JP4275716B2 - Color tone monitoring apparatus, color tone management system, color tone monitoring method, and color tone management method - Google Patents

Description

  The present invention relates to a color tone monitoring apparatus and a color tone monitoring method for monitoring color tone fluctuations of a printed matter continuously printed by a printing press, and a color tone that corrects an ink amount and maintains a constant color tone based on the color tone fluctuation monitoring result. The present invention relates to a management system and a color tone management method.

Conventionally, as a means for matching the color tone of the printed surface printed on a printing press to the target color tone, a solid color solid part such as a color patch or a specific combination pattern is printed on a part other than the picture of the printed matter, Many methods have been proposed for managing in a color system such as density, spectral characteristics, or color coordinate values.
JP 2001-18364 A

  However, when a color patch is used, it is easy to monitor the color of that part, but the actual printed matter differs in consumption for each ink depending on the location, and the same dot area ratio combination is the same. There is a problem that the color of the part you really want to match cannot be matched because it is not printed.

  In addition, these are methods for managing the selected part with a color system such as density, spectral characteristics, or color coordinate values, so even if you know the current color status of the part you are monitoring, you can do so at any location. There is a problem that it is not clear which ink should be increased or decreased.

  Furthermore, there is a printed matter such as a newspaper or a flyer that has no cutting margin and cannot be provided with a color patch. In this case, there is a problem that the above method cannot be used.

  Therefore, the present invention can easily monitor color tone and color matching, can detect a change in ink density in pixel units of an image, and can accurately estimate ink density without using a color patch or the like. An object is to provide a color tone monitoring device, a color tone management system, a color tone monitoring method, and a color tone management method.

(1) Imaging means for imaging a printed matter printed with a plurality of inks in a printing machine in a plurality of different wavelength regions, and outputting measured image data in each wavelength region in units of pixels;
Image processing means for generating reference image data of each wavelength region in the target state of the printed matter;
Said actual image data, and the reference image data, the measured image data and the difference component of the reference image data, the solid density deviation of a printed matter corresponding to the reference image data and the actual image data, i.e., the two image data The measured image based on the solid density difference of the printed matter corresponding to the above, or the conversion function that maps to the solid density difference realized assuming that the portion is a solid portion if the portion is not a solid portion. the corresponding solid density deviation of the data and the reference image data and calculating means for calculating one pixel or plurality of pixels for each ink,
It said calculating means aggregates the solid density deviation calculated by calculating the solid density difference of each ink for each predetermined range, based on the solid density difference, and controls the respective ink amount of the printing press for each fixed range control Control signal output means for outputting a signal;
It is provided with.

In this configuration, the color tone monitoring device includes actual measurement image data output by the imaging unit that captures and outputs an image of the printed matter, reference image data generated by the image processing unit, and
Based on the conversion function, a solid density deviation corresponding to the measured image data and the reference image data is calculated for each ink in units of one pixel or a plurality of pixels . Then, the calculated solid density deviation is totaled to calculate the solid density deviation of each ink for each fixed range, and based on this solid density deviation, a control signal for controlling each ink amount of the printing machine for each fixed range is generated. Output. Therefore, since the entire printed surface can be confirmed instead of a specific pattern, it is possible to see the part where the color tone is actually to be adjusted, and the difference between the measured image data and the reference image data is always the solid color of each ink. Since it is related to the density fluctuation, it becomes clear that how much ink in which part can be made to match the solid density of the target image data. Further, even if there is no solid portion such as a color batch or a known halftone dot area rate independent for each color, the density value of the solid portion can be estimated. In addition, the amount of ink in which part should be changed and how much it should be changed for each area related to the ink supply mechanism, and by adjusting the ink supply amount, it is possible to automatically match the color tone to the intended one. It becomes easy. In addition, when the printing press is, for example, an offset rotary press, the solid density deviation of each ink is counted in units of the width of the ink key, and a control signal based on the result is output to the ink key control device. The amount can be feedback-controlled, and the color tone of the printed matter can always be managed to be constant.

  (2) The image processing means generates reference image data in which actual image data of the imaging means is estimated from upstream plate-making data based on an ICC profile or a multidimensional LUT.

  In this configuration, the image processing unit generates reference image data generated from upstream plate-making data based on the ICC profile or the multidimensional LUT as the reference image data. Therefore, the reference image data can be easily obtained from the upstream plate making data. In addition, by generating and acquiring reference image data from upstream plate-making data, there is no need to manually acquire the reference image from the sensor, and color tone can be monitored and controlled automatically immediately after printing starts, reducing paper loss.・ Improve quality and shorten printing time. Furthermore, by generating and acquiring reference image data from upstream plate-making data, the standard for matching the color tone is unified, and consistent color management at each office and company is possible.

(3) the image processing means, the imaging means on the basis of the criteria printed matter of an image captured, and generating a pre Kimoto quasi image data.

In this configuration, the image processing means generates a reference image data from the reference printed copy of an image captured by an imaging means. Therefore, even when upstream plate-making data cannot be acquired, the reference image data can be easily acquired. Further, by obtaining the reference image data after adjusting the color tone of the printed matter to a desired color tone, and monitoring and controlling the color tone based on the reference image data, the desired color tone determined by the person can be maintained.

(4) When the conversion function is a linear expression, the arithmetic means calculates the coefficient of the linear expression for each ink with respect to the differences ΔColor1, ΔColor2,..., ΔColorM between the measured image data and the reference image data, N × M matrix ∂ink1 / ∂color1, ∂ink1 / ∂Color2, ..., ∂ink1 / ∂ColorM
∂ink2 / ∂Color1, ∂ink2 / ∂Color2, ..., ∂ink2 / ∂ColorM
...
∂inkN / ∂Color1, ∂inkN / ∂Color2, ..., ∂inkN / ∂ColorM
The multiplied, solid density difference Δink1 of each ink, Derutaink2, · · ·, and outputs out calculate the DerutainkN.

  In this configuration, when the conversion function is a linear expression, the arithmetic means calculates an N × M matrix that is a matrix of the linear expression coefficient, that is, a change rate coefficient in each ink, as a difference ΔColor1, between the measured image data and the reference image data. Multiplying ΔColor2,..., ΔColorM, solid density deviations Δink1, Δink2,. Therefore, the solid density deviation of each ink can be easily calculated. Further, since the amount of calculation required for calculating the solid density deviation of the ink is small, it can be processed at high speed. Furthermore, since the coefficients only need to be obtained in advance, complicated and time-consuming processing can be employed according to the required accuracy when obtaining the coefficients.

(5) When the conversion function is a linear expression, the arithmetic means calculates the coefficient of the linear expression for each ink with respect to the differences ΔColor1, ΔColor2,..., ΔColorM between the measured image data and the reference image data, N × M matrix ∂ink1 / ∂color1, ∂ink1 / ∂Color2, ..., ∂ink1 / ∂ColorM
∂ink2 / ∂Color1, ∂ink2 / ∂Color2, ..., ∂ink2 / ∂ColorM
...
∂inkN / ∂Color1, ∂inkN / ∂Color2, ..., ∂inkN / ∂ColorM
, .DELTA.inkN are calculated, and the solid density values of the printed matter corresponding to the reference image, reference ink1, reference ink2,..., Reference inkN are calculated. from those obtained by adding, separately set target density value, the target Ink1, target Ink2, · · ·, and outputs to subtract target InkN.

In this configuration, when the conversion function is a linear expression, the arithmetic means calculates an N × M matrix that is a matrix of the linear expression coefficient, that is, a change rate coefficient in each ink, as a difference ΔColor1, between the measured image data and the reference image data. Multiplying ΔColor2,..., ΔColorM, solid density deviations Δink1, Δink2,. Then, from the sum of the solid density value of the printed matter corresponding to the reference image, the reference ink1, the reference ink2,..., And the reference inkN, a separately set target density value, target ink1, target ink2,. The target inkN is subtracted and output. Therefore, the density of the monitoring image can be obtained by adding the density of the reference image to the density difference ΔInk between the monitoring image and the reference image, and a difference between the density of the monitoring image and the arbitrarily specified target density is newly added. By outputting as Δink, it is possible to perform printing in accordance with a target density different from the density of the reference image.

  (6) When the conversion function is a linear expression, using a printing press model that calculates the image data of the printed material based on the dot area ratio of each ink in the printed material and the solid density value of each ink, It is characterized by comprising a change rate coefficient acquisition means for obtaining a matrix of the linear equation coefficients, that is, change rate coefficients in ink.

  In this configuration, when the conversion function is a linear expression, there is provided a change rate coefficient creating means for obtaining a matrix of a linear expression coefficient, that is, a change rate coefficient for each ink, using a printing press model. Therefore, a change rate coefficient can be created based on the dot area ratio of each ink in the printed image and the solid density value of each ink.

  (7) In the case where the conversion function is a linear expression, when there are a plurality of lattice points and the halftone dot area ratio of the image is input, the coefficient of the linear expression in each ink, that is, each change rate of the matrix of change rate coefficients It is characterized by comprising change rate coefficient obtaining means for obtaining a matrix of the change rate coefficients based on the LUT for outputting the coefficients and the halftone dot area ratio of the image.

  In this configuration, when the conversion function is a linear expression, it has a plurality of grid points, and when the halftone dot area ratio of the image is input, the coefficient of the linear expression in each ink, that is, the change rate coefficient matrix. It is possible to obtain each change rate coefficient of the matrix of change rate coefficients by inputting the halftone dot area rate of the image to the LUT that outputs the coefficients. Therefore, by creating the LUT in advance, each change rate coefficient can be easily obtained in a short time by inputting the halftone dot area ratio of the image. In addition, by using the LUT, the amount of calculation for obtaining the change rate coefficient is reduced, and processing can be performed at high speed. Furthermore, since it is sufficient to create the LUT in advance, when creating the LUT, it is possible to employ a complicated and time-consuming process according to the required accuracy.

  (8) When the conversion function is a linear expression, when there are a plurality of grid points and the reference image data or the measured image data is input, each of the coefficients of the linear expression in each ink, that is, the matrix of change rate coefficients It is characterized by comprising change rate coefficient acquisition means for obtaining a matrix of the change rate coefficients based on the LUT that outputs the change rate coefficients and the reference image data or the measured image data.

  In this configuration, when the conversion function is a linear expression, the coefficient of the linear expression in each ink, that is, a matrix of change rate coefficients, has a plurality of lattice points, and when actually measured image data is input, a matrix of change rate coefficients Are obtained based on the LUT that outputs each change rate coefficient and the measured image data. The input of the LUT may be an image (sensor image) output by the imaging means as measured image data, and can be used for a system that does not receive a solid ink density value image and a reference image from upstream.

  (9) The LUT is created using a printing press model that calculates image data of a printed material based on a halftone dot area ratio of each ink in the printed material and a solid density value of each ink. To do.

  In this configuration, the LUT is created using the printing press model. Therefore, the LUT can be created by giving the dot area ratio of each ink in the printed image and the solid density value of each ink. Further, since the LUT is created from the printing press model, the regression analysis need not be performed.

