JP4801700B2 - Method and apparatus for confirming pattern color of printing machine before printing - Google Patents

Description

  The present invention relates to a pre-printing confirmation method and apparatus for a picture color tone of a printing machine, which is suitable for use in a picture color tone control of a printing machine.

Various techniques have been proposed for controlling the color tone of a picture of a printing press.
For example, in the techniques proposed in Patent Document 1 and Patent Document 2, the spectral reflectance of a pattern printed by each color printing unit is measured with a spectrometer, and the spectral reflectance for each key zone of the ink key (the entire key zone). The average spectral reflectance of the key zone is calculated, and the spectral reflectance of each key zone is converted into color coordinate values (L ^* a ^* b ^* ). Then, when the test printing is performed by adjusting the ink supply amount of each color and a print sheet having a desired color tone (hereinafter referred to as “OK sheet”) is obtained, the color coordinate value of each key zone of the OK sheet is set to the target color coordinate value. Set to. Next, the actual printing is started, and the color coordinate value difference (color difference) between the OK sheet and the printing sheet (hereinafter, the printing sheet obtained by the main printing is referred to as the main printing sheet) is calculated for each key zone. The opening degree of each ink key of each printing unit is adjusted by online control so that becomes zero.

  However, a spectrometer used as a measuring means in such a technique is high in cost, and it is difficult in terms of processing capability to measure an object (printed sheet) that moves at a very high speed like a newspaper rotary press. In the above technique, since the color tone control is started after the OK sheet is printed, a lot of damaged paper is generated between the rising edge and the printing of the OK sheet.

In order to solve these problems, Patent Document 3 proposes a technique for performing color tone control according to the following procedure.
First, a target color mixture halftone density is set for each ink supply unit width when the printed pattern is divided by the ink supply unit width of the ink supply apparatus. The ink supply unit width of the ink supply device is the key width (key zone) of each ink key when the ink supply device is an ink key device, and when the ink supply device is a digital pump device. It is the pump width of each digital pump. A method for setting the target color mixture halftone density will be described later.

  When printing is started and a main printing sheet is obtained, an actual color mixture halftone density for each ink supply unit width of the main printing sheet is measured using an IRGB densitometer. Then, the actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density is obtained based on the correspondence relationship between the halftone dot area ratio of each ink color and the mixed color halftone density. As a method for obtaining the actual halftone dot area ratio from the actual mixed color halftone density, a database storing the relationship between the halftone dot area ratio of each ink color and the mixed color halftone density, for example, newspaper printing Japan established by the ISO / TC130 National Committee A color scale based on Color (ISO12642) may be printed and a database measured with an IRGB densitometer may be used. More simply, a value approximated by a well-known Neugebauer equation may be used using the database. it can. Further, based on the correspondence between the halftone dot area ratio and the mixed color halftone density, the target halftone dot area ratio of each ink color corresponding to the target mixed color halftone density is also obtained. The target halftone dot area ratio does not need to be obtained every time as the actual halftone dot area ratio, and may be obtained once as long as the target mixed color halftone density does not change. For example, the target dot area ratio may also be obtained when the target color mixture halftone density is set.

  Next, an actual monochrome halftone density corresponding to the actual halftone dot area ratio is obtained based on a correspondence relationship between a preset halftone dot area ratio and the monochrome halftone density. As a method of obtaining the actual monochrome dot density from the actual dot area ratio, a map or table showing the relationship between the monochrome dot density and the dot area ratio is prepared, and the actual dot area ratio is set in these maps or tables. It may be applied, or more simply, the relationship may be approximated using a well-known Yule-Nielsen equation and used to determine the relationship. Further, based on the correspondence relationship between the halftone dot area ratio and the monochrome halftone density, a target monochrome halftone density corresponding to the target halftone dot area ratio is also obtained. The target monochromatic halftone density need not be obtained every time as in the case of the actual monochromatic halftone density, and may be obtained once as long as the target halftone dot area ratio does not change. For example, the target monochromatic halftone density may also be obtained when the target halftone dot area ratio is set.

  Next, based on the correspondence relationship between the halftone dot area ratio, the monochrome halftone density, and the solid density set in advance, the solid color corresponding to the deviation between the target monochrome halftone density and the actual monochrome halftone density under the target halftone dot area ratio. Obtain the concentration deviation. As a method for calculating the solid density deviation, a map or table showing the above-mentioned body correspondence may be prepared, and the target halftone dot area ratio, the target monochromatic halftone density, and the actual monochromatic halftone density may be applied to these maps and tables. More simply, the relationship may be approximated using a well-known Yule-Nielsen equation and obtained using this equation. Then, the ink supply amount is adjusted for each ink supply unit width based on the obtained solid density deviation, and the ink supply amount for each color is controlled for each ink supply unit width. The adjustment amount of the ink supply amount based on the solid density deviation can be easily obtained using a known API (Auto Preset Inking) function.

According to such a pattern color tone control method, the color tone control can be performed using an IRGB densitometer instead of a spectrometer, so that the cost for measuring means can be reduced and the high-speed printing machine such as a newspaper rotary press can be used. It becomes possible to respond sufficiently.
In addition, as a method for setting a target color mixture halftone density when kcmy halftone dot area ratio data [e.g., image data for plate making (plate making data)] of a print target pattern can be acquired from the outside (for example, a print request source or the like), The following points have been proposed.

  First, with respect to the acquired image data (kcmy halftone dot area ratio data), a pixel of interest corresponding to each ink color for each ink supply unit width among pixels constituting the pattern to be printed (a pixel of interest is a single pixel). (It may be a plurality of continuous pixels), and the halftone dot area ratio of the target pixel is converted into the mixed color halftone density based on the correspondence between the halftone dot area ratio and the mixed color halftone density. Then, the mixed color halftone density of the target pixel is set as the target mixed color halftone density, and the actual mixed color halftone density of the set target pixel is measured.

  According to this, since it is possible to estimate color development in units of pixels such as using a database of Japan Color (ISO12642), it is not necessary to wait for an OK sheet to be printed, and a specific attention point (attention pixel of interest) of a pattern immediately after the start of printing. ) Can be controlled. The kcmy halftone dot area ratio data may be bitmap data of a pattern to be printed (for example, 1-bit-Tiff plate-making data), or may be obtained by converting bitmap data into low resolution data equivalent to CIP3 data. Good.

In addition, as a method of setting a target point (target pixel), a method of displaying an image of a printed pattern on a display device such as a touch panel using bitmap data, and an operator arbitrarily specifying a target point, or for each ink color In addition, a method has been proposed in which a pixel having the highest density sensitivity or a pixel having the highest autocorrelation with respect to the dot area ratio of each pixel is automatically extracted and set as a pixel of interest for each ink color. In addition, as a specific method of setting the target pixel, an autocorrelation sensitivity H is introduced, a pixel having the highest autocorrelation sensitivity H is set as a pixel having the highest autocorrelation, and this pixel is set as the target pixel. Yes. For example, the autocorrelation sensitivity Hc of cyan, pixel area ratio data (c, m, y, k ) ^{using, "Hc = c n / (} c + m + y + k)" can be represented by, the autocorrelation sensitivity Hc The pixel having the highest value is the cyan attention point (n: auto-correlation power, for example, about 1.3 is selected).

In this way, for each ink color, the pixel having the largest autocorrelation with respect to the dot area ratio of each pixel is calculated and extracted, and this is set as the target pixel. By calculating the halftone density and performing feedback control of the ink supply amount so that the actual single color halftone density approaches the target single color halftone density, more stable color tone control can be performed.
JP 2001-18364 A JP 2001-47605 A JP 2004-106523 A

By the way, when printing is performed, it is necessary to perform plate making in advance. That is, plate making data is acquired, and each pixel area ratio data (c, m, y, k) of the plate making data is made by, for example, CTP (Computer to Plate), and the made plate is transferred to a printing machine such as a rotary press. It will be installed and printed. Each color tone control described above is performed by actual printing.
Therefore, whether or not the color tone is appropriate cannot be confirmed without looking at the hue of the actually printed matter. For this reason, the printing is started and the color of the printing result is checked to determine the good paper. However, the paper is inevitably generated before the good paper is determined, which is a cost issue. . Also, if the print content requires a delicate color tone, the required color tone may not be obtained easily, and it takes time to determine good paper, resulting in an increase in paper loss. In addition, there may be complaints from customers for printed materials that are judged to be good paper, such as in the case of printed materials that are particularly strict in color tone. In this case, printing has failed, and all printed items are broken paper. Therefore, after making some change so that the color tone is appropriate, the required amount of printing must be performed again.

  The reason why the printed color tone does not become appropriate will be considered. When performing plate making by CTP, plate making is performed by obtaining a CTP output corresponding to the dot area ratio of the plate making data (halftone dot area ratio when actually making the plate). At this time, the plate making data is most commonly used. The halftone dot area ratio is directly used as the CTP output halftone dot area ratio. However, even if the halftone dot area ratio of the plate making data is applied to the plate making as it is and printing is performed using the obtained printing plate, depending on the printing machine, the color density may be in spite of the standard ink supply state. It may be too strong or too weak.

