JP4176815B1 - Color tone monitoring apparatus, color tone management system, color tone monitoring method, and color tone management method - Google Patents

Abstract

Color tone monitoring apparatus, color tone management system capable of detecting change in ink density without being affected by unstable factors that can easily perform color tone monitoring and color matching, and without color patches or the like, and Provide a color monitoring method.
A color tone monitoring apparatus 21 is configured to print RGBIr of a printed matter printed by a rotary press 19 based on an estimated solid density assumed by a solid density adjustment unit 50 and a halftone dot area ratio calculated by a multi-value processing unit 41. The value is estimated by the printing press model calculation unit 47, and the estimated solid density is calculated by a predetermined calculation method based on the estimated RGBIr value and the actual measured RGBIr value of the printed matter imaged by the optical sensor 25. Then, a control signal for controlling the ink amount is output to the ink key control unit 23 so that the estimated solid density and the standard solid density read from the standard solid density storage unit 45 match. Thereby, the ink density can be accurately estimated without using a color patch or the like, and the color tone can be easily monitored and the color matching can be easily performed.
[Selection] Figure 1

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;
Estimated image data obtained by estimating the measured image data of each wavelength region of the imaging means based on the halftone dot area ratio for each ink of the printed matter and the solid density value of each ink is calculated in units of one pixel or a plurality of pixels. A mathematical model that simulates the printing press, and determines the solid density value of each ink as an unknown, the estimated image data, and a pixel unit or a pixel unit according to the calculated pixel unit of the estimated image data An estimated solid density output means for obtaining a solution when the measured image data processed in units of a plurality of pixels are substantially equal, and outputting the solution as an estimated solid density value of each ink;
Storage means for storing a target solid density value which is a target value of the solid density of each ink;
A density difference calculating means for calculating a solid density difference that is a difference between the estimated solid density value of each ink and the target solid density value of each ink;
The solid density difference calculated by the density difference calculating means is totaled to calculate a solid density difference for each fixed range. Based on the solid density difference for each fixed range, each ink amount of the printing press is calculated for each fixed range. Control signal output means for outputting a control signal to be controlled;
It is provided with.

  In this configuration, the estimated solid density value (estimated solid value) of each ink is calculated from the difference between the measured image data output by the imaging unit and the estimated image data calculated by the estimated solid density output unit using a mathematical model of the printing press. (Concentration value). Then, the solid density difference, which is the difference between the estimated solid density value and the target solid density value, is calculated, and the solid density difference is totaled to control the ink amount for each fixed range based on the solid density difference for each fixed range. A control signal for outputting is output. 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 a portion is changed and how much it can be matched with the target solid density of the image data, and the ink amount can be easily controlled for each fixed range.

(2) The estimated solid density output means includes a printing press model calculation means for calculating estimated image data in units of one pixel or a plurality of pixels by the printing press model,
The printing press model calculation means includes:
A color mixture model calculation unit that calculates the density value of the solid overprinting part of each ink from the single color solid density of each ink,
From the density value of the solid overprint portion of each ink calculated by the color mixture model calculation unit, a reflectance calculation unit that calculates the reflectance,
A dot gain model calculation unit for determining the dot area ratio on the actually printed paper from the solid density of each ink and the dot area ratio value on the digital data;
From the dot area rate on the paper surface determined by the dot gain model calculation unit, an area rate calculation unit that calculates the area rate of the solid overlap portion of each ink;
Based on the reflectance calculated by the reflectance calculation unit and the area ratio calculated by the area rate calculation unit, a reproduction color for each ink combination is obtained, and estimated image data obtained by estimating the measured image data of the imaging unit is obtained. An estimated value calculation unit to be calculated;
It is provided with.

In this configuration, the estimated solid density output means includes a printing press model calculation means for calculating estimated image data in units of one pixel or a plurality of pixels by the printing press model,
The printing press model calculation means includes a color mixture model calculation unit, a dot gain model calculation unit, and an estimated value calculation unit that calculates estimated image data based on outputs from the reflectance calculation unit and the area ratio calculation unit. ing. By using the color mixture model and the dot gain model, the density value of the solid overprint portion of each ink and the halftone dot area ratio value of each solid overprint portion can be easily calculated, so the estimated image data can be calculated efficiently. can do. In addition, since all the images expressed in a plurality of different wavelength regions can be linked to the monochromatic solid density, the increase / decrease in the ink can be accurately estimated.

  (3) The color mixture model calculation unit converts the single-color solid density into an ink film thickness, and uses a film thickness model or a function approximation method to obtain a relationship between the ink film thickness and the ink density, so that solid ink is printed over each ink. The density value of the part is calculated.

  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 a model that reproduces the above in the calculation. In this configuration, by applying the film thickness model to the color mixture model calculation unit, it is possible to easily calculate the density value of the solid overprint portion of each ink. In addition, by using a film thickness model, it is possible to replace a monochrome grayscale image that can be seen when a mixed color part is viewed with a certain light source with a virtual film thickness of monochromatic ink, and the relationship between the virtual film thickness and the film thickness of each ink Therefore, it is possible to obtain the ink film thickness of the monochromatic solid part, and further to obtain the density of the monochromatic solid part. In addition, by using, for example, a polynomial approximation method as a function approximation method, it is possible to obtain arbitrary accuracy by changing the degree of the polynomial, and since no model is assumed, it does not depend on a specific printing method, Applicable to printing methods.

  (4) The estimated solid density output means calculates estimated image data based on a halftone dot area ratio of each ink obtained by converting the upstream plate making data into a multi-value and a solid density value of each ink. To do.

  In this configuration, the estimated solid density output means obtains the halftone dot area ratio of each ink by converting the upstream plate making data into multiple values, and the estimated image based on the halftone dot area ratio and the solid density value of each ink. Calculate the data. Therefore, by acquiring the upstream plate making data, the dot area ratio can be acquired easily and easily, and the estimated image data can be calculated quickly. In addition, by acquiring upstream image data, it is possible to use an accurate halftone dot area ratio instead of estimation, and it is possible to reduce an error factor in the calculation of the printing press model.

