JP2003346129A - Printed matter measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compare two kinds of colorimetric data, and to compare colorimetric data with color data corresponding to a preparation between pixels corresponding to each other in a positionally correct manner. <P>SOLUTION: A printed matter measuring instrument picks up an image of a lattice chart, and calculates the deviation of positions of lattice points P'<SB>i</SB>,<SB>j</SB>in an actual picked-up image (b) with the positions of the lattice points P<SB>i</SB>,<SB>j</SB>at an ideal image (a) free from any geometrical distortion or positional deviation of pixels as references, and calculates the positional deviation of pixels other than the lattice points by interpolation based on the positional deviation of each lattice point. Based on the positional deviation of each pixel, data of the pixels (Pac, Pbc, etc.), to be located at each pixel (Pa, Pb, etc.), of the ideal picked-up image is successively extracted from actual picked-up data of the print, and separately saved. Thus, image data with any geometrical distortion or positional deviation of pixels removed from actual image pickup data of the print is generated, and two kinds of colorimetric data are compared between the pixels corresponding to each other by using colorimetric data based on the image data. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed matter measuring apparatus for measuring colors, densities, etc. in printed matter for controlling color tone in printing.

[0002]

2. Description of the Related Art In color tone management in printing, a printed matter measuring device is used to measure the color and density of a printed matter. Conventionally, in this type of printed matter measuring apparatus, a line sensor has been used as an imaging unit for capturing an image of the printed matter, and the line sensor scans the printed matter.
It was configured to obtain dimensional image data. But,
Such a configuration in which a two-dimensional image of a printed matter is obtained by scanning requires a driving system for scanning, and thus has a problem in that the device configuration is complicated and measurement time is long.

For this reason, a printed matter measuring apparatus using two-dimensional image pickup means for collectively imaging printed matter has been proposed as an image pickup means for picking up an image of a printed matter, instead of an image pickup means based on a scanning method. For example, JP-A-2001-3
No. 53852 discloses that image data is obtained by collectively imaging printed matter placed on a table by two-dimensional imaging means.
A printing device assisting device that processes the image data to measure the color density or the like of a printed material is disclosed. According to such a configuration, since a scanning mechanism is not required, the complexity of the device configuration is suppressed, and the measurement time is shortened.

[0004]

By the way, in color tone management in printing, inks of respective colors in a printing apparatus are so arranged that colorimetric values of a proof print which is to be a reference and a target print which is an original print match. The supply amount and the like are adjusted. For this purpose, it is necessary to match the measurement positions between the proof print and the target print. That is, the captured image of the proof print and the captured image of the target print are compared on a pixel-by-pixel basis for color tone management in printing. At this time, the positions of the compared pixels are relative to each other in the proof print and the target print. Must match in position. In some cases, color tone management is performed so that the colorimetric data of the target print matches the PPF (Print Production Format) data representing the image recorded on the printing plate used for printing. It is necessary to compare the data of the captured image of the printed matter and the PPF data between corresponding pixels. Note that this PPF data is CI
P3 (International Cooperation for Integration of
Prepress, Press, and Postpress), which is image data obtained by converting image data for actually recording an image on a printing plate into a low-resolution image. Each pixel has an ink color (cyan ( C), magenta (M), yellow (Y), black (K)).

However, as described above, between two types of image data representing print contents, that is, between the colorimetric data of the target print and the colorimetric data of the proof print, or between the colorimetric data of the target print and the PPF data If the two-dimensional image pickup device of the printed matter measuring apparatus has a distortion or a shift in the pixel position, the two types of colorimetric data to be compared with each other are compared. Cannot be accurately associated with each other in pixel units.

Therefore, in the present invention, a comparison between two types of colorimetric data and a comparison between colorimetric data and color data (PPF data) corresponding to plate making, while suppressing the complexity of the apparatus configuration and prolonging the measurement time. It is an object of the present invention to provide a printed matter measuring apparatus capable of performing the same between pixels corresponding in position accurately.

[0007]

A first aspect of the present invention is a printed matter measuring device for measuring the color and / or density of a printed matter, comprising: a table on which the printed matter is placed; Illuminating means for illuminating, two-dimensional imaging means for collectively imaging the printed matter placed on the table, and correcting the position of a pixel constituting an image of the printed matter by the two-dimensional imaging means, Geometric correction means for generating corrected image data representing an image from which the geometric distortion and the displacement of the pixel position have been removed, and generating colorimetric data indicating the color and / or density of the printed matter by generating the corrected image data. It is characterized by obtaining.

According to the first aspect of the invention, the geometric correction is performed on the image data of the printed matter by the two-dimensional image pickup means which does not require a scanning mechanism, so that the apparatus configuration is complicated and the measurement time is long. It is possible to obtain image data from which geometric distortion and pixel position shift have been removed, as corrected image data. For this reason, comparison between colorimetric data based on the corrected image data (comparison of two types of colorimetric data), and comparison between colorimetric data based on the corrected image data and color data (for example, PPF data) corresponding to plate making. When performing the comparison, the comparison can be made at exactly the same pixel position. That is, in the above comparison, the measurement positions viewed from the viewpoint of the image (picture) to be printed can be accurately matched.

According to a second aspect of the present invention, in the first aspect, the apparatus further comprises suction fixing means for sucking and fixing the printed matter on the table, and the illumination means includes a flash light source.

According to the second aspect of the present invention, the printed matter placed on the table is flattened by the suction fixing means and is illuminated with strong light from the flash light source, so that the illuminance distribution varies. It is possible to image the printed matter without any favorable lighting conditions.

In a third aspect based on the first aspect, the image processing apparatus further comprises image storage means for storing image data, wherein the geometric correction means corresponds to each pixel position of an ideal picked-up image with respect to the printed matter. The corrected image data is generated by extracting pixel data to be extracted from the pixel data of the image captured by the two-dimensional imaging unit and ordering the corrected pixel data. The image storage unit stores the corrected image data generated by the geometric correction unit. Is stored.