  This is because each printing machine has its own printing characteristics. For example, the dot gain characteristics also differ depending on the printing machine. If the printing machine has a relatively large dot gain, the color density tends to increase, and the dot gain is compared. If the printer is small, the color density tends to be weak. Therefore, although the color tone should have been set to be appropriate, the actual printed matter may not have the appropriate hue.

  Of course, if the characteristics of the printing press to be used are recognized and a process for reflecting these characteristics is performed in advance, the color tone can be made appropriate from the beginning of printing. For example, a plate making curve C (relationship of halftone dot area ratio of CTP output to halftone dot area ratio of plate making data) which is a printing characteristic specific to each printing press as shown in FIG. 13 is obtained in advance, and based on this plate making curve. If plate making by CTP is performed, the color tone can be made more appropriate from the beginning of printing.

  However, this is based on the premise that a plate making curve C is obtained. In general plate making by CTP, as described above, plate making is performed using the halftone dot area ratio of the plate making data as it is as the halftone dot area ratio of the CTP output. In other words, plate making is performed using a linear characteristic line L as shown in FIG. With respect to such a characteristic line L, most of the plate-making curve of the rotary press actually used for printing is slightly curved like a plate-making curve C shown in FIG.

  The present invention has been devised in view of such problems, so that the hue can be confirmed before printing is performed, so that printing failure can be prevented and occurrence of waste paper can be suppressed. It is an object of the present invention to provide a method and an apparatus for confirming the color tone of a printing press before printing.

In order to achieve the above-described object, a color tone confirmation method before printing of a printing machine according to the present invention (Claim 1) is performed using a device profile of a printing machine used for printing and a device profile of a monitor or printer. The plate-making data used for the printing is converted into a color state of a printed pattern when printed by the printing machine, and the color state of the printed pattern when printed by the printing machine corresponding to the plate-making data is output as an image or printed matter An output step; and a determination step for determining whether an image output to the monitor in the output step or a color tone of a colored state of the printed matter output to the printer is within an allowable range. in step, if the tone is to be within the scope of the allowable, set before printing as the value of the target density which is a target value of the density of the printed pattern The value of the target concentration before printing, and remains the value of the target density of the reference corresponding to the plate making data, when the color tone is not within the range of the allowable, the value of the target concentration before the printing, the reference The target tone value is corrected to increase or decrease while confirming with the monitor or printer so that the color tone falls within the allowable range, and the corrected color development state is output to the monitor or printer as an image or printed matter. Then, the determination step is performed again.

Further, the color tone confirmation method before printing of the printing press according to the present invention (claim 2) uses the device profile of the printing press used for printing and the device profile of the monitor or printer to make plate making data used for printing. An output step of converting to a color state of a printed pattern when printing by the printing machine, and outputting the color state of the printed pattern when printing by the printer corresponding to the plate making data as an image or printed matter, and the output And determining whether the color tone of the image output to the monitor or the printed matter output to the printer is within an allowable range in the step. If it is within the allowable range, plate making is performed using a standard plate making curve, and if the color tone is not within the first allowable range, the printing press is used. The judgment is made by correcting the plate-making curve so as to be the plate-making curve of the printing press while confirming with the monitor or printer using the device profile, and outputting the corrected color development state as an image or printed matter to the monitor or the printer. When the color tone is within the second tolerance range set within the first tolerance range as a range narrower than the first tolerance range, the step is performed again, and the printed is a target value of the concentration of the picture values of target density before printing to be set before printing as the value of the target density, and leave the value of the target density of the reference corresponding to the plate making data, the color tone is the second If it is not within the range of acceptable, the monitor value of the target concentration before the printing, so that the color tone with respect to the values of the target concentrations of the reference is within the scope of the second tolerance Increases or decreases the correction while checking the printer, the monitor or the output to the corrected color-developed state as an image or printed material to said printer is characterized by re performing the determining step.

Further, the color tone confirmation apparatus before printing of the printing machine according to the present invention (claim 3) uses the device profile of the printing machine used for printing and the device profile of the monitor or printer to generate plate making data used for printing. An output means for converting to a colored state of a printed pattern when printing with the printing machine, and outputting the colored state of the printed pattern when printing with the printing machine corresponding to the plate making data as an image or printed matter; and the output and a determining means for determining whether the color tone of the printed matter which is output to the image or the printer output to the monitor is in the range of allowable in means, the color tone that by the prior Symbol judging means the and is within the tolerance determination, the value of the target concentration before printing to be set before printing as the value of the target density which is a target value of the density of the printed pattern, corresponding to the plate making data Criteria are determined to remain the target density value, the determination of the color tone by the determining means is not within the scope of the acceptable, the value of the target concentration before the printing, the value of the target concentration of the reference The color tone is corrected while increasing or decreasing while confirming with the monitor or printer so that the color tone falls within the allowable range, and the corrected color development state is output to the monitor or printer as an image or printed matter. It is characterized in that the determination is performed again.

The color tone confirmation apparatus before printing of the printing machine according to the present invention (Claim 4) uses the device profile of the printing machine used for printing and the device profile of the monitor or printer to generate plate making data used for printing. An output means for converting to a colored state of a printed pattern when printing with the printing machine, and outputting the colored state of the printed pattern when printing with the printing machine corresponding to the plate making data as an image or printed matter; and the output Determining means for determining whether the color tone of the image output to the monitor or the printed matter output to the printer is within a permissible range, wherein the determining means has the first color tone. it is determined whether the range of the allowable, the determination which the color tone that by the judgment means is in the range of the first acceptable performs plate making by using a reference plate making curve of the color tone before If it is not within the first allowable range, the plate making curve is corrected so that it becomes the plate making curve of the printing press while confirming with the monitor or printer using the device profile of the printing press, and the monitor or the The determination is to determine that the corrected coloring state is output as an image or printed matter and the determination unit is executed again. The determination unit sets the color tone as a range narrower than the first allowable range. It is determined whether or not the color tone is within the second allowable range by determining whether or not the color is within the second allowable range set within the allowable range. of the value of the target concentration before printing to be set before printing as the value of the target density which is a target value of the concentration, it is judged that remain value of the target density of the reference corresponding to the plate making data, the determination unit Determination of the color tone due to the not within the acceptable, the value of the target concentration before the printing, so that the color tone with respect to the value of the target concentration of the reference is within the scope of the second tolerance It is characterized in that the increase / decrease correction is performed while confirming with the monitor or printer, the corrected color development state is output as an image or printed matter to the monitor or printer, and the determination by the determination means is performed again.

  In the color tone confirmation apparatus before printing of each printing machine, the printing machine sets a target density that is a target value of the density of the printed pattern, and the actual color density of the printed pattern becomes the target density. The color tone control may be performed based on the detection value of the density detection sensor for the printed pattern so as to approach.

  According to the color tone confirmation method (Claims 1 and 2) and the color tone confirmation device (Claims 3 and 4) of the printing press of the present invention, when printing is performed with a predetermined printing machine before actual printing Therefore, by this confirmation, it is possible to confirm in advance whether the change or correction of the target density is appropriate and correct the target density appropriately and efficiently. Therefore, it is possible to make the color tone appropriate from the beginning of printing by appropriately changing the printing conditions and the like. As a result, it is possible to suppress the generation of waste paper and to prevent printing failures.

Embodiments of the present invention will be described below with reference to the drawings.
Here, the pre-printing confirmation method and apparatus and the plate making method of the pattern color tone of the printing press will be described, and then the pattern color tone control method and apparatus of the printing press using these pre-printing confirmation method, apparatus, and plate making method will be described. .
(A) Embodiment for Confirmation of Pre-Printing of Pattern Color of Printing Machine and Plate Making FIG. 3 is a diagram showing a flow of printing-related data before printing. As shown in FIG. 3, here, it is assumed that a newspaper company prints an advertisement surface, and the newspaper company receives an order for printing the advertisement surface from a client such as an advertising agency. At this time, the client side checks the plate-making data of the produced advertisement surface with its own monitor or printer, and if there is no problem, uses the plate-making data and uses the printing machine (printer, flatbed proof machine, etc.) A proof paper (galley) is created by printing a printed pattern of the sample on the printing paper. This plate-making data includes data (half-tone dot area rate data) that determines the halftone dot area ratio of each color of each part of the pattern to be printed. The prepress data and sample galley are sent from the client side to the newspaper company. Sent.

  In a newspaper company, normally, for example, at the head office, plate-making data and sample galley are sent to each printing factory (for example, printing factories A to C). In each printing factory, plate making is performed based on plate making data, and printing is performed by mounting the plate making plate on a printing machine. At this time, for example, as in the technique described in Patent Document 3, an actual printing result is obtained. The ink supply amount is controlled so that the color density of the ink approaches the target density value.

In the technology of the present embodiment, a simulated printing tool such as a personal computer and a monitor (or a printer) connected thereto after printing is sent from the client side to the head office of a newspaper company and sample galley before printing. This is characterized in that simulated printing (or display simulating printing) is performed using, and the color (tone) of the confirmation print pattern is confirmed in advance.
That is, as shown in FIG. 4A, the head office side of the newspaper company uses the device profile of the reference rotary machine on the head office side and the simulated printing tool (monitor or printer) for the plate making data k, c, m, y. And is output to a monitor (or printer) which is a simulated printing tool corresponding to the colored state of the printed pattern when printing is performed on the reference rotary press corresponding to the plate making data k, c, m, and y. The color density (mixed halftone density) R, G, B is obtained.