  (10) In the LUT, in a plurality of color charts printed by independently varying the density of a plurality of inks, a matrix element is used for a set of image data in each patch of each color chart, and a regression analysis method is used. It was created using the change rate coefficient of each patch obtained in this way.

  In this configuration, a LUT is created by using a regression analysis method for image data at each grid point of a plurality of color charts printed by varying the density of a plurality of inks independently. Therefore, it is possible to create an LUT with high accuracy. Also, if conditions are good, much higher accuracy can be achieved than when using a printing press model. Furthermore, since it is not necessary to build a printing press model, it can be applied to any printing method.

  (11) The imaging unit outputs the reflected light amount for each wavelength region or another value based on the reflected light amount for each wavelength region as the measured image data.

    In this configuration, the imaging unit outputs a reflected light amount value for each wavelength region or another value based on the reflected light amount value as measured image data in units of pixels. Therefore, for example, by converting the reflected light amount value to something like a logarithmic function, the required accuracy can be changed between dark and light areas, and appropriate accuracy close to the gradation of density can be achieved overall. You can get across to.

  (12) When the imaging unit outputs a reflected light amount value for each wavelength region, the imaging unit includes a converting unit that converts the reflected light amount value into another value based on the reflected light amount value.

  In this configuration, the conversion unit converts the reflected light amount value for each wavelength region output from the imaging unit into another value. Therefore, when the imaging means outputs the reflected light amount value for each wavelength region, the same effect as in (11) can be obtained by converting to another value.

(13) A monitoring point setting unit that sets a plurality of monitoring points on the printed matter and outputs the coordinate information to the image processing unit and the calculation unit;
The image processing means and the calculation means perform processing in units of monitoring points.

  In this configuration, the image processing unit and the calculation unit perform processing in units of monitoring points set by the monitoring point setting unit. Therefore, since the number of pixels to be monitored can be reduced by appropriately setting the monitoring points, the color tone monitoring process can be speeded up.

(14) Notifying means for notifying at least one of the solid density deviation of one ink or a plurality of pixels calculated for each ink by the arithmetic means or the solid density deviation for each fixed range of each ink calculated by the control signal output means. It is provided with.

In this configuration, the notification means notifies the solid density deviation of each ink calculated by the calculation means. Therefore, the operator of the printing press can adjust the ink amount based on the notification content of the notification means.

(15) Instead of the control signal output means, there is provided an informing means for informing a solid density deviation of one ink or a plurality of pixels of each ink outputted from the arithmetic means.

In this configuration, the solid density deviation of each ink output from the calculation means is notified by the notification means. Therefore, since it is possible to compare the entire printed surface, it is possible to see the part where the color tone is actually to be matched, and the difference in the estimated image data is always linked to the fluctuation of the single color solid density of each ink. It becomes clear that how much ink in the portion is changed and how much the ink can be matched with the target solid density of the image data, and the operator can control the ink amount of the printing press based on the notification content of the notification means. Even if there is no color batch, the density value of the solid portion can be estimated.

(16) Instead of the control signal output means,
Totaling means for calculating the solid density deviation of each ink in units of a certain range by calculating the solid density deviation of each pixel or each pixel calculated by the calculation means;
Informing means for informing at least one of the solid density deviation of one or more pixels of each ink calculated by the calculating means and the solid density deviation for each fixed range of each ink calculated by the counting means;
It is provided with.

In this configuration, the notification means includes a solid density difference of 1 pixel or more pixels of each ink calculating means is calculated, and the solid density deviation for each predetermined range of each ink aggregated unit has calculated, at least one of Is notified. Therefore, the operator of the printing press can adjust the ink amount based on the notification content of the notification means.

(17) The color tone monitoring device according to any one of (1) to (14);
An ink amount control device that adjusts an ink amount used for printing by the printing press based on a control signal output by the control signal output means of the color tone monitoring device;
It is provided with.

  In this configuration, the color tone monitoring device monitors the color tone of the printed matter printed by the printing press, and adjusts the ink amount of the printing press with the control signal output means. Therefore, the color tone of the printed matter can always be kept accurately within a certain range.

(18) A color tone monitoring method of a color tone monitoring device for monitoring the color tone of a printed matter,
An imaging means for imaging a printed matter printed with a plurality of inks in a printing machine in a plurality of different wavelength regions, and outputting measured image data in each wavelength region in units of pixels;
A procedure in which image processing means generates reference image data of each wavelength region in the target state of the printed matter;
The computing means corresponds to the measured image data, the reference image data, the difference between the measured image data and the reference image data, the solid density deviation between the measured image data and the reference image data, that is, both the image data. The measured image data based on the difference in the solid density of the printed matter, or the conversion function that maps to the solid density difference that is realized assuming that the portion is a solid portion when the portion is not a solid portion. A procedure for calculating the corresponding solid density deviation of the reference image data in units of one pixel or a plurality of pixels for each ink ;
A notification means for notifying the solid density deviation calculated by the calculation means;
It is provided with.

  In this configuration, the same effect as (15) can be obtained.

(19) A color tone management method for a color tone management system including a color tone monitoring device for monitoring the color tone of a printed material and an ink amount control device for adjusting an ink amount of a printing press,
An imaging means for imaging a printed matter printed with a plurality of inks in a printing machine in a plurality of different wavelength regions, and outputting measured image data in each wavelength region in units of pixels;
A procedure in which image processing means generates reference image data of each wavelength region in the target state of the printed matter;
The computing means corresponds to the measured image data, the reference image data, the difference between the measured image data and the reference image data, the solid density deviation between the measured image data and the reference image data, that is, both the image data. The measured image data based on the difference in the solid density of the printed matter, or the conversion function that maps to the solid density difference that is realized assuming that the portion is a solid portion when the portion is not a solid portion. A procedure for calculating the rising solid density deviation of the reference image data in units of one pixel or a plurality of pixels for each ink ;
The control signal output means calculates the solid density deviation for each fixed range by summing up the solid density deviation calculated by the calculation means, and based on the solid density deviation , each ink amount of the printing press is calculated for each fixed range. A procedure for outputting a control signal to be controlled;
The ink amount control means adjusts the ink amount used for printing by the printing machine for each fixed range based on the control signal output by the control signal output means;
It is provided with.

  In this configuration, the same effect as (1) can be obtained.

  According to the present invention, a method is used in which actually measured image data of an optical sensor that captures a printed matter is compared with reference image data equivalent to the sensor image, and based on the difference, the density variation of the single-color solid portion of each ink is linked. This makes it possible to compare the entire printed surface, not a specific pattern such as a color patch, so that it is possible to see the part where the actual color tone is to be matched, and the difference between the measured image data and the reference image data is always the same. Since it is related to the change in the monochromatic solid density of each ink, it becomes clear which amount of ink in which portion can be matched with the target reference image data. In addition, it is possible to automatically adjust the color tone to the target by controlling the ink supply amount by summing up each region related to the ink supply mechanism, and how much ink in which part should be changed. It becomes easy. In addition, the color tone can be adjusted even in printing in which a color patch cannot be printed, such as a newspaper or a leaflet.

  FIG. 1 is a block diagram showing a schematic configuration of a printing system including a color tone management system according to an embodiment of the present invention. A color tone management system 3 shown in FIG. 1 is a system that manages the color tone of newspaper as an example of printed matter. In addition, although the general thing is described about the structure of the newspaper company side of this structure, it is not restricted to this.

  The printing system 1 includes a paper surface editing device (computer) 11 to which a monitor 113 is connected, a RIP (Raster Image Processor) 12, an image server 13 that stores and provides image files, and an image conversion device that performs image processing of proof data ( (Computer) 14, calibration printer 15 for printing calibration paper, CTP (Computer to Plate) 17 for producing a printing plate, offset rotary press (hereinafter simply referred to as rotary press) 19 for printing printed matter (newspaper), printed matter A color tone monitoring device 21 that monitors the color tone of the ink, a monitor 22 that displays the ink state estimated by the color tone monitoring device 21, an ink key control device 23 that controls the opening degree of the ink keys 72A to 72H, and a printed matter printed by the rotary press 19. It is the structure provided with the optical sensors 25F and 25R which image the image. The color tone management system 3 of the present invention includes a color tone monitoring device 21, an ink key control device 23, and optical sensors 25F and 25R. In addition, in order to notify the ink state of the rotary press 19, not only the color tone information is notified by the monitor 22, but also the color tone information may be notified by voice by providing a speaker or a buzzer.

  Here, in the rotary press 19, characters and designs are printed on both sides of the printed matter (newspaper), and these are imaged by the optical sensors 25F and 25R to manage the color tone of both sides of the printed matter. In order to simplify the above description, only the description of imaging the surface of the printed matter with the optical sensor 25F and monitoring and managing the color tone will be described, but the back side of the printed matter is similarly imaged and monitored and managed with the optical sensor 25R. And

  The paper editing device 11 is used by the editor H to edit paper by displaying an article, a color photograph, a color advertisement for newspaper publication requested by the client K, and the like on the monitor 113. The paper surface editing apparatus 11 stores a profile set so as to have a color tone characteristic suitable for a standard rotary press in the storage unit 111. In the paper surface editing apparatus 11, the control unit 112 reads this profile from the storage unit 111, converts the edited image such as a color advertisement into a profile, and outputs it to the RIP 12. The RIP 12 creates binary halftone dot image data corresponding to a plurality of inks from the profile-converted image, and outputs these binary halftone dot image data to the image server 13. The RIP 12 creates, for example, 1-bit Tiff format image data as binary halftone image data.

  The image server 13 accumulates these image data.

  The image conversion apparatus 14 stores a profile set so as to have the color tone characteristics of the calibration printer 15 in the storage unit 141. In the image conversion apparatus 14, the control unit 142 reads out this profile from the storage unit 141 and reads out each binary halftone image data stored in the image server 13 so as to obtain the color tone characteristics of the calibration printer 15. Multi-value conversion and profile conversion are performed, and the converted image data is output to the calibration printer 15.

  The calibration printer 15 prints an image based on the image data output from the image conversion device 14 and outputs a calibration paper 31. The client K confirms the contents of the proof paper 31 and informs the editor H of the problem if there is a problem with the contents of the proof paper 31. In this case, the editor H corrects the image with the paper surface editing device 11 and asks the client K to confirm the calibration paper 31 printed with the calibration printer 15 again. If there is no problem (or disappears) in the contents of the proof paper 31, the client K notifies the editor H to that effect.

  When the editor H detects that the editor H has no problem with the contents of the proof paper 31, the paper editing apparatus 11 outputs this image data to the RIP 12 as normal image data, and outputs the binary halftone dot image data to the image server 13. To accumulate.

  The CTP 17 reads regular image data (binary halftone dot image data) from the image server 13 and produces a printing plate for each ink of the rotary press 19.