According to the third aspect of the invention, all the pixel data constituting the image data of the printed matter subjected to the geometric correction are stored as the corrected image data, so that the colorimetric values based on the corrected image data are stored. Can be performed accurately and at high speed.

In a fourth aspect based on the third aspect, the geometric correction means is obtained by previously imaging the sheet having a predetermined lattice pattern placed on the table by the two-dimensional imaging means. A grid point detecting means for detecting a position of each grid point in the grid image, and a shift amount of a position of each grid point in the grid image based on a position of each grid point in an ideal captured image with respect to the grid pattern. By a grid position shift calculating means for calculating a grid position shift amount, and by interpolation based on the grid position shift amount,
A pixel position shift calculating means for calculating a pixel position shift amount which is a shift amount of each pixel position of the lattice image with reference to each pixel position of the ideal captured image; A correction data generation unit configured to generate the correction image data from pixel data of a captured image of the printed matter by the two-dimensional imaging unit.

According to the fourth aspect, the displacement of each pixel in the captured image is calculated by interpolation based on the displacement of each grid point in the captured image of the lattice pattern, and the position of each pixel is calculated. Since the corrected image data is generated from the image data of the printed matter based on the shift amount, it is possible to perform highly accurate geometric correction on the image data of the printed matter.

According to a fifth aspect of the present invention, in the first aspect, plate making image data storage means for storing plate making image data representing an image recorded on a printing plate to be used for producing the printed matter, and printing by the printing plate. Based on pattern matching by the matching means for associating the target image data indicating the color and / or density of the target printed matter, which is the printed matter as the measurement target, with the plate making image data for each pixel by pattern matching, Comparing means for comparing colorimetric data based on the target image data and color data based on the plate-making image data between corresponding pixels, wherein the target image data is an image of the target print by the two-dimensional imaging means. Corrected image data generated from a captured image, and colorimetric data based on the target image data is the target image data. Data is data that expresses a predetermined color system, the color data based on the plate making image data, characterized in that said plate making image data is data expressed in the color system.

According to the fifth aspect of the invention, based on pattern matching between the corrected image data for the target print and the plate making image data (for example, PPF data) representing the image recorded on the printing plate, the target print is obtained. Is corrected for each pixel, and colorimetric data based on the corrected image data and color data based on the platemaking image data are compared between the corresponding pixels. Therefore, in combination with the effect based on the geometric correction described above, even if the relative position of the image (pattern) to be printed on the printing paper is shifted (print position shift), the colorimetric data based on the corrected image data is used. And the color data based on the plate making image data can be compared positionally accurately (at the same pixel position).

According to a sixth aspect, in the first aspect, target image data indicating the color and / or density of a target print, which is a print as a measurement target, printed by the printing plate; Matching means for associating calibration image data indicating the color and / or density of the proof print to be a reference of the printed matter for each pixel by pattern matching, and measurement based on the target image data based on the pattern matching by the matching means. And comparing means for comparing color data and colorimetric data based on the calibration image data between corresponding pixels, wherein the target image data is generated from a captured image of the target print by the two-dimensional imaging unit. Colorimetric data based on the target image data, wherein the target image data is a predetermined color Wherein the calibration image data is correction image data generated from the captured image of the proof print by the two-dimensional imaging means, and the colorimetric data based on the calibration image data is the calibration image data Is represented in the color system.

According to the sixth aspect of the present invention, the target image data is corrected based on the pattern matching between the target image data, which is the corrected image data for the target printed matter, and the proof image data, which is the corrected image data for the proof print. And the calibration image data are associated with each other for each pixel, and colorimetric data based on the calibration image data and colorimetric data based on the calibration image data are compared between the corresponding pixels. Therefore, in combination with the effect based on the geometric correction described above, even if there is a deviation between the mounting position of the target print on the table and the mounting position of the proof print, there is also a deviation in the print position of both prints. Even if there is a difference (even if the printing position is different), the colorimetric data based on the calibration image data and the colorimetric data based on the calibration image data can be compared positionally accurately (at the same pixel position). it can.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. <1. FIG. 1 is a block diagram for explaining a color tone management system in printing. In this color tone management system, a printed matter measuring device according to an embodiment of the present invention is used. The printed matter measuring device is a device for measuring the color, density, etc. of the printed matter, and is called a "color stand" or "DCC (Digital Color Console)". Hereinafter, before describing the details of the printed matter measuring apparatus according to the embodiment of the present invention, the color tone management system shown in FIG. 1 will be described.

In order to create a printed matter, first, digital data representing print contents is created as plate making data Dp.
By performing rasterization processing (also called RIP processing) on the plate making data Dp, bitmap image data is generated. Then, a printing plate is produced based on the image data. That is, plate making (P11) is performed. Next, a proof print (P13) is performed to obtain a proof print that is to be a reference for the print using the prepared printing plate. A proof print Drp obtained by the proof print (P13) is a color stand (DCC) as a print measurement device.
Is used to measure the color and density. That is, the color measurement (P17) is performed on the proof print material Drp by the DCC, and thereby, image data indicating the color and density of the proof print material Drp is generated as the proof color measurement data Drm. In addition, printing (P15) for an original printed matter (hereinafter, referred to as "target printed matter") to be created by printing using the printing plate created by the plate making (P11) is performed. The color of the target print Dtp is also measured by DCC, and image data indicating the color and density of the target print Dtp is generated as target colorimetric data Dtm. However, color measurement is not performed for all target prints, but is usually performed for some target prints extracted as samples.

Next, the colorimetric data Dtm of the target print Dtp obtained as described above is compared with the colorimetric data Drm of the proof print Drp.
11) and printing (P15). For example, the printing (P1) is performed in accordance with the comparison result of the two colorimetric data Dtm and Drm so that the color and the density at the corresponding predetermined positions between the target print material Dtp and the proof print material Drp match.
The control of the ink supply amount in 5) (specifically, the adjustment of the opening degree of the in-key in the printing apparatus) is performed. Further, the PPF data Dppf, which is color data obtained from the plate making data Dp, is compared with the colorimetric data Dtm of the target printed matter Dtp, and the comparison result is used for plate making (P11) and printing (P11).
15) is also reflected.