For this purpose, a device profile of a reference rotary press and a device profile of a simulated printing tool are required. Therefore, as shown in FIG. 2, a color chart (color scale) such as JapanColor (ISO 12642) is used at a reference density by the reference rotary press. Is printed (step A10), the printed pattern is measured by a sensor capable of detecting the color density such as an IRGB densitometer, and the halftone dot area ratios k, c, m, y and color coordinate values (L ^{*) of the} color chart are measured ^. a ^* b ^*) and the corresponding relationship to create the (device profile or ICC profile of the reference rotary press ^{L * a * b * / kcmy} ) of (step A20), the measured values IRGB and color coordinate values of the sensor (L ^* a ^* b ^* ) (sensor device profile L ^* a ^* b ^* / IRGB) is created (step A30).

The device profile of the monitor or printer that is a simulated printing tool is an ICC profile (cmyk / L ^* a ^* b ^* , RGB) provided by the monitor or printer manufacturer.
/ L ^* a ^* b ^* ), or the chart color is output to a monitor or printer as described above, and is measured and created.
The halftone dot area ratio is simply described as kcmy, the mixed color halftone density is simply described as RGB or RGBI, and the color coordinate value is simply described as Lab.

It should be noted that the sensor device profile, the device profile (cmyk 印刷 Lab) of the printing press, etc., can be made into an ICC profile if created in the ICC format, and can be made to match the general format of the simulated printing tool.
The output color of the simulated printing tool (the image printed by the printer or the image displayed on the monitor) is made to correspond to the sample galley, and the output color is compared with the color sample color of the target print. It is determined whether it is within the allowable range.

  This determination can also be made visually by an operator involved in the plate making or printing on the newspaper company side. However, for example, a picture printed by a printer is sent to the client side, and the hue of the output is checked on the client side. It may be determined whether the output hue is within an allowable range as compared with the hue. Alternatively, a simulation printing tool may be provided on the client side and the determination may be made by the client itself.

  For example, as shown in FIG. 4B, a monitor as a simulated printing tool is provided on the client side, and information (data) of color density (mixed halftone density) R, G, B to be displayed on the monitor is displayed in the newspaper. The transmitted color density R, G, B may be output to the monitor as transmitted from the company side, and the output hue may be determined by comparing the output hue with the galley hue of the color sample. In this method, if the sensor device profile and the printer device profile are acquired in advance on the client side, the output corresponding to the plate making data can be output to the simulated printing tool on the client side without sending the plate making data to the newspaper company ( The above determination can be made by performing screen display for a monitor and output display for a printer.

In the technology of the present embodiment, if the hue of the output of the simulated printing tool is not within the allowable range, the contents of the plate making are changed (corrected) or the density target value of the above-described color tone control is changed (corrected). I have to.
FIG. 1 is a flowchart for explaining such confirmation before printing, plate making, and change of density target value. It is assumed that the device profile of the reference rotary press, the sensor device profile, and the device profile of the simulated printing tool (printer or monitor) are acquired in advance.

As shown in FIG. 1, first, plate making data k, c, m, y are acquired from the upstream plate making system (plate making data acquisition step, step B10), and the plate making data k, c, m, y are used as the reference rotary press device. A color coordinate value (L ^* a ^* b ^* ) is calculated and obtained by acting on the profile (ICC profile) (first conversion step, step B20). Further, the obtained color coordinate values (L ^* a ^* b ^* ) are applied to the device profile (ICC profile) of the simulated printing tool (printer or monitor), and both (reference rotary device profile, simulated printing tool device profile). The color-converted data R, G, B or k, c, m, y to be given to the monitor or printer with the same L ^* a ^* b ^* is calculated and acquired (second conversion step, step B30). Then, the simulated printing tool (monitor or printer) outputs a picture corresponding to the plate-making data of the data k, c, m, y or R, G, B after color conversion (output step, step B40).

It is determined whether or not the hue is OK, assuming that the output of the simulated printing tool (monitor or printer) simulates the color of the reference rotary press (determination step, step B50).
Here, the determination result is that the hue is OK (determination 1), the hue is not OK but the difference in hue is slight (determination 2), and the hue is not OK but the difference in hue is large (determination 3). There are three categories.

If the hue is OK (determination 1), the plate making data k, c, m, and y are reflected as they are, plate making is performed by CTP or the like (step B60), and printing is performed (step B70). That is, the plate-making curve in this case is linear with an inclination of 1 (see FIG. 13).
If the hue is not OK but the difference in hue is slight (decision 2), the reference rotary printing target mixed color network density Io, Ro, Go, Bo of each pixel of the plate-making data is changed (step B80). The target color mixture halftone density Io, Ro, Go, Bo is applied to the sensor device profile to obtain a color coordinate value (L ^* a ^* b ^* ) (step B90). In this case, returning to step B30, the color coordinate value (L ^* a ^* b ^* ) changed corresponding to the target mixed color halftone density change is applied to the device profile of the simulated printing tool (printer or monitor), and simulated. Data R, G, B or k, c, m, y to be output to the printing tool is acquired. Thereafter, the same processing as described above is performed. The target mixed color halftone density change will be described later.

  If the color difference is large (judgment 3), the reference rotary press device profile and the printer output output by the newspaper company are sent to the client (step B100), and the client side uses the reference rotary press device profile based on the reference rotary press device profile. It is also effective to change the plate-making curve (step B110). In this case, the plate-making curve is an appropriate curve (see FIG. 13). In this case, since the plate making data is changed, the process returns to step B10 and the same process as described above is performed again.

Therefore, when the difference in hue is large (judgment 3), the platemaking curve is corrected, the platemaking data is corrected using the corrected platemaking curve, and the confirmation process before printing is performed again. It is possible to appropriately correct the plate making curve while confirming in advance whether or not the correction is appropriate.
If the hue is slightly different (judgment 2), the target halftone dot area ratio is changed and corrected, and the confirmation process before printing is performed again based on this, so the target mixed color halftone density is changed and corrected. The target mixed color halftone density can be appropriately corrected while confirming in advance whether or not the color is appropriate.

  In particular, when there is a large difference in hue (decision 3), correction of the target value for color tone control may not be possible, but in this case, the printing plate itself is corrected, so the color tone is adjusted from the beginning of printing. Can be properly optimized. In addition, when the hue is slightly different (judgment 2), it can be adequately corrected by correcting the target value of the color tone control, which is a relatively simple correction. Can be handled efficiently.

  It should be noted that here, as a judgment criterion for hue, a first allowable range that is a criterion for whether or not a difference in hue is large and a second allowable range that is a criterion for whether or not the hue is OK ( Naturally, it is within the range of the first allowable range) as a sensuous standard by visual observation of the printing operator or the person in charge on the client side, and whether or not the color is OK is within the second allowable range. It is determined whether or not there is a large difference in hue when the hue is not OK, and it is determined whether or not it is within the first allowable range.

Alternatively, the galley Lab is measured with a scanner or the like, the Lab output of the simulated printing tool is confirmed or measured with data, and the difference between the galley Lab and the simulated printing tool Lab is converted into a numerical value (color difference ΔE) for comparison. You can also In this case, the threshold value △ E _S chrominance △ E provided, does not exceed the color difference △ E is the threshold △ E _S shades OK, tint After exceeds the threshold △ E _S can be determined not OK. In particular, as described above, when the determination is made in two stages of the first allowable range and the second allowable range, a threshold value indicating whether the difference in hue is large (the threshold value of the first allowable range). ) Set △ E _S1 and the threshold value of whether or not the hue is OK (the second allowable range threshold) △ E _S2 (where △ E _S1 > ΔE _S2 ) Good.

  These allowable ranges are obtained by comparing the Lab output of the simulated printing tool (monitor or printer) and the galley Lab as a color difference threshold, comparing the output Lab and the galley color difference ΔE *, If the output Lab is within a second threshold value that defines the second allowable range (for example, average color difference ΔE * <3 for all pixels, pixel: size corresponding to the sensor detection area), the determination is made 1, and the output R, If G and B are not within the second threshold, but are within the first threshold that defines the first allowable range (for example, the average color difference ΔE * <6 of all pixels), the determination is made 2, and the outputs R and G , B if it is not within the first threshold value, it is possible to constitute a determination means for performing the determination mechanically if the determination is made as 3.

(B) First Embodiment for Changing Target Color Mixing Density In a printing machine (here, a reference rotary press) to which the above-mentioned pre-printing confirmation technique and plate making technique are applied, printing is performed while performing pattern color tone control to be described later. In this picture color tone control, the target values of color density (target color mixture halftone densities) Io, Ro, Go, Bo are set, and the color density (mixed color halftone densities) I, R, G, B of the actual printing result are set to this value. The ink supply amount is controlled so as to approach the target color mixture halftone density Io, Ro, Go, Bo. More specifically, the set target mixed color halftone density Io, Ro, Go, Bo and the detected actual mixed color halftone density I, R, G, B are obtained by using each device profile to obtain a monochrome halftone dot area ratio (simply, halftone dot). The target halftone dot area ratio is converted into a target single color halftone density based on a known correspondence, and the actual density and Taking the target density and deviation, the ink supply amount is controlled so that this deviation becomes zero.

