JPH07134014A - Device for measuring magnification/angle of pattern - Google Patents

Abstract

PURPOSE:To automatically measure the magnification and angle of a pattern by calculating the contour distances from the center of gravity of the pattern to contour pixels and plotting the contour distances at respective angle positions to form a graph and calculating the dispersion of a contour distance ratio. CONSTITUTION:The pattern (a) on a printing manuscript A and the pattern (b) on layout specifying paper B are inputted to a computer 100. Edge detection processing is performed with respect to the pattern (a) and the patterns (a), (b) are subjected to binarization processing to become a line image consisting of black and white pixels. The center of gravity of line image data is set as an end, point to define the half straight line Ltheta arranged at an arbitrary angle position theta and the black pixel present at the remotest distance from the center of gravity on the line Ltheta is determined as a contour pixel Ptheta. A contour line is constituted by the aggregate of pixels P, over 360'. The contour line is corrected in fault by smoothing processing and the distance rtheta of the pixel Ptheta and the center of gravity is calculated over 360 deg.. A graph taking positions theta on horizontal axes and the contour distances ratheta, rbtheta of the patterns (a), (b) on vertical axes are formed. The ratio rbtheta/rtheta at the position theta becomes the relative magnification to be calculated of both patterns and the phase distance between both graphs becomes a relative angle of rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a picture magnification / angle measuring device, and more particularly, to show a first picture formed on a printing original in a printing plate making process and a layout state of the first picture. A second pattern drawn as a line drawing on the designated paper for layout,
For measuring the relative magnification and rotation angle of the.

[0002]

2. Description of the Related Art Generally, a printed matter is formed by allocating elements such as a picture, a figure, and a character to a predetermined position, a predetermined size, and a predetermined direction (rotation angle). In recent years, electronic plate making technology using a computer has been advanced, and a pattern on a print document (for example, a photograph) is captured as image data by a scanner device, and a plate collecting process is performed by the computer. In order to perform the plate collection process using this computer accurately and smoothly, it is preferable to take in the image data in consideration of the actual allocation state. For example, when a picture on a photograph is captured by a scanner device, it is preferable to set the capture magnification and the rotation angle as image data so as to match the size and the rotation angle on the printed matter of the original size. For this reason, conventionally, a layout designated paper showing a state in which each pattern is laid out at its original size is prepared, and the design on the photograph is projected on this layout designated paper using a projector, and the projected image is drawn on the layout designated paper. The projection magnification and the orientation of the photograph were adjusted so as to match the pattern showing the allocated layout, and the proper magnification and orientation (rotation angle) were measured. For example,
JP-A-60-112039 discloses a measuring device for measuring such a magnification and an angle.

[0003]

The work of measuring the magnification and the angle using the projector described above is performed manually by a skilled worker. That is, the worker sets the photograph on the projector, manually adjusts the projection magnification and the angle of the photograph in a state where the image of the design on the photograph is projected on the designated layout paper,
After confirming the matching of the patterns with the eyes, the work of measuring the projection magnification and the angle of the photograph at that time is performed.
Moreover, this work is performed in a dark place in order to make the projected image easy to see. Since work in a dark place like this places a heavy burden on the worker, work time is increased and a work error is likely to occur.

Therefore, an object of the present invention is to provide a magnification / angle measuring device capable of automatically measuring the magnification and angle of a picture.

[0005]

[Means for Solving the Problems]

(1) The first invention of the present application is, in an apparatus for measuring a relative rotation angle of two patterns having similar characteristics, a pattern to be measured from a binary image represented by black pixels and white pixels. Image capturing means for capturing as line drawing data, center of gravity calculating means for calculating the center of gravity position of the black pixel for the line drawing data captured by the image capturing means, and radial lines at predetermined angle Δθ intervals centered on the center of gravity position A contour pixel determining means that defines a plurality of half lines and obtains a black pixel at a position farthest from the barycentric position on each half line as a contour pixel, and a contour distance defined as a distance between the barycentric position and each contour pixel. By defining the angular position of the half line on the horizontal axis and the contour distance obtained for the half line on the vertical axis, respectively. Create a graph showing the relationship between, first obtained based on the first picture to be measured
Is shifted by a predetermined shift amount in the horizontal axis direction with respect to the second graph obtained based on the second pattern to be measured, and the vertical axis value of the first graph on the same horizontal coordinate is The ratio with respect to the vertical axis value of the second graph is obtained for a plurality of different abscissa positions, the variance calculation means for calculating the variance for the obtained plurality of ratios, and a plurality of different deviation amounts are set,
The variance for each shift amount is obtained by the variance calculation means, and the shift amount with the smallest variance is calculated as the second shift of the first pattern.
Angle determining means for determining the rotation angle with respect to the pattern.