<2. Configuration of Printed Measuring Apparatus> Next, the configuration of a printed matter measuring apparatus (DCC) for measuring the color and density of the target print Dtp and the proof print Drp in the above-described color tone management system will be described with reference to FIGS. explain.

As shown in FIG. 2, the printed matter measuring apparatus includes a table 1 on which printed matter is placed, and a table 1 for placing the printed matter.
, A gantry 3 for supporting the table 1, an illuminating unit 4 for illuminating the printed matter placed on the table 1, and a table mounted on the table 1. An imaging unit 5 for imaging the printed material, a light-shielding roof member 6 for blocking light that is specularly reflected on the table 1 and incident on the imaging unit 5, and for controlling the operation of the printed material measuring device. And a touch panel 8 for operating the printed matter measuring device. In addition, the printed matter measuring apparatus is provided with a suction fixing mechanism 2 as shown in FIG. 3 for sucking and fixing the printed matter placed on the table 1.

The table 1 is a flat table-shaped table member. On the table 1, suction holes and suction grooves are formed for sucking and fixing printed matter, and a positioning member for positioning the printed matter is provided. Have been.

The suction fixing mechanism 2 is constituted by using the suction holes and the suction grooves formed in the table 1, a vacuum pump, a solenoid valve and the like. That is, as shown in FIG. 3, suction holes 13a to 13c are formed in the table 1 and suction grooves (not shown) are formed so as to communicate with the suction holes 13a to 13c. , Each suction hole 13a ~
13c are solenoid valves 15, 16, 17 as shown in FIG.
Are connected to the vacuum pump 18 through the respective components. A vacuum switch 19 that is turned on when a predetermined degree of vacuum is reached is connected in the middle of the pipe between the vacuum pump 18 and the solenoid valves 15 to 17. In the suction fixing mechanism 2, based on a control signal from the control unit 7, the solenoid valves 15 to 1
The suction holes for vacuum evacuation can be switched by appropriately opening and closing the nozzles 7 in combination, whereby the suction area can be set according to the size of the printed matter. It should be noted that the suction fixing mechanism is not limited to the suction fixing mechanism 2 using vacuum evacuation, but may instead use, for example, a suction fixing mechanism using static electricity.

The gantry 3 is a housing for supporting the table 1, and has a control unit 7, a vacuum pump 18 and the like built therein.

The illuminating section 4 is illuminating means provided with a flash light source for illuminating a printed matter placed on the table 1, and is provided on each of the left and right sides of the table 1. The installation position and the projection direction of the illumination light are set so that the irradiation angle with respect to the table 1 becomes shallow. Further, on the side surface on the table 1 side of the illumination unit 4, that is, on the projection surface of the illumination light, the density is increased temporarily or stepwise from top to bottom so as to make the illuminance distribution on the table 1 uniform. An ND filter, which is a filter plate with a concentration gradient, is provided. The lighting unit 4
Although the use of a flash light source is advantageous in that the object to be imaged can be illuminated with strong light, there is a problem in that the illuminance distribution varies when the printed matter as the object to be imaged is not flat. However, in the present embodiment, the printed matter placed on the table 1 is sufficiently flattened by the suction fixing mechanism 2, so that the illuminance distribution of the printed matter to be imaged does not vary.

The image pickup unit 5 is a digital camera configured to separate incident light into three primary colors of RGB by a dichroic mirror and to receive each of the three primary colors by a separate two-dimensional CCD (Charge Coupled Device) array. , The image data of the printed matter is generated by collective imaging without scanning. The imaging unit 5 as such a two-dimensional imaging unit is fixed to the table 1 by a support 24 provided on the gantry 3, and an opening (not shown) provided in the light-shielding roof member 6. The printed matter on the table 1 is imaged through the. By imaging the printed material in this way, image data can be obtained for each of the RGB planes (hereinafter, this image data is referred to as “imaging data”).

The light-shielding roof member 6 is supported by the gantry 3 and has two columns 2 extending above the table 1 with its upper end curved.
5 and has a curved shape in the front-rear direction of the printed matter measuring device. The light-shielding roof member 6 blocks light that is specularly reflected on the table 1 and enters the imaging unit 5, for example, light from a lighting device arranged on the ceiling.

As shown in FIG. 4, the control unit 7 includes a CPU 51 as a central processing unit and a memory 54 as a main memory.
And a disk interface unit 53 to which a hard disk device 56 as an auxiliary storage device is connected, an I / O interface unit 52, and a display control unit 55 connected by a bus. The touch panel 8 is connected to the display control unit 55, and the imaging unit 5 and the touch panel 8 are connected to the I / O interface unit. In the control unit 7, the hard disk device 5
The CPU 51 stores the predetermined program stored in the memory 5 in the memory 5.
4 and executed, control of each unit of the printed matter measuring apparatus and processing of image data are performed.
A control signal for controlling each unit in the printed matter measuring apparatus by the control unit 7 is supplied to each unit via the I / O interface unit 52.

The touch panel 8 is a liquid crystal monitor having a pressure-sensitive input function. The touch panel 8 functions as input means for operating the printed matter measuring apparatus, and also functions as a display means for displaying the processing results of the control unit 7. . In place of such a touch panel 8, display means such as a CRT and input means such as a keyboard and a mouse may be used.

<3. Operation of Printed Material Measuring Apparatus> The printed matter measuring apparatus according to the present embodiment configured as described above acquires image data by imaging the printed matter (the target printed matter Dtp and the calibration printed matter Drp) placed on the table 1. Then, based on the acquired imaging data, the colorimetric data of the target print and the colorimetric data of the proof print are compared, or the colorimetric data of the target print and color data based on the PPF data are compared. In the former case, it is necessary to compare the colorimetric data of the pixels corresponding in position between the captured image of the target print and the captured image of the proof print, and in the latter case, the captured image of the target print and the PPF It is necessary to compare the colorimetric data and the color data for the pixels that correspond in position to the image represented by the data. However, the imaging unit 5
If there is a distortion or a shift in the pixel position in the captured image obtained by the above, it is not possible to accurately correlate the captured image data or the PPF data, which is the image data, with the pixel unit. Therefore, in the present embodiment, when image data of a printed matter is obtained, geometric comparison is performed on the image data before comparing colorimetric data or the like based on the image data (details will be described later). Image data (hereinafter, referred to as “corrected image data”) representing the captured image from which the target distortion and the displacement of the pixel position have been removed is generated.