  As for the target mixed color halftone density of the above-described simulated printing tool, the target mixed color halftone density of each pixel (specifically, pixels corresponding to 1200 dpi and 50 dpi) is calculated and converted into Lab. In this embodiment, the target color mixture halftone density in the control paragraph of the printing press is the plate making data as will be described later. The plate making data is the output data (RGB or cmyk) of each pixel. The average density of the control points (target pixel) selected from (1) is expressed.

  As a first method for changing the target color mixture halftone density, a change ratio ra1 for the target color mixture halftone density Io, Ro, Go, Bo is set, and this change ratio ra1 is used as the target color mixture halftone density Io, Ro, Go, The target mixed color halftone density can be changed by multiplying Bo. However, as described above, in the design tone control, attention is paid to the point that the target halftone dot area ratio is obtained from the target mixed color halftone density Io, Ro, Go, Bo. As a second method for changing the target mixed color halftone density, the target mixed color halftone density can be changed by changing the target halftone dot area ratio.

  In general, the printing operator wants to increase the indigo color or weaken the ink, or assumes the strength of the ink single color density. However, in reality, increasing the indigo color will increase the RGB density of the sensor and weaken the ink. Thus, the IRGB density becomes weak. For this reason, it is assumed that even if the target mixed color halftone density is changed directly, it does not become the operator's intention. This method is more advantageous.

  That is, when it is desired to change the target color mixture density, the operator or the client sets the change ratio ra for the density change and inputs it to the PC 12 (change ratio setting step, see step S06 in FIG. 7). The setting of the change ratio ra in step S06 is performed as necessary while the operator or the client side is watching the output of the simulated printing tool (monitor or printer).

The target halftone dot area ratio ko ′, co ′, mo ′, yo ′ calculated in the target halftone dot area ratio calculation step is multiplied by the change ratio ra set in step S06 to obtain the target halftone dot. The area ratios ko, co, mo, and yo are changed (refer to the target halftone dot area ratio changing step, step S08).
As described above, when the target dot area ratios ko ′, co ′, mo ′, and yo ′ for each ink color are changed, the target dot area ratios ko ′, co ′ in step B90 of FIG. 1 described above. , Mo ′, yo ′ are applied to the device profile of the printing press to obtain the color coordinate value (L ^* a ^* b ^* ) of each pixel of the platemaking data. Also in this case, the process returns to step B30 and the same processing as described above is performed.

In the following, pattern color tone control of a printing press using the pre-printing confirmation technique related to the target color mixture halftone density change will be described.
(C) First Embodiment of Pattern Color Tone Control Method and Apparatus for Printing Press FIG. 5 shows a schematic configuration of a newspaper offset rotary press according to the first embodiment of a pattern color tone control method and apparatus for a printing press according to the present invention. FIG. The newspaper web offset press of this embodiment is a multi-color printing duplex printing machine, and ink colors [black (k), indigo (c), red (m), yellow (y )] Is provided for each printing unit 2a, 2b, 2c, 2d. In the present embodiment, the printing units 2 a, 2 b, 2 c, and 2 d are provided with an ink key type ink supply device including an ink key 7 and an ink source roller 6. In this type of ink supply apparatus, the ink supply amount can be adjusted by the amount of gap between the ink key 7 and the ink base roller 6 (hereinafter, this gap amount is referred to as the ink key opening). A plurality of ink keys 7 are juxtaposed in the printing width direction, and the ink supply amount can be adjusted in the width unit of the ink key 7 (hereinafter, the ink supply unit width by the ink key 7 is referred to as a key zone). The ink whose supply amount is adjusted by the ink key 7 is moderately kneaded in the ink roller group 5, is supplied to the plate surface of the plate cylinder 4 after forming a thin film, and the ink adhering to the plate surface passes through the blanket cylinder 3. As shown in FIG. Although omitted in FIG. 5, the newspaper offset rotary press of the present embodiment is a double-sided printing, and therefore a pair of printing units 2 a, 2 b, 2 c, and 2 d is provided so as to sandwich the conveyance path of the printing sheet 8. Blanket cylinders 3 and 3 are provided, and a plate cylinder 4 and an ink supply device are provided for each blanket cylinder 3.

  The newspaper offset rotary press of this embodiment includes a line sensor type IRGB densitometer 1 further downstream of the most downstream printing unit 2d. The line sensor type IRGB densitometer 1 reflects the color of the pattern on the print sheet 8 on the line in the print width direction by reflection density (mixed color network) of I (infrared light), R (red), G (green), and B (blue). It is possible to measure the reflection density of the entire print sheet 8 or to measure the reflection density at an arbitrary position. Since the newspaper offset rotary press of this embodiment is a double-sided printing, the line sensor type IRGB densitometer 1 is arranged on both the front and back sides so as to sandwich the conveyance path of the printing sheet 8, and the reflection density on both the front and back sides can be measured. .

  The reflection density measured by the line sensor type IRGB densitometer 1 is transmitted to the arithmetic unit 10. The computing device 10 is a device that computes ink supply amount control data, performs computation based on the reflection density measured by the line sensor type IRGB densitometer 1, and matches the pattern color of the printing sheet 8 with the target color. The opening of the ink key 7 is calculated. Here, FIG. 6 is a diagram showing a schematic configuration of a design color tone control device for a newspaper offset rotary press according to an embodiment of the present invention, and at the same time, a functional block diagram focusing on the color tone control function of the arithmetic unit 10. .

  The arithmetic unit 10 is composed of a DSP (digital signal processor) 11 and a PC (personal computer) 12 that are installed apart from the printing press. The PC 12 includes a color conversion unit 14, an ink supply amount calculation unit 15, an online system. Functions as the control unit 16 and the key opening limiter calculation unit 17 are assigned. If the personal computer performance is sufficient, it is not necessary to use a DSP, and all of the arithmetic unit 10 may be composed of a personal computer. Of course, a DSP may be used as appropriate to perform fast processing. The line sensor type IRGB densitometer 1 is connected to the input side of the arithmetic device 10, and the control device 20 with a built-in printing press is connected to the output side. The control device 20 functions as an ink supply amount adjusting means for adjusting the ink supply amount for each key zone of the ink key 7, and controls an opening / closing device (not shown) that opens and closes the ink key 7, and each printing unit 2a, The key opening can be adjusted independently for each of the ink keys 7 of 2b, 2c, and 2d. Further, a touch panel 30 as a display device is connected to the arithmetic device 10. On the touch panel 30, a printing surface of the printing sheet 8 imaged by the line sensor type IRGB densitometer 1 or a printing surface colored from the plate making data is displayed, and an arbitrary area on the printing surface can be designated with a finger. Yes.

FIG. 7 is a diagram showing a processing flow of color tone control by the arithmetic unit 10. Hereinafter, the processing content of the color tone control by the arithmetic unit 10 will be described with reference to FIG.
Prior to the color tone control, the solid density value Di (λ) of each wavelength λ in each color of I (infrared light), R (red), G (green), and B (blue) is preliminarily set as a reference color at JapanColor. It is obtained from data obtained by printing a color scale such as (ISO12642). In other words, a color scale such as JapanColor (ISO12642) is printed in advance using a printing machine to be used, and the density of the printed result of the color scale is detected by an IRGB densitometer. Accordingly, the solid density value Di (λ) of each color (each single color and a mixed color of two colors, three colors, or four colors) of each wavelength λ can be acquired. Once these solid density values Di (λ) are obtained, they can be used as long as the characteristics of the printing press do not change due to deterioration over time or the like.

In addition, the plate making data is input to the arithmetic device 10 in advance, and the arithmetic device 10 obtains k, c, m, y data of each pixel in advance from the plate making data.
In the color tone control, after performing the processing of steps S02 and S04 shown in FIG. 7, printing is started based on the processing result, and the processing of each step of steps S10 to S110 excluding steps S40A and S50A is set in advance. It is designed to be performed repeatedly at a specified cycle. The processing in steps S06 and S08 is basically performed by appropriately interrupting the necessary ink color as necessary while confirming the printed matter printed by the operator after starting printing. For example, if the phenomenon that the ink becomes stronger every time is known, it may be changed before printing. Further, the process of step S40A may be performed only in the first control cycle at the start of printing, and thereafter, the value obtained in the first control cycle is used. The processing in step S50A only needs to be performed when the first control period at the start of printing and the processing in steps S06 and S08 are performed, and thereafter, the obtained values are used.

First, a target pixel region (simply referred to as a target point) is set (step S02), and color tone control processing is performed based on the set target pixel region.
The automatic setting of the pixel region of interest will be described. The DSP 11 of the arithmetic unit 10 selects a region having a high autocorrelation for each ink color from the kcmy halftone dot area ratio data obtained based on the plate-making data. The pixel area of interest corresponding to each ink color is automatically set for each ink color.