(2) According to a second aspect of the present invention, in a device for measuring relative magnifications of two patterns having similar characteristics, the pattern to be measured is a binary value expressed by black pixels and white pixels. Image capturing means for capturing as line drawing data consisting of images, center of gravity calculating means for calculating the center of gravity position of the black pixel for the line drawing data captured by the image capturing means, and center of the center of gravity position at predetermined angle Δθ intervals Contour pixel determining means that radially defines a plurality of half lines and obtains a black pixel at a position farthest from the center of gravity position on each half line as a contour pixel, and a distance between the center of gravity position and each contour pixel By defining the contour distance calculation means for calculating the contour distance and the angular position of the half line on the horizontal axis and the contour distance obtained for the half line on the vertical axis, the angular position of the half line is defined. A graph showing the relationship with the contour distance is created, and the first graph obtained based on the first pattern to be measured is the second graph obtained based on the second pattern to be measured. With respect to a plurality of different abscissa positions, the ratio of the ordinate value of the first graph and the ordinate value of the second graph on the same abscissa is determined for each of a plurality of different abscissa positions. The variance calculation means for calculating the variances of the obtained plurality of ratios and a plurality of different deviation amounts are set, and the variance for each deviation amount is obtained by the variance calculation means. And a magnification determining means for determining an average value of the ratios as a magnification of the first pattern with respect to the second pattern.

(3) The third invention of the present application is the measuring apparatus according to the above-mentioned first or second invention, wherein the variance calculating means obtains the first variance by the first calculation, and then calculates this variance. The second calculation is performed by using only the ratio value within the predetermined variation range determined on the basis of the second dispersion, and the rotation angle determining unit or the magnification determining unit
The decision is made using this second variance.

[0008]

[Working] The present invention is an improvement of the basic invention disclosed in Japanese Patent Application No. 5-251125. In this basic invention, the contour pixels forming the contour line of each pattern are extracted, and the contour distance, which is the distance between the center of gravity of the pattern and each contour pixel, is obtained. Then, based on the contour distance in each angle direction (a plurality of directions radially outward from the center of gravity position) obtained for the two patterns, the magnification and the rotation angle for these two patterns are obtained.

The present invention discloses a method for obtaining the magnification and the rotation angle of two patterns with high accuracy after obtaining the information of the contour distance in each angle direction. Now, it is assumed that the contour distances in the respective angular directions have been obtained for the first picture and the second picture having a similar shape obtained by multiplying the first picture by X. At this time, if the rotation angles (directions) of both patterns are the same, the contour distance of the latter should be X times the contour distance of the former at each angular position. In other words, the ratio of both contour distances should always be constant X at any angular position. However, if the rotation angles (directions) of the two patterns are misaligned, the ratio of the contour distances of the two patterns is not constant unless the patterns are perfect circles, and the values differ for each angular position.

The present invention focuses on this point to obtain the rotation angles of both patterns. That is, a graph is created by defining the angular position on the horizontal axis and the contour distance on the vertical axis, and the first graph obtained based on the first pattern to be measured becomes the measurement target. The vertical axis value of the first graph and the vertical axis value of the second graph on the same abscissa are shifted by a predetermined shift amount in the horizontal axis direction with respect to the second graph obtained based on the second pattern. And a ratio for each of a plurality of different abscissa positions. If the directions of the two patterns coincide with each other by shifting by a predetermined shift amount, the ratio of the vertical axis values obtained at that time should always be a constant value. Therefore, if the variance of the ratio value is calculated and the shift amount that minimizes the variance is calculated, this shift amount becomes the rotation angle between the two patterns. Further, the value of the ratio at this time (which is theoretically constant, but is actually averaged due to variations) is the magnification of both patterns.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to illustrated embodiments. FIG. 1 shows the magnification of a pattern according to an embodiment of the present invention /
It is a block diagram showing the basic composition of an angle measuring device. This measuring device is configured so that the first pattern drawn on the print original A and the second pattern drawn as a line drawing on the designated allocation paper B for indicating the layout state of the first pattern are relative to each other. It has a function to measure the effective magnification / angle. The image input device 10 has a function of scanning the print document A and inputting the first pattern drawn therein as image data indicating the density value of each pixel. Similarly, the line image input device 20 has a function of scanning the layout designation paper B and inputting the second pattern drawn here as line image data indicating the density value of each pixel. As will be described later, in this embodiment, a color positive photograph is used as the print document A, and the image input device 10 performs a process of inputting the first pattern from the photograph. On the other hand, the second pattern drawn on the layout-designating paper B is a line drawing showing the layout mode of the first pattern, and the line image input device 20 performs a process of inputting this line drawing. Of course, actually, the same scanner device may be used as both the image input device 10 and the line image input device 20.

The computer 100 includes an image input device 10
The image data input from the line image input device 20 and the line image data input from the line image input device 20 are fetched, and various arithmetic processings described later are performed on these data, and the first pattern drawn on the print original A and the designated allocation paper B are printed. It has a function of obtaining a relative magnification and a rotation angle with respect to the second pattern drawn in FIG. The computer 100 is actually a general-purpose computer in which dedicated software is incorporated, but in FIG. 1, it is expressed as a device including five functional blocks for convenience of description. The edge detection unit 110 performs an edge detection process for detecting an edge portion of the image data input from the image input device 10 where the density value changes abruptly. Printed manuscript A used in this embodiment
Is a photographic manuscript, but by performing edge detection processing on the image data obtained from this photographic manuscript, the edge portion where the density value changes rapidly, that is, the line image data in which only the boundary line of the pattern is extracted is can get. Since various methods such as mask processing using a 3 × 3 Laplacian operator are known as such edge detection processing, detailed description thereof will be omitted here.

The binarization processing unit 120 includes an edge detection unit 11
Binarization processing is performed on the line image data (the pattern of the print document A) subjected to the edge detection process by 0 and the line image data (the pattern of the designated allocation sheet B) input by the line image input device 20. Have a function. For example, these line image data are 0 for each pixel arranged vertically and horizontally.
When given as a definition of a density value of ~ 255, pixels having a density value of a predetermined threshold value (for example, a density value of 128) or more are white pixels, and pixels having a density value less than the threshold value are black. The binarization process is performed by defining the pixel as. Here, the pixels forming the line portion of the line drawing are called black pixels, and the pixels forming the background portion are called white pixels.