<3.1 Preprocessing for Geometric Correction> In the printed matter measuring apparatus according to the present embodiment, as the preprocessing for the above geometric correction, a grid chart, which is a sheet having a predetermined grid pattern, is used. Assuming an ideal picked-up image when placed on the table 1 and picked up, that is, a picked-up image with no geometric distortion or pixel position shift (hereinafter referred to as an “ideal image”), each grid point in the ideal image Is calculated (hereinafter referred to as “grid point coordinates”, the unit of which is a pixel). FIG.
Is a flowchart showing the procedure of this preprocessing. In this preprocessing, the CPU 51 of the control section 7 operates as follows. In the following, four white reference plates 101 to 101 are placed on the table 1 as shown in FIG.
The rectangle 110 circumscribing 104 is 1280 mm × 1024
The rectangular region 120 of 1280 mm × 1024 mm is arranged at the center of the rectangular region 120 of
Is the origin O of the table 1. Also, part 1
A rectangular area 120 of 280 mm × 1024 mm is a region 1 in a captured image obtained by the CCD array of the imaging unit 5.
Image area 2 consisting of 280 pixels x 1024 pixels
20 (FIG. 6B), the origin O on the table 1
Corresponds to the upper left point O ′ of the image area 220 composed of 1280 pixels × 1024 pixels.

In this preprocessing, first, initial conditions for calculating grid point coordinates are set (step S12). More specifically, data indicating the size of the rectangular area 120 that is an area to be considered on the table 1 (1280 m wide)
m, 1024 mm in height) and data (L [mm], indicating the size of the rectangle 110 circumscribing the white reference plates 101 to 104.
H [mm]), data (Δa [mm], Δb [mm], Δc [m] indicating the position where the grid chart 105 is placed.
m]), data (M [dpi]) indicating the resolution of the CCD array (the number of pixels per inch), interstitial distance in the X direction (horizontal direction) and Y in the grid chart 105
Data (Δx [m
m], Δy [mm]) are stored in the hard disk device 56 in advance, and in step S12, these data are read out from the hard disk device 56 and
To be stored.

Next, using the above data, the coordinates of the lattice points (the unit is pixels) in the ideal image are calculated as follows (step S14). That is, first, the coordinates (X0, Y0) of the upper left point P0 in the grid chart 105 on the table 1 are calculated by the following equation. X0 = ΔL + Δa + Δc (1) Y0 = ΔH + Δa + Δb (2) where ΔL = (1280−L) / 2 (3) ΔH = (1024−H) / 2 (4) where Δa is a white reference. The width in the short direction of the plates 101 to 104, Δb is the distance from the bottom of the upper white reference plate 102 to the upper side of the grid chart 105, Δc is the distance from the right side of the left white reference plate 101 to the left side of the grid chart 105, L Is the horizontal length of the rectangle 110 circumscribing the white reference plates 101-104, and H is the rectangle 11 circumscribing the white reference plates 101-104.
It indicates the length in the vertical direction of 0. These values are obtained by, for example, actually measuring with a ruler or the like.

The coordinates (X0 ', Y0') of the point P0 'on the ideal image corresponding to the upper left point P0 of the grid chart 105
X0 ′ = (X0 / 25.4) × M (5) Y0 ′ = (Y0 / 25.4) × M (6) Further, the lattice distance Δ in the X direction on the ideal image
x ′ and the interstitial distance Δy ′ (unit: pixel) in the Y direction are as follows: Δx ′ = (Δx / 25.4) × M (7) Δy ′ = (Δy / 25.4) × M (8) Becomes Here, M may be set to an appropriate value from the characteristics of the printed matter measuring device. In this example, M = 25.4 [dp]
i], but is not limited to this value.
Further, Δx and Δy are obtained by actually measuring the distance between lattices in the lattice chart 105 (unit: mm).

On the ideal image, i in the X direction (lateral direction)
The coordinates P _{i, j} of the j-th grid point in the Y direction (vertical direction)
(X _{i, j} , Y _{i, j} ) can be calculated by the following equation using X0 ′, Y0 ′, Δx ′, and Δy ′ calculated by the above equations (5) to (8). X _{i, j} = X 0 ′ + (i × Δx ′) (9) Y _{i, j} = Y ₀ ′ + (j × Δy ′) (10) Therefore, in step S 14, each lattice point on the ideal image is The coordinates are calculated by the above equations (9) and (10), and data indicating those coordinates is stored in the hard disk device 56 as an ideal image grid point file.

After the grid point coordinates on the ideal image are calculated and stored as described above, the grid chart 105 is actually placed on the table 1 and imaged (step S1).
6). That is, after the grid chart 105 is placed at a predetermined position on the table 1 and fixed by suction, the flash light source in the illumination unit 4 is turned on, and in synchronization with this, the grid chart 105 on the table 1 is imaged by the imaging unit 5. I do. As a result, image data (hereinafter, referred to as “lattice image data”) representing the captured image of the grid chart 105 (hereinafter, “captured lattice image”) is generated.