The plate making data is given as bitmap data. In setting the target pixel area, the bitmap data is converted into low resolution data equivalent to CIP4 data according to the format of the printing press, and the following Processing is performed in units of pixels of such sensors.
That is, the region where the autocorrelation is high for each ink color is specifically a region where the autocorrelation sensitivity H is equal to or higher than a predetermined value, and is defined as a pixel unit region of the sensor (IRGB densitometer) 1. . The pixel unit of the sensor is a minimum unit of resolution of the sensor (IRGB densitometer) 1. Specifically, a collection of a large number of pixels for plate making data corresponds to one pixel (one block) in sensor pixel units. For example, if the low resolution data of CIP4 is 50.8 dpi and the resolution of the sensor 1 block is 25.4 dpi, the area for 2 pixels in the vertical direction and 2 pixels in the horizontal direction (2 × 2 = in pixel units of the plate making data) 4 pixels) is one pixel unit of sensor pixel unit.

The autocorrelation sensitivity H, for example, the autocorrelation sensitivity Hc of cyan, using pixel area ratio data (c, m, y, k ) and can be represented by ^{"Hc = c n / (c} + m + y + k)", this When the autocorrelation sensitivity Hc is compared with a reference autocorrelation sensitivity value (predetermined value) H ₀ set in advance and the autocorrelation sensitivity Hc is equal to or higher than the reference autocorrelation sensitivity value H ₀ , Become. Similarly, the other color inks, calculates the value of the autocorrelation sensitivity H, for preset reference autocorrelation sensitivity value respectively (predetermined value) H ₀ Comparison. In this case, the index value n is selected to be about 1.3, for example.

The reference autocorrelation sensitivity value H ₀ can be set by an operator's input operation. Therefore, to set a higher reference autocorrelation sensitivity value H _0, by setting the target pixel region autocorrelation Search in rather high area, and tone monochrome ink noticed pixel region decreases but the corresponding or to raise accuracy of up to tone controlling the concentration detection sensitivity from a strong point, the reference autocorrelation sensitivity value H ₀ is set to low, to set the noticed pixel region including even a region autocorrelation is not very high As a result, although the density detection sensitivity is lowered, it is possible to increase the accuracy of the color tone control by expanding the target pixel region. Of course, a recommended value of the reference autocorrelation sensitivity value H ₀ (for example, the autocorrelation average value of the entire picture) is input in advance, and an operator who is not accustomed can use this recommended value. In principle, the reference autocorrelation sensitivity value H ₀ is a common value for each ink color, but it is also conceivable to change the reference autocorrelation sensitivity value H ₀ depending on the ink color.

  Next, a target color mixture halftone density is set for each target pixel area of each set ink (step S04). That is, the arithmetic unit 10 acquires the pixel dot area ratio (or the key zone average image ratio) Ak, Ac, Am, Ay data of the pixel area of interest in the key zone unit based on the plate making data. Yes. Further, the color conversion unit 14 of the PC 12 includes a database 141 that associates the dot area ratio of each ink color with the mixed color halftone density. The database 141 is a newspaper printed by JapanColor (ISO12642) standard printed matter established by the ISO / TC130 National Committee and measured by an IRGB densitometer [dot ratio of standard color halftone (k, c, m, y)] And a color conversion halftone density (I, R, G, B) and a conversion table that defines the correspondence between color coordinate values (L, a, b)]. Using this database 141, the color conversion unit 14 corresponds to each pixel halftone dot area ratio (or key zone average image ratio) Ak, Ac, Am, Ay of the input target pixel area in the key zone unit. The key zone average mixed color halftone density is obtained for each key zone and set as the target mixed color halftone density Io, Ro, Go, Bo.

  It should be noted that even if the print patterns have the same key zone average image area ratios Ak, Ac, Am, and Ay, the density (50% flat screen, 80% flat screen, solid, etc.) of the print pattern is considered in consideration of dot gain. ) The color density value varies. Therefore, the color conversion unit 14 can change the dot gain for each density of the halftone, and the parameters with the dot gain as a function can be used to set the image line ratios Ak, Ac, Am, Ay to the mixed color halftone densities Io, Ro, Go, Bo. The target color mixture density Io, Ro, Go, Bo considering the dot gain can be set. Note that dot gain correction for setting a target color mixture halftone density in consideration of dot gain for each pixel halftone dot area ratio of plate making data will be described in a second embodiment to be described later.

  As described above, when the target color mixture halftone densities Io, Ro, Go, Bo are set, printing is started and the processes in and after step S10 are repeatedly executed. First, as step S10, the line sensor type IRGB densitometer 1 measures the reflected light amounts i ', r', g ', b' for each pixel on the entire surface of the print sheet 8. The amount of reflected light i ′, r ′, g ′, b ′ of each pixel measured by the IRGB densitometer 1 is input to the DSP 11.

In step S20, the DSP 11 performs a moving average of the reflected light amounts i ′, r ′, g ′, and b ′ of each pixel in units of a predetermined number of printed sheets, so that the reflected light amounts i, r of each pixel from which the noise component has been removed. , G, b are calculated. In step S30, the reflected light amounts i, r, g, and b of the target pixel area are averaged for each key zone, and the mixed color halftone density (actual mixed color halftone density) I, R, G and B are calculated. If there is only an average image line ratio of the ink key zone, the reflected light amounts i, r, g, and b of the key zone are averaged for each key zone, and the mixed color halftone density (actual mixed color halftone density based on the reflected light amount of the blank paper portion) ) Calculate I, R, G, and B. For example, assuming that the reflected light amount of infrared light on the blank paper portion is ip and the average reflected light amount of infrared light in the key zone is ik, the actual mixed color halftone density I of infrared light is I = log ₁₀ (ip / ik) As required. The actual mixed color halftone densities I, R, G, and B for each target pixel area calculated by the DSP 11 are input to the color conversion unit 14 of the PC 12.

  The color conversion unit 14 performs the processes of steps S40A, S40B, S50A, S50B, and S60. First, in step S40A, the target mixed color halftone densities Io, Ro, Go, Bo set in step S04 are calculated. In step S40B, the actual mixed color halftone densities I, R, G, B calculated in step S30 are calculated. The dot area ratio of each corresponding ink color is calculated. For these calculations, the database 141 is used, and based on the correspondence stored in the database 141, the halftone dot area ratio of each ink color corresponding to the target color mixture halftone density Io, Ro, Go, Bo is calculated as the target halftone dot area ratio ko. , Co, mo, yo and the halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density I, R, G, B is calculated as the actual halftone dot area ratio k, c, m, y.

  Here, as described above, a color scale such as Japan Color (ISO 12642) is printed in the database 141 at a reference density, and a conversion table [also referred to as a look-up table (LUT) created based on the printing result. On the other hand, the relationship between the halftone dot area ratio and the mixed color halftone density value is almost linear for the Nielsen coefficient (Yul Nielsen coefficient) n created based on the printing result. A well-known extended Neugebauer equation having a predetermined value n (n is set to, for example, about n ≧ 100) is also input.

  In the formula (A), c, m, y, k, kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, and kcmy represent the dot area ratio of each color (single color or mixed color). Show. For color mixing, for example, kc represents the product of the dot area ratio of black (k) and cyan (c), and for example, kcmy represents black (k), cyan (c), magenta (m), and yellow (y). The product of each dot area ratio is shown.

  In addition, Dkc (λ), Dkm (λ),..., Dkcmy (λ) [solid density value Di (λ) of wavelength λ in each color i] is the wavelength at the target density value of each color mixture. The solid overlap density value of λ is shown. For example, Dkc (λ) represents the density value of the wavelength λ in each color target density value of the superposition of black (k) and cyan (c). For example, Dkcmy (λ) represents black (k) and cyan (c). The density value of the wavelength λ in each color target density value of magenta (m) and yellow (y) is shown. Here, λ is each wavelength of I, R, G, and B. These Di (λ) are obtained in advance as described above.

  If the Nielsen coefficient n is not set appropriately even in the known Neugebauer equation or the extended Neugebauer equation, the relationship between the halftone dot area ratio and the mixed color halftone density is usually curved as shown by the broken line in FIG. It will be something. The example of FIG. 8 is a cross section in which the relationship between the monochrome halftone dot area ratio of k and the mixed color halftone density is plotted by FIX with a halftone dot area ratio c = m = y = 0 as an example. Such a non-linear relationship also exists in a multidimensional space. On the other hand, in the case of the well-known extended Neugebauer equation (A) in which the Nielsen coefficient n is set to about 1000, for example, the relationship between the halftone dot area ratio and the mixed color halftone density is linear as shown by the solid line in FIG. Become a relationship. Such a linear relationship is obtained even in a multidimensional space.

  Therefore, as shown in FIG. 9 by the one-dot chain line, the relationship between the halftone dot area ratio and the mixed color halftone density in the color space region assumed according to the reference density is shown by the two-dot chain line in FIG. In addition, it can be easily extended to the outer area of the color space. In other words, the relationship between the halftone dot area ratio and the mixed color halftone density can be applied to the external space of the color space area indicated by the solid circle in FIG. 9, and the relationship between the halftone dot area ratio and the mixed color halftone density depends on the reference density. As shown in FIG. 9, the color space can be substantially enlarged. A region where the dot area ratio exceeds 100% is a virtual dot region. That is, the halftone dot area rate that cannot be made on the plate-making data is defined as the virtual halftone dot area rate by the known extended Neugebauer equation (A).