The contour line extracting unit 130 includes a binarizing processing unit 12.
The line image data binarized by 0 has a function of extracting a contour line, and the magnification / angle calculation unit 140 has a function of calculating magnifications and angles of two patterns based on the extracted contour line. Have. The processing in each of these parts forms the center of the technical idea of the present invention, and will be described in detail below with reference to specific examples.

Here, more specifically, an example using a print document A as shown in FIG. 2 (a) and a layout designation paper B as shown in FIG. 2 (b) will be described below. I will decide. The print document A is a color positive photograph in this embodiment, and the pattern a is shown in it. On the other hand, the designated layout paper B is a paper of the same size as the actual printed matter, and the design b for indicating the actual layout state of the design a is drawn. As shown in the figure, usually, the relative magnification between the pattern a and the pattern b is different, and the orientation (relative rotation angle) is also different. In the example of FIG. 2, the pattern b is an enlarged version of the pattern a. Further, when the lower side A1 of the print document A and the lower side B1 of the designated layout paper B are defined as reference sides, the lower side B2 of the pattern b is the reference side B1.
Parallel to (i.e., the rotation angle is 0), the lower side A2 of the pattern a is inclined by the rotation angle α with respect to the reference side A1. An object of the present invention is to automatically obtain the relative magnification and relative angle (angle α) between the pattern a and the pattern b.
Conventionally, the print document A is set on a projector, the pattern a is projected on the designated layout paper B, and the projection magnification and the direction of the print document A are adjusted so that the projected image of the pattern a and the pattern b match. The above process was manually performed to measure the magnification and the angle α.
However, as described above, such work is burdensome and error-prone.

By using the measuring apparatus shown in FIG. 1, the magnification and the angle can be measured by the following simple work. First, the operator inputs the picture a on the print document A by the image input device 10 (scanner device). At this time, the orientation of the print document A may be based on, for example, the reference side A1 (in other words, when inputting as image data of the XY coordinate system, the reference side A1 is input in the X-axis direction). Should be done). Then, the operator inputs the picture pattern b on the designated allocation paper B by the line image input device 20 (scanner device). At this time, the orientation of the designated allocation sheet B may be based on, for example, the reference side B1 (in other words, if inputting as image data of the XY coordinate system, the reference side B1 is set to the X-axis direction). Just type in). All the work done by the worker is now complete.
After that, the computer 100 automatically calculates the magnification and the angle. Hereinafter, the processing in the computer 100 will be described in detail.

The image data taken into the computer 100 is binarized by the binarization processing unit 120. However, for the image data of the picture a on the print document A, the edge detection unit 110 first performs edge detection processing. This is because, as shown in FIG. 2, the design b on the layout-designated paper B is a line drawing, whereas the design a on the print document A is a so-called photographic image. By performing the edge detection processing, it is possible to obtain a line drawing in which only the boundary line portion is extracted from the photographic image. When the binarization processing is performed by the binarization processing unit 120, both the patterns a and b become line drawings composed of two types of pixels, black pixels and white pixels. FIG. 3 is an enlarged view of a part of the line drawing thus obtained. In the computer, each pixel is represented as “0” or “1”, but in the present specification, as described above, the pixel forming the line portion of the line drawing is the black pixel and the background portion is the black pixel. The constituent pixels are called white pixels. In the example shown in FIG. 3, the hatched squares are black pixels, and the open squares are white pixels.

The contour line extraction unit 130 performs contour line extraction processing on the line drawing data subjected to the binarization processing. Here, in order to facilitate understanding of this contour line extraction processing, as shown in FIG. 4, the contour line extraction unit 130 is further provided with four functional blocks (a center of gravity calculation unit 131, a contour pixel determination unit 132, and a contour distance calculation unit). 133, contour correction unit 134)
Think separately.

The center-of-gravity calculation unit 131 has a function of calculating the center-of-gravity position of a black pixel for given line drawing data. For example, consider a case where each pixel is arranged in j rows and i columns on the XY coordinate system, and the density value f (i, j) of each pixel is given as line drawing data. The density value f (i,
j) is either "0" or "1". here,
Moment M (p, q) of the image becomes what, M (p, q) = Σ i, j f (i, j) · i If p · ^{j q} and definition, the position coordinates of the center of gravity _(X G, Y _G) is given by _{X G = M (1,0) /} M (0,0) Y G = M (0,1) / M (0,0). The center-of-gravity calculator 131 has a function of performing such a calculation to obtain the position of the center of gravity G. For example, for the line drawing data of the pattern a, the center of gravity G of the black pixel is found at the position shown in FIG.