Next, based on the grid image data, grid points in the captured grid image are detected (step S1).
8). Hereinafter, the processing for detecting the grid points will be described with reference to FIGS. FIG. 7A shows a captured grid image, and FIG. 7B shows image data of a region near one grid point in the captured grid image. In FIG. 7B, “0” corresponds to a black line portion of the grid chart 105, and “1” corresponds to a white background portion of the grid chart 105. In the present step S18, first, on the captured grid image, “coordinate values where a grid point is likely to exist” (hereinafter, the position indicated by these coordinate values is referred to as “grid point candidate position”).
Is determined for all grid points. Then, a cross-shaped operator as shown in FIG. 8 performs a scanning operation in the vicinity of the lattice point candidate position, and detects a position where the operation result is minimum as a lattice point position in the captured lattice image. In FIG. 8, MS
Represents the mask size of the cross-shaped operator. W1 is the number of "1" s set in the vertical direction in the cross-shaped operator, and W2 is the number of "1" s set in the horizontal direction in the cross-shaped operator. W1 is a set width of “1” as the number of pixels of the line width in the captured grid image increases.
And W2 need to be increased. Here, the scanning operation means that a cross-shaped operator sequentially scans a grid image as a captured image, and multiplies, at each position, a value of each pixel of the cross-shaped operator by a corresponding pixel value of the captured grid image. Then, the multiplication result is added for each pixel of the cross operator. For example, if the coordinates of the grid point candidate position are P
c _{i, j} and (X _{i, j,} Y _{i, j)} and, given a predetermined number of pixels width [Delta] P, for X-direction X _i, the _{j -Δp} X _i, until _j + Delta] p, for Y-direction Y _{i , j−} Δp to Y _{i, j} + Δp, the grid point candidate position Pc
_For each _{i, j} , (1 + 2 × Δp) × (1-2 × Δp) calculation results are obtained. Then, these operation results are compared with each other, and the lattice position P ′ _{i, j} (x ′ _{i, j} , y ′) where the mask position (the position at the center of the mask) of the cross operator that gives the minimum operation result is most likely to be obtained. _{i, j} ). In this way, the most probable grid point position P ′ _{i, j} (x ′ _{i, j} , y ′ _{i, j} ) is obtained for each grid point in the captured grid image, and data indicating their coordinates is stored in the captured image grid. It is stored in the hard disk device 56 as a point file.

Next, the amount of positional shift between each grid point on the ideal image and each corresponding grid point on the captured grid image is calculated, and the calculated amount of positional shift is calculated for each grid point in the captured grid image. (Hereinafter, simply referred to as “position shift amount of imaging lattice point”) (step S20). That is, coordinates (x _{i, j} , y _{i, j} ) indicating each grid point position on the ideal image from the ideal image grid point file, and coordinates indicating each grid point position on the captured grid image from the captured image grid point file. (X ′ _{i, j} , y ′ _{i, j} ) are read out, and the displacement amounts Δx _{i, j} , Δy _{i, j} for each grid point are calculated by the following equation, and these are used as a reference file as a reference file.
6 (i = 1, 2,...; J = 1, 2,...). Δx _{i, j} = x ′ _{i, j} −x _{i, j} (11) Δy _{i, j} = y ′ _{i, j} −y _{i, j} (12) In the above, in the X direction (horizontal direction) in the ideal image, The coordinates of the i-th grid point in the Y direction (vertical direction) and the j-th grid point in the vertical direction are (x _{i, j} , y _{i, j} ), and the i-th and Y direction in the X direction (horizontal direction) in the captured grid image. Let (x ′ _{i, j} , y ′ _{i, j} ) be the coordinates of the j-th grid point (vertically).

When the positional deviation amounts Δx _{i, j} and Δy _{i, j of} the imaging lattice points are calculated and stored in the reference file as described above, the pre-processing for geometric correction ends. Thereafter, it is possible to perform geometric correction on the imaging data using the reference file.

<3.2 Colorimetric Data Acquisition Processing> After the above preprocessing, the printed matter is imaged, and the obtained image data is subjected to geometric correction. As a result, image data representing the printed matter, from which geometric distortion and pixel displacement have been removed, is obtained. This image data includes information indicating the color and density of the printed matter in pixel units. Hereinafter, a process for obtaining such image data is referred to as a colorimetric data acquisition process. FIG. 9 is a flowchart showing the procedure of such colorimetric data acquisition processing. In this colorimetric data acquisition process, the CPU 51 of the control unit 7 operates as follows.

First, the positional deviation amounts Δx _{i, j} and Δy _{i, j} of the imaging grid points are read from the reference file (step S10).
2). Next, the printed matter (the target printed matter Dtp or the calibration printed matter Drp) placed on the table 1 is suction-fixed by the suction-fixing mechanism (FIG. 3), and the printed matter is imaged by the imaging unit 5 to obtain image data. (Step S
104).

Thereafter, each pixel in the ideal image is sequentially focused (step S106), and the following processing is executed each time one pixel is focused, thereby performing geometric correction on the acquired imaging data. Is applied.

First, in an image represented by the acquired image data (hereinafter simply referred to as “captured image”), a positional shift amount of a pixel corresponding to a target pixel of an ideal image (hereinafter referred to as “target positional shift amount”) is The amount of displacement Δx of the imaging lattice point
_{i, j} , Δy _{i, j} (i = 1, 2,...; j = 1, 2,...). Hereinafter, the calculation of the target position shift amount will be described with reference to FIGS. 10 and 11. FIG. 10A is a schematic diagram showing a part of an ideal image.
(B) is a schematic diagram showing a part of a captured image. In the following, for convenience of description, it is assumed that a grid point is formed by one pixel in an ideal image and a captured image. In FIGS. 10A and 10B, black circles “•” indicate pixels at lattice points, and diamonds “◇” indicate pixels other than lattice points.