  Next, the color conversion unit 14 calculates the target single color halftone density of each ink color corresponding to the target halftone dot area ratios ko, co, mo, yo as step S50A, and the actual halftone dot area ratio as step S50B. The actual single color halftone density of each ink color corresponding to k, c, m, y is calculated. A map as shown in FIG. 10 is used for these calculations. FIG. 10 is an example of a map in which the monochromatic halftone density actually measured when the halftone dot area ratio is changed is plotted as a characteristic curve. The map is created from data measured in advance (pick up from the values in the database 141). ). In the example shown in FIG. 10, by comparing the black target halftone dot area ratio ko and the real halftone dot area ratio k with the map, the target single color halftone density Dako and the real single color halftone density Dak are respectively obtained from the characteristic curves in the map. It has been demanded. In this way, the color conversion unit 14 obtains the target monochromatic halftone densities Dako, Dako, Damo, Dayo and the actual monochromatic halftone densities Dak, Dac, Dam, Day for each ink color.

  Next, in step S60, the color conversion unit 14 sets the solid density deviation ΔDsk of each ink color corresponding to the deviation between the target monochrome color density Dako, Dako, Damo, Dayo and the actual monochrome color density Dak, Dac, Dam, Day. , ΔDsc, ΔDsm, ΔDsy are calculated. The solid density also depends on the halftone dot area ratio. For the same monochrome halftone density, the higher the halftone dot area ratio, the lower the solid density. Therefore, the color conversion unit 14 performs calculation using a map as shown in FIG. FIG. 11 is an example of a map in which the monochromatic halftone density measured when the monochromatic solid density is changed is plotted as a characteristic curve for each halftone dot area ratio, and is created from data measured in advance. The color conversion unit 14 selects a characteristic curve corresponding to the target halftone dot area ratios ko, co, mo, and yo for each ink color from the map shown in FIG. 11, and sets the target monochromatic halftone densities Dako, Dako, The solid density deviations ΔDsk, ΔDsc, ΔDsm, ΔDsy are obtained by associating the Damo, Dayo with the actual monochromatic halftone densities Dak, Dac, Dam, Day. In the example shown in FIG. 11, when the black target halftone dot area ratio ko is 75%, the target monochrome color density Dako and the actual single color halftone density Dak are checked against the map so that the black color is obtained from the 75% characteristic curve in the map. The solid density deviation ΔDsk is obtained.

  The solid density deviations ΔDsk, ΔDsc, ΔDsm, ΔDsy of each ink color calculated by the color conversion unit 14 are input to the ink supply amount calculation unit 15. In step S70, the ink supply amount calculation unit 15 calculates key opening deviation amounts ΔKk, ΔKc, ΔKm, and ΔKy corresponding to the solid density deviations ΔDsk, ΔDsc, ΔDsm, and ΔDsy. The key opening deviation amounts ΔKk, ΔKc, ΔKm, ΔKy are the current key opening Kk0, Kc0, Km0, Ky0 of each ink key 7 (the key opening output to the control device 20 of the printing press in the process of the previous step S100). Kk, Kc, Km, Ky), and the ink supply amount calculation unit 15 performs calculation using a known API function (auto-preset inking function). The API function is a function showing the correspondence between the image area ratio A (Ak, Ac, Am, Ay) and the key opening K (Kk, Kc, Km, Ky) in each key zone in order to obtain the reference density. As the image line ratio A, the one used in step S04, that is, the one obtained by averaging the halftone dot area ratio in the key zone can be used. Specifically, the ratio kd (kd = ΔDs / Ds) of the solid density deviation ΔDs (ΔDsk, ΔDsc, ΔDsm, ΔDsy) with respect to the reference density Ds (Dsk, Dsc, Dsm, Dsy) is obtained, and for the line drawing ratio A A key opening K for obtaining a reference concentration is obtained using an API function, and a key opening deviation amount ΔK (ΔK = kd × K) for making the solid concentration deviation ΔDs zero is obtained as a product of these.

  Next, in step S80, the online control unit 16 sends the key opening deviation amounts ΔKk, ΔKc, ΔKm, ΔKy calculated by the color conversion unit 14 to the line sensor type IRGB from the respective printing units 2a, 2b, 2c, 2d. Correction is made in consideration of the dead time to the densitometer 1, the reaction time of the ink key 7 per hour, and the printing speed. This correction is detected as a change in the amount of reflected light by the IRGB densitometer 1 when the ink key 7 is moved after the key opening signal is input, the key opening is changed and the amount of ink supplied to the printing sheet changes. The time delay until is taken into consideration. As such an online feedback control system with a large dead time, for example, PI control with dead time compensation, fuzzy control, robust control and the like are optimal. The online control unit 16 is for online control in which the current key opening Kk0, Kc0, Km0, Ky0 is added to the corrected key opening deviation (online control key opening deviation) ΔKk, ΔKc, ΔKm, ΔKy. The key opening degrees Kk1, Kc1, Km1, and Ky1 are input to the key opening limiter calculation unit 17.

  In step S90, the key opening limiter calculation unit 17 performs correction for restricting the upper limit value for the online control key openings Kk1, Kc1, Km1, and Ky1 calculated by the online control unit 16. This is a process for restricting an abnormal increase in the key opening due to the estimation error of the color conversion algorithm (the processes of steps SS40, S50, and S60) particularly in the low image area. Then, in step S100, the key opening limiter calculating unit 17 transmits the key opening Kk, Kc, Km, Ky whose upper limit value is restricted as a key opening signal to the control device 20 of the printing press.

In step S110, the control device 20 of the printing press determines the opening of each ink key 7 of each printing unit 2a, 2b, 2c, 2d based on the key opening signals Kk, Kc, Km, Ky transmitted from the arithmetic unit 10. Adjust. As a result, the ink supply amount of each ink color is controlled to match the target color tone for each key zone.
When the target color mixture density is changed as described above, the change ratio ra is set (step S06, change ratio setting step). Multiplying the target halftone dot area ratios ko ′, co ′, mo ′, yo ′ of each ink color calculated in the target halftone dot area ratio calculating step in step S40 by the change ratio ra set in step S06, The target halftone dot area ratios ko, co, mo, and yo are changed (step S08, target halftone dot area ratio changing step).

Of course, if this change ratio ra is not specifically input, the target dot area ratio that uses the target dot area ratios ko ′, co ′, mo ′, yo ′ of each ink color calculated in step S40 in the next step as they are. set to ko, co, mo, and yo (or a logic of calculating the target dot area ratios ko, co, mo, and yo using the change ratio ra as the reference value 1).
When the change ratio ra is set in this way, thereafter, the target dot area ratios ko, co, mo, yo changed in step S08 become the target single color halftone densities Dako, for each ink color in step S50A. Calculation of Daco, Damo, Dayo, calculation of solid density deviations ΔDsk, ΔDsc, ΔDsm, ΔDsy in subsequent step S60, calculation of key opening deviation amounts ΔKk, ΔKc, ΔKm, ΔKy in step S70 and step S80 Is reflected in the calculation of the online control key openings Kk1, Kc1, Km1, and Ky1, and the color tone is controlled to the changed target density.

  Since the color tone control method and apparatus according to the present embodiment are configured as described above, color tone control can be performed immediately after the start of the printing press (after the OK sheet). Then, the target pixel region (target point) is set, and the mixed color halftone density of the target point is set as the target mixed color halftone density Io, Ro, Go, Bo, and the actual mixed color network of the target point of the corresponding printing sheet. Since the density I, R, G, and B are measured and feedback control is performed, even when there is no plate-making data such as 1-bit-Tiff or CIP4 data, the color tone control can be performed for a specific attention point of the pattern.

In addition, since the measured values are not averaged over the entire key zone, the line sensor type IRBG is used even if the line drawing rate of the pattern in the key zone is low (for example, even if a small pattern of one point exists in the key zone). There are few measurement errors of the densitometer 1, and stable color tone control can be performed. In particular, by calculating and automatically extracting the pixel with the highest density sensitivity for each ink color and setting it as the target pixel area, more stable color tone control is performed when the image area ratio of the pattern in the key zone is low. be able to. Specifically, for example, the density sensitivity Hdc of cyan can be defined as “Hdc = R ⁿ / (R + G + B + I)” using the measured density data (R, G, B, I) (n: self The pixel having the highest value of the density sensitivity Hdc is the cyan attention point. Similarly, a pixel having the highest density sensitivity is calculated for other ink colors, and the pixel is set as a point of interest.

Then, the value of the change ratio (= change coefficient) ra with respect to the target density (target dot area ratio) is appropriately set as necessary, and the target dot area ratio is changed to meet the customer's request more. It is possible to print in a different color tone, and it is possible to realize printing with higher merchantability by adjusting the color tone.
In particular, when the target mixed color halftone density is directly changed, changing the target mixed color halftone density of the wavelength with the highest sensitivity for a certain ink color affects the density of other ink colors. Since the target density (target mixed color halftone density) is changed by changing the target halftone dot area ratio of one color, even if the target density of one ink color is changed, the density of other ink colors This can be done appropriately without causing confusion in the density change.