The contour pixel determining section 132 has a function of determining a contour pixel using the center of gravity G thus obtained. Now, as shown in FIG. 6, a half line L ₀ is defined in a direction parallel to the reference side A1 with the center of gravity G obtained for the pattern a as an end point. Then, the direction of the half line L ₀ is set as an angle reference 0 °, and hereinafter, the angle is measured counterclockwise to define an angle up to 360 °. Here, a half line L _θ arranged at an arbitrary angular position θ is defined with the center of gravity G as an end point, and a black pixel at a position farthest from the center of gravity G on this half line L _θ is determined as a contour pixel. Of. In the example of FIG. 6, there are two black pixels Q1 and Q2 on the half line L _θ , but the black pixel Q2 farthest from the center of gravity G is the contour pixel. In the case where the line has a thickness corresponding to a plurality of pixels, it means that a plurality of black pixels are included in the position shown as a point Q2 in FIG. in this case,
The black pixel located farthest from the center of gravity G becomes the contour pixel. For example, in the example shown in FIG. 7, the thickness of the line is about 3 pixels, and three black pixels P1, P2, P3 are present adjacent to each other on the half line L _θ , but the farthest of them is the farthest. The black pixel P3 at the position becomes the contour pixel.

In FIG. 6, the angular position θ is set to a predetermined angle Δθ.
By changing only the value, a half line with the center of gravity G as the end point is obtained. For example, if Δθ = 1 °, 360 half-lines can be defined radially about the center of gravity G at predetermined angle 1 ° intervals, such as half-lines L ₁ , L ₂ , ..., L ₃₆₀ . Then, the contour pixel is determined for each of the half lines. If a contour line is formed by a set of 360 contour pixels determined in this way, a contour line as shown in FIG. 8 can be obtained, for example. In a strict sense, a perfect contour line cannot be obtained unless the angle Δθ is set to an infinitesimal small value. With a roughness of Δθ = 1 °, it is more like “a rough outline position than a contour line”. Although it should be called an “aggregate”, in the present specification, even such a rough one will be referred to as a contour line for the sake of convenience. In Figure 8, there is shown a half-line L _theta at an arbitrary angular position theta, contour pixel P _theta on this half line L _theta is. As compared with the original line drawing shown in FIG. 6, it can be seen that the line segment passing through the point Q1 disappears. In this way, the contour pixels extracted by the contour pixel determination unit 132 indicate only the contour outside the pattern. In addition, when the thickness of the line is a plurality of pixels as in the example shown in FIG. 7, the obtained contour line has a thickness of about one pixel as shown in FIG.

As shown in FIG. 8, the contour distance calculation unit 133 has a function of _obtaining the distance r _θ between the contour pixel P _θ and the center of gravity G. As described above, if 360 half lines are defined radially at a predetermined angle of 1 °, the contour distances r ₁ , r ₂ , ..., R ₃₆₀ are obtained for each half line.

The contour correcting section 134 has a function of correcting the position of the contour pixel by performing a smoothing process on the contour line obtained as described above. This contour correction function is effective in the following cases. For example, in FIG.
As shown in, the image data obtained from the original pattern,
Consider a case where the noise pixel P4 is mixed. There are various possible causes of the noise pixel P4, such as mixing of noise when inputting with the scanner device and adhesion of dust to the surface of the print document A. As described above, the contour pixel determination unit 132 determines, as the contour pixel, the pixel farthest from the center of gravity G among the pixels existing on the half line L _θ defined at each angular position. Therefore, FIG.
In the case of the pattern as shown in, the noise pixel P4 may be selected as the contour pixel. In such a case, the contour line obtained is as shown in FIG. 11, and the contour line includes a defect. The contour correction unit 134 performs processing for correcting such a defect in the contour line. That is, the position of the contour pixel P4 in FIG. 11 can be corrected to the position of the pixel P5 by smoothing the contour line. Since various methods such as a method using a median filter are known as the contour line correction processing based on such smoothing, detailed description thereof will be omitted here.

The outline extraction unit 130 is divided into four functional blocks, and the individual functions of each functional block have been described above. Next, the operation of the outline extraction unit 130 as a whole is shown in the flowchart of FIG. It will be explained based on. First, in step S1, the center of gravity of the given line drawing data is calculated. That is, the position of the center of gravity G is obtained by the center of gravity calculation unit 131. Subsequent steps S2 to S7 are processing performed by the contour pixel determination unit 132 and the contour distance calculation unit 133. That is, in step S2, the angle parameter θ is set to the initial value θ = 0 °, and in the next step S3, θ is increased by the predetermined angle Δθ.
Then, the half line L _θ is defined in step S4, and the contour pixel P _θ is determined in step S5. Further, in step S6, the contour distance r _θ is calculated. The above procedure is repeated until θ ≧ 360 ° in step S7. Therefore, for example, if Δθ = 1 ° is set, the parameter θ becomes 1 °, 2 °, ..., 360.
The same procedure will be repeated 360 times while being updated to. By this iterative procedure, the contour distance r ₁ ,
r ₂ , ..., R ₃₆₀ are obtained.

In subsequent step S8, a contour correction process is performed. That is, when there is a defect in the contour line, the contour correction unit 134 corrects the contour line based on smoothing. Then, in step S9, a new center of gravity is calculated. The center of gravity calculation in step S1 described above is the center of gravity of the original line drawing (for example, the line drawing as shown in FIG. 5) before the contour pixel is determined. It is the center of gravity. Then, in step S10, the old center of gravity (the center of gravity obtained in step S1) and the new center of gravity (step S9)
It is determined whether or not the deviation from the center of gravity obtained in step 1) is within a preset allowable range. If the deviation is within the allowable range, the work of the contour line extracting unit 130 is finished as it is. In this case, the contour distances r ₁ , r ₂ , ..., R ₃₆₀ obtained based on the old center of gravity are used as they are in the next calculation process (process in the magnification / angle calculation unit 140). If the deviation exceeds the allowable range, the procedure from step S2 is repeated. However,
The object to be redone is the image of the contour line that has undergone the contour correction processing in step S8. Pixel P shown in FIG.
When the correction process in step S8 is performed when a large number of noise components such as 4 are included, the position of the center of gravity may be significantly changed. In such a case, step S10
Then, the process returns to step S2, and the processing for re- _obtaining the contour distance r _θ is performed based on the correct center of gravity.