When the pixel of interest is the pixel of the grid point P _{i, j} , the amount of displacement Δ of the imaging grid point corresponding to the grid point
Let x _{i, j} and Δy _{i, j} be the positional displacement amounts of interest. If the target pixel is not the pixel of the grid point P _{i, j} , the target positional shift amount is calculated by interpolation based on the positional shift amount of the imaging grid point corresponding to the grid point near the target pixel. For example, FIG.
As shown in (a), two pixels P are located between a grid point P _{i, j} and an adjacent grid point P _{i + 1, j in the} X direction in the ideal image.
a, in a case where Pb is present, when the pixel Pa is target pixel, the grid points P _i, position shift amount [Delta] x i of _{j, j} =
_{x 'i, j -x i,} j and _{Δy i, j = y' i} , j -y i, j and the position deviation amount [Delta] x i _{+ 1} of the grid points P _{i + 1, j} adjacent to each other in the X _{direction, j} =
x ′ _{i + 1, j} −x _{i + 1, j} and Δy _{i + 1, j} = y ′ _{i + 1, j} −y
_The target positional deviation amounts Δxa and Δya in the X direction and the Y direction are calculated by interpolation using the following expression using _{i + 1 and j} . Δxa = (1 × Δxi _{+ 1, j} + 2 × Δxi _{, j} ) / 3 (13) Δya = (1 × Δyi _{+ 1, j} + 2 × Δyi _{, j} ) / 3 (14) for example, when the pixel Pb is target pixel, similarly lattice points P _i, position shift amount [Delta] x i of _{j, j,} [Delta] y _i, position shift amount of _j and the lattice point _{P i + 1, j Δx i} + 1, j , Δy _{i + 1, j} to calculate the target positional deviation amounts Δxb, Δyb in the X direction and the Y direction. Δxb = (2 × Δxi _{+ 1, j} + 1 × Δxi _{, j} ) / 3 (15) Δyb = (2 × Δyi _{+ 1, j} + 1 × Δyi _{, j} ) / 3 (16)

FIG. 11 shows an order for calculating the target positional deviation amount in this manner. That is, first,
Attention is paid to the pixels on each row (row) passing through the grid points sequentially, and the target positional shift amounts are calculated by interpolation based on the positional shift amounts of the grid points adjacent to each other in the X direction (see numbers 1 and 2 in FIG. 11). . Next, attention is paid to the pixels on each column (column) passing through the grid points sequentially, and the target positional shift amount is calculated by interpolation based on the positional shift amounts of two grid points adjacent to each other in the Y direction (see FIG. 11). Number three
And 4). Then, by the interpolation based on the amount of displacement of the pixels between the lattice points obtained in this way, the amount of displacement of interest (see numbers 5 and 6 in FIG. 11) when focusing on the other pixels is calculated. Therefore, the order in which attention is paid to the pixels on the ideal image in step S106 follows the order shown in FIG.

Next, a pixel (hereinafter referred to as “corresponding pixel”) which should correspond to the target pixel in the captured image based on the displacement amount of the target pixel at the present time (target displacement amount) is determined. The pixel data of the pixel is extracted from the imaging data, and the extracted pixel data is separately stored in an order so as to be the pixel data at the position of the target pixel (step S110). For example, when the pixel Pa is set as the target pixel in the example illustrated in FIG. 10, the pixel that corresponds to the target pixel Pa in the captured image illustrated in FIG.
Although the pixel is apparently the pixel Pam, the positional shift amount of interest at this time is Δxa and Δya, so
c corresponds in position to the pixel of interest Pa. Therefore, the pixel data of the pixel Pac is extracted from the imaging data, and the pixel data is separately stored as the pixel data at the position of the target pixel Pa. Further, for example, the pixel P shown in FIG.
When b is the pixel of interest, the pixel positionally corresponding to the pixel of interest Pb in the captured image shown in FIG. 10B is apparently the pixel Pbm, and the amount of positional shift of interest at this time is Δxb, Δyb, the pixel Pbc
Correspond positionally to the pixel of interest Pb. Therefore, the pixel data of the pixel Pbc is extracted from the imaging data, and the pixel data is separately stored in the hard disk device 56 as the pixel data at the position of the target pixel Pb.

As described above, if the pixel data extracted from the imaging data as pixel data corresponding to the pixel of interest in the ideal image is separately stored with the pixel position changed, It is determined whether or not all pixel data corresponding to each pixel in the image has been extracted from the imaging data (step S112). As a result of this determination, if there is unextracted pixel data among the pixel data positionally corresponding to each pixel in the ideal image, step S1
Return to 06. In this case, since an unfocused pixel exists in the ideal image, any one of the unfocused pixels is newly set as the focused pixel. At this time, as described above, the order of attention for the pixels on the ideal image follows the order shown in FIG.

Thereafter, steps S106 to S112 are repeatedly executed until all the pixel data corresponding to each pixel in the ideal image is extracted from the imaged data, that is, until there are no unfocused pixels in the ideal image.
When there are no more unfocused pixels in the ideal image, the colorimetric data acquisition process ends. After the colorimetric data acquisition processing, image data (hereinafter, “corrected image data”) composed of pixel data of the captured image corresponding to each pixel of the ideal image in position.
Is stored in the hard disk device 56.

The corrected image data represents data representing a captured image from which geometric distortion and pixel displacement have been removed, that is, captured data subjected to geometric correction. It is used as colorimetric data indicating the density in pixel units or as original data of the colorimetric data. In the above description, the corrected image data is stored in the hard disk device 56, but may be stored in the memory 54 instead.

<3.3 Comparison between Colorimetric Data and PPF Data> In the color tone management system shown in FIG. 1, in order to adjust the color tone of the printed material, the target printed material Dtp is imaged by the printed material measuring apparatus according to the present embodiment. Then, the target image data is generated as the corrected image data by performing the geometric correction, and the target colorimetric data Dtm based on the target image data is used. That is, for color tone management of the printed matter, for example, colorimetric data based on the target image data and color data based on the PPF data Dppf are compared. FIG. 12 is a flowchart showing the procedure of such comparison processing for color tone management. In this comparison processing, the CPU 51 of the control unit 7 operates as follows. In the following, the target image data is already stored in the hard disk device 56 by executing the colorimetric data acquisition process (FIG. 9) on the target print Dtp, and the platemaking data Dp corresponding to the target print Dtp is obtained. The obtained PPF data Dppf is also stored in the hard disk device 56 in advance. It is also assumed that the target image, which is the image represented by the target image data, and the PPF image, which is the image represented by the PPF data, have been adjusted in advance so that their resolutions are the same.

