FIG. 2 is a flowchart showing each step of the color adjustment method according to the present embodiment. First, each step of the color adjustment method will be schematically described with reference to FIG. 2, and details will be described later.

  First, the analysis unit 111 divides the image data stored in the image data storage unit 101 into a plurality of parts in either the vertical direction or the horizontal direction when the image data is output as an image by the calibration color printer 2. Using the image data, the distribution amount for the dot area ratio (distribution amount for the parameter value) in the direction divided for each of C, M, Y, and K is analyzed (step S101 in FIG. 2, hereinafter abbreviated as S101, others) This step is also omitted). The distribution amount of the halftone dot area ratio analyzed here corresponds to the difference depending on the amount of image and the position of density, which is a standard for adjusting the amount of ink supplied to the ink roller performed by the printing press.

  Next, based on the analysis result by the analysis unit 111, the correction unit 112 performs C, M, Y for each combination of CMYK of the image data according to the position in the direction in which the distribution amount for the halftone dot area ratio is analyzed. , K are corrected (S102).

  Further, the color adjustment unit 113 performs color adjustment by converting C, M, Y, and K, which have been corrected for C, M, Y, and K, respectively, by the correction unit 112 using a reference gradation correction curve (S103).

  Then, the CMYK corrected and converted image data is transmitted to the calibration color printer 2, and the calibration color printer 2 outputs an image based on the transmitted image data.

(S101)
In this example, the distribution amount of the halftone dot area ratio is analyzed based on the image data. For the description, an image A shown in FIG. 3 is used. The image A is a layout of various standard images standardized by ISO (International Organization for Standardization) and JIS (Japan Industrial Standard), and has a horizontal direction of 80 cm and a vertical direction of 50 cm. This image A is formed of C, M, Y, and K, and images of C, M, Y, and K colors obtained by color separation are shown in FIGS. 4A to 4D, respectively.

  Next, the direction in which the distribution amount of the halftone dot area ratio is analyzed will be described with reference to FIG. The arrow Y shown in FIG. 5 is the printing direction of the image A by the printing press, and the arrow X is the axial direction of the ink roller, and the printing direction and the axial direction of the ink roller are perpendicular to each other. The color adjustment method of the present embodiment is to reproduce density unevenness generated by adjusting the ink supply amount in the axial direction of the ink roller according to the image to be printed. The distribution amount is analyzed in the axial direction of the ink roller, that is, in the direction of the arrow X. Hereinafter, the analysis of the distribution amount for the dot area ratio will be described.

  First, as shown in FIG. 5, it is divided into 8 pieces at intervals of 10 cm in the direction of arrow X. In FIG. 5, the dividing line indicating the dividing position and the divided areas are indicated by numbers 1 to 8 (hereinafter, the area indicated by “1” is also referred to as “area 1”. The same applies to other areas). ). Further, the interval and the number of divisions are merely examples, and may be different from the example in FIG. In addition, if the printing direction by the printing machine is the arrow X direction and the ink roller axial direction is the arrow Y direction, the dividing direction is divided by a dividing line orthogonal to the dividing line shown in FIG. Then, the image is divided in either the vertical or horizontal direction according to the direction of the image when printing with the printing press.

  Next, an average value of the halftone dot area ratio in each region divided by the dividing line for each of C, M, Y, and K is obtained from the image data as a distribution amount for the halftone dot area ratio. FIGS. 6A to 6D show the average value of the halftone dot area ratio in each divided area corresponding to the image of each color shown in FIGS. 4A to 4D and the halftone dot in the entire image of each color. The average area ratio (this is equivalent to the average of the halftone dot area ratios in each divided region).

  In this example, the average value of the halftone dot area ratios in the divided areas is used as an indication of the distribution amount. However, for example, the total value of the halftone dot area ratios may be used. Raster data representing an image with 0 and 1 is created from the halftone dot area ratio, and the distribution of the halftone dot area ratio by the total number of data of “1”, the area of the image measured from the image output for each color, etc. It is possible to indicate the quantity. In addition, when the gradation value is used as the parameter value, the amount indicating the distribution amount for the parameter value of the present invention is the average value of the gradation values in the divided areas or the sum of the gradation values. Value.

(S102)
Next, correction performed by the correction unit 112 will be described. First, the correction amount for each divided region for each color is obtained from the distribution amount for the halftone dot area ratio of each color analyzed by the analyzing unit 111 as shown below, for example.

The average values of the halftone dot area ratios in the divided regions 1 to 8 shown in FIG. 6 are respectively A (1), A (2), A (3), A (4), A (5), Let A (6), A (7), and A (8) be the average of the entire image as AA. The correction amounts R (1), R (2), R (3), R (4), R (5), R (6), R (7), R (8) in each region are
Region 1 and Region 8:
R (i) = (A (i) −AA) × 0.1
Region 2 to Region 7:
R (i) = ((A (i−1) + A (i) + A (i + 1)) / 3−AA) × 0.1
Asking.