Now, in the apparatus shown in FIG. 1, the contour line extraction unit 130 causes the contour distances r ₁ , r ₂ , ..., R _360.
Is obtained as described above. Moreover, the processing for obtaining the contour distance is performed on the line drawing based on the first picture a on the print document A shown in FIG. 2 (a), and on the layout-designated paper B shown in FIG. 2 (b). A line drawing based on the second pattern b is also performed. Here, the contour distance obtained by the processing for the former is expressed as ra _θ (ra ₁ ,
_{ra 2,} ..., ra ₃₆₀₎ and calls, rb contour distance obtained by the processing for the latter _{θ (rb 1, rb 2,} ...,
rb ₃₆₀ ). FIG. 13 is a graph obtained by defining the angular position θ on the horizontal axis and the contour distance ra _θ obtained for the angular position on the vertical axis. FIG. 14 is a graph similarly obtained for the contour distance rb _θ . In other words, FIG. 13 shows FIG.
14 is a graph obtained based on the pattern a shown in FIG.
Is a graph obtained based on the pattern b shown in FIG. 2 (b).

Here, comparing the features of the two graphs, it can be seen that almost the same patterns appear. This is because the position of the pattern b should be assigned to the pattern a, the size,
This is because the pattern a and the pattern b have similar characteristics because they are drawn as a line drawing indicating an angle.
If the operator ideally draws the pattern b, both patterns have similar shapes and differ only in size (magnification) and direction (angle). Therefore, let us consider how the difference between the magnification and the angle appears on both graphs.

First, it can be seen that the magnification appears as a ratio of contour distances. If it is considered that both patterns are ideally similar figures, the position of the center of gravity G is also similar. Therefore, the contour distance defined as the distance between the center of gravity G and the contour line should show a difference based on the similarity ratio between the two patterns. For example, if the pattern b is 1.5 times the pattern a, it can be considered that the corresponding contour distances are also 1.5 times. Therefore, the pattern shown in FIG. 14 should be obtained by multiplying the pattern shown in FIG. 13 by 1.5 in the vertical direction. After all, if the two patterns are in the same orientation, the ratio of the contour distances at each angular position in both graphs, rb _θ / ra _θ, is calculated, and this is the relative magnification of the two patterns to be obtained.

On the other hand, it can be understood that the angle appears as a phase difference between both graphs. In FIG. 2, the pattern b
Focusing on, it can be seen that the result obtained by adding a rotation of the angle −α corresponds to the pattern a. This appears as a phase difference between both graphs. That is, focusing on the graph of the pattern b shown in FIG. 14 (hereinafter, referred to as the graph rb _θ ), the graph of the pattern a shown in FIG. 13 is obtained by shifting the graph rb _θ by the angle −α. (Hereinafter, referred to as a graph ra _θ ). Therefore, the graph rb _θ
Is shifted by a predetermined shift amount in the horizontal axis direction, and if it is checked whether or not the features of both graphs overlap on each same abscissa, the shift amount when the features overlap is the phase difference of both graphs,
That is, it is the relative rotation angle of the two patterns to be obtained.

This will be described with reference to the concrete examples shown in FIGS. Now, graph ra _θ and graph rb _θ
Try to overlap and on the same coordinate system. At this time, try differently changing the phase difference between the two graphs. In other words, one of the graphs is arranged so as to be shifted in the horizontal axis direction by a predetermined shift amount. In this case, the degree of overlap between both graphs changes according to the amount of deviation. For example, the overlapping condition as shown in FIG. 15 may be obtained, and the overlapping condition as shown in FIG. 16 may be obtained. As it happens, in FIG. 15, it can be seen that the features of both graphs overlap in the horizontal axis direction. In this way, the amount of deviation for bringing the features of the graphs together is the phase difference between the graphs, that is, the relative rotation angle of the two patterns to be obtained. In order to obtain this specific deviation amount, the deviation amount is 1 °, 2 °, 3 °, ...
Set it to and check the degree of overlap between the features of both graphs.