  The rotary press 19 is set with a printing plate manufactured by the CTP 17, supplies a web-like continuous paper P from the roll paper R, and is black (Black: hereinafter referred to as K) / cyan (hereinafter referred to as K) by the printing unit 73. Cyan: hereinafter referred to as C.) Magenta (hereinafter referred to as M) Yellow (Yellow: hereinafter referred to as Y) ink is supplied from a plurality of ink keys 72A to 72H. Print letters and designs on both sides. The ink supply order is not limited to this order, and the ink is supplied in a different order depending on the newspaper company or the printing factory. The ink keys 72A to 72H have a constant width, and a plurality of ink keys 72A to 72H are arranged on the surface of the continuous paper P. Further, although not shown in the rotary press 19, there are five or more colors such as hexachrome printing with six colors of CMYK, orange, and green, and high-fidelity printing with seven colors of CMYK, red, green, and blue (RGB). Printing with ink is possible. The rotary press 19 can also perform spot color printing using CMYK and one or more spot colors (also referred to as spot colors or special training colors) ink.

  In the rear stage (downstream side) of the printing unit 73, an optical sensor 25F is provided to face the front side of the continuous paper P, and an optical sensor 25R is provided to face the back side of the continuous paper P. The optical sensors 25F and 25R take images of the front surface (front cylinder side) and the back surface (back cylinder side) of the running printing paper surface that has been printed with CMYK or other color inks by the printing unit 73, so that a plurality of wavelengths can be obtained. The image data (sensor value) of the area is output for each pixel.

  As an example, the optical sensors 25F and 25R receive light irradiated from a light source (not shown) and reflected from the surface of the continuous paper P, and receive red (hereinafter referred to as R) and green (hereinafter referred to as R). G.) ・ Blue (Blue: hereinafter referred to as “B”) ・ Infrared rays (hereinafter referred to as “Ir”). , RGBIr may be described)), image data (sensor values) in four wavelength regions is output for each pixel. The optical sensors 25F and 25R output the reflected light amount value as digital data as an example.

  The light source (not shown) may irradiate light including all wavelengths of visible light, may irradiate light in only four wavelength regions of R, G, B, and Ir, or may be a single light source. A plurality of light sources may be used. When printing is performed using inks of other colors in addition to CMYK, the printed pattern may be imaged in the wavelength region of RGBIr or in another wavelength region.

  The rotary press 19 is connected to an ink key control device 23 that controls the opening amounts of the plurality of ink keys 72A to 72H to adjust the amount of ink supplied to the paper surface. The color tone monitoring device 21 is connected to a monitor 22. Yes. The ink key control device 23 adjusts the opening of each of the ink keys 72A to 72H according to a control signal from the color tone monitoring device 21 or according to an operation performed by the operator according to the display content of the monitor 22.

  The color tone monitoring device 21 of the color tone management system 3 monitors the newspaper image before dry-down printed by the rotary press 19 with the optical sensor 25F, outputs a control signal to the ink key control device 23, and each ink key 72A of the rotary press 19. Adjust the opening of ~ 72H. As a result, the color tone (ink density value) of the newspaper 33 after the continuous paper P printed on the rotary press 19 is dry-down is substantially matched with the color tone of the appropriate printing state determined by the newspaper company. Become.

  Next, the concept of color tone monitoring of the present invention will be described.

  Here, as a method for obtaining a solution by a conversion function representing the relationship between the change amount of the image data and the change amount of each ink, there is the following method.

  The conversion function maps ΔR, ΔG, ΔB, and ΔIr to ΔC, ΔM, ΔY, and ΔK, and generally, polynomials relating to ΔR, ΔG, ΔB, and ΔIr apply. In this embodiment, the linear expression of ΔRGBIr is described. For example, when the conversion function is a quadratic expression, the following expression is obtained (however, only ΔC is described).

ΔC ＝ ∂C / ∂R × ΔR + ∂C / ∂G × ΔG + ∂C / ∂B × ΔB + ∂C / ∂Ir × ΔIr
+1/2 {∂ ² C / ∂ ² R × ΔR ² + ∂ ² C / ∂ ² G × ΔG ² + ∂ ² C / ∂ ² B × ΔB ² + ∂ ² C / ∂ ² Ir × ΔIr ²
+ 2 × (∂ ² C / ∂R∂G × ΔR × ΔG + ∂ ² C / ∂R∂B × ΔR × ΔB + ∂ ² C / ∂R∂Ir × ΔR × ΔIr
+ ∂ ² C / ∂G∂B × ΔG × ΔB + ∂ ² C / ∂G∂Ir × ΔG × ΔIr + ∂ ² C / ∂B∂Ir × ΔB × ΔIr)}
Further, when the conversion function is a cubic expression, it is as follows (however, only ΔC is described).

  Further, a higher-order expression can be used as the conversion function.

  In the present invention, the solution of the conversion function is obtained by approximation using the above polynomial or approximation by other functions.

  In the following description, in order to simplify the description, a case where the conversion function is a linear expression will be described as an example. Further, the coefficient of this linear expression is referred to as a change rate coefficient.

Here, terms and symbols are defined as follows.
Sensor value: The reflected light amount itself detected by the optical sensor, or the value calculated by the following relationship between the reflected light amount detected by the optical sensor and the reflected light amount of the blank portion.

Sensor value = -log ₁₀ (light intensity / light intensity of blank page)
However, the bottom of the log is not limited to 10 and may be other values. The sensor value is not limited to these values, and may be any other monovalent function. Whether the optical sensor 25F / 25R outputs the reflected light amount value or a predetermined value obtained by converting the reflected light amount value. It may be defined according to whether (a value different from the reflected light amount value) is output.

C, M, Y, K: Density of the solid solid part of printed matter
R, G, B, Ir: Sensor value at the monitoring point of the printed matter ΔC, ΔM, ΔY, ΔK: Density deviation of the solid solid portion of the monitored printed matter with respect to the reference printed matter ΔR, ΔG, ΔB, ΔIr: Sensor of the monitored printed matter with respect to the reference printed matter Value deviation
C0, M0, Y0, K0: Density value of the solid solid part of the standard print
R0, G0, B0, Ir0: Sensor value at the monitoring point of the standard printed matter
Ac, Am, Ay, Ak: CMYK halftone dot area ratio of the monitoring points.

  The optical sensors 25F and 25R image in the four wavelength regions of RGBIr as described above, and output sensor values (measured image data) in each wavelength region for each pixel. The sensor values in the wavelength region are collectively referred to as RGBIr values.

What is necessary for the management of the color tone is the density deviation ΔC, ΔM, ΔY, ΔK of the single-color solid portion of the monitored print relative to the reference print, and this is the sensor value (R0, G0, B0, If it is possible to obtain accurately from Ir0) and the sensor values (R, G, B, Ir) of the monitoring points of the printed matter, the color tone can be managed without problems.

  In many cases, the printed matter that is subject to color tone monitoring and management does not actually have a solid monochrome part. In this case, the above C, M, Y, and K are assumed to have a solid solid part. Thus, the density of the monochromatic solid portion is expressed.

what if,
C = C (R, G, B, Ir)
M = M (R, G, B, Ir)
Y = Y (R, G, B, Ir)
K = K (R, G, B, Ir)
If the functions C (), M (), Y (), K () satisfying the above can be obtained with high accuracy, the density deviation ΔC, ΔM, ΔY, ΔK of the monochrome solid portion of the monitored print with respect to the reference print is
ΔC = C (R, G, B, Ir) − C (R0, G0, B0, Ir0)
ΔM = M (R, G, B, Ir) − M (R0, G0, B0, Ir0)
ΔY = Y (R, G, B, Ir) − Y (R0, G0, B0, Ir0)
ΔK = K (R, G, B, Ir) − K (R0, G0, B0, Ir0)
And the problem can be solved. However, since there are a plurality of variables (factors of change), it is difficult to accurately obtain C (), M (), Y (), and K (). Therefore, the following method is used.

  If the CMYK area ratio space is divided into a plurality of sufficiently small blocks, the following function can be accurately defined for an arbitrary j-th block.

ΔC = Cj (ΔR, ΔG, ΔB, ΔIr)
ΔM = Mj (ΔR, ΔG, ΔB, ΔIr)
ΔY = Yj (ΔR, ΔG, ΔB, ΔIr)
ΔK = Kj (ΔR, ΔG, ΔB, ΔIr)
Each Cj (), Mj (), Yj (), Kj () is represented by, for example, a first to third order polynomial of ΔR, ΔG, ΔB, ΔIr. Similarly, it can be divided into a plurality of sufficiently small blocks in the RGBIr space.

  In the present invention, the result of applying the above algorithm for each monitoring point is averaged for each column (ink key width) to control the ink keys 72A to 72H. The results for each monitoring point are not necessarily averaged, but may be performed according to the configuration of the apparatus.

  A specific calculation flow when each Cj (), Mj (), Yj (), Kj () is a linear expression of ΔR, ΔG, ΔB, ΔIr is as follows.

ΔC = Cj (ΔR, ΔG, ΔB, ΔIr) = ∂C / ∂R × ΔR + ∂C / ∂G × ΔG + ∂C / ∂B × ΔB + ∂C / ∂Ir × ΔIr (Formula 1)
ΔM = Mj (ΔR, ΔG, ΔB, ΔIr) = ∂M / ∂R × ΔR + ∂M / ∂G × ΔG + ∂M / ∂B × ΔB + ∂M / ∂Ir × ΔIr (Formula 2)
ΔY = Yj (ΔR, ΔG, ΔB, ΔIr) = ∂Y / ∂R × ΔR + ∂Y / ∂G × ΔG + ∂Y / ∂B × ΔB + ∂Y / ∂Ir × ΔIr (Formula 3)
ΔK = Kj (ΔR, ΔG, ΔB, ΔIr) = ∂K / ∂R × ΔR + ∂K / ∂G × ΔG + ∂K / ∂B × ΔB + ∂K / ∂Ir × ΔIr (Formula 4)
Here, the change rate coefficient such as ∂C / ∂R depends on the monitoring point. That is, the change rate coefficient has a different value for each monitoring point.

  The above formulas 1 to 4 are represented by determinants as follows.

  Next, a specific configuration of the color tone monitoring device 21 will be described. FIG. 2 is a diagram illustrating a configuration of the color tone monitoring apparatus.

  The color tone monitoring device 21 includes a multi-value quantization processing unit 41, an image processing unit 43, a profile storage unit 44, a change rate coefficient image creation unit 45, a change rate coefficient determination unit 46, a monitoring point coordinate output unit 47, a change rate LUT with interpolation. (Look Up Table) 48, a difference calculation unit 49, a product calculation unit 50, a totaling unit 51, a sensor value conversion unit 52, and an image memory 53.

  Here, in the color tone monitoring device 21, the image data picked up by the optical sensors 25 F and 25 R and output in pixel units is one pixel unit, or a group of a plurality of pixels as one element, and this is used as a unit for multi-value. The conversion processing unit 41, the image processing unit 43, and the sensor value conversion unit 52 can perform processing. There are the following methods for this compilation.

  1. A plurality of pixels are averaged to form one processing unit. For example, an average value of an area of 3 vertical pixels × 3 horizontal pixels is handled as one processing unit. As a result, there is an advantage that the influence of noise per pixel is reduced or the processing speed is increased.

