JP5129982B2 - Color matching method and color matching device for printing press - Google Patents

Description

  The present invention relates to a color matching method and a color matching device of a printing machine for matching the color tone of an image displayed on a monitor with the color tone of a printed image when the image is printed.

Conventionally, predicted data that anticipates a print image formed on a print sheet on a monitor is created and displayed in advance on a monitor without printing image data created by a user. In order to do this, the printed material is measured in advance based on specific printing parameters to determine the characteristics of the printing press, the expected image data is created based on this characteristic data, and the expected image is displayed on the monitor. It was. As a result, when printing is performed using the printing parameters when the characteristic data is created, a printed matter suitable for the monitor display can be obtained. However, the print image can be predicted here only at the time of the print parameters for which the characteristic data is created. When trying to obtain a printed matter with a different hue from this, it is left to the skill level of the printing press operator as before. It was necessary to change the printing parameters and relied on the technology of the printing press operator. Therefore, the print image formed on the print paper is predicted based on the set print parameters and displayed, and printing is performed with the set print parameters that are not adjusted, so that the expected print screen and printed matter of the monitor are displayed. There is a proposal to combine the two. For example, print parameters such as ink supply amount and dampening water supply amount are input, and based on the image data and the print parameters, a print image formed on the printing paper to be printed is predicted and the expected image data Prints that are printed on the printing machine in the shades of the expected image by using the print parameters that are not adjusted from the predicted image based on the predicted image data. The colors of the images are matched. (See Cited Document 1)
JP 2001-347645 A

Based on the image data and print parameters, in order to create predicted image data that predicts the print image formed on the printing paper to be printed, not only the ink fountain key opening but also the print image It is not only necessary to consider a large number of data such as image arrangement data and image area ratio data, but also inputting all of them is complicated and difficult, and is complicated.
In addition, there is a possibility that the hue of the image of the printed product when it is actually printed and the hue of the predicted image displayed on the monitor do not match only by printing with the printing parameters that created the predicted image, and there is room for improvement. there were.

  The present invention has been made in view of the above problems, and can easily and quickly match the color of a printed image to the color of a monitor image while reducing wasteful printing paper required for color matching with a simple configuration. An object of the present invention is to provide a color matching method and a color matching apparatus for a printing press.

Color matching method for a printing press of the present invention includes: a display monitor for displaying an images, a plurality of ink fountain keys for adjusting ink supply amount from a plurality of ink fountain based on image displayed on the display monitor operation In the printing press including a control unit for performing printing, the Lab value is acquired from the gray patch of the image displayed on the display monitor, and the image displayed on the display monitor is printed on the printing press. to measure the Lab values of the gray patch image printed matter the printing, the color matching as Lab values of the gray patch image of the display monitor into Lab values of the gray patches of the printed matter of an image measurement matches When the image data of the display monitor is changed after the execution, the gray scale of the image is changed by the same amount as the change of the image data. Change the Lab values of Ji is characterized by adjusting the ink supply amount of the respective ink fountain keys as Lab values of the gray patches of the print image into Lab values of the gray patches after the change match.
The control unit for performing a display monitor for displaying an images, the printing by operating a plurality of ink fountain keys for adjusting ink supply amount from a plurality of ink fountain based on image displayed on the display monitor In the printing machine comprising: the control unit prints the Lab value acquisition means for acquiring the Lab value from the gray patch of the image displayed on the display monitor; and the image displayed on the display monitor. and measuring means for measuring the Lab values of the gray patches printed matter images, the image of the printed material of the display monitor into Lab values of the gray patches of gray patch image Lab values for performing color matching to match After color matching is performed by the color matching means and the color matching means, the image data of the display monitor is changed. The Lab data is acquired from the CMYK value corresponding to the gray that has changed by the same amount as the display data correction means that changes the data of the image on the display monitor by the display data correction means, and the acquired Lab It may be a color matching device of a printing press provided with an ink supply amount adjusting means for adjusting the ink amount for each of the plurality of ink fountain keys so that the Lab value of the gray patch of the image of the printed matter matches the value .
The inventor of the present application displays so that the color of the image displayed on the display monitor matches the gray color of at least three of the colors of the print image when the image displayed on the display monitor is printed. The gray patch of the image displayed on the display monitor is considered to be the same as the color of the image displayed on the display monitor and the color of the print image by matching the gray of the print image of the printed matter with the gray of the monitor. The Lab value is acquired from the image, the image displayed on the display monitor is printed by a printing machine, the Lab patch gray value of the printed image is measured, and the measured gray patch Lab value of the printed image is measured. After color matching was performed so that the Lab patch gray value of the display monitor image was the same, the display monitor image data was changed. In this case, the Lab value of the gray patch of the image is changed by the same amount as the change of the image data, and the Lab value of the gray patch of the printed image matches the Lab value of the gray patch after the change. By adjusting the ink supply amount for each ink fountain key, the conclusion was reached that the hues of the two images could be matched immediately. Note that the color of the image displayed on the display monitor indicates the color stored in the monitor as data in addition to the display color actually displayed on the display monitor.