  The results are shown as the correction amount R in each region for each of C, M, Y, and K in FIGS. Then, C, M, Y, and K are corrected for each combination of CMYK of the image data with the correction amount R in that region. However, when the dot area ratio shows a negative value as a result of the correction, 0 is set, and 100 is set when it exceeds 100. In addition, when a positive correction is performed in the same manner on a white background portion, halftone dots are entered, so the white background correction amount may be 0, and the correction amount may be close to 0 in a halftone dot area ratio close to a white background. When the negative correction is performed in the same manner for 100% solid, halftone dots are entered, so that the solid correction amount may be 0, and the correction amount may be close to 0 in the halftone dot area ratio close to solid. According to this correction, when the average value of the halftone dot area ratio of the region along the dividing direction, that is, the axial direction of the ink roller is larger than the average in the entire image, the halftone dot area ratio is corrected so as to increase. If the average is smaller than the overall average, the dot area ratio is corrected to be small, so the amount of ink supplied to the ink roller according to the difference in the image and density position in the axial direction of the ink roller of the printing press It is possible to reproduce the uneven density due to the adjustment.

  Further, since the average value of the halftone dot area ratios of the adjacent areas is used in the areas 2 to 7, even if there is a large difference in the average halftone dot area ratio of the adjacent areas, the correction is performed. The change in the color of the image at the dividing position is made inconspicuous.

In order to make the change in the color of the image inconspicuous, for example, the position of the center line of each region shown in FIG. 8, the left side of the center line of region 1 and the right side of the center line of region 8 are described above. For example, in a range between the center line of region 1 and the center line of region 2, for example, the ratio of the distance to the center line of region 1 and the distance to the center line of region 2 is 0. 7: At the position of 0.3, the correction amount R is R = R (1) × 0.3 + R (2) × 0.7
And may be obtained by interpolation.

  In addition, the coefficient “0.1” used for calculating the correction amount R described above is obtained by printing various image data in which grays are arranged in advance on various portions of the image with a printing machine and measuring, for example, the density of each of CMYK. It calculates | requires beforehand using the measurement result.

(S103)
First, a method for creating a reference gradation correction curve will be described. First, as an example, it can be created using the method described in Japanese Patent Application No. 2002-090702 by the present applicant. Specifically, first, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, CMY are the same halftone dot area ratios in the printing press. 21 levels of gray (first color image) corresponding to 75, 80, 85, 90, 95, and 100% are output, and the L * a * b * color system value of each gray is measured. Here, the value of the L * a * b * color system is one of the values of the color system representing the color, and represents the color in the three-dimensional space of the L * axis, a * axis, and b * axis. Therefore, hue and saturation are represented by the a * b * plane, and L * is a value of a color characteristic orthogonal to the a * b * plane and representing lightness. Hereinafter, the value of the L * a * b * color system is expressed as an L * a * b * value.

  Next, a plurality of grays corresponding to 0, 20, 40, 60, 80, and 100% with the same dot area ratio of CMY in the proof color printer 2, and a CM plane, MY plane, and CY plane including the grays C, M, and Y are added to each plane of C, and a CMY combination color image (second color image) is formed so as to form a lattice at equal intervals (for example, 10% interval). The L * a * b * values are measured.

  A combination of CMY for outputting the gray L * a * b * values output by the printing press with the color printer for calibration corresponds to the combination of CMY of the second color image. A halftone dot for reproducing the gray of the printing press with the proof color printer 2 on the output side with the dot area ratio corresponding to a plurality of grays of the printing press for each of C, M, and Y. Create a reference tone correction curve for the area ratio.

  Furthermore, for K, the dot area ratio of K single color is 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80 on the printing press. , 85, 90, 95, and 100% of gray corresponding to 100% (third color image) is output, the L * value of the gray is measured and obtained, and the color printer 2 for calibration similarly uses K single color. Corresponds to 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% Are output (fourth color image), and the L * value of the gray is measured and obtained. Based on these L * values, the input side is a K halftone dot area ratio corresponding to the gray of the printing press, and the output side is a reference for setting K for outputting the gray of the printing press with the calibration color printer 2. Create a tone correction curve.

Further, as another example, the C, M, and Y gradation correction curves can be created by using the method described in Japanese Patent Application Laid-Open No. 2003-078775 by the present applicant.
Specifically, first, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, CMY are the same halftone dot area ratios in the printing press. 21 levels of gray (first color image) corresponding to 75, 80, 85, 90, 95, and 100% are output, and the L * a * b * color system value of each gray is measured.