  2. An RGBIr or CMYK halftone dot area ratio within a certain range is taken as one unit, and this average value is taken as one processing unit. For example, when each RGBIr is expressed by a value of 0 to 100, this is divided into 20 ranges each by dividing the RGBIr into 20 ranges, and divided into 20 × 20 × 20 × 20 = 16000 by the combination of RGBIr. Thus, the pixels that fall into this same section are averaged and treated as one processing unit. By this method, it is possible to increase the processing speed and accuracy for a pattern having a uniform pattern (flat mesh portion).

  Further, in the following description, a case where a plurality of monitoring points are set in units of one pixel or one element and the color tone is monitored / managed for each monitoring point will be described as an example.

  The multi-value processor 41 reads binary halftone dot image data from the image server 13, and from this binary halftone dot image data, the halftone dot area ratio (Ac, Am, Ay, Ak = A halftone dot area ratio in digital data) is created and output to the change rate coefficient image creating unit 45.

  The image processing unit 43 reads the binary halftone dot image data of the test chart from the image server 13, and this binary halftone dot image data and the color chart adjusted test chart read from the image memory 53 and read by the optical sensor 25 </ b> F. The profile P3 is created by analyzing the relationship with the image data (RGBIr value). The profile P3 is stored in the profile storage unit 44. In addition, the image processing unit 43 reads the profile P3 from the storage unit 44, converts the binary halftone dot image data read from the image server 13 into multivalue / profile conversion, and generates a reference value (reference RGBIr value) of the RGBIr value. ) Is output to the difference calculation unit 49.

  The profile storage unit 44 stores the profile P3.

  The rate-of-change coefficient image creating unit 45 creates a rate-of-change coefficient image based on the halftone dot area rate data of the printed matter output from the multilevel processing unit 41 and the data read from the interpolated rate of change LUT 48 and data. This change rate coefficient image is output to the change rate coefficient determination unit 46. The change rate coefficient image is an image in which a change rate coefficient is included in a one-to-one correspondence with each pixel of the reference image.

  The change rate coefficient determination unit 46 includes a memory (not shown) that stores the change rate coefficient image. The change rate coefficient determination unit 46 reads the change rate coefficient of the coordinates of the monitoring point from the change rate coefficient image stored in the memory, and calculates the product. Output to 50.

  The monitoring point coordinate output unit 47 analyzes the image data for each pixel and sets a plurality of monitoring points for each color of RGBIr. The monitoring point coordinate output unit 47 stores coordinate data of a plurality of monitoring points set as described above. The coordinate data of the monitoring points is stored in the image processing unit 43, the change rate coefficient determination unit 46, and the difference calculation. To the unit 49. In addition, as a monitoring point, all the pixels may be set, or some pixels may be selected and set.

  A change rate LUT (Look Up Table) 48 with interpolation has grid points of N × N × N × N and inputs four values Ac, Am, Ay, Ak of the halftone dot area ratio, and the following 16 corresponding to it. Number of values is output.

∂C / ∂R ∂C / ∂G ∂C / ∂B ∂C / ∂Ir
∂M / ∂R ∂M / ∂G ∂M / ∂B ∂M / ∂Ir
∂Y / ∂R ∂Y / ∂G ∂Y / ∂B ∂Y / ∂Ir
∂K / ∂R ∂K / ∂G ∂K / ∂B ∂K / ∂Ir
The details of the change rate with interpolation LUT will be described later.

  The difference calculation unit 49 calculates the difference between the measured RGBIr value read from the image memory 53 and the reference RGBIr value output from the image processing unit 43 for each monitoring point, and outputs the difference to the product calculation unit 50.

  The product calculation unit 50 multiplies the difference between the measured RGBIr value output from the difference calculation unit 49 and the reference RGBIr value by the change rate coefficient output from the change rate coefficient determination unit 46, so that the monochrome of the monitored print with respect to the reference print A solid density difference (solid density deviation) is calculated and output to the counting unit 51.

  The totaling unit 51 calculates the solid density deviation for each column by averaging the calculation result (solid density deviation) output from the product calculating unit 50 by the column (ink key width which is the control unit width of the ink amount). A control signal based on the average value is output to the ink key control device 23. In addition, the totaling unit 51 is at least one of the difference between the measured value and the reference value of the RGBIr value for each monitoring point output from the difference calculation unit 49, the solid density deviation output from the product calculation unit 50, and the solid density deviation for each column. These signals are output to the monitor 22 so that the monitor 22 displays them.

  The monitor 22 displays an image based on the signal received from the counting unit 51.

  The sensor value conversion unit 52 converts the light amount value output by reading the image of the printed matter by the optical sensor 25 </ b> F into a sensor value according to the term definition, and outputs the sensor value to the image memory 53. In the color tone monitoring device 21, when the reflected light amount value output from the optical sensors 25F and 25R is used as the sensor value without performing logarithmic conversion processing or the like, the optical sensor 25F and 25R uses another value based on the reflected light amount. When outputting (for example, a value obtained by objectively converting the reflected light amount value), the sensor value conversion unit 54 may not be provided. The sensor value conversion unit 52 may be provided on the downstream side of the image memory 53.

  The image memory 53 stores RGBIr values output by the optical sensor 25F reading a printed image.

  Next, a schematic operation of the color tone monitoring device 21 will be described with reference to FIGS. FIG. 3 is a flowchart showing a preprocessing procedure. FIG. 4 is a flowchart showing the procedure of the color tone monitoring process.

<Pretreatment>
The color tone monitoring device 21 performs the following processing as preprocessing at the time of initial setting.

  First, as shown in FIGS. 2 and 3A, the color tone monitoring device 21 performs color matching using a test chart, and prints an image of a test chart (printed material) printed in a state where color matching is normally completed. It is read by the optical sensor (RGBIr sensor) 25F (s1), and each reflected light amount value of RGBIr is output to the sensor value converter 52 (s2). The sensor value conversion unit 52 converts the reflected light amount value output by reading the image of the printed matter by the optical sensor 25F into a sensor value (RGBIr value), and outputs the sensor value to the image memory 53. The image memory 53 stores the sensor value of this image. (RGBIr value) is accumulated (s3).

  The image processing unit 43 reads the sensor value (RGBIr value) from the image memory 53 and reads the image data of the test chart stored in the image server 13 (s4), and the image processing unit 43 analyzes the relationship between the two. Then, a profile (ICC profile) P3 is created (s5). Then, the image processing unit 43 stores the profile P3 in the profile storage unit 44 (s6).

  In the color tone monitoring device 21, as shown in FIGS. 2 and 3B, the multi-value processing unit 41 acquires digital data (binary halftone image data) of the image file stored in the image server 13. (S11). Then, the multi-value processing unit 41 creates a halftone dot area ratio (Ac, Am, Ay, Ak = halftone dot area ratio in digital data) on the printing plate of each pixel from the binary halftone image data. Then, the data is output to the monitoring point coordinate output unit 47 and the change rate coefficient image creation unit 45 (s12).

  The monitoring point coordinate output unit 47 sets monitoring points. That is, a plurality of monitoring points are set for each color of CMYK in each column (ink key width) with the size of the pixel unit for the image data (s13).

On the other hand, the rate-of-change coefficient image creating unit 45 is based on the halftone dot area rate data of the printed matter output from the multilevel processing unit 41 and the data read from the interpolated rate of change LUT 48. Is obtained, a change rate coefficient image is created, and the change rate coefficient image is output to the change rate coefficient determination unit 46 (s14).
When the change rate coefficient determination unit 46 receives the change rate coefficient image from the change rate coefficient image creation unit 45, the change rate coefficient determination unit 46 stores this image in a memory (not shown) (s15).

  Note that the change rate with interpolation LUT 48 is created separately by a procedure described later.

  Further, the change rate coefficient image is necessary for each printed matter. If the monitored printed matter changes, it is necessary to recreate the change rate coefficient image. Similarly, if the printed matter changes, the monitoring point needs to be recreated.

  The profile P3 created by the image processing unit 43 may be an ICC profile, but a 4-input 4-output 4-dimensional LUT may be stored in the profile storage unit 44 instead of the profile P3.

  In addition, the color tone monitoring device 21 does not create a change rate coefficient image, and responds to the area rate of the monitoring point based on the data of the dot area rate of the printed material and the data read from the change rate LUT 48 with interpolation. It is also possible to obtain the obtained change rate coefficient.

<Tone management processing>
When printing is started by the operator, the rotary press 19 continuously prints, for example, images of eight pages of newspapers on the web-like continuous paper P supplied from the roll paper R as a predetermined image.

  As shown in FIG. 4, the monitoring point coordinate output unit 47 outputs the coordinates of the monitoring point of the image to be printed on the rotary press 19 to the image processing unit 43, the change rate coefficient determination unit 46, and the difference calculation unit 49. . When printing is started by the rotary press 19, the optical sensor 25F continuously captures images printed on the continuous paper P in four wavelength regions of R, G, B, and Ir. Image data in each wavelength region of G, B, and Ir is output to the sensor value conversion unit 52 in pixel units (s31).

  The sensor value conversion unit 52 converts the light amount value output by reading the image of the printed matter by the optical sensor 25F into a sensor value (RGBIr value) according to the term definition, and outputs the sensor value to the image memory 53 (s32).

  The image memory 53 stores the sensor value (RGBIr value) sent from the sensor value conversion unit 52 for one printing cycle (for example, for eight newspaper pages) (s33).

  On the other hand, the image processing unit 43 reads out binary halftone dot image data of an image being printed on the rotary press 19 from the image server 13 and calculates a reference RGBIr value from the storage unit 44 based on the profile P3 (or four-dimensional LUT). Generate (s34). Then, the image processing unit 43 outputs the RGBIr value (reference value) of each monitoring point to the difference calculation unit 49 (s35).

  The difference calculation unit 49 compares the RGBIr value (reference value) output from the image processing unit 43 with the RGBIr value (actual value) read from the image memory 53 for each monitoring point, and calculates the difference between both RGBIr values. It outputs to the calculating part 50 (s36).

  The change rate coefficient determination unit 46 reads the change rate coefficient of the coordinates of each monitoring point from the change rate coefficient image creation unit 45 based on the coordinate information of the monitoring points output by the monitoring point coordinate output unit 47 (s37). Subsequently, the change rate coefficient determination unit 46 outputs the change rate coefficient for each monitoring point to the product calculation unit 50 (s38).

  The product calculation unit 50 multiplies the difference value of the RGBIr values output from the difference calculation unit 49 by the change rate coefficient output from the change rate coefficient determination unit 46, thereby obtaining a single-color solid portion of the monitored print with respect to the reference print Is calculated for each monitoring point. Then, the product calculation unit 50 outputs the solid density deviation for each monitoring point to the counting unit 51 (s39).

  The totaling unit 51 averages the solid density deviation (calculation result) for each monitoring point output from the product calculation unit 50 for each column (ink key width which is the control unit width of the ink amount), and calculates the monochromatic solid density deviation for each column. And output to the ink key control device 23 (s40).