  (5) The estimated solid density output means assumes a standard solid density from the measured image data of the printed matter imaged by the imaging means, and the dot area ratio of each ink estimated from the assumed standard solid density; The estimated image data is calculated based on the solid density value of the ink.

  In this configuration, the estimated solid density output means assumes the standard density from the measured image data of the printed matter imaged by the imaging means, and estimates and acquires the dot area ratio of each ink from the assumed standard density. Then, estimated image data is calculated based on the halftone dot area ratio. Therefore, even when upstream image data cannot be acquired, it is possible to estimate and acquire the halftone dot area ratio of each ink and calculate estimated image data by assuming a standard solid density. Further, since upstream data is not required, it becomes easy to add a closed system to an existing printing press. In this case, although errors in the calculation of the printing press model remain, the halftone dot area ratio on the digital data becomes effective when the plate is actually made and used in the printing press. The effective halftone dot area ratio including the characteristics is used, and it can be expected that the error of the printing press model is covered.

  (6) The imaging unit outputs, as the measured image data, a reflected light amount value for each wavelength region or another value based on the reflected light amount value in units of pixels.

  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.

  (7) When the imaging means outputs a reflected light amount for each wavelength region, the imaging means includes a converting means for converting to 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 unit outputs the reflected light amount value for each wavelength region, the same effect as in (6) can be obtained by converting to another value.

(8) A monitoring point setting unit configured to set a plurality of monitoring points on the printed matter and output the coordinate information to the estimated solid density output unit and the estimated solid density output unit;
The estimated solid density output means and the estimated solid density output means perform processing in units of monitoring points.

  In this configuration, the estimated solid density output means and the estimated solid density output means perform processing in units of monitoring points set by the monitoring point setting means. 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.

(9) Image processing means for generating, in pixel units, reference image data obtained by estimating actual image data of the imaging means from upstream plate making data based on an ICC profile or multidimensional LUT,
The estimated solid density output means sets the solid density value of each ink as an unknown, the estimated image data, and the reference image data processed in units of one pixel or a plurality of pixels according to the calculated pixel unit of the estimated image data; Are obtained, and the solution is stored in the storage means as the target solid density value.

  In this configuration, the reference image data generated from the upstream plate making data is compared with the estimated image data calculated by the estimated solid density output means, and the solid density value when the difference between the two data is less than a certain value is obtained. The target solid density value is used. Therefore, by controlling the estimated solid density obtained from the measured image data captured by the imaging unit and the estimated image data output by the estimated solid density output unit to be close to the target solid density, the color tone of the printed matter is A value suitable for an image can be obtained.

  (10) The estimated solid density output means sets the solid density value of each ink as an unknown, and the reference is processed in units of one pixel or a plurality of pixels according to the estimated image data and the calculated pixel unit of the estimated image data. A solution when the image data becomes equal is obtained, and this solution is stored in the storage means as the target solid density value.

  In this configuration, the reference printed matter that has undergone color matching is imaged by the imaging means, a solid density value for each ink is obtained based on the reference image data and the estimated image data, and the target solid density value for each ink is determined. Is stored in the storage means. Therefore, the color tone of the printed matter can be monitored and adjusted based on the reference printed matter whose color tone is actually confirmed.

  (11) The storage unit stores a preset reference solid density value as a target solid density value of each ink.

  In this configuration, the storage unit stores a preset reference solid density value as the target solid density value of each ink. Therefore, by setting, for example, a standard solid density value of a newspaper company as the standard solid density value, the color tone of the printed material can be made to meet the standard of the new newspaper company.

  (12) At least one of an estimated solid density value output by the estimated solid density output means, a solid density difference calculated by the density difference calculation means, and a solid density difference for each predetermined range calculated by the control signal output means. An informing means for informing either of them is provided.

  In this configuration, the notifying means notifies at least one of the solid density difference calculated by the density difference calculating means, the solid density difference calculated by the density difference calculating means, and the estimated solid density value output by the density adjusting means. . Therefore, the operator of the printing press can adjust the ink amount based on the notification content of the notification means.

  (13) A notification means for notifying the estimated solid density value output by the estimated solid density output means is provided in place of the storage means, the density difference calculation means, and the control signal output means.

  In this configuration, an estimated solid density value, which is an estimated value of the solid density value of each ink, is obtained from the difference between the actually measured image data output by the imaging unit and the estimated image data calculated by the estimated solid density output unit. Then, the estimated solid density value is notified by a 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.

  (14) Instead of the control signal output means, the estimated solid density value output by the estimated solid density output means, the solid density difference calculated by the density difference calculation means, and a certain range that is totalized by the control signal output means It is characterized by comprising a notifying means for notifying at least one of the solid density difference for each.

  In this configuration, the operator can control the ink amount of the printing press based on the notification content of the notification means.

(15) Instead of the control signal output means, at least one of the estimated solid density value output by the estimated solid density output means or the solid density difference of each ink calculated by the density difference calculation means is summed up to a certain range. A counting means for calculating at least one of an estimated solid density value or a solid density difference for each;
The estimated solid density value output by the estimated solid density output means, the solid density difference calculated by the density difference calculating means, and the estimated solid density value for each fixed range calculated by the control signal output means or the solid for each fixed range It is characterized by comprising a notifying means for notifying at least one of the density difference.

  In this configuration, the operator can control the ink amount of the printing press based on the notification content of the notification means.

(16) The color tone monitoring device according to any one of (1) to (12);
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 characterized by including.

  In this configuration, the color tone monitoring device outputs a control signal for controlling the ink amount by monitoring the color tone of the printed matter printed by the printing press, and the ink amount control device outputs the control signal output means of the color tone monitoring device. The ink amount of the printing press is adjusted based on the control signal. Therefore, by adopting this color management system, it is possible to compare the entire printed surface, so that it is possible to see the part where the actual color tone is to be adjusted, and the difference in the estimated image data is always the solid color of each ink. Since it is related to density fluctuations, it becomes clear which ink in which part and how much it can be matched with the target solid density of the image data, and it is possible to keep the color tone of the printed matter within a certain range with high accuracy. it can.