The essential point of the present invention is that the variance value of the contour distance ratio is used to judge the degree of overlap between the features of both graphs. This method will be described with reference to FIGS. 15 and 16. Now, as shown in FIG. 15, the graph ra _θ
Consider a state in which the characteristics of the graph and rb _θ are exactly overlapped in the horizontal axis direction. In this case, when the ratio of the contour distances (rb _θ / ra _θ ) at a specific angular position is calculated, it can be understood that the value of this ratio is almost constant at any angular position. In the example shown in FIG. 15, 9
It is shown that the ratio value at each of the angular positions of 0 °, 180 °, and 270 ° is 1.5, but at any other arbitrary angular position, the ratio value is still 1.5. become. However, in reality, there will be some variation, but the ratio value at each angular position should be almost constant. On the other hand, as shown in FIG. 16, consider a state in which the characteristics of the graph ra _θ and the graph rb _θ are deviated in the horizontal axis direction. Also in this case, the ratio of the contour distances at a specific angular position (rb _θ
/ Ra _θ ), it can be seen that the value of this ratio varies depending on the angular position. In the specific example shown in FIG. 16, the ratio values at the respective angular positions of 90 °, 180 °, and 270 ° are 1.0, 2.6, and 2.1, respectively. Here, when the variance of the contour distance ratios at the plurality of angular positions is obtained, the variance is very small when the features of both graphs overlap exactly as shown in FIG. 15, but it is shown in FIG. It can be seen that the variance increases when the characteristics of both graphs are deviated. Therefore, if a certain amount of deviation is set and both graphs are overlapped and the variance of the contour distance ratio at each angular position in that state is obtained, it is possible to determine whether the features of both graphs overlap with each other by the set amount of deviation. it can. The present invention is based on such a principle, and the shift amount that allows the features of both graphs to be overlapped,
That is, the relative rotation angle of both patterns is calculated. The relative magnification of both patterns is obtained as the contour distance ratio when the features of both graphs overlap. Specifically, the contour distance ratio 1.
5 (actually, since variations occur, take an average value) is the required magnification.

The magnification / angle calculation unit 140 calculates the magnification and the angle based on this principle. This magnification /
The angle calculation unit 140 can be functionally divided into a dispersion calculation unit 141 and a magnification / angle determination unit 142. The variance calculation unit 141 uses the graph ra obtained for the first pattern.
_θ and the graph rb _θ obtained for the second pattern are shifted by a predetermined shift amount, and the ratio of the vertical axis value of the graph ra _{θ and} the vertical axis value of the graph rb _θ on the same abscissa is different from each other. It has a function of obtaining the abscissa position of and calculating the variance for the obtained plurality of ratios. Further, the magnification / angle determination unit 142 sets a plurality of different displacement amounts to the dispersion calculation unit, receives the variance for each displacement amount as a calculation result, and determines the displacement amount with the smallest dispersion as two patterns. And the average value of the ratios obtained for this amount of deviation is determined as the magnification of the two patterns.

Next, the calculation in the magnification / angle calculator 140 will be described more specifically. First, the magnification / angle determining unit 142 sets a predetermined shift amount j and gives the shift amount j to the variance calculating unit 141 to calculate the variance.
The variance calculation unit 141 obtains the contour distance ratio r (i, j) expressed by the following equation, r (i, j) = rb ((i + j) modM) / ra (i), for the given shift amount j. . Here, ra (i) is the value of the i-th contour distance ra _θ , and rb ((i + j) modM) is ((i + j) mo.
This is the value of the (dM) th contour distance rb _θ . Also, M is
The number of contour distance values, and Δθ as in the above-described embodiment.
When 360 contour distance values are obtained with = 1 °, M = 360. i is an angular position corresponding to the abscissa value of the graph, and 1 ≦ i ≦ M, that is, i
= 1, 2, 3, ..., 360. Also, j is
As described above, it is the amount of deviation set in the magnification / angle determination unit 142, and serves as a parameter indicating "how much one graph is displaced with respect to the other graph".

For example, when the deviation amount j = 1 is set, the variance calculator 141 calculates i = 1 to 3 in the above equation.
Up to 60, r (1,1) = rb (2) / ra (1) r (2,1) = rb (3) / ra (2) r (3,1) = rb (4) / ra (3) ……………………… r (359,1) = rb (360) / ra (359) r (360,1) = rb (1) / ra (360) Value r of
(1,1) to r (360,1) are obtained.

Subsequently, the variance calculation unit 141 calculates the average r _av (j) and the variance σ (j) ² for the obtained M (in the above example, 360) ratio values as r _av (j). = (1 / M) _{.. SIGMA.i} = 1 to M r (i, j) .sigma. (J) ² = (1 / M) _.SIGMA.i = 1 to M (r (i, j) -r _av (j). ) ² consisting calculated by the formula, reports the calculation result to the magnification / angle determination unit 142.

The magnification / angle determining unit 142 changes the setting value of j from 1 to 360, and receives the calculation result report from the variance calculating unit 141 for each value of j. Then, the smallest one of the obtained 360 variations σ (1) ^{2 to} σ (360) ² is searched. Then, the shift amount j that gives the minimum variance
= J is output as the relative rotation angle of the two patterns,
The average r _av (J) of the ratio for this shift amount j = J is
It is output as the relative magnification of the two patterns.

Although the "statistical variance" is used to determine the shift amount j = J in the above embodiment, the "statistical variance" need not necessarily be used in the present invention. Alternatively, any value may be used as long as it is a value indicating the degree of variation of a plurality of values. For example, Σ _{i = 1 to M} (r (i, j) −r _av (j)) ² , statistical standard deviation (square root of variance), and mean deviation (difference between each value and mean) A value obtained by averaging the sum of absolute values of) may be used. As described above, in this specification, the term “variance” is not limited to “statistical variance” but broadly includes values indicating the degree of variation of a plurality of values.

By the way, in the actual measurement, there is a possibility that the contour distance data obtained by the contour extraction unit 130 may include an extremely large error. For example, in FIG.
Two graphs ra _theta, but a laminated state rb _theta is shown, in the data constituting the graph rb _theta, since it contains error data E, the value of the graph rb _theta in angular position E _theta However, the value is extremely deviated. When even one data having such a large error exists, the variance calculated by the variance calculator 141 is greatly affected. That is, as shown in FIG.
If the features of both graphs overlap in the horizontal axis direction, the contour distance ratio should be essentially constant at any angular position. However, the angular position E _θ
Since only the contour distance ratio at is different from the contour distance ratio at other angular positions, a large variance value is unexpectedly obtained. This is a problem in determining the correct rotation angle.