  At this time, the totaling unit 51 may be configured to output a signal so that the monitor 22 displays the average solid density deviation for each column. Further, the aggregation unit 51 may be configured to output a signal so that the monitor 22 displays the solid density deviation for each monitoring point without averaging the solid density deviation for each column. Furthermore, the totaling unit 51 may be configured to display the estimated solid density value and the solid density deviation on the monitor 22.

  The ink key control device 23 adjusts the ink amount in the rotary press 19 by controlling the ink keys 72A to 72H of the respective colors based on the deviation of the single-color solid density for each column output by the product calculation unit 50 (s41).

  As a result, the color tone (ink density value) of the newspaper 33 after the continuous paper P printed by the rotary press 19 is dry-down and the color tone of the proper printing state determined by the newspaper company are substantially matched as a result. Become.

  In the above description, the image processing unit 43 is configured to read out binary halftone dot image data from the image server 13 and create a reference value for RGBIr values. However, the present invention is not limited to this. The reference image data picked up by the optical sensor 25F may be used as the reference value of the RGBIr value as it is.

<Configuration method of change rate LUT with interpolation>
Next, a configuration method of the interpolation change rate LUT 48 of the color tone monitoring device 21 will be described.

  The change rate LUT has N × N × N × N grid points, and receives four values Ac, Am, Ay, Ak of the halftone dot area ratio, and outputs the following 16 values corresponding to the values.

∂C / ∂R ∂C / ∂G ∂C / ∂B ∂C / ∂Ir
∂M / ∂R ∂M / ∂G ∂M / ∂B ∂M / ∂Ir
∂Y / ∂R ∂Y / ∂G ∂Y / ∂B ∂Y / ∂Ir
∂K / ∂R ∂K / ∂G ∂K / ∂B ∂K / ∂Ir
Hereinafter, for convenience, it is assumed that N = 5. Each grid point of the LUT is
Ac = 0, 25, 50, 75, 100
Am = 0, 25, 50, 75, 100
Ay = 0, 25, 50, 75, 100
Ak = 0, 25, 50, 75, 100
All combinations of 5 × 5 × 5 × 5 = 625.

  The above Cj (), Mj (), Yj (), Kj () can be handled as j = 0 to 624. However, since the block size is relatively large, the accuracy can be increased by using an LUT with interpolation. Can be raised.

  When the input to the LUT is C = 25, M = 50, Y = 75, and K = 25, there are LUT lattice points corresponding to this value. It is sufficient to output the output value. However, in the case of C = 40, M = 50, Y = 75, K = 25, etc., it does not fall on the grid point, so C = 25, M = 50, Y = 75, K = The output is determined by interpolating 25 grid points and 16 output values registered at the grid points of C = 50, M = 75, Y = 75, and K = 25.

  Various methods such as prism interpolation, quadratic interpolation, cubic interpolation, and spline interpolation can be applied as the interpolation method, but it is convenient to perform linear interpolation from 16 points near the input value.

  As typical LUT lattice point setting methods, two typical methods will be described below.

(1) Method for obtaining the coefficient set to the lattice point of the change rate LUT by the printing press model The printing press model uses the area ratios Ac, Am, Ay, Ak and the solid density Dc, Dm, Dy, Dk as inputs. , G, B, Ir can be regarded as a function that returns.

  Here, details of the printer model will be described. FIG. 5 is a schematic configuration diagram of the printing press model. The printing press model calculation unit 60 includes a solid color mixture model calculation unit 61, a reflectance calculation unit 63, a dot gain model calculation unit 65, an area ratio calculation unit 67, and a Neugebauer model calculation unit 69.

  The solid color mixture model calculation unit 61 calculates the density of the solid color solid portion based on the single color solid density of each ink based on the color mixture model for obtaining the density value of the solid overlapping portion of each ink. In the present invention, as an example, a solid color model calculation unit 61 that employs a film thickness model that converts a single-color solid density into an ink film thickness will be described.

  The reflectance calculation unit 63 calculates the reflectance of the single color solid portion and the mixed color solid portion.

  The dot gain model calculation unit 65 calculates a halftone dot area value on the paper based on a dot gain model for obtaining the area ratio of each overlapping portion from the solid density value and the halftone dot area rate value of each ink.

  The area ratio calculation unit 67 calculates the area ratios of the single color solid portion and the mixed color solid portion.

  The Neugebauer model calculation unit 69 uses the well-known Neugebauer equation, the reflectance of the single color solid portion and the mixed color solid portion output from the reflectance calculation unit 63, the single color solid portion output from the area rate calculation unit 67, and An estimated RGBIr value of the image of the printed matter is calculated from the area ratio of the solid color solid portion.

  Here, the dot gain model, the color mixture model, the film thickness model, and the Neugebauer model will be described. FIG. 6 is a schematic diagram for explaining the dot gain model and the color mixture model.

<Dot gain model>
In the plate-making process, as shown in FIG. 6 (A), a portion where ink is applied and a portion where ink is not applied are expressed by a set of small dots, and the difference between gradation and color is expressed by looking at this macroscopically. It is aimed. The ratio of the area occupied by the small dots on which this ink is placed is called the halftone dot area ratio. In offset printing, instead of directly from the plate to the paper, it is transferred to a roller (blanket cylinder) once attached with rubber, and then transferred to the paper. However, as shown in FIG. In the case of printing, the ink is applied three-dimensionally. Therefore, as shown in FIG. 6C, a phenomenon occurs in which the ink protrudes from the dots formed on the plate depending on the amount. In this case, a phenomenon called dot gain (halftone dot thickening) occurs in which the halftone dot area ratio on the actually printed paper is larger than the halftone dot area ratio formed on the plate.

  As shown in FIG. 6D, the dot gain ratio varies depending on the original dot area ratio and the amount of ink even in a rotary press using the same ink. In addition, there is a phenomenon in which the dot gain is different between the case where the ink is directly applied to the paper surface and the case where the ink is applied on the portion printed with the multicolor ink. Such characteristics are reproduced by calculation from the monochromatic solid density and the halftone dot area ratio, and the area ratio of the overprinting portion of each ink is referred to as a dot gain model. There are a plurality of causes of dot gain, and one of the main causes is due to the phenomenon that ink protrudes from the dots formed on the plate.

<Color mixing model>
For example, when printing with four colors of CMYK, each plate is a set of dots expressed by binary values indicating whether ink is applied or not. Therefore, when the printed one is viewed microscopically, ink is applied. It can be seen that the part is printed with 100% solids.

  Therefore, in the case of CMYK four-color printing, each is divided into two types, that is, a portion printed with 100% solids or a blank portion, so that it can be divided into two fourth power = 16 ways. That is, when all the parts are viewed in a microscopic manner, as shown in FIG. 6E, as shown in FIG. 6E, a white paper portion, a C single color solid portion, an M single color solid portion, a Y single color solid portion, a K single color solid portion, a CM mixed color portion, and a CY mixed color. 16 solid colors (including blank paper) expressed by the following sections: CK, CK color mixing unit, MY color mixing unit, MK color mixing unit, YK color mixing unit, CMY color mixing unit, CMK color mixing unit, CYK color mixing unit, MYK color mixing unit, and CMYK color mixing unit it can. On the other hand, since the input to the printer model is each area ratio of CMYK and each monochrome density of CMYK, the RGBIr each reflectance or reflection density of the 15 solid color portions of the C single color solid portion to the CMYK mixed color portion is input. A solid color model needs to be obtained from each CMYK single color density, and this is reproduced by calculation.

  Next, a case where a film thickness model is used will be described as an example of a method for expressing the reflectance of the solid color mixing portion.

<Film thickness model>
7-12 is a figure for demonstrating a film thickness model. The film thickness model is an example of a color mixture model. The film thickness model does not increase above a certain density no matter how much the ink film thickness increases, and the reflection of the surface determines the maximum density even when reflection on the surface of paper and ink is considered. Is reproduced in the calculation.

  The film thickness model is based on the following formula, and the following devices are added to it.

^{_{D = D ∞ · (1-}} e -mt)
t: film thickness m: coefficient depending on paper, ink, etc. D _∞ : maximum density [devise 1]
Depending on the order of ink printing, the relationship between the thickness of the single-color solid portion and the mixed-color portion changes. Therefore, the film thicknesses of the single color solid portion and the mixed color portion are considered as shown in FIG.

[Invention 2]
A gray-scale image that is visible when viewed with a monochrome camera with a monochromatic light source means that the image equivalent to that image can be reproduced with monochromatic ink, so each light source (in this case R, G, B, Ir) (This is not the case.) For each representative ink (here, C ink for the R light source, M ink for the G light source, Y ink for the B light source, K ink for the Ir light source) However, this is not the case) and is converted into the film thickness of the representative ink (see FIGS. 7 to 11).

[Convention 3]
From the above equation and the relationship between the film thicknesses, the density (ink amount) of the YMCK single-color solid portion is obtained from the RGBIr image by connecting the relationship shown in FIG.

<Neugebauer model>
This is a model that reproduces halftone dot colors using the well-known Neugebauer equation, measuring white background, single color ink part, secondary, tertiary, and quaternary ink solid parts as target colors, and each RGBIr in the mixed color model The reproducible color for any CMYK combination is obtained by multiplying the reflectance by the appearance probability of each color portion.

  The printing press model calculation unit 60 receives two values, that is, the sensor density of the single-color solid portion and the halftone dot area ratio of the digital data for printing plate acquisition acquired from the upstream system (image server 13). (RGBIr value) is calculated and output.

  The monochromatic solid portion density is the density of a solid portion having a solid color of 100% in the printed matter, and the monochromatic solid portion may not exist in the actual printed matter. The monochromatic solid portion density is an amount that correlates with the ink film thickness.

  As the above dot gain model and Neugebauer model, various correction formulas with higher accuracy have been proposed, and these can be applied and are not limited to the embodiments.

In addition to the film thickness model, a method using an approximate polynomial can be applied as the color mixture model.