In this comparison processing, first, the target printed matter Dt
The target image data, which is the corrected image data for p, is read from the hard disk device 56 (step S21).
2) Subsequently, the PPF data Dppf obtained from the plate making data Dp corresponding to the target printed matter Dtp is read from the hard disk device 56 (step S214).

Next, the target image and the PPF image are associated with each other by putter matching between the image represented by the target image data (target image) and the image represented by the PPF data (PPF image) (step S216). Usually, an image to be printed includes a positioning mark for adjusting a shift of a printing position of a picture (printing target) with respect to printing paper.
Therefore, the target image and the PPF image may be associated with each pixel by pattern matching between the positioning mark in the target image and the positioning mark in the PPF image. However, the target image and the PPF image may be associated with each pixel by pattern matching of a predetermined pattern other than the positioning mark. Various known methods can be used as the pattern matching method.
In addition, since pattern matching for adjusting print position deviation is a well-known technique, a detailed description of the procedure is omitted here.

Thereafter, colorimetric data (color measurement values) based on the target image data and P
The color data (color value) based on the PF data is compared at the same pixel position (step S218). Here, the target image and the PPF are obtained by the pattern matching.
Pixels associated with an image are pixels at the same pixel position. That is, the same pixel position here does not mean that the positions of the pixels constituting the two images on the two-dimensional array are the same, but that the relative positions in the image (picture) to be printed are the same. It means there is. The target image data is RGB, which is the three primary colors of light.
The PPF data is represented by multi-values for each of cyan (C), magenta (M), yellow (Y), and black (K). The data obtained by converting the target image data from the data for each RGM to the data for each CMYK is defined as colorimetric data. Then, the colorimetric value which is the value of the colorimetric data of the predetermined pixel in the target image is compared with the color value which is the value of the pixel corresponding to the predetermined pixel in the PPF image. The result of this comparison is fed back to plate making (P11) and printing (P15). For example, based on the comparison result, printing (P
The ink supply amount of each color is controlled by adjusting the opening degree of the in-key in the printing apparatus used in 15).

<3.4 Comparison between Target Colorimetric Data and Calibrated Colorimetric Data> FIG. 13 is a flowchart showing another example of comparison processing for color tone management in the color tone management system shown in FIG. When this comparison process is performed,
In the printed matter measuring apparatus according to the present embodiment, the target printed matter Dtp is imaged in advance and subjected to geometric correction, so that the target image data is generated as the corrected image data, and the proof printed matter Drp is imaged and geometrically corrected. By performing the correction, calibration image data is generated as the corrected image data. In this comparison processing, the CPU 51 of the control unit 7 operates as follows. In the following, the target print material Dtp and the proof print material Dr
It is assumed that the target image data and the calibration image data have already been stored in the hard disk device 56 by executing the colorimetric data acquisition process (FIG. 9) for each of p.

In this comparison processing, first, the target printed matter Dt
The target image data that is the corrected image data for p is read from the hard disk device 56 (step S22).
2) Then, the calibration image data, which is the correction image data for the proof print product Dtp, is read from the hard disk device 56 (step S224).

Next, the target image and the calibration image are associated with each other by putter matching between the target image, which is the image represented by the target image data, and the calibration image, which is the image represented by the calibration image data (step S226). A specific method of this pattern matching is described in step S2 shown in FIG.
16 is substantially the same.

After that, based on the correspondence for each pixel by the above-mentioned putter matching, the target colorimetric data, which is the colorimetric data based on the target image data, and the calibration colorimetric data, which is the colorimetric data based on the calibration image data, are the same. The comparison is made at the pixel position (step S228). The result of this comparison is
It is fed back to plate making (P11) and printing (P15). Note that, also here, the pixels associated between the target image and the calibration image by the pattern matching are pixels at the same pixel position. Further, both the target image data and the calibration image data are RGB, which are the three primary colors of light.
These are data represented by multiple values for each color, and these data may be used as target colorimetric data and calibration colorimetric data, respectively.However, based on a comparison result of these colorimetric data, the ink supply amount of each color in the printing apparatus is In the case of controlling, it is preferable to use the data after converting the target image data and the calibration image data from the data for each RGM to the data for each CMYK as the colorimetric data.

<4. Effect> According to the above embodiment, geometric correction is performed on the image data of the printed matter by the imaging unit 5 as the two-dimensional imaging unit (FIGS. 5 and 9), so that the device configuration becomes complicated and the measurement time is reduced It is possible to obtain, as corrected image data, imaging data with no geometric distortion and no displacement of the pixel position while suppressing the lengthening. Therefore, comparison between colorimetric data based on the corrected image data (comparison of target colorimetric data and calibration colorimetric data) and comparison between colorimetric data based on the corrected image data and PPF data as color data are performed. Can be performed at exactly the same pixel position. That is, the comparison between the colorimetric data or the comparison between the PPF data and the colorimetric data can be performed in an accurate positional relationship.

Further, according to the above embodiment, two images to be compared are associated with each pixel by pattern matching, and colorimetric values and the like are compared between the corresponding pixels (see FIGS. 12 and 13). 13) Combined with the effect of the geometric correction, it is possible to compare the colorimetric data of two printed materials having different placement positions on the table 1 at the same pixel position (the same measurement point). That is, for example, the target printed matter Dt
Even if there is a difference in the placement position on the table 1 during imaging between p and the proof print Drp, both colorimetric data can be compared with each other at the same pixel position in the image (picture) to be printed. . Further, even if the relative position of the image to be printed on the printing paper is shifted (print position shift), the colorimetric data can be compared at the same pixel position in the above sense.

As described above, according to the present embodiment, since the colorimetric data can be compared at the same pixel position based on the image data obtained by the two-dimensional image pickup means that does not require scanning, the configuration of the printed matter measuring apparatus is complicated. This makes it possible to control the color tone with high accuracy while suppressing the lengthening of the measurement and the prolongation of the measurement time.

In the color tone management described above, the colorimetric data (colorimetric values) and PPF data (color values) are
It is expressed in multiple values for each K, but if necessary, another color system, for example, L * defined by the International Commission on Illumination (CIE)
Colors may be digitized by the a * b color system.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a color tone management system in which a printed matter measuring device according to an embodiment of the present invention is used.