  Further, when the actual halftone dot area ratio is obtained from the actual mixed color halftone density and when the target halftone dot area ratio is obtained from the target mixed color halftone density, as a correspondence relationship between the halftone dot area ratio and the mixed color halftone density, I (red A solid density value Di (λ) of each wavelength λ in each color of outside light), R (red), G (green), and B (blue) is acquired in advance, and the Yule-Nielsen coefficient is used as a halftone dot area ratio and a mixed color halftone density. Since the well-known extended Neugebauer equation (A) set to a predetermined value n such that the relationship with the value is almost linear is used, the correspondence in the color space can be easily extended outside the color space.

  That is, in the case of the well-known extended Neugebauer equation (A) in which the Nielsen coefficient n is set to a value such that the relationship between the halftone dot area ratio and the mixed color halftone density value is substantially linear, the relationship between the halftone dot area ratio and the mixed color halftone density. 9 has a linear relationship as shown by a solid line in FIG. 9, and as shown by a black circle in FIG. 8, the actual print density (current density) is an area in a color space (solid line circle) corresponding to the reference density. Even in the case of deviating from the above, the relationship between the halftone dot area ratio in the color space region assumed according to the reference density and the mixed color halftone density can be easily extended and used.

  For this reason, the conversion from the mixed color halftone density to the halftone dot area ratio can be reliably performed for the area outside the color space defined by the reference density (in this case, the halftone dot area ratio is 100%). For example, the target color mixture network corresponding to the target halftone dot area ratio changed according to the change ratio when the change ratio is set to the increase side of the target halftone dot area ratio. Even if the density is set to a density exceeding the color space defined by the reference density, and the actual mixed color halftone density printing exceeds the color space defined by the reference density, the actual halftone dot area ratio can be reliably obtained. Color tone control corresponding to the change ratio.

(D) Second Embodiment for Changing Target Color Mixing Density The target color mixing halftone density change can also be performed by changing the dot gain correction coefficient.
In other words, the dot gain correction coefficients kc, km, ky, and kk are corrected according to the following equation (D), and each color dot gain amount (after correction) DGc to DGk when the monochrome dot area ratio of the plate data is 50%. Is calculated.
DGc = kc × DGc ′
DGm = km × DGm ′
DGy = ky × DGy ′
DGk = kk × DGk ′ (D)
However, kc, km, ky, and kk are dot gain correction coefficients, which are normally set to 1.

DGc ′, DGm ′, DGy ′, and DGk ′ are values of a single color 50% halftone density D50 and a single color 100% solid density D100 obtained by printing a color scale such as JapanColor (ISO12642) at a standard density in advance. Calculated using
DG = (1-10- ^D50 ) / (1-10- ^D100 ) -0.5
Then, the dot area correction data k ′, k, m, and y can be obtained by correcting the dot gain of the plate making halftone area ratio data c ′ to k ′ by the following equation (E).
c = −DGc / 0.25 × (c′−0.5) ² + DGc + c ′
m = −DGm / 0.25 × (m′−0.5) ² + DGm + m ′
y = −DGy / 0.25 × (y′−0.5) ² + DGy + y ′
k = −DGk / 0.25 × (k′−0.5) ² + DGk + k ′ (E)
However, c to k: dot area correction data with dot gain correction c ′ to k ′ ′ plate making halftone area data The target density can be changed by changing the dot gain correction coefficient. For example, when the dot gain is increased due to deterioration of a roller, a blanket or the like of a printing machine, an accurate target value can be calculated by increasing the dot gain correction coefficient from 1.

In the following, pattern color tone control of a printing press using the pre-printing confirmation technique related to the target color mixture halftone density change will be described.
(E) Second embodiment according to pattern color tone control method and apparatus of printing press A second embodiment according to the pattern color tone control of the printing press according to the present invention will be described. In the present embodiment, a well-known Neugebauer equation (B) corrected for dot gain is used in place of the conversion table of each of the above embodiments.

  That is, instead of the conversion table created based on the correspondence obtained by printing a color scale such as JapanColor (ISO12642) at the reference density in the first embodiment in advance, I (infrared light), R (red) ), G (green), and B (blue), the solid density value Di (λ) of each wavelength λ is obtained from data obtained by printing a color scale such as JapanColor (ISO12642) at a reference density in advance. At the same time, a known Neugebauer equation (B) subjected to dot gain correction is defined as follows, and the mixed color halftone density is obtained using this equation (B).

The above equation is obtained by removing the Nielsen coefficient n from the above-mentioned known extended Neugebauer equation (A).
Even if it does in this way, the effect similar to 1st Embodiment can be acquired.
The dot gain correction of the known Neugebauer equation (B) will be described. The dot area ratio data k, c, m, and y of the equation (B) are dot gain corrected as follows.

First, by extracting from the color scale density value data, the monochrome dot densities Dc50 to Dk50 when the halftone dot area ratio of the plate making data is 50% and the halftone dot area ratio of the plate making data are solid (1
00%) monochromatic solid density (monochromatic solid halftone density) Dc100 to Dk100, and based on these values, according to the following formula (C), each color dot when the monochromatic halftone dot area ratio of the plate making data is 50% Gain amounts (pre-correction values) DGc ′ to DGk ′ are calculated.
DGc '= (1-10 ^-Dc50 ) / (1-10 ^-Dc100 ) -0.5
DGm '= (1-10 ^-Dm50 ) / (1-10 ^-Dm100 ) -0.5
DGy '= (1-10 ^-Dy50 ) / (1-10 ^-Dy100 ) -0.5
DGk '= (1-10- ^Dk50 ) / (1-10- ^Dk100 ) -0.5 (C)
However,
DGc to DGk: each dot gain amount when the monochrome dot area ratio of the plate making data is 50% Dc50 to Dk50: monochrome dot density when the dot area ratio of the plate making data is 50% (extracted from the color scale density value data)
Dc100 to Dk100: Monochromatic solid density when the dot area ratio of the plate making data is solid (100%) (extracted from color scale density value data)
Next, the dot gain correction coefficients kc, km, ky, and kk are corrected by the above equation (D), and each color dot gain amount (corrected value) DGc˜ when the monochrome dot area ratio of the plate data is 50% DGk is calculated.

Then, the dot area correction data k, c, m, y are obtained by correcting the dot gain of the plate making halftone area ratio data c ′ to k ′ by the above equation (E).
(F) Third Embodiment of Pattern Color Tone Control Method and Apparatus for Printing Machine A third embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized by a method for setting a target density (target color mixture halftone density) for a target pixel region (target point), and the flowchart shown in FIG. 12 corresponds to the processing content in the present embodiment (step S04 in FIG. 7). Details of processing to be performed). Since the other processing contents for the pattern color tone control are as described with reference to FIG. 7, the description thereof is omitted here.

  In the present embodiment as well, as in the first embodiment, the newspaper page information is transmitted from the head office of the newspaper company to the printing factory in the form of bitmap data. However, in the present embodiment, as a difference from the second embodiment, in addition to the bitmap data of the page information, the ICC profile of the input device that created the color information of the page is also transmitted. In step S321, the bitmap data is converted into low-resolution data corresponding to CIP4 data corresponding to the format of the printing press. In step S322, attention points corresponding to each ink color are set for each ink supply unit width. Since the processing contents of these steps S321 and S322 are the same as the processing contents of steps S311 and S312 according to the second embodiment, detailed description thereof will be omitted.

  In step S323, the halftone dot area ratio ki, ci, mi, yi of the target point is converted into the color coordinate values L, a, b using the ICC profile transmitted from the newspaper company headquarters. In step S324, using the conversion table stored in the database 141, the color coordinate values L, a, and b obtained in step S323 are converted into mixed color halftone densities. However, since the color coordinate value is three-dimensional information and the mixed color halftone density is four-dimensional information, the mixed color halftone density corresponding to the color coordinate value is not uniquely determined. In order to uniquely determine the mixed-color halftone density, some additional information is required, but only three-dimensional information such as color coordinate values can be obtained from the ICC profile.

Therefore, in the present embodiment, as will be described in the following steps, halftone dot area ratio data of the printed pattern, that is, halftone dot area ratios ki, ci, mi, yi corresponding to the color coordinate values L, a, b are used. As a result, in the development from such 3D information to 4D information, the most appropriate 4D information is selected from among a myriad of 4D information candidates.
First, in step S325, the halftone dot area ratio ki, ci, mi, yi of the target point is converted into color coordinate values L ′, a ′, b ′ using the conversion table stored in the database 141. In step S326, color differences ΔL ′, Δa ′, Δb ′ between the color coordinate values L, a, b obtained in step S323 and the color coordinate values L ′, a ′, b ′ obtained in step S325 are calculated. In S327, halftone dot area rate changes Δk ′, Δc ′, Δm ′, Δy ′ corresponding to the color differences ΔL ′, Δa ′, Δb ′ are calculated. Each change amount of the halftone dot area ratio can be approximated by the following equation using each change amount of the color coordinate value. However, a and b in the following equation are linear approximation coefficients.