(17) a procedure in which the imaging unit images a printed matter printed using a plurality of inks in a printing machine in a plurality of different wavelength regions, and outputs measured image data in each wavelength region;
Estimated solid density output means estimates estimated image data obtained by estimating measured image data in each wavelength region of the imaging means based on the dot area ratio for each ink of the printed matter and the solid density value of each ink. A mathematical model that is calculated in units of pixels or a plurality of pixels, and a printing press model that simulates a printing press, with a solid density value of each ink as an unknown, the estimated image data, and a calculated pixel unit of the estimated image data A procedure for obtaining a solution when the measured image data processed in units of one pixel or a plurality of pixels is equal to each other, and outputting the solution as an estimated solid density value of each ink;
A notification means for notifying the estimated solid density value;
It is provided with.

  In this configuration, the same effect as (13) can be obtained.

(18) a procedure in which the imaging means images a printed matter printed using a plurality of inks in a printing machine in a plurality of different wavelength regions, and outputs measured image data in each wavelength region in units of pixels;
Estimated solid density output means estimates estimated image data obtained by estimating measured image data in each wavelength region of the imaging means based on the dot area ratio for each ink of the printed matter and the solid density value of each ink. A mathematical model that is calculated in units of pixels or a plurality of pixels, and a printing press model that simulates a printing press, with a solid density value of each ink as an unknown, the estimated image data, and a calculated pixel unit of the estimated image data A procedure for obtaining a solution when the measured image data processed in units of one pixel or a plurality of pixels is equal to each other, and outputting the solution as an estimated solid density value of each ink;
A storage means for storing a target solid density value which is a target value of the solid density of each ink;
A procedure for calculating a solid density difference between the estimated solid density value of each ink and the target solid density value of each ink;
The control signal output means sums up the solid density differences calculated by the density difference calculation means to calculate a solid density difference for each fixed range, and based on the solid density difference for each fixed range, each ink of the printing press A procedure for outputting a control signal for controlling the amount;
An ink amount control means, based on the control signal, a procedure for adjusting the ink amount used for printing by the printing machine for each predetermined range; and
It is provided with.

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

  According to the present invention, the measured image data of the optical sensor that captures the printed matter is compared with estimated image data equivalent to the image of the sensor, and an estimated value of the solid density value of each ink is obtained from the difference, and this estimated solid density The difference between the value and the target solid density value is calculated for each monitoring point. 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 estimated image data is always Since it is related to the variation of the single-color solid density of each ink, it becomes clear which amount of ink in which part can be matched to the target image. 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.

  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 sheet editing device (computer) 11 to which a monitor 113 is connected, an RIP (Raster Image Processor) 12, an image server 13 for storing and providing image files, and an image processing device 14 for performing image processing of proof data. A proof printer 15 for printing proof paper, a CTP (Computer to Plate) 17 for producing a printing plate, an offset rotary press (hereinafter simply referred to as a rotary press) 19 for printing printed matter (newspaper), and the color tone of the printed matter. An image of the printed matter printed by the color tone monitoring device 21 to be monitored, the monitor 22 that displays the ink state estimated by the color tone monitoring device 21, the ink key control device 23 that controls the opening degree of the ink keys 72 </ b> A to 72 </ b> H, and the rotary press 19. It is the structure provided with the optical sensors 25F and 25R which 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 processing apparatus 14 stores a profile set so as to be the color tone characteristic of the calibration printer 15 in the storage unit 141. In the image processing apparatus 14, the control unit 142 reads out the profile from the storage unit 141, and also reads out each binary halftone image data stored in the image server 13 so that the color tone characteristics of the calibration printer 15 can be obtained. Quantization 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 processing 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.

  Here, 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 are red (hereinafter referred to as R) and green (Green). : Hereinafter referred to as G), blue (Blue: hereinafter referred to as B), infrared (Infrared rays: hereinafter referred to as Ir), imaging is performed in four wavelength regions, and R, G, B, Image data (sensor values) in four wavelength regions of Ir (hereinafter also referred to as RGBIr) 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.

In the following description, sensor values are defined as follows.
Sensor value: The reflected light amount itself detected by the optical sensor, or a value calculated as follows 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.

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

  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 includes a multi-value processing unit 41, a monitoring point coordinate output unit 42, an image processing unit 43, a profile storage unit 44, a standard solid density storage unit 45, a printing press model calculation unit 47, and a first comparison calculation unit 49. , A solid density adjustment unit 50, a second comparison calculation unit 51, a totaling unit 52, an image memory 53, and a sensor value conversion unit 54.

  Here, in the color tone monitoring device 21, the multi-value processing unit is a unit of image data that is captured by the optical sensors 25 </ b> F and 25 </ b> R and output in units of pixels, in units of one pixel or in units of a plurality of pixels. 41, the image processing unit 43, and the sensor value conversion unit 54 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 monitoring point coordinate output unit 42 and the printing press model calculation unit 47.

  The monitoring point coordinate output unit 42 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 42 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 printing press model calculation unit 47, and the first. The result is output to one comparison calculation unit 49. In addition, as a monitoring point, as long as it is a pixel unit, all the pixels may be set, or some pixels, for example, a pixel suitable for color tone monitoring may be selected and set.

  The image processing unit 43 reads the binary halftone dot image data of the test chart from the image server 13 and outputs the binary halftone dot image data and the optical sensor output via the image memory 53 and the sensor value conversion unit 54. A profile P3 is created by analyzing the relationship between the sensor value (RGBIr value) obtained by reading the image data of the color-tone-adjusted test chart at 25F. The profile P3 is stored in the profile storage unit 44. In addition, the image processing unit 43 reads the profile P3 from the brofile storage unit 44, and converts the binary halftone dot image data from the image server 13 into a multivalued / profile-converted standard value (reference image data). ) Is output to the first comparison calculation unit 49.

  The profile storage unit 44 stores the profile P3 created by the image processing unit 43.

  The standard solid density storage unit 45 stores a standard value (target value) of the solid density.