The display area of the display monitor is divided so as to correspond to the plurality of ink fountain keys, and the gray patch of the image of the printed matter is changed to the Lab value after being changed by the display data correction unit for each of the divided display area portions . The ink supply amount for each ink fountain key corresponding to the divided display area portion may be adjusted by the ink supply amount adjusting means so that the Lab value matches .

In After color matching as Lab values of the gray patches printed image when printing the image displayed on the display monitor to Lab values of the gray patch of the image displayed on the display monitor match, displays When the monitor image data is changed, the gray patch Lab value of the image is changed by the same amount as the change of the image data, and the printed matter is changed to the changed gray patch Lab value. The color of the image displayed on the display monitor and the image displayed on the display monitor with a simple configuration that only adjusts the ink supply amount for each ink fountain key so that the Lab values of the gray patches of the image match. Can be easily and quickly matched with the color tone of the printed image when printing, reducing the amount of printing paper required for color matching. In performing the control of the amount, skill level of the printing press operator can provide a color matching method and the color matching apparatus of the printing press can without requiring color matching.

  The display monitor includes image data used for display on the monitor, and display data correction means for changing the image data to change display on the monitor, and the Lab value acquisition means includes the Lab value acquisition means. A Lab value is obtained from the CMYK value corresponding to the gray that has changed by the same amount as the change made by the display data correction means. The Lab value corresponding to the changed gray and the gray patch of the printed matter By calculating the difference with the Lab value by the difference calculating means and adjusting the ink amount for each of the plurality of ink fountain keys of the printing press so that the gray patch matches the gray after the change, the gray hue is changed. Even in such a case, the shade of the gray patch of the printed matter can be adjusted according to the degree of change.

  The display area of the display monitor is divided so as to correspond to the plurality of ink fountain keys, the difference between the two Lab values is calculated by the difference calculating means for each of the divided display area portions, and the calculated difference is calculated. Based on this, by adjusting the ink supply amount for each of the plurality of ink fountain keys, the ink supply amount can be finely adjusted, and the print image can be brought closer to the display image on the monitor with higher accuracy.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a control block diagram showing the configuration of the present invention. Image data from a display monitor 1 for projecting a target print image, and a printed matter obtained by printing the image projected on the display monitor with a printing machine 2. 3 shows the configuration of the control unit S for controlling the ink supply amount based on the image data of the print image 3.

  In order to correct the display data so as to obtain a desired display and print with the corrected management gray Lab value at this time as a target, the control unit S displays the gray Lab of the image displayed on the display monitor 1. The Lab value acquisition means 4 for acquiring the value, the measurement means 5 for measuring the gray Lab value of the printed material 3 obtained by printing the image displayed on the display monitor 1 by the printing machine 2, and the measurement means 5 The difference calculation means 6 that calculates the difference by comparing the Lab value of the print image with the target Lab value of the display monitor image acquired by the Lab value acquisition means 4, and the difference calculated by the difference calculation means 6 And an ink supply amount adjusting means 7 for adjusting the ink supply amount for each of the plurality of ink fountain keys.

  In a display system such as the display monitor 1 (including a display), the data is displayed by RGB data which are so-called three primary colors of light of red (R), green (G), and blue (B). In the printing system such as CMYK, CMYK data in which black (K) is added to “CMY of the three primary colors” of cyan (c), magenta (M), and yellow (Y) is used. However, the original data of the display image data displayed on the display monitor 1 is CMYK data, and the Lab value is acquired by CMYK / Lab conversion means for converting the CMYK image data into color data in the Lab space.