Δc ′ = a11 × ΔL ′ + a12 × Δa ′ + a13 × Δb ′ + bc (1)
Δm ′ = a21 × ΔL ′ + a22 × Δa ′ + a23 × Δb ′ + bm (2)
Δy ′ = a31 × ΔL ′ + a32 × Δa ′ + a33 × Δb ′ + by (3)
Δk ′ = a41 × ΔL ′ + a42 × Δa ′ + a43 × Δb ′ + bk (4)
In step S328, the amount of change Δk ′, Δc ′, Δm ′, Δy ′ obtained in step S327 is added to the halftone dot area ratio ki, ci, mi, yi of the target point, and the value is added to the virtual halftone dot area ratio k. Set as ', c', m ', y'. In step S329, the virtual dot area ratios k ′, c ′, m ′, y ′ are collated with the conversion table recorded in the database 141, and the virtual network is selected from the plurality of mixed color halftone density candidates obtained in step S324. The one corresponding to the point area ratios k ′, c ′, m ′, y ′ is selected. The selected mixed color halftone density is set as the target mixed color halftone density Io, Ro, Go, Bo, and the actual mixed color halftone density I, R, G, B of the target point calculated in step S330, and the processing in step S40 and subsequent steps. Used.

  According to this method, since the color tone can be controlled using the ICC profile obtained from the print requester or the like, the print requester or the like can be compared with the conventional color matching compared with the proof print. Can be accurately and easily matched to the desired color tone. Therefore, according to this method, it is possible to significantly reduce the amount of lost paper until an OK sheet is obtained.

(G) Others While the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to those described above.
For example, in the embodiment according to the pre-printing confirmation of the pattern color tone of the printing press shown in FIG. 1, the allowable range of the color tone (hue) is set as the first allowable range, the first threshold, the second allowable range, and the first allowable range. If the difference in hue is large (decision 3), it is dealt with by correcting the printing plate itself. If the hue is slightly different (determination 2), color tone control is performed. However, the allowable range of hue is set to only one stage (only the first allowable range and the first threshold, or just the allowable range and only the threshold). The correction may be performed by either correcting the printing plate itself or efficiently responding to the poor hue.

  Regarding color tone control, for example, in each of the above embodiments, a line sensor type IRGB densitometer is used, but a spot type IRGB densitometer is used to scan the print sheet two-dimensionally. May be.

It is a flowchart explaining one Embodiment of the confirmation method before printing of the pattern color tone of the printing machine of this invention, an apparatus, and the platemaking method. It is a flowchart explaining one Embodiment of the confirmation method before printing of the pattern color tone of the printing press of this invention, and an apparatus. FIG. 7 is a diagram illustrating a flow of printing-related data before printing, illustrating an embodiment of a method for checking a pattern color tone of a printing press according to the present invention before printing. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining an embodiment of a pre-printing confirmation method and apparatus for pattern color tone of a printing machine according to the present invention, and a platemaking method; (a) shows a confirmation method and apparatus before printing; and (b) shows a platemaking method. . It is a figure which shows schematic structure of the newspaper offset rotary press concerning 1st Embodiment of the pattern color tone control of this invention. FIG. 6 is a functional block diagram focusing on a color tone control function of the arithmetic device in FIG. 5. It is a flowchart which shows the processing flow of the color tone control by the arithmetic unit of FIG. It is a figure explaining expansion of the color space concerning 1st Embodiment of the pattern color tone control of this invention. It is a figure which shows the correspondence of the halftone dot area rate and mixed color halftone density concerning 1st Embodiment of the pattern color tone control of this invention. 6 is a map that associates a monochrome halftone density with a halftone dot area ratio. 6 is a map that associates a solid density with a halftone dot area ratio and a monochrome halftone density. It is a flowchart which shows the processing flow of the color tone control concerning 3rd Embodiment of the pattern color tone control of this invention. It is a figure explaining a platemaking curve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Line sensor type IRGB densitometer 2a, 2b, 2c, 2d Printing unit 3 Blanket cylinder 4 Plate cylinder 5 Ink roller group 6 Ink source roller 7 Ink key 8 Print sheet 10 Arithmetic unit 11 DSP
12 PC
14 Color conversion unit 15 Ink supply amount calculation unit 16 Online control unit 17 Key opening limiter calculation unit 20 Control device with built-in printing machine 30 Touch panel

Claims (4)

Using the device profile of the printing machine used for printing and the device profile of the monitor or printer, the plate making data used for printing is converted into a color state of a printing pattern when printing with the printing machine, and the plate making data is converted into the plate making data. Correspondingly, an output step of outputting the color development state of the printed pattern when printing with the printing machine as an image or printed matter;
A determination step of determining whether or not the color tone of the colored state of the image output to the monitor or the printed matter output to the printer in the output step is within an allowable range; and
By the determination step,
When the tone is to be within the scope of the allowable, the value of the target concentration before printing to be set before printing as the value of the target density which is a target value of the density of the printed pattern, corresponding to the plate making data Keep the standard target concentration value ,
If the color tone is not within the allowable range, the target density value before printing is set to the monitor or printer so that the color tone is within the allowable range with respect to the reference target density value . A method for confirming a color tone before printing of a printing machine, wherein the increase / decrease correction is performed while checking, the corrected color development state is output as an image or printed matter to the monitor or the printer, and the determination step is performed again. Using the device profile of the printing machine used for printing and the device profile of the monitor or printer, the plate making data used for printing is converted into a color state of a printing pattern when printing with the printing machine, and the plate making data is converted into the plate making data. Correspondingly, an output step of outputting the color development state of the printed pattern when printing with the printing machine as an image or printed matter;
A determination step of determining whether the color tone of the image output to the monitor or the printed matter output to the printer in the output step is within an allowable range; and
By the determination step,
If the color tone is within the first allowable range, plate making is performed using a standard plate making curve. If the color tone is not within the first allowable range, the device profile of the printing press is used. The plate making curve is corrected so that it becomes the plate making curve of the printing press while confirming with the monitor or printer, and the corrected coloring state is output to the monitor or the printer as an image or printed matter, and the determination step is performed again. And
If it is determined that the color tone is within a second allowable range set within the first allowable range as a range narrower than the first allowable range, the target value of the density of the printed pattern is obtained. the value of the target concentration before printing to be set before printing as the value of a target concentration, and remains the value of the target density of the reference corresponding to the plate making data,
If the color tone is not within the second allowable range, the target density value before printing is set so that the color tone is within the second allowable range with respect to the reference target density value . the increase or decrease correction while checking the monitor or printer, the monitor or the said corrected colored state to a printer and output as an image or a printed matter which comprises carrying out the determination step again, before printing of the printing machine Color tone confirmation method. Using the device profile of the printing machine used for printing and the device profile of the monitor or printer, the plate making data used for printing is converted into a color state of a printing pattern when printing with the printing machine, and the plate making data is converted into the plate making data. Correspondingly, an output means for outputting the colored state of the printed pattern when printing with the printing machine as an image or printed matter,
Determination means for determining whether the color tone of the image output to the monitor or the printed matter output to the printer in the output means is within an allowable range;
The determination of the color tone that by the determining means is within the scope of the acceptable, the value of the target concentration before printing to be set before printing as the value of the target density which is a target value of the density of the printed pattern a determination that remain value of the target density of the reference corresponding to the plate making data,
The determination by the determination means that the color tone is not within the allowable range is such that the target density value before printing is set so that the color tone is within the allowable range with respect to the reference target density value . The determination is performed by performing increase / decrease correction while confirming with the monitor or printer, outputting the corrected color development state as an image or printed matter to the monitor or the printer, and performing the determination by the determination unit again. A color tone confirmation device before printing on a printing press. Using the device profile of the printing machine used for printing and the device profile of the monitor or printer, the plate making data used for printing is converted into a color state of a printing pattern when printing with the printing machine, and the plate making data is converted into the plate making data. Correspondingly, an output means for outputting the colored state of the printed pattern when printing with the printing machine as an image or printed matter,
Determination means for determining whether the color tone of the image output to the monitor or the printed matter output to the printer in the output means is within an allowable range;
The determination means determines whether the color tone is within a first allowable range;
The determination of the color tone that by the determining means is within the scope of the first tolerance is determined if row plate making by using a reference plate making curve,
Determination, plate making such a plate making curve of the printing press while checking the monitor or printer using the device profile of the printing press of which the color tone by the determining means is not within the scope of the first tolerance A determination of correcting the curve, outputting the corrected color development state to the monitor or the printer as an image or printed matter , and performing the determination unit again ;
The determination means determines whether the color tone is within a second allowable range set within the first allowable range as a range narrower than the first allowable range ;
Determination, printed target density value before printing to be set before printing as the value of the target density which is a target value of the density of the picture that the color tone by the determining means is within the scope of the second tolerance Is a standard target density value corresponding to the plate-making data ,
The determination by the determination means that the color tone is not within the second allowable range is performed by setting the target density value before printing to the second target allowable density value with respect to the reference target density value . The determination is performed by performing increase / decrease correction while confirming with the monitor or printer so as to be within a range, and outputting the corrected color development state as an image or printed matter to the monitor or printer, and performing the determination by the determination unit again. A color tone confirmation device before printing of a printing machine, characterized by:

Images