In order to solve such a problem, when the variance is calculated in the variance calculator 141, the following two-step process may be carried out. That is, first, after obtaining the first variance by the first calculation, the second calculation is performed by using only the value of the ratio within the range of the square root (standard deviation) of this variance to obtain the second variance, The second variance is used as the variance value reported to the magnification / angle determination unit 142. For example, when 360 different ratio values r (1, j) to r (360, j) are obtained for a predetermined set value j, r _av (j) = (1/360) · Σ _{i = 1 to 1 360} r (i, j) σ (j) ² = (1/360) · Σ _{i = 1 to 360} (r (i, j) −r _av (j)) ² First, the first dispersion Calculate σ (j) ² . Then, the above-mentioned 360 ratio values r (1, j)
For each of r (360, j), the first variance σ
It is determined whether or not it is within the range of (j). And r
Ratio values outside the range of _av (j) ± σ (j) are excluded. As a result, the value of the ratio at the angular position E _θ shown in FIG. 17 is excluded. In this way, only the value of the ratio within the range of r _av (j) ± σ (j) is used to calculate the average and the variance again, and the second variance is reported to the magnification / angle determination unit 142. . In this way, if the variance is obtained by a two-step process, even if there is data with a large error,
It is possible to get the correct variance.

In the above embodiment, the standard deviation is used to exclude the error data. However, a value that is an integral multiple of the standard deviation or a value of the average deviation may be used instead. In short, any value may be used as long as it can define a predetermined range of variation.

In this way, the magnification and angle obtained by the magnification / angle calculation unit 140 are output from the computer 100. In the end, the worker is the image input device 10
The required magnification and angle are automatically obtained only by performing an operation of inputting an image from the line image input device 20.

The present invention has been described above based on the illustrated embodiment, but the present invention is not limited to this embodiment and can be implemented in various modes other than this. For example, in the above-described embodiment, M = 360 is set by setting Δθ = 1 °, but the setting value of Δθ is arbitrary and does not necessarily have to be a constant value. For example, Δθ = 1 ° and Δθ = 2 ° may be alternately repeated.

In the above embodiment, the computer 1 is used.
All the processing in 00 was automatically performed, and the operator did not need to perform any procedure at all, but the operator may check it if necessary. For example, if the relative magnification and the angle between the picture a and the picture b are obtained in the computer 100, the operator can make a check before immediately outputting the magnification and the angle. Specifically, the pattern a is magnified by the obtained magnification and rotated by the obtained angle to be displayed on the display, and the pattern b is also displayed on the same screen so that the operator can confirm that the two match. Good. Also,
In the above-described embodiment, the contour line correction processing is automatically performed, but it is also possible to leave the matters such as whether or not the correction is necessary to the operator's judgment.

In the above embodiments, this device has been described as a measuring device for measuring magnification / angle. When used as a single measuring device in this way, the computer 1
A printing device such as a printer may be connected to the stage after 00 to print out the obtained magnification and angle. In contrast,
When this device is used by being connected to another device, a necessary interface may be connected to the subsequent stage of the computer 100. For example, if a device for creating plate-making information using the obtained magnification and angle is added to the latter stage of the computer 100, this device can be used by being incorporated in a part of the plate-making system. Specifically, this device can be incorporated into a part of the drum scanner device. That is, the image input device 10 and the line image input device 20 in this device are used as a prescan device to obtain the magnification and the angle when the print document A is input by the drum scanner device. Computer 100
In the plate-making information creating apparatus connected to the latter stage, the range of the scanner decomposition and the coordinates of the characteristic points used for the position alignment at the time of plate making can be added to the obtained magnification and angle.

Alternatively, the image scanner 10 itself has a sufficient resolution (a resolution that is of a quality that can be practically used even after performing scaling processing such as enlargement and reduction, and rotation processing). With this configuration, this device can also be used as a part of a fully automatic plate collecting device. In this case, the image input device 10 functions not as a pre-scan device but as a formal scan device, and the scanner input operation for the print document A is performed only once. In this case, it is preferable to finely adjust the values of the magnification and the angle obtained by the calculation so that the final appearance is finished. So computer 1
It is advisable to add a function for performing this fine adjustment to the plate-making information creating apparatus connected to the latter stage of 00.

[0046]

As described above, the magnification of the pattern according to the present invention /
According to the angle measuring device, the contour distance from the center of gravity of the pattern to the contour pixel is obtained, a graph in which the contour distance is plotted at each angular position is created, and the variance of the contour distance ratios in the graphs of the two patterns is calculated. As a result, the relative magnification and angle of both patterns are obtained, so that the magnification and angle of the pattern can be automatically measured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a pattern magnification / angle measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a specific example of a print document A and a designated layout sheet B shown in FIG.

3 is a partially enlarged view of a pattern a shown in FIG.

4 is a block diagram showing the function of a contour line extracting unit 130 in the apparatus shown in FIG. 1 in an exploded manner into four functional blocks.

5 is a diagram showing a center of gravity G obtained by a center of gravity calculation unit 131 shown in FIG.