  As shown in FIG. 2A, the display area 15 of the display monitor 1 is divided so as to correspond to the plurality of ink fountain keys K, and the vertically long display area portions 15A to 15G (here, seven) are divided. However, the difference calculation means 6 calculates the difference between the two Lab values for each number). By calculating and adjusting the ink supply amount for each of the plurality of ink fountain keys K based on the calculated difference, the ink supply amount can be finely adjusted, and the print image is further displayed on the display image of the display monitor 1. There is an advantage that it can be close with high accuracy.

  The printing machine 2 has a plurality of different basic color printing inks, for example, four basic color inks of cyan (C), magenta (M), yellow (Y), and black (K). Depending on the color, C, M, Y, and K basic color images respectively formed in CMY may be sequentially printed on the printing paper, and a color print image may be printed on the printing paper. Although a paper feed unit (not shown), a printing unit including four printing units, a paper discharge unit, and the like are provided, other configurations may be used.

  Although not shown, each of the printing units is a general-purpose unit, and is configured by a plate cylinder, a rubber cylinder, and an impression cylinder as a set of main components. Is provided with a printing plate. The plate is supplied with ink and water, and the ink is transferred to the rubber cylinder according to the plate. The ink transferred to the rubber cylinder is further transferred to the printing paper conveyed while being held between the rubber cylinder and the impression cylinder. Thereby, it is possible to perform printing on the printing paper supplied from the paper feeding unit using the plates respectively provided on the plate cylinder. Each of the plates here, for example, prints basic color images of C, M, Y, and K by leaving a non-printing area on the printing paper and orthogonally crosses the printing paper in the non-printing area as shown in FIG. In this direction, a color bar (in this case, CMYK 4 colors + gray (CMY) color patches. In the present invention, this gray patch is used) 3B can be printed.

  In addition to the plate cylinder, rubber cylinder, and impression cylinder described above, each printing unit includes an ink supply device 9 and a swing device 70, an ink source roller 10, an ink fountain key K, etc., as shown in FIG. ing.

  FIG. 3A is an enlarged schematic view of the main part of the ink supply device 9 and its peripheral part, and FIG. 3B is a diagram showing the distance G between the ink fountain key K and the ink base roller 10 described later in the ink supply device 9. It is a partial schematic diagram exaggerating the appearance. The ink supply device 9 can supply the printing ink 11 to the printing plate of the plate cylinder via an ink roller group or the like not shown.

  As shown in FIG. 3A, the ink supply device 9 includes an ink fountain 12, an ink source roller 10, a plurality of ink fountain keys K, a roller driving device 80, and an ink fountain key moving device 90.

  The ink fountain 12 can accommodate the ink 11 and is provided with an ink source roller 10 and an ink fountain key K. The ink base roller 10 is rotatably disposed at the bottom of the ink fountain 12 and is connected to a roller driving device 80. The roller driving device 80 is configured to be able to rotationally drive the ink base roller 10 in a predetermined direction (an arrow counterclockwise direction W in the drawing). As a result, the ink base roller 10 is driven to rotate while adhering the ink 11 contained in the ink fountain 12 to the surface, whereby the ink 11 on the surface can be supplied to the ink feed roller 16. As the roller driving device 80, various conventionally known devices can be applied as long as the ink source roller 10 can be rotationally driven, and detailed description of the configuration and the like is omitted here.

  The plurality of ink fountain keys K are arranged in parallel along the width direction of the ink fountain key (in the direction of the arrow X ′ in the drawing) with respect to the original roller 8 in the direction of the roller axis, and the moving direction crossing the ink fountain key width direction X ′ (see FIG. It is erected along the middle arrow Y ′ direction). The open end R of the ink fountain key K is connected to an ink fountain key moving device 90 configured to move the open ends R of the plurality of ink fountain keys K along the movement direction Y ′. As the ink fountain key moving device 90, various types of conventionally known devices can be applied as long as they can move the plurality of ink fountain keys K along the moving direction Y ′, and detailed description of the configuration and the like is omitted here. .