  The printing press model calculation unit 47 simulates the operation of the rotary press 19, and given the solid density value and the dot area ratio of the image, RGBIr of the image read by the optical sensor 25F at that time An approximate value (estimated image data) is output. The detailed configuration of the printing press model calculation unit 47 will be described later.

  The first comparison calculation unit 49 compares the RGBIr value (reference image data) generated by the image processing unit 43 with the RGBIr value (estimated image data) output from the printing press model calculation unit 47, for example, for each monitoring point. The difference between the RGBIr values is calculated and output to the solid density adjustment unit 50.

  The solid density adjustment unit 50 makes the RGBIr value output from the printing press model calculation unit 47 close to the RGBIr value output from the image processing unit 43, that is, the difference between both RGBIr values output from the first comparison calculation unit 49. The solid density value (estimated solid density value) is calculated and output so that is converged below a certain value.

  The printing press model calculation unit 47, the first comparison calculation unit 49, and the solid density adjustment unit 50 correspond to an estimated solid density output unit.

  The second comparison calculation unit 51 reads a target single-color solid density value (target solid density value) from the standard solid density storage unit 45, and uses the target single-color solid density value (target solid density value) and the printing press model. The estimated monochromatic solid density value (estimated solid density value) is compared with each monitoring point, for example, and a solid density difference (solid density deviation) as a comparison result is output to the totaling unit 52.

  The totaling unit 52 averages the calculation result (solid density difference) output by the second comparison calculation unit 51 for each fixed range, that is, for each column (ink key width that is a control unit width of the ink amount), and this average solid density. The deviation is output to the ink key control device 23. The totaling unit 52 also calculates the estimated solid density value output by the solid density adjustment unit 50, the solid density difference output by the second comparison calculation unit 51, or the average solid density deviation (average solid density difference) calculated as described above. These signals are output to the monitor 22 so that the monitor 22 displays at least one of the above.

  The monitor 22 displays an image based on the signal received from the counting unit 52.

  The image memory 53 stores RGBIr reflected light amount values or values based on the reflected light amount values output by the optical sensor 25F reading the image of the printed matter.

  The sensor value conversion unit 54 reads the RGBIr reflected light amount values from the image memory 53, converts them into sensor values based on the above-mentioned term definition, and outputs them to the image processing unit 43 or the first comparison calculation unit 49.

  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. Further, the sensor value conversion unit 54 may be provided on the upstream side of the image memory 53.

  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.

  Further, if the solid density value and the area ratio of the image are given to the printing press model calculation unit 47 of the color tone monitoring device 21, an approximate value of the RGBIr value of the image read by the optical sensor 25F at that time is obtained. In this way, a printing press model (mathematical model) (formula, table or combination thereof) that simulates the operation of the rotary press 19 is set. Since the printing press model calculates the RGBIr value of the image by simulating the operation of the rotary press 19, it is not necessary to perform a large amount of test printing for adjusting the color tone in the initial state as in the conventional case. This makes it possible to reduce the number of times of test printing, and to prevent a large amount of ink and newspaper from being used for the test.

  FIG. 2 is a diagram illustrating a configuration of the printing press model calculation unit. The printing press model calculation unit 47 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 (estimated value calculation unit) 69. ing.

  The solid color mixture model calculation unit 61 calculates the density of the mixed 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 overlap portion (overlapping portion) of each ink. In the present invention, the solid color mixture model calculation unit 61 calculates the density of the color mixture solid part based on a film thickness model that converts the single color solid density into the ink film thickness.

  The reflectance calculation unit 63 calculates the reflectance of the single color solid part and the mixed color solid part based on the density of the mixed color solid part calculated by the solid color mixing model calculation unit 61.

  The dot gain model calculation unit 65 calculates the area ratio of each overlapping portion (overlapping portion) from the solid density value of each ink output from the solid density adjusting unit 50 and the halftone dot area ratio value output from the multilevel processing unit 41. Based on the obtained dot gain model, a dot area value on the paper surface is calculated.

  The area ratio calculation unit 67 calculates the area ratios of the single color solid portion and the mixed color solid portion based on the halftone dot area value on the paper surface calculated by the dot gain model calculation unit 65.

  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 used for calculation in the solid color mixture model calculation unit 61, the dot gain model calculation unit 65, and the Neugebauer model calculation unit 69 will be described. To do. FIG. 3 is a diagram for explaining the dot gain model and the color mixture model.

<Dot gain model>
In the plate-making process, as shown in FIG. 3 (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 in 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. As shown in FIG. In the case of printing, the ink is applied three-dimensionally. Therefore, as shown in FIG. 3C, 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. 3D, the dot gain ratio varies depending on the original halftone 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. 3E, a blank 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. Expressed in 16 solid colors (including white paper): CK, CK color, MY color, MK color, YK color, CMY color, CMY color, CYK color, MYK color, CMYK color 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.

  In the present invention, as a method for expressing the reflectance of the solid color mixing portion, a film thickness model devised uniquely is adopted.

<Film thickness model>
4 to 9 are diagrams for explaining the 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. 5 to 8).

[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 47 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 plate making 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 as the color mixture model, for example, a method using an approximate polynomial can be applied as the function approximation method.

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 matter using a regression analysis method (for example, the least square 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. .

  Hereinafter, a calculation method for obtaining a solid density from a sensor image using the above-described printer model will be described.

  First, details of the configuration and operation of the color tone monitoring device 21 will be described with reference to FIGS. 1 and 10 to 12. FIG. 10 is a flowchart showing the preprocessing procedure. FIG. 11 is a flowchart showing the procedure of the target single color solid density setting process. FIG. 12 is a flowchart showing the procedure of the color tone monitoring process.

<Profile calculation process>
The color tone monitoring device 21 performs the following processing as profile calculation processing when the device is installed or readjusted.

  First, as shown in FIGS. 1 and 10A, the color tone monitoring device 21 performs color matching using a test chart, and displays 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 the reflected light amount value for each pixel of the image data is stored in the image memory 53 (s2).

