JP2004042517A - Measuring device for printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring device for a printed matter, the color densities of the correctly corresponding positions on both the images on a reference paper and on which can be measured even under the condition that the size of the reference paper is different from that of the printed matter. <P>SOLUTION: In this measuring device for the printed matter, the reference paper and the printed matter are filmed at the steps S1 and S2 so as to memorize each image data. Next, both the image data are displayed on a display means so as to specify two corresponding points on both the image data for each image. At the step S5, the corresponding points on each image are judged whether they are separated from each other by at least a predetermined distance or not. When the separating condition is not satisfied, a procedure is sent back to the step S4 so as to resume the specification of the corresponding points. When the corresponding points are fixed, the coordinates of the corresponding points are memorized at the step S6. At the step S7, the observing points for calculating color densities based on the obtained corresponding points are calculated. Next, at the step S8, the measurement of the color densities of the coordinates is executed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a printed matter measuring device for measuring the color density and the like of a printed matter from image data obtained by imaging the printed matter.
[0002]
[Prior art]
There is a printed matter measuring device that mounts a printed matter on a table, performs imaging, and measures the color density at an arbitrary position on the printed matter based on the obtained image data, and is disclosed in JP-A-2001-353852. ing. In such a printed matter measuring apparatus, a printed matter extracted from a printing press (hereinafter, referred to as a extracted printed matter) is measured, and an ink supply amount of the printing press is controlled according to a result of comparison with preset reference image data. ing. As the reference image data, for example, it is conceivable that the reference image data is obtained by capturing an image of a reference print material prepared in advance (a print material or a print sample created by proof printing or the like; hereinafter, referred to as reference paper).
[0003]
Note that the measurement of the color density referred to in this specification is to convert the color of a printed matter into a numerical value using a predetermined color system. For example, a density value corresponding to each color such as YMCK or RGB, L ^* a ^* b ^* Means to find a value based on a known color system.
[0004]
[Problems to be solved by the invention]
The reference paper is not always the same size as the sample print. For example, if the reference paper prepared in advance is used for a previous print job and the print size of this print job has been changed, or there is a limit on the corresponding size of the proof printing apparatus itself. Proofs are printed in different sizes. In addition, there are also subtle differences in dimensions of the printed matter itself, and positional deviations during imaging by the printed matter measuring device. If the size and the imaging position of the reference paper and the extracted printed material are different as described above, for example, when selecting a point of interest on the image and performing color matching, the corresponding positions of both image data are different and accurate color density is obtained. There is a problem that comparison cannot be performed.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a printed matter measuring apparatus capable of performing an accurate comparison even when the reference paper and the sampled printed matter have different sizes.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, image data is obtained by imaging a sample printed material extracted from a printing device, and the color density of the printed material is calculated based on the image data in order to perform ink control of the printing device. In the printed matter measuring device, first storage means for storing first image data obtained by imaging the extracted printed matter, and second storage means for storing reference image data as reference printed matter as second image data Display means for selectively or simultaneously displaying the first image data and the second image data, and two correspondences respectively to the first image data and the second image data displayed by the display means A means for designating a point, and associating the first and second image data based on the corresponding point, and the other image corresponding to predetermined coordinates of any of the image data Comprising coordinate calculation means for calculating the coordinates of the chromatography data, and a color density computing means for obtaining a color density of the corresponding coordinate position from the values of pixels in the corresponding coordinates of the first and second image data.
[0007]
The invention according to claim 2 is the printed matter measuring apparatus according to claim 1, wherein the second image data stored in the second storage means is used for plate making data used when printing the printed matter. The image data is based on
[0008]
According to a third aspect of the present invention, in the printed matter measuring apparatus according to the first aspect, the second image data stored in the second storage unit is obtained by imaging a prepared reference sheet. It is characterized by the following.
[0009]
In the printed matter measuring device according to any one of claims 1 to 3, even if the size of the printed matter is different from that of a reference paper or the like which is a reference for performing color matching, an arbitrary coordinate position corresponds to the corresponding point. As a result, accurate color tone management can be performed.