  In the ink supply device 9 shown in FIG. 3A, the printing ink 11 accommodated in the ink fountain 12 flows out from the gap G between the ink fountain roller 10 and the ink fountain key K, and the outer periphery of the rotating ink fountain roller 10. Supplied to the surface. The interval G can be adjusted by moving the ink fountain key K in the moving direction Y ′ by the ink fountain key moving device 90. The gap G increases as the degree of opening of the ink fountain key K increases, and the ink fountain key K comes out of the ink fountain 12. While the ink amount increases, when the opening degree of the ink fountain key K decreases, the gap G becomes narrower and the amount of ink exiting from the ink fountain 12 decreases.

  As shown in FIG. 3A, the ink feed roller 16 is swingably disposed between the ink base roller 10 and the ink roller 17, and the ink feed roller 16 is close to the ink base roller 10. (Moving in the Z1 direction) or swinging configured to be selectively arranged so as to be away from the ink source roller 10 and close to the ink roller 17 (moving in the Z2 direction) It is connected to the device 70.

  In this way, the ink 11 in the ink fountain 12 moves from the ink base roller 10 to the ink feed roller 16 and the ink roller 17 and is supplied to the printing plate via a group of ink rollers not shown.

  In this way, the printing unit starts from the four ink fountains 12 that respectively store four colors of printing inks of C (cyan), M (magenta), Y (yellow), and K (black), and the width direction X of the ink fountain key in each ink fountain 12. A plurality of ink fountain keys K, which are arranged side by side so that the ink supply amount can be adjusted, are provided corresponding to the ink fountain 12 with the basic color inks whose ink supply amount is adjusted for each of the plurality of ink fountain keys K. C, M, Y, and K basic color images are respectively supplied to four printing plates (not shown).

Based on the flowchart of FIG. 4, the control unit S configured as described above performs control until the hue of the print image of the printed matter 3 printed by the printer 2 matches the hue of the display image of the display monitor 1. explain.
First, target print image data is input (step S1). In order to create a profile of a printing press for displaying this image data on a display monitor, a predetermined color chart (see FIG. 6, reference numeral 3A) is printed on the printing press, and the printed matter is measured and made. However, a profile created in advance and converted into data may be input, or a color chart may be read using a scanner or the like, and the read image data may be converted into data (profile) and input. After inputting the print image data, an image is displayed on the screen using the profile of the printing press (step S2). In the display image, as shown in FIG. 2A, the gray patch 18 is displayed for each of the display area portions 15A to 15G as described above, and the data of each gray patch 18 is controlled by the control unit. S is stored so that the data of the gray patch 18 can be extracted, or the CMY value of the gray patch is stored in the monitor 1. From the CMY value, the display monitor 1 acquires the gray Lab value from the profile of the printing press set for color matching with the printed matter. Next, printing is performed by the printer 2 with the display image displayed on the display monitor 1 as a target (step S3). It is determined whether or not there is a request to change the color of the image on the display monitor 1 (step S4). If there is a request, the image data (or profile) displayed on the display monitor 1 is changed and displayed. The color of the image is changed (step S5). At this time, as shown in FIG. 2A, the hue may be changed for each of the display area portions 15A to 15G, or the whole display image may be changed at once. Further, it may be for each color of CMY. If there is no request for changing the hue, the process proceeds to step S7. Each time the hue of the display image is changed, it is confirmed whether or not the display image on the display monitor 1 has the desired hue (step S6), and the change is made until the desired hue is obtained. When the color change is completed or there is no request for the color change, the gray patch data of the display image of the display monitor 1 is extracted to obtain the Lab value and the Lab patch Lab value of the printed image of the printed matter is obtained. For example, the Lab value read by a scanner equipped with a spectrocolorimeter is stored in the control unit S (step S7). After the color change, the gray CMYK for each acupuncture point is checked how it is corrected, and the corresponding Lab value is obtained from the correction value and the profile of the printing press (also in this case, as described above) The correction value is converted using an arithmetic expression or acquired from a previously stored comparison table or the like). Then, for each division unit, the difference between the gray patch data (Lab value) of the display image and the gray patch data (Lab value) of the print image is calculated to obtain a color difference (step S7). The angle of each ink fountain key K is adjusted based on the color difference (step S8), and the control for matching the color of the print image with the display image is terminated.