  The sensor value conversion unit 54 reads the reflected light amount value for each pixel of the printed material from the image memory 53, converts the reflected light amount value into a sensor value (RGBIr value) according to the term definition, and outputs it to the image processing unit 43 (s3). ).

  When the image processing unit 43 acquires the sensor value (RGBIr value) from the sensor value conversion unit 54, the image processing unit 43 reads the image data of the test chart stored in the image server 13 (s4). To generate a profile (ICC profile) P3 (s5). Then, the image processing unit 43 stores (stores) the profile P3 in the profile storage unit 44 (s6).

  The profile P3 created by the image processing unit 43 may be an ICC profile, but instead of this profile P3, a four-input four-output four-dimensional LUT may be stored in the profile storage unit 44. Further, the present invention is not limited to a four-dimensional LUT, and may be a multi-dimensional LUT having four or more variables.

<Monitoring point setting process>
The color tone monitoring device 21 performs a monitoring point setting process and a target monochromatic solid density setting process, which will be described later, at the start of daily printing. Even before printing, the above two processes can be performed as long as the creation of the pattern data to be printed on the day is completed. However, in the case of the method using measured image data, it cannot be performed unless printing is started.

  In the color tone monitoring device 21, as the monitoring point setting process, as shown in FIGS. 1 and 10B, the image processing unit 43 performs digital data (binary halftone dot image data) of the image file stored in the image server 13. ) Is acquired (s11). Then, the image processing unit 43 performs multi-value conversion / profile conversion on the binary halftone dot image data, and outputs the obtained image data (RGBIr value) for each pixel to the monitoring point coordinate output unit 42 ( s12).

  The monitoring point coordinate output unit 42 analyzes the image data for each pixel and sets a plurality of monitoring points for each color of RGBIr (s13). That is, the monitoring point coordinate output unit 42 ranks the image data in an order suitable for monitoring, and assigns an appropriate number of monitoring points set in advance to each column (ink key width) for each color of RGBIr. Choose from those with high By setting the monitoring points in this way, when selecting some images as monitoring points, it is possible to select an appropriate point as the monitoring point with high accuracy.

  The monitoring point coordinate output unit 42 outputs the coordinates of the monitoring point to the image processing unit 43, the printing press model calculation unit 47, and the first comparison calculation unit 49 in the following processing. As monitoring points, all the pixels may be set or some pixels may be selected and set.

<Target monochromatic solid density setting process>
Subsequently, the color tone monitoring device 21 performs the following processing in order to estimate the solid density of the rotary press 19.

  As shown in FIGS. 1 and 11, the monitoring point coordinate output unit 42 displays coordinates of monitoring points of an image to be printed on the rotary press 19, an image processing unit 43, a printing press model calculation unit 47, and a first comparison calculation unit. 49. Further, the image processing unit 43 reads data of an image to be printed on the rotary press 19 from the image server 13 (s21), and reads the profile P3 (or four-dimensional LUT) from the profile storage unit 44 (s22). Then, the image processing unit 43 performs multi-value conversion and profile conversion on the image data, and creates RGBIr values (reference image data) of a plurality of monitoring points of the image based on the coordinate information of the monitoring points. Then, the RGBIr value of each monitoring point is output to the first comparison calculation unit 49 (s23).

  The multi-value processing unit 41 acquires digital data (binary halftone image data) of an image file to be printed on the rotary press 19 from the image server 13. Then, a halftone dot area ratio (Ac, Am, Ay, Ak = halftone dot area in digital data) on the printing plate of each pixel is created from the binary halftone dot image data, and is sent to the monitoring point coordinate output unit 42. Output (s24). Further, since the initial value of the iterative solution may start from anywhere, the solid density adjustment unit 50 appropriately outputs the monochromatic solid density of each ink and outputs it to the printing machine model calculation unit 47 (s25). In order to speed up the convergence, the standard solid density is suitable as the provisional value of the monochromatic solid density.

  The printing press model calculation unit 47 prints the RGBIr values (estimated values) of the respective monitoring points obtained from the solid density value output from the solid density adjustment unit 50 and the area ratio output from the multilevel processing unit 41. Calculate based on machine model. At this time, changes in dot gain due to dot gain and density are considered. Subsequently, the calculated RGBIr value is output to the first comparison calculation unit 49 (s26).

  The first comparison calculation unit 49 compares the RGBIr value created by the image processing unit 43 and the RGBIr value output by the printing press model calculation unit 47 for each monitoring point, and calculates the difference between both RGBIr values. It outputs to the solid density adjustment part 50 (s27).

  The solid density adjustment unit 50 determines whether the RGBIr value output from the printing press model calculation unit 47 is close to the RGBIr value output from the image processing unit 43 and the correction amount has converged to a certain value or less (s28). . Here, each RGBIr value is a vector quantity, and it is determined whether or not the norm (absolute value) of this vector has converged below a certain value.

  If the correction amount (norm) has not converged to a certain value or less (s28: N), the solid density adjustment unit 50 calculates a correction value for the provisional value of the solid density from the difference between the two RGBIr values, and this solid density. Are output to the printing press model calculation unit 47 (s25).

  Then, the solid density adjustment unit 50, the printing press model calculation unit 47, and the first comparison calculation unit 49 perform the processing of steps s25 to s28 again, and calculate the RGBIr values (Rr, Rg, Rb, Rir) and the RGBIr values (Sr, Sg, Sb, Sir) imaged by the optical sensor 25F are compared, the monochromatic solid density is corrected so that both RGBIr values are closest, and the calculated RGBIr value and the optical sensor 25F The above processing is repeated until the difference from the RGBIr value is equal to or less than a certain value or the correction amount is equal to or less than a certain value. The termination condition varies depending on which method of the multidimensional nonlinear optimization algorithm is selected and the image to be printed.

  On the other hand, if the difference between the two RGBIr values converges to a certain value or less (s28: Y), the standard solid density storage unit uses the monochromatic solid density for each monitoring point as the target monochromatic solid density value (target solid density value). 45 (s29).