[0010]
The invention according to claim 4 is the printed matter measuring device according to any one of claims 1 to 3, wherein the specifying means specifies a first corresponding point on an image displayed on the display means, Next, a second corresponding point is designated at a position separated from the first corresponding point by a predetermined distance or more.
[0011]
In the printed matter measuring device according to the fourth aspect, the distance between two corresponding points can be set to be equal to or longer than a predetermined value, so that the accuracy of the coordinate calculation does not decrease.
[0012]
According to a fifth aspect of the present invention, there is provided the printed matter measuring apparatus according to any one of the first to fourth aspects, wherein the designation unit automatically detects a corresponding point according to preset condition data. Features.
[0013]
In the printed matter measuring device according to the fifth aspect, since the corresponding points are automatically extracted, the work load of the operator is reduced, and there is no individual difference in the designation of the corresponding points.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
[Description of printing device]
Hereinafter, an example of a printed matter measuring device according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the printed matter measuring device.
[0015]
The printed matter measuring device 1 includes an imaging unit 3 that captures an image of a printed matter (sampled printed matter or reference paper) placed on a table 2, first and second storage units 4 that store image data obtained by the imaging unit, 5, operation control means 6 for performing an operation based on the image data, display means 7 for displaying the image data, designation means 8 for designating a position on an image on the display means, operation results, etc. And a third storage means 9 for storing The printed matter measuring device 1 is connected to the printing device 10 and the plate making device 11 so that data communication is possible.
[0016]
The table 2 is in the shape of a flat table on which printed matter can be placed, and is preferably provided with suction holding means and the like on the surface so that the printed matter can be supported smoothly.
[0017]
The imaging means 3 is composed of a two-dimensional CCD camera or the like mounted on the table 2, captures an image of a printed matter or the like on the table 2 illuminated by light source means (not shown), and generates image data by photoelectric conversion. Note that the imaging unit 3 may be configured by a one-dimensional line sensor that moves relative to the table 2 so that the printed matter is scanned and imaged.
[0018]
Image data obtained by the imaging unit 3 is stored in the first storage unit 4 or the second storage unit 5. In this embodiment, the first and second storage means 4 and 5 are each constituted by a RAM memory, and the first storage means 4 captures a sample of a printed material extracted from the printing apparatus for easy understanding. Image data (hereinafter, referred to as first image data), and the second storage means 5 stores image data (hereinafter, referred to as second image data) obtained by imaging a reference sheet prepared in advance. Shall be. Of course, the first and second image data may be stored in different storage areas of the same memory means in parallel as an apparatus configuration.
[0019]
The arithmetic control unit 6 performs image processing on the first and second image data stored in the first and second storage units 4 and 5, and calculates a color density at an arbitrary position on the corresponding image. In addition, the device configuration includes a microcomputer having an arithmetic processing function. The arithmetic control means 6 functions as a coordinate arithmetic means and a color density arithmetic means in the present invention according to the processing operation of the program.
[0020]
The display means 7 is composed of a CRT or a liquid crystal panel capable of displaying image data, and displays the first and second image data. The designating means 8 is composed of a known mouse, pen tablet or the like, and can designate an arbitrary position on the image displayed on the display means 7. The display means 7 and the designation means 8 may be integrated by adopting, for example, a liquid crystal display means having a touch panel function.
[0021]
The third storage unit 9 is configured by a RAM memory or the like, like the first and second storage units 4 and 5, and stores measurement results and the like. As described above, the same memory means as the first and second storage means may be used.
[0022]
The printing device 10 is a printing device that prints the above-described sampled printed material, and corresponds to, for example, an offset printing device that can adjust the print density for each color of YMCK. Such a known offset printing apparatus includes an ink amount adjusting mechanism such as an ink fountain device. The printed matter measuring apparatus 1 according to this embodiment compares the first image data of the extracted printed matter with the second image data of the reference paper, and adjusts the comparison result or the ink adjustment derived from the comparison result. The amount is transmitted to the printing device 10 and the color adjustment in the printing device 10 is performed accordingly.