  As described above, the gray patch data of the display image of the display monitor 1 is converted from CMYK data to Lab data by the CMYK / Lab conversion means from the print characteristic data, and the gray patch of the print image of the other printed matter is spectroscopically measured. Read Lab data with a scanner equipped with a color meter. Then, the difference between the two Lab data is calculated, and from the graph showing the relationship between the Lab data of the obtained difference and the angle of each ink fountain key K, for example, it is tabulated and extracted from the tabulated data. The angle of each ink fountain key K can be obtained, but the angle (opening) of each ink fountain key K may be obtained by other different methods.

  FIG. 5 shows a display of a correction curve 19 indicating the hue of the display image of the display monitor 1 by pixels (pixels) arranged in the vertical and horizontal directions constituting the screen of the display monitor 1. The curve lines corresponding to each ink fountain key K in the curve lines to be averaged may be averaged, and the average value may be obtained as an angle (opening) corresponding to each ink fountain key K. In addition, the change ratio of each display data to be displayed for display on the display monitor 1 may be arbitrarily changed. For example, by changing the output when the input to each pixel is 50% to, for example, 70%, the output is changed by changing the input / output relationship to the input at an arbitrary ratio instead of 1: 1. Will be set. Specifically, each pixel of the display data is corrected with the conversion curves shown in FIGS. In FIG. 8 (a), the input and output have the same ratio, whereas in FIG. 8 (b), the output when the input is 50% is 70%, and gradually increases from the vicinity to the front and back. Shows a conversion curve drawn so that the difference between the input and output becomes moderate. The conversion curve is not limited to that shown in FIG. 8B, and can be arbitrarily changed.

  Actually, the image displayed on the display monitor 1 is obtained by performing color matching with the image of the printed matter 3 in advance, which is called monitor proof, and is an RGB / Lab monitor profile and CMYK / Lab. The color matching of the printed matter is displayed on the display monitor 1 based on the profile of the printing press. This is because the Lab of the target gray value (C: 70, M: 60, Y: 60) is obtained from the profile of the CMYK / Lab printer, printing is performed using this Lab as the target value, and the image of the printed matter 3 is obtained. Color matching will be performed. This is omitted in FIG. That is, as shown in FIG. 7, the image of the printed material 3, that is, the color chart 3 </ b> A of the printed material 3 shown in FIG. The image is measured and a monitor profile is created (for example, the Lab displayed on the display monitor 1 is measured using a color sensor or the profile stored in the display monitor 1 is taken in). After the measurement is completed, color matching of the display monitor 1 is completed in the color matching step 23 of the display monitor 1 using the monitor profile and the profile of the printing press.

  From the state where the color matching of the display monitor 1 is completed, as shown in FIG. 7, the gray values (for example, C: 70, M: 60, Y) previously input (stored) by the gray value input means 20 are displayed. : 60) When the display data changed in accordance with the change in the hue of the display image is corrected by the display data correction means 24 and the display monitor 1 is adjusted to a desired color, the gray value at that time is changed from the corrected value. Is calculated. The correction is performed in units of the printed material feed direction, and the display image on the display monitor 1 is changed to a desired color. That is, the reference gray CMY component changes with the correction. The changed gray value (corrected gray value) is converted into a Lab value by the Lab value acquisition unit 4 using an arithmetic expression, and the converted Lab value is input to the difference calculation unit 6 as a new target value. . On the other hand, the Lab patch gray value of the printed matter 3 printed after the display monitor 1 is adjusted to a desired color is measured by the measuring means 5 in the same manner as described above to obtain the Lab patch gray value (reference numeral 14). ). Then, the Lab value of the gray patch is input to the difference calculation means 6, and the difference between the gray Lab displayed on the monitor and the gray patch Lab of the printed matter is calculated for each ink fountain.