Example of approximate polynomial: When solid density Dc_r, Dm_g, Dy_b, Dk_ir is given
Dc_g = C2c_r ・ Dc_r ² + C1c_r ・ Dc_r + C0c_r
Dc_b = C2c_b ・ Dc_r ² + C1c_b ・ Dc_r + C0c_b
Dc_ir = C2c_ir ・ Dc_r ² + C1c_ir ・ Dc_r + C0c_ ir
Dm_r = C2m_r ・ Dm_g ² + C1m_r ・ Dm_g + C0c_r
Dm_b = C2m_b ・ Dm_g ² + C1m_b ・ Dm_g + C0c_b
Dm_ir = C2m_ir ・ Dm_g ² + C1m_ir ・ Dm_g + C0c_ir
Dy_r = C2y_r ・ Dy_b ² + C1y_r ・ Dy_b + C0y_r
Dy_g = C2y_g ・ Dy_b ² + C1y_g ・ Dy_b + C0y_g
Dy_ir = C2y_ir ・ Dy_b ² + C1y_ir ・ Dy_b + C0y_ir
Dk_r = C2k_r ・ Dk_ir ² + C1k_r ・ Dk_ir + C0k_r
Dk_g = C2k_g ・ Dk_ir ² + C1k_g ・ Dk_ir + C0k_r
Dk_b = C2k_b ・ Dk_ir ² + C1k_b ・ Dk_ir + C0k_r
(Hereafter, x, r, g, b, ir shall be entered.)
Dcm_x = C2cm_x ・ Dc_x + C1cm_x ・ Dm_x + C0cm_x ・ Dc_x ・ Dm_x
Dcy_x = C2cy_x ・ Dc_x + C1cy_x ・ Dy_x + C0cy_x ・ Dc_x ・ Dy_x
Dck_x = C2ck_x ・ Dc_x + C1ck_x ・ Dk_x + C0ck_x ・ Dc_x ・ Dk_x
Dmy_x = C2my_x ・ Dm_x + C1my _x ・ Dy_x + C0my _x ・ Dm_x ・ Dy_x
Dmk_x = C2mk_x ・ Dm_x + C1mk_x ・ Dk_x + C0mk_x ・ Dm_x ・ Dk_x
Dyk_x = C2yk_x ・ Dy_x + C1yk_x ・ Dk_x + C0yk_x ・ Dy_x ・ Dk_x
Dcmy_x = C7cmy_x ・ Dc_x + C6cmy_x ・ Dm_x + C5cmy_x ・ Dy_x +
C4cmy_x ・ Dcm_x + C3cmy_x ・ Dcy_x + C2cmy_x ・ Dmy_x +
C1cmy_x ・ Dc_x ・ D m_x ・ D y_x + C0cmy_x
Dcmk_x = C7cmk_x ・ Dc_x + C6cmk_x ・ Dm_x + C5cmk_x ・ Dk_x +
C4cmk_x ・ Dcm_x + C3cmk_x ・ Dck_x + C2cmk_x ・ Dmk_x +
C1cmk_x ・ Dc_x ・ Dm_x ・ Dk_x + C0cmk_x
Dcyk_x = C7cyk_x ・ Dc_x + C6cyk_x ・ Dy_x + C5cyk_x ・ Dk_x +
C4cyk_x ・ Dcy_x + C3cyk_x ・ Dck_x + C2cyk_x ・ Dyk_x +
C1cyk_x ・ Dc_x ・ Dy_x ・ Dk_x + C0cyk_x
Dmyk_x = C7myk_x ・ Dm_x + C6myk_x ・ Dy_x + C5myk_x ・ Dk_x +
C4myk_x ・ Dmy_x + C3myk_x ・ Dmk_x + C2myk_x ・ Dk_x +
C1myk_x ・ Dm_x ・ Dy_x ・ Dk_x + C0myk_x
Dcmyk_x = C15_x ・ Dc_x + C14_x ・ Dm_x + C13_x ・ Dy_x + C12_x ・ Dk_x +
C11_x ・ Dcm_x + C10_x ・ Dcy_x + C9_x ・ Dck_x +
C8_x ・ Dmy_x + C7_x ・ Dmk_x + C6_x ・ Dyk_x +
C5_x ・ Dcmy_x + C4_x ・ Dcmk_x + C3_x ・ Dcyk_x + C2_x ・ Dmyk_x +
C1_x ・ Dc_x ・ Dm_x ・ Dy_x ・ Dk_x + C0_x
The coefficients of the approximate polynomial (coefficients starting with C1, C2, C3, etc.) are determined by fitting to the actual printed material using a regression analysis method. In the method using approximate polynomial, it is possible to obtain arbitrary accuracy by changing the degree of the polynomial, and since it does not assume a model, it does not depend on a specific printing method and can be applied to any printing method. .

By using the printing press model configured as described above, it is possible to obtain the change rate coefficient set at the lattice point of the change rate with interpolation LUT 48 as follows. In the formula
R = PM_R (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk)
G = PM_G (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk)
B = PM_B (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk)
Ir = PM_Ir (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk)
Therefore, it is obtained as follows using the numerical differentiation method. In the example below, the first-order central difference formula is used, but the calculation method of numerical differentiation is not particularly limited.

The area ratio Ac, Am, Ay, Ak, the standard printing density as Dc, Dm, Dy, Dk, and the minute density difference as d,
∂R / ∂C = (PM_R (Ac, Am, Ay, Ak, Dc + d, Dm, Dy, Dk) -PM_R (Ac, Am, Ay, Ak, Dc-d, Dm, Dy, Dk)) / (2d)
∂G / ∂C = (PM_G (Ac, Am, Ay, Ak, Dc + d, Dm, Dy, Dk) -PM_G (Ac, Am, Ay, Ak, Dc-d, Dm, Dy, Dk)) / (2d)
∂B / ∂C = (PM_B (Ac, Am, Ay, Ak, Dc + d, Dm, Dy, Dk) -PM_B (Ac, Am, Ay, Ak, Dc-d, Dm, Dy, Dk)) / (2d)
∂Ir / ∂C = (PM_Ir (Ac, Am, Ay, Ak, Dc + d, Dm, Dy, Dk) -PM_Ir (Ac, Am, Ay, Ak, Dc-d, Dm, Dy, Dk)) / (2d)
∂R / ∂M = (PM_R (Ac, Am, Ay, Ak, Dc, Dm + d, Dy, Dk) -PM_R (Ac, Am, Ay, Ak, Dc, Dm-d, Dy, Dk)) / (2d)
∂G / ∂M = (PM_G (Ac, Am, Ay, Ak, Dc, Dm + d, Dy, Dk) -PM_G (Ac, Am, Ay, Ak, Dc, Dm-d, Dy, Dk)) / (2d)
∂B / ∂M = (PM_B (Ac, Am, Ay, Ak, Dc, Dm + d, Dy, Dk) -PM_B (Ac, Am, Ay, Ak, Dc, Dm-d, Dy, Dk)) / (2d)
∂Ir / ∂M = (PM_Ir (Ac, Am, Ay, Ak, Dc, Dm + d, Dy, Dk) -PM_Ir (Ac, Am, Ay, Ak, Dc, Dm-d, Dy, Dk)) / (2d)
∂R / ∂Y = (PM_R (Ac, Am, Ay, Ak, Dc, Dm, Dy + d, Dk) -PM_R (Ac, Am, Ay, Ak, Dc, Dm, Dy-d, Dk)) / (2d)
∂G / ∂Y = (PM_G (Ac, Am, Ay, Ak, Dc, Dm, Dy + d, Dk) -PM_G (Ac, Am, Ay, Ak, Dc, Dm, Dy-d, Dk)) / (2d)
∂B / ∂Y = (PM_B (Ac, Am, Ay, Ak, Dc, Dm, Dy + d, Dk) -PM_B (Ac, Am, Ay, Ak, Dc, Dm, Dy-d, Dk)) / (2d)
∂Ir / ∂Y = (PM_Ir (Ac, Am, Ay, Ak, Dc, Dm, Dy + d, Dk) -PM_Ir (Ac, Am, Ay, Ak, Dc, Dm, Dy-d, Dk)) / (2d)
∂R / ∂K = (PM_R (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk + d)-PM_R (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk-d)) / (2d)
∂G / ∂K = (PM_G (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk + d) -PM_G (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk-d)) / (2d)
∂B / ∂K = (PM_B (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk + d) -PM_B (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk-d)) / (2d)
∂Ir / ∂K = (PM_Ir (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk + d)-PM_Ir (Ac, Am, Ay, Ak, Dc, Dm, Dy, Dk-d)) / (2d)
Calculate
∂R / ∂C ∂R / ∂M ∂R / ∂Y ∂R / ∂K
∂G / ∂C ∂G / ∂M ∂G / ∂Y ∂G / ∂K
∂B / ∂C ∂B / ∂M ∂B / ∂Y ∂B / ∂K
∂Ir / ∂C ∂Ir / ∂M ∂Ir / ∂Y ∂Ir / ∂K
By calculating the inverse matrix of
∂C / ∂R ∂C / ∂G ∂C / ∂B ∂C / ∂Ir
∂M / ∂R ∂M / ∂G ∂M / ∂B ∂M / ∂Ir
∂Y / ∂R ∂Y / ∂G ∂Y / ∂B ∂Y / ∂Ir
∂K / ∂R ∂K / ∂G ∂K / ∂B ∂K / ∂Ir
Can be requested. By performing this calculation for the lattice points of the LUT, the coefficients of the lattice points of the LUT can be set.

Here, in practice, the matrix before obtaining the inverse matrix may not be a 4 × 4 square matrix. For example, in the patch with Ac = 0, there is no C ink.
∂R / ∂M ∂R / ∂Y ∂R / ∂K
∂G / ∂M ∂G / ∂Y ∂G / ∂K
∂B / ∂M ∂B / ∂Y ∂B / ∂K
∂Ir / ∂M ∂Ir / ∂Y ∂Ir / ∂K
As shown, it becomes 4 rows and 3 columns. In such a case, calculation can be performed using a generalized inverse matrix.

  In a patch that does not include four colors at the same time (printed with only one color, two colors, and three colors), it is treated as a square matrix with 1 row, 1 column, 2 rows, 2 columns, and 3 rows and 3 columns, and the inverse matrix is In some cases, sufficient accuracy may be obtained.

Also,
∂C / ∂R ∂C / ∂G ∂C / ∂B ∂C / ∂Ir
∂M / ∂R ∂M / ∂G ∂M / ∂B ∂M / ∂Ir
∂Y / ∂R ∂Y / ∂G ∂Y / ∂B ∂Y / ∂Ir
∂K / ∂R ∂K / ∂G ∂K / ∂B ∂K / ∂Ir
In addition, depending on the combination of Ac, Am, Ay, and Ak, it may be preferable to ignore any of the columns, and such a column may be forced to zero.

When the number of wavelength regions of the image captured by the optical sensor 25F is M and the number of inks used for printing is N, the following N × M matrix ∂ink1 / ∂color1, ∂ink1 / ∂Color2,. , ∂ink1 / ∂ColorM
∂ink2 / ∂Color1, ∂ink2 / ∂Color2, ..., ∂ink2 / ∂ColorM
...
∂inkN / ∂Color1, ∂inkN / ∂Color2, ..., ∂inkN / ∂ColorM
Can be requested. By performing this calculation for the LUT lattice points, the coefficients of the LUT lattice points can be set.

  Then, the difference ΔColor1, ΔColor2,..., ΔColorM between the measured image data and the reference image data is multiplied by the above N × M matrix that is a matrix of the change rate coefficient of each ink, thereby obtaining a solid image of each ink. The density deviations Δink1, Δink2,..., ΔinkN can be calculated as ink correction amounts.

Further, the difference ΔColor1, ΔColor2,..., ΔColorM between the actually measured image data and the reference image data is multiplied by the above N × M matrix that is a matrix of change rate coefficients of each ink to obtain a solid density of each ink. Deviations Δink1, Δink2,..., ΔinkN are calculated, and a solid density value of the reference image, a reference ink1, a reference ink2,. The ink correction amount can be calculated by subtracting ink1, target ink2,..., target inkN. By outputting the difference between the density of the monitoring image and the arbitrarily specified target density as Δink, printing according to the target density different from the density of the reference image becomes possible.