FIG. 6 is a diagram showing a method of determining a contour pixel by a contour pixel determination unit 132 shown in FIG.

FIG. 7 is a partially enlarged view of the pattern a shown in FIG.

FIG. 8 is a diagram showing contour lines obtained for the design shown in FIG.

9 is a partially enlarged view of the contour line shown in FIG.

FIG. 10 is a diagram showing an example of a pattern in which a noise pixel P4 is present.

11 is a diagram showing a contour line obtained based on the pattern shown in FIG.

FIG. 12 is a contour line extraction unit 130 in the device shown in FIG.
6 is a flowchart showing the operation procedure of FIG.

FIG. 13 is a graph showing a contour distance / angle position relationship obtained for the pattern a shown in FIG. 2 (a).

FIG. 14 is a graph showing a contour distance / angle position relationship obtained for the pattern b shown in FIG. 2 (b).

FIG. 15 is a diagram showing a state in which the graph ra _θ shown in FIG. 13 and the graph rb _θ shown in FIG. 14 are overlapped with a shift amount such that the positions of the characteristic portions of the graph in the horizontal axis direction match.

16 is a diagram showing a state in which the graph ra _θ shown in FIG. 13 and the graph rb _θ shown in FIG. 14 are overlapped with a shift amount in which the positions of the characteristic portions of the graph in the horizontal axis direction do not match.

FIG. 17 is a diagram showing a case where the graph shown in FIG. 15 includes data E having a large error.

[Explanation of symbols]

10 ... Image input device 20 ... Line image input device 100 ... Computer 110 ... Edge detection unit 120 ... Binarization processing unit 130 ... Contour line extraction unit 131 ... Centroid calculation unit 132 ... Contour pixel determination unit 133 ... Contour distance calculation unit 134 ... Contour correction unit 140 ... Magnification / angle calculation unit 141 ... Dispersion calculation unit 142 ... Magnification / angle determination unit A ... Printed document (photograph) B ... Designation sheet E ... Data including error G ... Center of gravity _L.theta . P1 to P3, Q1, Q2 ... Black pixel P4 ... Noise pixel P5 ... White pixel P? ... Contour pixel a, b ... Picture r _? ... Contour distance ra _? , rb _?

Claims (3)

[Claims] 1. An apparatus for measuring a relative rotation angle between two patterns having similar characteristics, wherein line drawing data consisting of a binary image in which a pattern to be measured is represented by black pixels and white pixels. Image capturing means for capturing as, the center of gravity calculating means for calculating the center of gravity position of the black pixel for the line drawing data captured by the image capturing means, and a plurality of radial lines centered on the center of gravity position at predetermined angle Δθ intervals. A contour pixel determining unit that defines a half line and obtains a black pixel at a position farthest from the barycentric position on each half line as a contour pixel, and a contour distance defined as a distance between the barycentric position and each contour pixel By defining the contour distance calculating means for calculating the angle position of the half line on the horizontal axis and the contour distance obtained for the half line on the vertical axis,
A graph showing the relationship between the angular position of the half line and the contour distance is created, and the first graph obtained based on the first pattern to be measured is obtained based on the second pattern to be measured. A plurality of different second graphs that are different from each other in the horizontal axis direction by a predetermined shift amount and have different ratios of the vertical axis value of the first graph and the vertical axis value of the second graph on the same abscissa. Of the abscissa position of, and the variance calculating means for calculating the variance for the obtained multiple ratios, and a plurality of different deviation amounts are set, and the variance for each deviation amount is obtained by the dispersion calculating means, and the most variance is calculated. An angle determining device that determines the amount of deviation that reduces the rotation angle as the rotation angle of the first pattern with respect to the second pattern. 2. An apparatus for measuring relative magnifications of two patterns having similar characteristics, wherein the pattern to be measured is line drawing data composed of binary images represented by black pixels and white pixels. Image capturing means for capturing, a center of gravity calculating means for calculating the center of gravity position of the black pixel for the line drawing data captured by the image capturing means, and a plurality of half-radial portions centered on the center of gravity position at predetermined angle Δθ intervals. A straight line is defined, and a contour pixel determining unit that obtains a black pixel at a position farthest from the center of gravity position on each half line as a contour pixel, and a contour distance defined as a distance between the center of gravity position and each contour pixel, By defining the contour distance calculation means for calculating and the angular position of the half line on the horizontal axis and the contour distance obtained for the half line on the vertical axis, respectively,
A graph showing the relationship between the angular position of the half line and the contour distance is created, and the first graph obtained based on the first pattern to be measured is obtained based on the second pattern to be measured. A plurality of different second graphs that are different from each other in the horizontal axis direction by a predetermined shift amount and have different ratios of the vertical axis value of the first graph and the vertical axis value of the second graph on the same abscissa. Of the abscissa position of, and the variance calculating means for calculating the variance for the obtained multiple ratios, and a plurality of different deviation amounts are set, and the variance for each deviation amount is obtained by the dispersion calculating means, and the most variance is calculated. The average value of the obtained ratios for the amount of deviation
And a magnification determining unit that determines a magnification of the pattern with respect to the second pattern. 3. The measuring device according to claim 1, wherein the variance calculation means obtains the first variance by the first calculation, and then within a predetermined variation range determined based on this variance. The second calculation is performed using only a certain ratio value to obtain the second variance, and the rotation angle determining unit or the magnification determining unit makes the determination using the second variance. Magnification / angle measuring device for pictures.