  In steps s25 to s28, a known multidimensional nonlinear optimization algorithm (Newton Raphson method, quasi-Newton method, steepest descent method, conjugate gradient method, etc.) is used.

  Here, in the color tone management system 3, instead of creating reference image data from the image file stored in the image server 13, a printed matter (reference printed matter) for which color matching has been completed is imaged by the optical sensors 25F and 25R. The obtained sensor value (RGBIr value) can be used as the reference image data. In this case, instead of the processing in steps s21 to s23 described above, the optical sensor 25F (25R) images a printed matter (reference printed matter) that has undergone color matching, and the optical sensor 25F (25R) RGBIr values (reference image data) of a plurality of monitoring points may be generated from the output sensor values by the sensor value conversion unit 54 and output to the first comparison calculation unit 49. Then, step s24 and subsequent steps in the target single color solid density setting process may be performed.

  Accordingly, the color tone of the printed matter can be monitored and adjusted based on the reference printed matter whose color tone has been actually confirmed.

  Further, instead of storing the target single-color solid density (target solid density) in the standard solid density storage unit 45 as described above, for example, a standard solid density value of a newspaper company may be stored in advance. good. As a result, the color tone of the printed matter can be adjusted to the standards of the newspaper company.

  In the color tone management system 3, the area ratio value of CMYK halftone dots may not be acquired from the image file stored in the image server 13. As described above, when the image file cannot be acquired from the upstream system, as shown in FIG. 2B, at the initial setting, the monochrome model solid portion density is given to the printing press model calculation unit 47, and a temporary By giving a halftone dot 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 acquired. The CMYK halftone dot area ratio can be obtained by iterative calculation using a standard solid density as a target value for the sensor image captured by the optical sensor 25F. In addition, the halftone dot area ratio can be obtained by iterative calculation using an image generated at the top instead of the sensor image as a target value.

  In the former case, there is no data from the upstream, but in the latter case, in an environment where the upstream data can be used, the data transfer amount is reduced, the data transfer trouble is dealt with, the printing machine It is possible to cope with the case where the area ratio from the upstream is not used in order to absorb model defects.

<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 FIGS. 1 and 12, the monitoring point coordinate output unit 42 displays coordinates of monitoring points of an image to be printed on the rotary press 19, an image processing unit 43, a printing press model calculation unit 47, a first comparison calculation unit. 49. When printing is started by the rotary press 19, the optical sensor 25F continuously captures the image printed on the continuous paper P in four wavelength regions of R, G, B, and Ir. The image data (reflected light amount value) in each wavelength region of B and Ir is output to the image memory 53 in units of pixels (s31).

  The image memory 53 stores image data (reflected light amount values) of R, G, B, and Ir wavelength regions sent from the optical sensor 25F in units of pixels for one printing cycle (for example, for eight pages of newspapers). (S32).

  The sensor value conversion unit 54 reads out image data (reflected light amount value) in each wavelength region of R, G, B, and Ir from the image memory 53 and converts it into a sensor value (actual value of RGBIr value). It outputs to the comparison calculating part 49 (s33).

  On the other hand, the multi-value processor 41 outputs the halftone dot area ratio of each monitoring point in the image being printed on the rotary press 19 created in the target single color solid density setting process (s34).

  Further, the solid density adjusting unit 50 assumes the solid density of each ink of the printed matter printed by the rotary press 19, and outputs a temporary value of the solid density to the printing press model calculating unit 47 (s35).

  The printing press model calculation unit 47 is based on the halftone dot area ratio of each monitoring point set in the target single color solid density setting process and the monochromatic solid density (provisional value of the solid density) of each ink appropriately assumed. The RGBIr value (estimated value) observed by the optical sensor 25F when the printed matter having the above-mentioned area ratio is printed with this monochromatic solid density is calculated using a printer model. At this time, changes in dot gain due to dot gain and density are considered. Subsequently, the calculated RGBIr value (estimated value) of each monitoring point is output to the first comparison calculation unit 49 (s36).

  The first comparison calculation unit 49 compares the RGBIr value (actual measurement value) acquired from the sensor value conversion unit 54 with the RGBIr value (estimated value) acquired from the printing press model calculation unit 47 for each monitoring point. The difference is output to the solid density adjustment unit 50 (s37).

  The solid density adjustment unit 50 determines whether or not the difference (correction amount) between the two RGBIr values has converged to a certain value or less (s38). Here, as in the target monochromatic solid density setting process, each RGBIr value is a vector quantity, and it is determined whether or not the norm (absolute value) of this vector has converged below a certain value.

  If the correction amount (norm) has not converged below a certain value (s38: N), the solid density adjustment unit 50 calculates a correction value of the provisional value of the solid density from the difference between both RGBIr values, and this solid density. Is output to the printing press model calculation unit 47 (s35).

  Then, the solid density adjustment unit 50, the printing press model calculation unit 47, and the first comparison calculation unit 49 perform the processes of steps s35 to s38 again, and calculate the RGBIr values (Rr, Rg, Rb, Rir) and the RGBIr values (Sr, Sg, Sb, Sir) observed by the optical sensor 25F are compared, the monochromatic solid density is corrected so that both RGBIr values are closest, and the calculated RGBIr value and the optical sensor 25F The above processing is repeated until the difference from the RGBIr value is equal to or less than a certain value or the correction amount is equal to or less than a certain value.

  The termination condition varies depending on which method of the multidimensional nonlinear optimization algorithm is selected and the image to be printed.

  In steps s35 to s38, a known multidimensional nonlinear optimization algorithm (Newton Raphson method, quasi-Newton method, steepest descent method, conjugate gradient method, etc.) is used.

  On the other hand, if the difference between the two RGBIr values converges to a certain value or less (s38: Y), the solid density adjusting unit 50 estimates the single color solid density for each monitoring point at this time by using the printing press model. (Estimated solid density) is output to the second comparison calculation unit 51 (s39).