(2) Method of obtaining coefficient set to lattice point of change rate LUT by using regression analysis method for actual print data FIG. 13 illustrates an example of a color chart and a method of changing the density of the color chart. FIG. Printing is performed by changing the density of a color chart including 625 colors of LUT lattice points. For example, a color chart as shown in FIG. 13A is used. This color chart is provided with a LUT lattice point 625 patch and a CMYK solid patch.

  As a method for changing the density of the color chart, for example, as shown in FIG. 13B, the density is changed by ± 0.1 for each color of C, M, Y, and K with respect to the standard density image. Print. That is, in step 0, the four colors CMYK are adjusted to the standard density. In step 1, the concentration of C is lowered by 0.1 from the standard concentration. In step 2, the concentration of C is returned to the standard concentration, and the concentration of M is lowered by 0.1 from the standard concentration. In step 3, the density of M is returned to the standard density, and the density of Y is lowered by 0.1 from the standard density. In step 4, the density of Y is returned to the standard density, and the density of K is lowered by 0.1 from the standard density. In step 5, the concentration of K is returned to the standard concentration, and the concentration of C is increased by 0.1 from the standard concentration. In step 6, the concentration of C is returned to the standard concentration, and the concentration of M is increased by 0.1 from the standard concentration. In step 7, the density of M is returned to the standard density, and the density of Y is increased by 0.1 from the standard density. In step 8, the Y density is returned to the standard density, and the K density is increased by 0.1 from the standard density. In step 9, the density of K is returned to the standard density, and all four colors of CMYK are adjusted to the standard density. Then, the image with the density changed as described above is picked up by the optical sensor 25F, and the following calculation is performed using the obtained RGBIr value.

During the printing test, optical sensor images are acquired at regular time intervals. In the following description, it is assumed that 100 sensor images have been obtained. (In each sensor image, the printed material at the time when the image was acquired appears as if it was photographed.)
The number of the optical sensor image is i (i = 0 to 99)
The number of the LUT lattice point 625 patch is j (j = 0 to 624)
Xj (xj = 0 to 19) is the number of the CMYK solid patch belonging to the same column as the patch with the patch number j
The value of the optical sensor 25F of the j-th lattice point patch of the i-th image is set to Rij, Gij, Bij, Irij
The density of the xj-th CMYK solid patch of the i-th image is defined as Cixj, Mixj, Yixj, Kixj
The 0th image of the image of the optical sensor 25F is a reference image. ΔRij = Rij -R0j
ΔGij = Gij -G0j
ΔBij = Bij -B0j
ΔIrij = Irij-Ir0j
ΔCij = Cixj-C0xj
ΔMij = Mixj-M0xj
ΔYij = Yixj-Y0xj
ΔKij = Kixj-K0xj
.DELTA.Cij.apprxeq.a00.times..DELTA.Rij + a01.times..DELTA.Gij + a02.times..DELTA.Bij + a03.times..DELTA.Irij + a04 for each patch j.
ΔMij ≒ a10 × ΔRij + a11 × ΔGij + a12 × ΔBij + a13 × ΔIrij + a14
ΔYij ≒ a20 × ΔRij + a21 × ΔGij + a22 × ΔBij + a23 × ΔIrij + a24
ΔKij ≒ a30 × ΔRij + a31 × ΔGij + a32 × ΔBij + a33 × ΔIrij + a34
However, the goal is to obtain a00,..., A34 that holds for all i as accurately as possible.

  As the solution, a plurality of documents concerning the least square method, the normal equation, the minimum absolute value deviation method, the minimum distance method, and the like and the improvement methods thereof are known, and the details of the solution are omitted.

  Here, the least square method for fitting to a four-variable linear expression will be briefly described as an example of a regression analysis method.

In order to obtain a00, a01, a02, a03, a04 that minimizes ECj, the above equations are partially differentiated with a00, a01, a02, a03, a04, respectively, and from the condition of extreme values,
∂ECj / ∂a00 = 2Σ (a00 × ΔRij + a01 × ΔGij + a02 × ΔBij + a03 × ΔIrij + a04 -ΔCij) × ΔRij = 0
∂ECj / ∂a00 = 2Σ (a00 × ΔRij + a01 × ΔGij + a02 × ΔBij + a03 × ΔIrij + a04 -ΔCij) × ΔRij = 0
∂ECj / ∂a01 = 2Σ (a00 × ΔRij + a01 × ΔGij + a02 × ΔBij + a03 × ΔIrij + a04 -ΔCij) × ΔGij = 0
∂ECj / ∂a02 = 2Σ (a00 × ΔRij + a01 × ΔGij + a02 × ΔBij + a03 × ΔIrij + a04 -ΔCij) × ΔBij = 0
∂ECj / ∂a03 = 2Σ (a00 × ΔRij + a01 × ΔGij + a02 × ΔBij + a03 × ΔIrij + a04 -ΔCij) × ΔIrij = 0
∂ECj / ∂a04 = 2Σ (a00 × ΔRij + a01 × ΔGij + a02 × ΔBij + a03 × ΔIrij + a04 -ΔCij) = 0
If the simultaneous equations to be solved are described with the multiplication symbol x omitted,
a00Σ (ΔRij x0_i) + a01Σ (ΔGijΔRij) + a02Σ (ΔBijΔRij) + a03Σ (ΔIrijΔRij) + a04ΣΔRij -Σ (ΔCijΔRij) = 0
a00Σ (ΔRij x1_i) + a01Σ (ΔGijΔGij) + a02Σ (ΔBijΔGij) + a03Σ (ΔIrijΔGij) + a04ΣΔGij-Σ (ΔCijΔGij) = 0
a00Σ (ΔRij ΔBij) + a01Σ (ΔGijΔBij) + a02Σ (ΔBijΔBij) + a03Σ (ΔIrijΔBij) + a04ΣΔBij-Σ (ΔCijΔBij) = 0
a00Σ (ΔRij ΔIrij) + a01Σ (ΔGijΔIrij) + a02Σ (ΔBijΔIrij) + a03Σ (ΔIrijΔIrij) + a04ΣΔIrij-Σ (ΔCijΔIrij) = 0
a00ΣΔRij + a01ΣΔGij + a02ΣΔBij + a03ΣΔIrij + 100a04-ΣΔCij = 0
Thus, a00, a01, a02, a03, a04 can be obtained as a solution of the simultaneous equations. (This method is omitted in many books.)
Similarly,

As
It is possible to obtain a10, a11, a12, a13, a14 that minimize Em, a20, a21, a22, a23, a24 that minimize Ey, and a30, a31, a02, a33, a34 that minimize Ek.

  Of the obtained a00,..., A34, a04, a14, a24, and a34 are constant terms, and in this case, they are not used because they should in principle be very close to 0 or 0.

When the dot area ratio of the j-th patch is Acj, Amj, Ayj, Akj, the grid point data of LUT Acj, Amj, Ayj, Akj
∂C / ∂R = a00 ∂C / ∂G = a01 ∂C / ∂B = a02 ∂C / ∂Ir = a03
∂M / ∂R = a10 ∂M / ∂G = a11 ∂M / ∂B = a12 ∂M / ∂Ir = a13
∂Y / ∂R = a20 ∂Y / ∂G = a21 ∂Y / ∂B = a22 ∂Y / ∂Ir = a23
∂K / ∂R = a30 ∂K / ∂G = a31 ∂K / ∂B = a32 ∂K / ∂Ir = a33
Set as follows.

  By performing the above process for each j (0 to 624), coefficients can be set for all lattice points of the LUT.

  In the above, the density is increased and decreased independently for each color, and the coefficient is obtained by the regression analysis method based on the continuous images acquired at that time, but if an independent result is finally obtained for the increase and decrease of the ink, The order and combination of the ink density increase / decrease are not limited to this, for example, CM is raised, this is returned, MY is raised, this is returned, YK is raised, this is returned, and KC is raised. . . Combinations such as are also possible.

  Also, instead of using a continuous image regression analysis method, it is possible to acquire one data each time the concentration is increased or decreased, thereby acquiring the data. However, the embodiment is not limited to this.

  In the above description, the case where the coefficient set for the lattice point of the change rate LUT is obtained from the actual print data has been described. However, the present invention is not limited to this, and the image processing unit 43 has read out from the image server 13. For binary halftone dot image data (reference image data), a coefficient set at a lattice point of the change rate LUT may be obtained.

  Note that one interpolation rate LUT with interpolation may be normally created for each rotary press or factory, or a plurality may be created.

  In the above description, the change rate coefficient image that is input to the change rate coefficient determination unit 46 uses the one created by the change rate coefficient image creation unit 45 based on the upstream data acquired from the image server 13. However, the present invention is not limited to this. For example, an image created by estimation from an image captured by the optical sensor 25F may be used.

  When an image file cannot be acquired from the upstream system, as shown in FIG. 5B, a monochrome solid portion density is given to the printing press model calculation unit at the time of initial setting, and a temporary halftone dot is displayed. By giving an area ratio and repeatedly calculating so that the halftone dot area ratio converges to a certain value or less, the area ratio value of the CMYK halftone dot can be obtained.

  In the above description, the color tone monitoring and color tone management of the printed matter printed using the four-color inks of CMYK on the offset rotary press has been described. However, five or more colors such as the above-described hexachrome printing and hi-fi printing are described. In multi-color printing, it is possible to monitor the color tone and manage the color tone of the printed matter by creating a printing machine model suitable for it.

  That is, in the above description, the case of 4-color process printing with Ink1 = C, Ink2 = M, Ink3 = Y, and Ink4 = K has been described, but printing using five or more colors, for example, Ink1, Ink2 In the case of 6 color printing of Ink3, Ink3, Ink4, Ink5 and Ink6, since most of the areas are printed with 4 colors or less, the color tone is similarly set by setting monitoring points in such areas. It is possible to monitor.

  For example, with regard to the monitoring points printed with four color overlays of Ink1, Ink2, Ink4, and Ink6 at most, in the above description, C is replaced with Ink1, M is replaced with Ink2, Y is replaced with Ink4, and K is replaced with Ink6. Good. In this case, the printing press model and the LUT correspond to the six colors Ink1 to Ink6, or there are six combinations for selecting four colors from the six colors. Therefore, the printer model and the LUT corresponding to the four colors as described above. 6 sets are prepared and used by switching. The same applies to special color printing using CMYK and one or more special colors (also called spot colors or special training colors).

  Further, in the printing system 1, when the operator adjusts the color tone of the printed matter, the color tone monitoring device 21 may not include a configuration for outputting a control signal to the ink key control device 23. For example, in the case where it is sufficient to be able to confirm the difference between the actual measured value of RGBIr value for each monitoring point of each ink and the reference value, instead of the change rate coefficient determination unit 46 and the product calculation unit 50 of the color tone monitoring device 21, it is not shown. A notification unit may be provided to output a signal that causes the monitor 22 to display the difference between the actual measurement value of the RGBIr value output from the difference calculation unit 49 and the reference value.