  Next, the halftone dot area ratios of the four basic colors are equally divided from the minimum value 0 to the maximum value 100 using the proofreading color printer 2, and the gradation values of C, M, Y, and K are respectively calculated. A color image (fifth color image) in which a plurality of combined color images are arranged is output. Then, the L * a * b * color system values of the plurality of color images are measured. Further, based on the combination of C, M, Y, and K and the measured L * a * b * value, a device color profile (CMYK → L * a * b * LUT) is obtained for the calibration color printer 2. create.

  Then, the combination of CMY for outputting the gray L * a * b * values output by the printing machine with the calibration color printer is obtained as the device color profile (CMYK → L * a * b * LUT) of the calibration color printer 2. ), And for each of C, M, and Y, the input side is a halftone dot area ratio corresponding to a plurality of grays of the printing press, and the output side is a halftone dot for reproducing the gray of the printing press by the proof color printer 2 Create a reference tone correction curve for the area ratio.

  In this embodiment, the reference tone correction curve is stored in advance in the LUT storage unit 102.

  In addition, the first to third color images output from the printing press are printed at each position in the ink roller axial direction so that there is no influence of density unevenness in the ink roller axial direction. It is preferable to arrange such that the distribution of K halftone dot area ratios is uniform.

  The color adjusting unit 113 converts C, M, Y, and K corrected for C, M, Y, and K, respectively, by the correcting unit 112 using a reference gradation correction curve stored in advance in the LUT storage unit 102 to adjust the color. I do.

  Then, the corrected image data composed of C, M, Y, and K is transmitted to the calibration color printer 2, and the calibration color printer 2 outputs an image based on the transmitted image data, thereby correcting the color for calibration. It is possible to obtain an image that reproduces the density unevenness that occurs in the axial direction of the ink roller of the printing press with the color that is output by the printer 2 as the target of the printer 2.

  In addition, it is preferable to perform correction based on the C, M, Y, and K distribution amounts as described in the above color adjustment method, and then correct using the reference gradation correction curve. After the correction is performed, correction based on the distribution of the dot area ratio may be performed.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described. In the following, detailed description of configurations substantially similar to those of the first embodiment will be omitted, and different points will be mainly described.

  In the present embodiment, the correction unit 112 corrects each of C, M, Y, and K of the combination of CMYK according to the halftone dot area ratio using a density unevenness correction curve (second correction characteristic). .

  Hereinafter, the color adjustment method according to the second embodiment will be described with reference to the flowchart shown in FIG.

(Color adjustment method)
(S201)
First, similarly to the description of S101 in FIG. 2 of the first embodiment, the analysis unit 111 performs the vertical direction when the image data stored in the image data storage unit 101 is output as an image by the calibration color printer 2. Alternatively, the image data is divided into a plurality of horizontal directions, and the distribution amount of the halftone dot area ratio in the direction divided for each of C, M, Y, and K is analyzed using the divided image data (S202).
Next, a density unevenness correction curve is obtained. First, as in the first embodiment, a correction amount R for each color and position in each division direction is obtained. The density unevenness correction curve F (j) is
F (j) = j + R × D (j),
j is the halftone dot area ratio, 0, 5, 10,... 90, 95, 100
D (j) is a numerical value predetermined for each halftone dot area ratio j,
D (0) = 0.0
D (5) = 0.145
D (10) = 0.3
D (15) = 0.43
D (20) = 0.55
D (25) = 0.68
D (30) = 0.8
D (35) = 0.885
D (40) = 0.95
D (45) = 0.99
D (50) = 1.0
D (55) = 0.99
D (60) = 0.95
D (65) = 0.885
D (70) = 0.8
D (75) = 0.68
D (80) = 0.55
D (85) = 0.43
D (90) = 0.3
D (95) = 0.145
D (100) = 0.0
Asking.

  In addition, as with the coefficient “0.1” used for calculating the correction amount R in the first embodiment, this D (j) is a variety of image data in which gray is previously arranged at various locations in the image. For example, the density of each of CMYK is measured, and the measurement result is used to obtain in advance.

  An example of the density unevenness correction curve thus obtained is shown in FIG. FIG. 10 shows an example in which the correction amount R is R = −2.2. Then, C, M, Y, and K are corrected for each combination of CMYK in the image data by using a density unevenness correction curve obtained for each color and each position in the division direction. At this time, when the halftone dot area ratio on the input side is between, for example, each point (0, 5,... 95, 100), it is obtained by interpolation from the previous and next points.

  Here, the correction amount R may be obtained for each region, or may be obtained by interpolation according to the position as described with reference to FIG.

(S203)
Similar to the description of S103 in FIG. 2 of the first embodiment, the color adjustment unit 113 corrects C, M, Y, and K corrected by the correction unit 112 using a reference tone correction curve, and performs color adjustment. Do.