  At this time, the solid density adjusting unit 50 further outputs the monochromatic solid density (estimated solid density) estimated by the printing press model to the totaling unit 52, and the totaling unit 52 displays the estimated solid density value in the column (control of the ink amount). It may be configured to output a signal so that the monitor 22 displays the average solid density value averaged for each ink key width (unit width). Further, the totaling unit 52 may be configured to output a signal so that the monitor 22 displays the estimated solid density value for each monitoring point without averaging the estimated solid density value.

  The second comparison calculation unit 51 reads the target single color solid density (standard solid density) stored in the standard solid density storage unit 45 in step s19 (s40), and sets the target single color solid density (standard solid density). The monochrome solid density (estimated solid density) estimated by the printing press model is compared for each monitoring point, and the solid density deviation as a comparison result is output to the totaling unit 52 (s41). The totaling unit 52 averages this result for each column (ink key width which is the control unit width of the ink amount), and outputs this average solid density deviation to the ink key control device 23 (s42).

  At this time, the totaling unit 52 may be configured to output a signal so that the monitor 22 displays the average solid density deviation for each column. Further, the totaling unit 52 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. Further, the totaling unit 52 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 second comparison calculation unit 51 (s43). .

  As a result, the color tone of the proper printing state determined by the newspaper company for 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.

  In the above description, the color tone monitoring and color tone management of the printed matter printed using the four-color ink of CMYK by the offset rotary press has been described. However, like the above-described hexachrome printing, hi-fi printing, special color printing, etc. Even in multi-color printing of five or more colors, 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 six colors of Ink1 to Ink6, or there are six combinations for selecting four colors out of the six colors, so the printer model and LUT corresponding to the four colors as described above. 6 sets are prepared and used by switching.

  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, when it is only necessary to check the estimated solid density value for each monitoring point, a notification (not shown) is used instead of the standard solid density storage unit 45, the second comparison calculation unit 51, and the totaling unit 52 of the color tone monitoring device 21. It is good to comprise so that the signal which displays the estimated solid density value for every monitoring point which the 1st comparison calculating part 49 output on the monitor 22 may be output.

  In addition, a not-illustrated notifying unit is provided instead of the totaling unit 52 of the color tone monitoring device 21, and the estimated solid density value for each monitoring point output by the first comparison calculation unit 49 or the solid density adjusting unit 50 outputs. A signal for displaying the estimated solid density value on the monitor 22 may be output.

  Further, the totaling unit 52 does not output a control signal to the ink key control device 23, and the totaling unit 52 averages the estimated solid density value output by the solid density adjusting unit 50 for each column. It is configured to calculate at least one of a density value or an average solid density deviation (average solid density difference) obtained by averaging the solid density difference output from the second comparison calculation unit 51 for each column, and the estimated solid density value, average A signal for causing the monitor 22 to display at least one of the estimated solid density value, the solid density difference, and the average solid density deviation (average solid density difference) may be output.

  Further, in the printing system 1, when monitoring by the operator is unnecessary, the monitor 22 may not be provided, and the counting unit 52 may not output a signal to the monitor 22.

  Further, the printing press model is not limited to the above, and may be another model as long as it is a mathematical model that simulates a rotary press (printing press). That is, using the solid density value of each ink as an unknown quantity, a solution is obtained when the estimated image data and the measured image data processed in units of one pixel or a plurality of pixels are equal according to the calculated pixel unit of the estimated image data. As long as this solution is output as the estimated solid density value of each ink, the estimated solid density value of each ink is output in a single operation even if it is configured as described above. May be.

  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 printing press model calculating part. It is a figure 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 flowchart which shows the procedure of pre-processing. It is a flowchart which shows the procedure of a target monochromatic solid density setting process. It is a flowchart which shows the procedure of a color tone monitoring process.

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 42 ... Monitoring point coordinate output unit 43 ... Image processing unit 44 ... Profile storage unit 45 ... Standard solid density storage unit 47 ... Printing machine model calculation unit 49 ... 1st comparison calculation part 50 ... Solid density adjustment part 51 ... 2nd comparison calculation part 52 ... Aggregation part 53 ... Image memory 54 ... Sensor value conversion part 61 ... Solid color mixture model calculation part 63 ... Reflectance calculation part 65 ... Dot gain Model calculation unit 67 ... Area ratio calculation unit 69 ... Neugebauer model Arithmetic unit 72a to 72h ... ink keys 73 ... printing unit

Claims (18)