  In addition, a not-illustrated notifying unit is provided instead of the totaling unit 51 of the color tone monitoring device 21, and the solid density deviation for each monitoring point calculated by the product calculating unit 50 or for each monitoring point output by the difference calculating unit 49. A signal for displaying on the monitor 22 at least one of the difference between the actual measurement value of the RGBIr value and the reference value may be output.

  Further, the totaling unit 51 is configured not to output a control signal to the ink key control device 23, and the totaling unit 51 has a solid density deviation for each column, a solid density deviation for each monitoring point calculated by the product calculation unit 50, Alternatively, it may be configured to output a signal for causing the monitor 22 to display at least one of the difference between the measured value of the RGBIr value for each monitoring point output by the difference calculation unit 49 and the reference value.

  In the printing system 1, when monitoring by the operator is unnecessary, the monitor 22 may not be provided, and the counting unit 51 may not output a signal to the monitor 22.

  In the above description, an offset rotary press has been described as an example of a printing press. However, the present invention is not limited to this, and the color tone of a printed matter printed by another printing press is monitored (managed). Of course, it can also be applied. For example, when printing with an inkjet printer or a laser printer, it is possible to monitor the color tone in the same manner by using a printer model suitable for the apparatus.

1 is a block diagram showing a schematic configuration of a color tone management system according to an embodiment of the present invention. It is a figure which shows the structure of a color tone monitoring apparatus. It is a flowchart which shows the procedure of pre-processing. It is a flowchart which shows the procedure of a color tone monitoring process. It is a schematic block diagram of a printing machine model. It is a schematic diagram for demonstrating a dot gain model and a color mixture model. It is a figure for demonstrating a film thickness model. It is a figure for demonstrating a film thickness model. It is a figure for demonstrating a film thickness model. It is a figure for demonstrating a film thickness model. It is a figure for demonstrating a film thickness model. It is a figure for demonstrating a film thickness model. It is a figure for demonstrating an example of a color chart and the method of changing the density of a color chart.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printing system 3 ... Color tone management system 11 ... Paper surface edit device 12 ... RIP 13 ... Image server 14 ... Image processing device 15 ... Calibration printer 19 ... Rotary press 21 ... Color tone monitoring device 22 ... Monitor 23 ... Ink key control device 25F, 25R ... Optical sensor 31 ... Calibration paper 33 ... Newspaper 41 ... Multi-value processing unit 43 ... Image processing unit 44 ... Profile storage unit 45 ... Change rate coefficient image creation unit 46 ... Change rate coefficient determination unit 47 ... Monitoring point coordinate output unit 48 ... Change rate with interpolation LUT 49 ... Difference calculation unit 50 ... Product calculation unit 51 ... Totaling unit 52 ... Sensor value conversion unit 53 ... Image memory 61 ... Solid color model calculation unit 63 ... Reflectance calculation unit 65 ... Dot gain model calculation Unit 67 ... Area ratio calculation unit 69 ... Neugebauer model calculation 72A~72H ... ink keys 73 ... printing unit

Claims (19)

Imaging means for imaging a printed matter printed with a plurality of inks in a printing machine in a plurality of different wavelength regions, and outputting measured image data in each wavelength region in units of pixels;
Image processing means for generating reference image data of each wavelength region in the target state of the printed matter;
Said actual image data, and the reference image data, the measured image data and the difference component of the reference image data, the solid density deviation of a printed matter corresponding to the reference image data and the actual image data, i.e., the two image data The measured image based on the solid density difference of the printed matter corresponding to the above, or the conversion function that maps to the solid density difference realized assuming that the portion is a solid portion if the portion is not a solid portion. the corresponding solid density deviation of the data and the reference image data and calculating means for calculating one pixel or plurality of pixels for each ink,
It said calculating means aggregates the solid density deviation calculated by calculating the solid density difference of each ink for each predetermined range, based on the solid density difference, and controls the respective ink amount of the printing press for each fixed range control Control signal output means for outputting a signal;
Color tone monitoring device.   The color monitoring apparatus according to claim 1, wherein the image processing unit generates reference image data obtained by estimating actual image data of the imaging unit from upstream plate-making data based on an ICC profile or a multidimensional LUT. Said image processing means on the basis of the imaging means of the criteria prints captured image, before Kimoto color monitoring apparatus according to claim 1 for generating a quasi image data. When the conversion function is a linear expression, the arithmetic means calculates a coefficient of the linear expression in each ink, that is, a change rate coefficient with respect to the differences ΔColor1, ΔColor2,..., ΔColorM between the measured image data and the reference image data. The following N × M matrix ∂ink1 / ∂color1, ∂ink1 / 2, Color2, ..., ∂ink1 / ∂ColorM
∂ink2 / ∂Color1, ∂ink2 / ∂Color2, ..., ∂ink2 / ∂ColorM
...
∂inkN / ∂Color1, ∂inkN / ∂Color2, ..., ∂inkN / ∂ColorM
The multiplied, solid density difference Δink1 of each ink, Derutaink2, · · ·, color monitoring device according to any one of claims 1 to 3 outputs out calculate the DerutainkN. When the conversion function is a linear expression, the arithmetic means calculates a coefficient of the linear expression in each ink, that is, a change rate coefficient with respect to the differences ΔColor1, ΔColor2,..., ΔColorM between the measured image data and the reference image data. The following N × M matrix ∂ink1 / ∂color1, ∂ink1 / 2, Color2, ..., ∂ink1 / ∂ColorM
∂ink2 / ∂Color1, ∂ink2 / ∂Color2, ..., ∂ink2 / ∂ColorM
...
∂inkN / ∂Color1, ∂inkN / ∂Color2, ..., ∂inkN / ∂ColorM
, .DELTA.inkN are calculated, and the solid density values of the printed matter corresponding to the reference image, reference ink1, reference ink2,..., Reference inkN are calculated. from those obtained by adding, separately set target density value, the target Ink1, target Ink2, · · ·, color monitoring device according to any one of claims 1 to 3 goals inkN by subtraction outputs.   When the conversion function is a linear expression, based on the halftone dot area ratio of each ink in the printed matter and the solid density value of each ink, using the printing press model that calculates the image data of the printed matter, 6. The color tone monitoring apparatus according to claim 1, further comprising a change rate coefficient acquisition unit that obtains a coefficient of a linear expression, that is, a matrix of change rate coefficients.   When the conversion function is a linear expression, it has a plurality of grid points, and when the halftone dot area ratio of the image is inputted, the coefficient of the linear expression in each ink, that is, each change rate coefficient of the matrix of change rate coefficients is output. The color tone monitoring apparatus according to claim 1, further comprising a change rate coefficient acquisition unit that obtains a matrix of the change rate coefficients based on an LUT to be performed and a dot area ratio of an image.   When the conversion function is a linear expression, it has a plurality of grid points, and when the reference image data or the measured image data is input, the coefficient of the linear expression in each ink, that is, each change rate coefficient matrix 6. The color tone according to claim 1, further comprising a change rate coefficient acquisition unit that obtains a matrix of the change rate coefficients based on a LUT that outputs a coefficient and the reference image data or the measured image data. Monitoring device.   The LUT is created using a printing machine model that calculates image data of a printed material based on a dot area ratio of each ink in the printed material and a solid density value of each ink. Color tone monitoring device.   In the LUT, in a plurality of color charts printed by independently varying the density of a plurality of inks, matrix elements were determined for each set of image data in each patch of each color chart using a regression analysis technique. The color tone monitoring apparatus according to claim 7 or 8, which is created using a change rate coefficient of each patch.   The color image monitoring apparatus according to claim 1, wherein the imaging unit outputs a reflected light amount for each wavelength region or another value based on the reflected light amount in units of pixels as the measured image data.   12. The color tone monitoring apparatus according to claim 1, further comprising a conversion unit that converts the value of the reflected light amount for each wavelength region into another value based on the reflected light amount value when the imaging unit outputs the reflected light amount value. A monitoring point setting unit that sets a plurality of monitoring points on the printed matter and outputs the coordinate information to the image processing unit and the calculation unit,
The color monitoring apparatus according to claim 1, wherein the image processing unit and the calculation unit perform processing in units of monitoring points. Informing means for informing at least one of the solid density deviation of one pixel or a plurality of pixels of each ink calculated by the computing means or the solid density deviation for each fixed range of each ink calculated by the control signal output means is provided. The color tone monitoring apparatus according to claim 1. The color tone monitoring apparatus according to any one of claims 1 to 13, further comprising a reporting unit that reports a solid density deviation in units of one pixel or a plurality of pixels of each ink output by the calculation unit instead of the control signal output unit. . Instead of the control signal output means,
Totaling means for calculating the solid density deviation of each ink in units of a certain range by calculating the solid density deviation of each pixel or each pixel calculated by the calculation means;
Informing means for informing at least one of the solid density deviation of one or more pixels of each ink calculated by the calculating means and the solid density deviation for each fixed range of each ink calculated by the counting means;
A color tone monitoring apparatus according to claim 1, comprising: The color tone monitoring device according to any one of claims 1 to 14,
An ink amount control device that adjusts an ink amount used for printing by the printing press based on a control signal output by the control signal output means of the color tone monitoring device;
Color management system with A color tone monitoring method for a color tone monitoring device for monitoring the color tone of a printed material,
An imaging means for imaging a printed matter printed with a plurality of inks in a printing machine in a plurality of different wavelength regions, and outputting measured image data in each wavelength region in units of pixels;
A procedure in which image processing means generates reference image data of each wavelength region in the target state of the printed matter;
The computing means corresponds to the measured image data, the reference image data, the difference between the measured image data and the reference image data, the solid density deviation between the measured image data and the reference image data, that is, both the image data. The measured image data based on the difference in the solid density of the printed matter, or the conversion function that maps to the solid density difference that is realized assuming that the portion is a solid portion when the portion is not a solid portion. A procedure for calculating the corresponding solid density deviation of the reference image data in units of one pixel or a plurality of pixels for each ink ;
A notification means for notifying the solid density deviation calculated by the calculation means;
Color tone monitoring method with A color tone management method of a color tone management system including a color tone monitoring device that monitors the color tone of a printed material and an ink amount control device that adjusts the ink amount of a printing press,
An imaging means for imaging a printed matter printed with a plurality of inks in a printing machine in a plurality of different wavelength regions, and outputting measured image data in each wavelength region in units of pixels;
A procedure in which image processing means generates reference image data of each wavelength region in the target state of the printed matter;
The computing means corresponds to the measured image data, the reference image data, the difference between the measured image data and the reference image data, the solid density deviation between the measured image data and the reference image data, that is, both the image data. The measured image data based on the difference in the solid density of the printed matter, or the conversion function that maps to the solid density difference that is realized assuming that the portion is a solid portion when the portion is not a solid portion. a step of calculating the solid density difference on a pixel or plurality of pixels for each ink to rise of the reference image data,
The control signal output means calculates the solid density deviation for each fixed range by summing up the solid density deviation calculated by the calculation means, and based on the solid density deviation , each ink amount of the printing press is calculated for each fixed range. A procedure for outputting a control signal to be controlled;
The ink amount control means adjusts the ink amount used for printing by the printing machine for each fixed range based on the control signal output by the control signal output means;
Color management method with.

Images