[0023]
The plate making device 11 corresponds to, for example, a printing plate recording device that creates a printing plate used in the printing device, an image data creating device in the preceding stage, and the like. From the plate making apparatus 11, the image data used to create the printing plate can be used as the reference image data and can be used in place of the second image data. That is, when there is no reference paper, image data obtained from the plate making apparatus 11, for example, PPF data in the CIP3 standard can be used. The printing device 10 and the plate making device 10 may be a printing device with a plate making mechanism that integrates both functions.
[0024]
Next, the operation procedure of the printed matter measuring apparatus 1 according to the present invention will be described with reference to the flowchart of FIG. FIG. 3 is an explanatory diagram showing an example of each image of the reference paper and the extracted printed material, which will be referred to in the following description as needed.
[0025]
In FIG. 2, first, in step S <b> 1, an image of a reference sheet is taken by the printed matter measuring apparatus 1, and the second image data is stored in the second storage unit 5. FIG. 3A shows an example of the image data of the reference paper. Instead of capturing the reference paper and taking in the image data, image data obtained from the plate making apparatus 11 may be used.
[0026]
In the next step S2, an image of the extracted printed material is similarly taken, and the first image data is stored in the first storage means 4. FIG. 3B shows an example of the image data of the extracted printed material. In this example, the case where the size of the reference paper is smaller than the size of the sampled printed matter is shown.
[0027]
In step S3, the obtained first and second image data are displayed on the display means. As this display method, for example, it is preferable that two image data are appropriately reduced and displayed in parallel on the same screen. Alternatively, two image data may be sequentially and selectively displayed.
[0028]
In step S4, two points corresponding to each displayed image are designated using the designation means. The corresponding points are designated as indicated by P1 and P2 on the second image data as shown in FIG. 3, for example. Then, also on the first image data, corresponding points R1 and R2 corresponding to the same position on the picture relative to the corresponding points P1 and P2 are designated. In the specification, it is easy to specify a characteristic portion on the image, for example, the tip of the mast in the example of the picture shown in FIG.
[0029]
It is preferable that the corresponding points P1, P2 and R1, R2 are respectively specified at positions substantially diagonally separated from the image data by a predetermined distance or more, particularly near two opposing corners on the image. Good to do. This is to reduce a calculation error in a coordinate calculation described later.
[0030]
The specific order of the corresponding points P1, P2, R1, R2 does not matter, but if the distance between the corresponding points P1 and P2 (also the distance between R1 and R2) is not more than a predetermined distance, In step S5, it is determined that there is a designation error, and step S4 is performed again. The determination of the distance between the corresponding points P1 and P2 (similarly, the distance between R1 and R2) is preferably performed for each XY coordinate of the image data.
[0031]
In the above description, if the two corresponding points are not separated by the predetermined distance, the specification error is determined in step S5. However, after specifying the first point, the area for specifying the next second point is set in advance by the predetermined distance. Range display may be performed so as to be set in a separated range. Of course, range display may be performed on the image such that the first point and the second point are selected and designated from within a predetermined range set in advance.
[0032]
In step S6, when the four corresponding points are determined, the coordinates on the image data are stored in the third storage means 9.
[0033]
In step S7, the coordinates of the target point for calculating the color density are calculated. This point of interest is a position that is important when performing color adjustment on the printed matter, and is specified in advance by the operator. For example, in the example of FIG. 3, it is assumed that a point of interest P3 is specified on the second image data. If the point on the first image data corresponding to the noted point P3 is R3, the coordinate data of R3 is calculated as follows based on the coordinates of the four corresponding points.