1 is a functional block diagram showing an embodiment of an image output system according to the present invention. 6 is a flowchart illustrating a procedure of a color adjustment method using a reference gradation correction curve including correction for reproducing density unevenness generated in the printing press according to the first embodiment. It is a figure which shows an example of the image used for description of the color adjustment method. It is a figure which shows the image about C of the image shown in FIG. It is a figure which shows the image about M of the image shown in FIG. It is a figure which shows the image about Y of the image shown in FIG. It is a figure which shows the image about K of the image shown in FIG. It is a figure for demonstrating the division | segmentation of an image. It is a figure which shows the average value of the area | region and halftone dot area rate about C. It is a figure which shows the average value of the area | region and halftone dot area rate about M. It is a figure which shows the average value of the area | region and halftone dot area rate about Y. It is a figure which shows the average value of the area | region and halftone dot area ratio about K. FIG. It is a figure which shows the area | region and correction amount which were divided | segmented about C. It is a figure which shows the area | region and correction amount which were divided | segmented about M. It is a figure which shows the area | region and correction amount which were divided | segmented about Y. It is a figure which shows the area | region and correction amount which were divided | segmented about K. It is a figure for demonstrating the relationship between the correction amount calculated | required by interpolation, and the position in a division direction. 6 is a flowchart illustrating a procedure of a color adjustment method using a reference tone correction curve including correction for reproducing density unevenness generated in a printing press according to a second embodiment. It is a figure which shows an example of a density nonuniformity correction curve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control apparatus 10 Storage part 101 Image data storage part 102 LUT storage part 11 Control part 111 Analysis means 112 Correction means 113 Color adjustment means 2 Color printer for calibration

Claims (11)

Based on the image data, the first color image output device uses the combination of a plurality of basic color parameter values as the target of color matching, and the second color image output device based on the image data. A color adjustment method for adjusting a color of an output image to be the target color,
Based on the image data, an analysis step of analyzing a distribution amount of parameter values of each basic color in either one of vertical and horizontal directions when the image data is output as an image by the second color image output device When,
A first correction stage for correcting the parameter value of each basic color based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction for each basic color;
A parameter value for each basic color is corrected so that the color value output by the first color image output device is reproduced by the second color image output device. And a second correction stage for further correction using the first correction characteristic. The first correction stage includes
Obtaining a correction amount of the parameter value of each basic color based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction;
The color adjustment method according to claim 1, wherein the parameter value of each basic color is corrected by the correction amount.   The correction amount according to claim 2, wherein the correction amount is obtained based on a difference between a parameter value distribution amount of each basic color and an average value of the distribution amounts of each basic color according to a position in the analysis direction. Color adjustment method. The first correction stage includes
A second correction characteristic for correcting the parameter value of each basic color according to the size of the parameter value based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction Including the step of seeking
The color adjustment method according to claim 1, wherein the parameter value of each basic color is corrected using the second correction characteristic.   The second correction characteristic obtains a correction amount of the parameter value of each basic color based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction, and based on the correction amount The color adjustment method according to claim 4, which is required.   5. The second correction characteristic is obtained based on a difference between a parameter value distribution amount of each basic color and an average value of the distribution amounts of each basic color according to a position in the analysis direction. The color adjustment method described in 1.   The second correction characteristic is based on a difference between a parameter value distribution amount of each basic color and an average value of the distribution amounts of each basic color according to a position in the analysis direction. The color adjustment method according to claim 4, wherein a correction amount of the parameter value is obtained and obtained based on the correction amount. The first color image output device outputs an image while supplying a plurality of basic color inks to respective ink rollers,
The supply of the ink to the respective ink rollers is made adjustable in its axial position,
The vertical or horizontal direction when the image data is output as an image by the second color image output device is the ink for the image when the image is output by the first color image output device. The color adjustment method according to claim 1, wherein the color adjustment method is an axial direction of the roller.   A program for causing a computer to execute the color adjustment method according to claim 1.   A recording medium in which the program according to claim 9 is recorded so as to be readable by the computer. A second color image that outputs the image based on the image data, with the color of the image output by the combination of the parameter values of the plurality of basic colors as the color matching target based on the image data An image output system comprising an output device, and adjusting the color of an image output from a second color image output device based on the image data so as to be the target color,
Based on the image data, an analysis means for analyzing a distribution amount of parameter values of each basic color in one of vertical and horizontal directions when the image data is output as an image by the second color image output device When,
First correction means for correcting the parameter value of each basic color based on the distribution amount of the parameter value of each basic color according to the position in the analysis direction for each basic color;
The parameter value of each basic color corrected by the first correction unit is changed so that the color output by the first color image output device is reproduced by the second color image output device. Second correction means for correcting using a first correction characteristic for correcting the value;
Image output control means for controlling the second color image output device to output an image based on a combination of parameter values of a plurality of basic colors composed of parameter values corrected by the second correction means; An image output system comprising:

Images