  The color scale shown in FIG. 9 is stored in advance in the personal computer, this color scale is displayed on the screen, and a desired color (yellow, red, blue, green, magenta) and brightness are displayed for each key or a plurality of keys. A desired color and brightness can be instructed by clicking at an arbitrary position on the screen. By performing sensitive designation using the color scale in this way, CMY can be corrected (changed) at the same time and quickly compared to the case where matching with a favorite color is simply performed using CMY values. It is like that. Actually, various colors are displayed along the circumference in the annular region 26 on the right side displayed on the display monitor 1 shown in FIG. 9, and the brighter the color is toward the upper and lower belt-like regions 27 on the left side. May be shown to be

It is a control block diagram for performing color matching. (A) is the schematic diagram which expanded the principal part of the ink supply apparatus, and its peripheral part, (b) is a part which exaggeratedly represented the mode of the space | interval with the ink fountain roller of the ink fountain key mentioned later in an ink supply apparatus. It is a schematic diagram. (A) is a front view which shows the screen of a display monitor, (b) is a front view which shows the printing surface of printed matter. It is a flowchart which shows color matching control. It is a front view which shows the screen of another display monitor. It is a schematic front view which shows the color chart and color bar of printed matter. It is another control block diagram for performing color matching. (A), (b) is a graph which shows the conversion curve of an input and an output. It is a front view showing a Lab color system chromaticity diagram (color scale).

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Display monitor, 2 ... Printing machine, 3 ... Printed material, 3A ... Color chart, 3B ... Color bar, 4 ... Lab value acquisition means, 5 ... Measurement means, 6 ... Difference calculation means, 7 ... Ink supply amount adjustment means, DESCRIPTION OF SYMBOLS 8 ... Ink origin roller, 9 ... Ink supply apparatus, 10 ... Ink origin roller, 11 ... Printing ink, 12 ... Ink fountain, 15 ... Display area, 15A-15G ... Display area part, 16 ... Ink feeding roller, 17 ... Ink Roller, 18 ... gray patch, 19 ... correction curve, 20 ... gray value input means, 21, 22 ... measurement process, 23 ... color matching process, 24 ... display data correction means, 26 ... area, 27 ... band-like area, 70 ... Swing device, 80 ... roller drive device, 90 ... ink fountain key moving device, G ... spacing, K ... ink fountain key, R ... open end, S ... control unit, X, Y ... direction

Claims (3)

Comprising a display monitor for displaying an images, the control unit for performing printing by operating a plurality of ink fountain keys for adjusting ink supply amount from a plurality of ink fountain based on image displayed on the display monitor In the printing press
Get the Lab values from the gray patch image displayed on the display monitor, print the image displayed on the display monitor in a printing machine, measuring the Lab values of the gray patches of the printed matter of an image the printing in after color matching as Lab values of the gray patch image of the display monitor into Lab values of the gray patch image printed matter measurement match, if the data of the display monitor of the image is changed In addition, the Lab value of the gray patch of the image is changed by the same amount as the change of the data of the image, and the Lab value of the gray patch of the printed image matches the Lab value of the gray patch after the change. A color matching method for a printing press , wherein the ink supply amount for each ink fountain key is adjusted. Comprising a display monitor for displaying an images, the control unit for performing printing by operating a plurality of ink fountain keys for adjusting ink supply amount from a plurality of ink fountain based on image displayed on the display monitor In the printing press
The controller is
Measuring the Lab value acquisition means for acquiring the Lab values from the gray patches projected image on the display monitor, the Lab values of the gray patches printed print image an image displayed on the display monitor in the printing press A color matching means for performing color matching so that the Lab patch gray value of the display monitor image matches the Lab patch gray value of the printed image, and the color matching means Display data correction means for changing the image data of the display monitor, and the display data correction means changes the gray of the display monitor image data to the same amount as the change is made. The Lab value is acquired from the corresponding CMYK value, and the gray value La of the image of the printed matter is acquired in the acquired Lab value. Color matching apparatus for a printing press, characterized by comprising a ink supply amount adjusting means for adjusting the ink amount of the each ink fountain keys to values match. The display area of the display monitor is divided so as to correspond to the plurality of ink fountain keys, and the gray patch of the image of the printed matter is changed to the Lab value after being changed by the display data correction unit for each of the divided display area portions . 3. The color matching of a printing press according to claim 2 , wherein the ink supply amount for each ink fountain key corresponding to the divided display area portion is adjusted by the ink supply amount adjusting means so that the Lab value matches. apparatus.

Images