[0034]
Note that the XY coordinates of the corresponding point P1 on the image data are (p1x, p1y), and the coordinates of the corresponding points P2, R1, R2 are (p2x, p2y), (r1x, r1y), (r2x, r2y). And Further, assuming that the coordinates of the target point P3 are (p3x, p3y), the coordinates (r3x, r3y) of R3 to be obtained are obtained by the following equations.
[0035]
r3x = (p3x-p1x) (r2x-r1x) / (p2x-p1x) + r1x
r3y = (p3y−p1y) (r2y−r1y) / (p2y−p1y) + r1y
[0036]
According to the above coordinate calculation, the relative coordinate positions of the points of interest P3 and R3 on the first and second image data can be matched even if the size of the sample printed matter and the size of the reference paper are different.
[0037]
In step S8, the color density of each point of interest is calculated from the pixel values of the image data at the coordinates of the points of interest P3 and R3. Then, the two color densities are compared, and the amount of ink adjustment for the printing apparatus 10 is calculated so that the color density of the extracted printed matter approaches the reference paper. Of course, one or more sets of the attention points P3 and R3 may be specified. For example, the attention points may be specified for each ink fountain key area of each printing apparatus 10. In this case, the ink amount can be adjusted for each area designated by each ink fountain key. The printed matter measuring device 1 may perform only the calculation of the color density or the comparison calculation of the color density, and the calculation of the ink adjustment amount based on the calculation may be performed on the printing device 10 side.
[0038]
In the above embodiment, the operator specifies the corresponding point manually, but this may be performed automatically. For example, it is conceivable to automatically extract corresponding points from a picture by various pattern recognition and edge detection methods according to preset conditions. The simplest method is to extract a specific pattern, for example, a character or a line drawing from a line drawing portion on an image, and set a corresponding point at a position where the specific pattern exists. Alternatively, a register mark previously given to an image may be set as the specific pattern. Further, a corner vertex of the rectangular image may be set as the corresponding point. If the designation of the corresponding points is automated in this way, the work load of the operator is reduced, and there is no individual difference in the designation of the corresponding points.
[0039]
【The invention's effect】
According to the present invention, even when the size of the reference paper is different from the actual size of the printed matter, the attention point at the same position can be set accurately, so that the color tone management of the printed matter can be performed accurately.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a printed matter measuring device according to the present invention.
FIG. 2 is a flowchart showing an operation procedure in the printed matter measuring device.
FIG. 3 is an explanatory diagram illustrating corresponding points on first and second image data.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 printed matter measuring device 3 imaging means 4 first storage means 5 second storage means 6 arithmetic control means 7 display means 8 designation means 9 third storage means 10 printing device 11 plate making devices P1, P2, R1, R3 P3, R3 Points of interest

Claims (5)

In a printed matter measuring device that captures image data by sampling a printed material extracted from a printing device and obtains image data, and calculates the color density of the printed material based on the image data in order to perform ink control of the printing device,
First storage means for storing first image data obtained by imaging the sample printed matter;
Second storage means for storing reference image data as reference printed matter as second image data;
Display means for selectively or simultaneously displaying the first image data and the second image data;
Designating means for designating two corresponding points for the first image data and the second image data displayed by the display means,
Coordinate calculation means for associating the first and second image data based on the corresponding point and calculating coordinates of the other image data corresponding to predetermined coordinates of the one of the image data;
A color density calculating unit for obtaining a color density at a corresponding coordinate position from a pixel value at a corresponding coordinate of the first and second image data. 2. The printed matter measuring apparatus according to claim 1, wherein the second image data stored in the second storage means is image data based on plate making data used when printing the printed matter. 2. The printed matter measuring apparatus according to claim 1, wherein the second image data stored in the second storage unit is obtained by imaging a reference sheet prepared in advance. The designating means designates a first corresponding point on an image displayed on the display means, and subsequently designates a second corresponding point at a position separated from the first corresponding point by a predetermined distance or more. The printed matter measuring device according to claim 1, wherein 5. The printed matter measuring apparatus according to claim 1, wherein said specifying means automatically detects a corresponding point in accordance with preset condition data.

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