FIG. 2 is a perspective view showing the printed matter measuring device according to the embodiment.

FIG. 3 is a piping diagram for explaining a suction fixing mechanism in the printed matter measuring device according to the embodiment.

FIG. 4 is a block diagram showing a configuration of a control unit in the printed matter measuring device according to the embodiment.

FIG. 5 is a flowchart illustrating pre-processing for geometric correction of imaging data in the embodiment.

FIG. 6 is a plan view for explaining calculation of grid point coordinates on an ideal image showing a grid chart placed on a table in the embodiment.

FIG. 7 is a diagram showing a captured image and captured data of a grid chart.

FIG. 8 is a diagram illustrating a grid point position detection operator for detecting a grid point position in a captured image of a grid chart.

FIG. 9 is a flowchart showing a colorimetric data acquisition process in the embodiment.

FIG. 10 is a diagram for explaining geometric correction performed in the colorimetric data acquisition process in the embodiment.

FIG. 11 is a diagram showing the order of interpolation calculation for geometric correction performed in the colorimetric data acquisition process in the embodiment.

FIG. 12 is a flowchart illustrating an example of a comparison process executed in the embodiment for color tone management in printing.

FIG. 13 is a flowchart illustrating another example of the comparison process executed in the embodiment for color tone management in printing.

[Explanation of symbols]

1 ... table 2. Adsorption mechanism 3 ... Stand 4. Lighting unit 5 ... Imaging unit 6 ... Shading roof member 7 Control unit 8… Touch panel 51 ... CPU 54… Memory 56… Hard disk drive 105… Lattice chart Drp: Proof print Dtp: Target print Drm: Calibration colorimetric data Dtm: Target colorimetric data Dppf… PPF data

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06T 3/00 200 B41F 31/02 D H04N 1/40 F H04N 1/40 101Z (72) Inventor Kiyotada Amamori 4-chome, Horikawa-dori Teranouchi, Kamigyo-ku, Kyoto, Kyoto 1-2-1 Daijin Screen Manufacturing Co., Ltd. (72) Inventor Ryuji Yamamoto 4-chome, Horikawa-dori Terunouchi, Kamigyo-ku, Kyoto, Kyoto 1F, Tenjin Kitamachi 1 Dainippon Screen Mfg. Co., Ltd. F term (reference) 2C250 EB32 EB40 EB41 EB43 EB46 2G020 AA08 DA02 DA12 DA43 5B057 BA02 BA19 CA12 CA16 CB12 CB16 CC01 CD12 CH08 5C077 LL02 MM27 PP47 PP59 PQ12 SS01

Claims (6)

[Claims] 1. A printed matter measuring device for measuring the color and / or density of a printed matter, comprising: a table on which the printed matter is placed; lighting means for illuminating the table; A two-dimensional imaging unit that collectively images the printed matter; and correcting the positions of the pixels that form the captured image of the printed matter by the two-dimensional imaging unit to remove the image from which the geometric distortion and the displacement of the pixel position have been removed. And a geometric correction unit that generates corrected image data representing the image data. The print image measurement apparatus obtains colorimetric data indicating a color and / or density of the print material by generating the corrected image data. 2. The printed matter measuring apparatus according to claim 1, further comprising suction fixing means for sucking and fixing the printed matter on the table, wherein the illuminating means includes a flash light source. 3. An image storage unit for storing image data, wherein the geometric correction unit stores pixel data corresponding to each pixel position of an ideal captured image with respect to the printed matter by the two-dimensional imaging unit. The corrected image data is generated by extracting and ordering the pixel data of the captured image, and the image storage unit stores all the pixel data constituting the corrected image data generated by the geometric correction unit. The printed matter measuring device according to claim 1, wherein: 4. The geometric correction unit detects a position of each grid point in a grid image obtained by previously imaging a sheet having a predetermined grid pattern placed on the table by the two-dimensional imaging unit. A grid point detecting unit that calculates a grid position shift amount that is a shift amount of each grid point position in the grid image based on a position of each grid point in an ideal captured image with respect to the grid pattern. Calculating means for calculating a pixel position shift amount, which is a shift amount of each pixel position of the lattice image with respect to each pixel position of the ideal captured image, by interpolation based on the grid position shift amount; Calculating means for generating the corrected image data from pixel data of an image of the printed matter obtained by the two-dimensional imaging means, based on the pixel displacement amount Characterized in that it comprises a positive data generating means, print quality measuring apparatus according to claim 3. 5. Plate making image data storage means for storing plate making image data representing an image recorded on a printing plate to be used for producing said printed material, and an object which is a printed material as a measurement object printed by said printing plate Matching means for associating target image data indicating the color and / or density of a printed matter with the plate making image data for each pixel by pattern matching; and colorimetric data based on the target image data based on pattern matching by the matching means. A comparison unit that compares color data based on the plate making image data with corresponding pixels, wherein the target image data is corrected image data generated from a captured image of the target print by the two-dimensional imaging unit. The colorimetric data based on the target image data expresses the target image data in a predetermined color system. A data, the color data based on the plate making image data, characterized in that said plate making image data is data expressed in the colorimetric system, print quality measuring apparatus according to claim 1. 6. A target image data indicating a color and / or density of a target print, which is a print as a measurement target printed by the printing plate, and a proof print to be a reference of the print printed by the print plate. Matching means for associating calibration image data indicating color and / or density for each pixel by pattern matching; and colorimetric data based on the target image data and measurement based on the calibration image data based on the pattern matching by the matching means. Comparing means for comparing color data between corresponding pixels, wherein the target image data is corrected image data generated from a captured image of the target printed matter by the two-dimensional imaging unit, and the target image data Is colorimetric data based on the target image data is expressed in a predetermined color system, The normal image data is corrected image data generated from the captured image of the proof print by the two-dimensional imaging unit, and the colorimetric data based on the proof image data expresses the proof image data in the color system. 2. The printed matter measuring apparatus according to claim 1, wherein the measured data is data.