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;
Estimated image data obtained by estimating the measured image data of each wavelength region of the imaging means based on the halftone dot area ratio for each ink of the printed matter and the solid density value of each ink is calculated in units of one pixel or a plurality of pixels. A mathematical model that simulates the printing press, and determines the solid density value of each ink as an unknown, the estimated image data, and a pixel unit or a pixel unit according to the calculated pixel unit of the estimated image data An estimated solid density output means for obtaining a solution when the measured image data processed in units of a plurality of pixels are substantially equal, and outputting the solution as an estimated solid density value of each ink;
Storage means for storing a target solid density value which is a target value of the solid density of each ink;
A density difference calculating means for calculating a solid density difference that is a difference between the estimated solid density value of each ink and the target solid density value of each ink;
The solid density difference calculated by the density difference calculating means is totaled to calculate a solid density difference for each fixed range. Based on the solid density difference for each fixed range, each ink amount of the printing press is calculated for each fixed range. Control signal output means for outputting a control signal to be controlled;
Color tone monitoring device. The estimated solid density output means includes a printing press model calculation means for calculating estimated image data in units of one pixel or a plurality of pixels by the printing press model,
The printing press model calculation means includes:
A color mixture model calculation unit that calculates the density value of the solid overprinting part of each ink from the single color solid density of each ink,
From the density value of the solid overprint portion of each ink calculated by the color mixture model calculation unit, a reflectance calculation unit that calculates the reflectance,
A dot gain model calculation unit for determining the dot area ratio on the actually printed paper from the solid density of each ink and the dot area ratio value on the digital data;
From the dot area rate on the paper surface determined by the dot gain model calculation unit, an area rate calculation unit that calculates the area rate of the solid overlap portion of each ink;
Based on the reflectance calculated by the reflectance calculation unit and the area ratio calculated by the area rate calculation unit, a reproduction color for each ink combination is obtained, and estimated image data obtained by estimating the measured image data of the imaging unit is obtained. An estimated value calculation unit to be calculated;
The color tone monitoring apparatus according to claim 1, further comprising:   The mixed color model calculation unit converts the single-color solid density into an ink film thickness, and uses a film thickness model or a function approximation method to obtain a relationship between the ink film thickness and the ink density, and the density of the solid overprint portion of each ink. The color tone monitoring apparatus according to claim 2, wherein a value is calculated.   4. The estimated solid density output means calculates estimated image data based on a halftone dot area ratio of each ink obtained by multi-leveling upstream plate-making data and a solid density value of each ink. The color monitoring device according to the above.   The estimated solid density output means assumes a standard solid density from the measured image data of the printed matter imaged by the imaging means, and the dot area ratio of each ink estimated from the assumed standard solid density and the solid density of each ink. The color tone monitoring apparatus according to claim 1, wherein the estimated image data is calculated based on the density value.   6. The color tone monitoring apparatus according to claim 1, wherein the imaging unit outputs a reflected light amount value for each wavelength region or another value based on the reflected light amount value for each wavelength region as the measured image data.   The color tone monitoring apparatus according to claim 1, further comprising a conversion unit configured to convert the imaging unit to another value based on the reflected light amount value when the reflected light amount value is output for each wavelength region. Monitoring point setting means for setting a plurality of monitoring points on the printed matter and outputting the coordinate information to the estimated solid density output means and the estimated solid density output means;
The color tone monitoring apparatus according to claim 1, wherein the estimated solid density output unit and the estimated solid density output unit perform processing in units of monitoring points. Image processing means for generating, in pixel units, reference image data obtained by estimating measured image data of the imaging means from upstream plate-making data based on an ICC profile or a multidimensional LUT;
The estimated solid density output means sets the solid density value of each ink as an unknown, the estimated image data, and the reference image data processed in units of one pixel or a plurality of pixels according to the calculated pixel unit of the estimated image data; The color tone monitoring apparatus according to claim 1, wherein a solution when and are equal to each other is obtained, and the solution is stored in the storage unit as the target solid density value. The imaging means images a reference printed material that is a reference of the printed material in a plurality of different wavelength regions, and outputs measured image data of each wavelength region as reference image data,
The estimated solid density output means sets the solid density value of each ink as an unknown, the estimated image data, and the reference image data processed in units of one pixel or a plurality of pixels according to the calculated pixel unit of the estimated image data; The color tone monitoring apparatus according to claim 1, wherein a solution when and are equal to each other is obtained, and the solution is stored in the storage unit as the target solid density value.   The color monitoring apparatus according to claim 1, wherein the storage unit stores a preset reference solid density value as a target solid density value of each ink.   At least one of the estimated solid density value output by the estimated solid density output means, the solid density difference calculated by the density difference calculation means, and the solid density difference for each fixed range calculated by the control signal output means. The color tone monitoring apparatus according to any one of claims 1 to 11, further comprising an informing means for informing.   12. The apparatus according to claim 1, further comprising a notification unit that notifies the estimated solid density value output by the estimated solid density output unit, instead of the storage unit, the density difference calculation unit, and the control signal output unit. The color tone monitoring device described.   Instead of the control signal output means, the estimated solid density value output by the estimated solid density output means, the solid density difference calculated by the density difference calculation means, and the solid for each fixed range calculated by the control signal output means. The color tone monitoring apparatus according to claim 1, further comprising a notification unit that notifies at least one of the density difference. Instead of the control signal output means, at least one of the estimated solid density value output by the estimated solid density output means or the solid density difference of each ink calculated by the density difference calculation means is aggregated to estimate for each fixed range. A counting means for calculating at least one of a solid density value or a solid density difference;
The estimated solid density value output by the estimated solid density output means, the solid density difference calculated by the density difference calculating means, and the estimated solid density value for each fixed range calculated by the counting means or the solid density difference for each fixed range And a color tone monitoring apparatus according to any one of claims 1 to 11, further comprising a notification unit configured to notify at least one of the following. A color tone monitoring apparatus according to any one of claims 1 to 12,
An ink amount control device that adjusts the ink amount used for printing by the printing machine for each predetermined range based on the control signal output by the control signal output means of the color tone monitoring device;
Color management system with 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;
Estimated solid density output means estimates estimated image data obtained by estimating measured image data in each wavelength region of the imaging means based on the dot area ratio for each ink of the printed matter and the solid density value of each ink. A mathematical model that is calculated in units of pixels or a plurality of pixels, and a printing press model that simulates a printing press, with a solid density value of each ink as an unknown, the estimated image data, and a calculated pixel unit of the estimated image data A procedure for obtaining a solution when the measured image data processed in units of one pixel or a plurality of pixels is equal to each other, and outputting the solution as an estimated solid density value of each ink;
A notification means for notifying the estimated solid density value;
Color tone monitoring method with 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;
Estimated solid density output means estimates estimated image data obtained by estimating measured image data in each wavelength region of the imaging means based on the dot area ratio for each ink of the printed matter and the solid density value of each ink. A mathematical model that is calculated in units of pixels or a plurality of pixels, and a printing press model that simulates a printing press, with a solid density value of each ink as an unknown, the estimated image data, and a calculated pixel unit of the estimated image data A procedure for obtaining a solution when the measured image data processed in units of one pixel or a plurality of pixels is equal to each other, and outputting the solution as an estimated solid density value of each ink;
A storage means for storing a target solid density value which is a target value of the solid density of each ink;
A procedure for calculating a solid density difference between the estimated solid density value of each ink and the target solid density value of each ink;
The control signal output means sums up the solid density differences calculated by the density difference calculation means to calculate a solid density difference for each fixed range, and based on the solid density difference for each fixed range, each ink of the printing press A procedure for outputting a control signal for controlling the amount;
An ink amount control means, based on the control signal, a procedure for adjusting the ink amount used for printing by the printing machine for each predetermined range; and
Color management method with.

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