JPS5951025B2 - Image matching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image matching device that matches registered image data (registered image) and inputted image data (matching image) by matching their positions and angles.

A conventional device of this type is shown in FIG.

In the figure, 1 is an input device, 2 is a pattern memory, 3 is a center measuring device, 4 is a pattern rotation device, 5 is a coincidence degree measuring device, and 6 is a determining device. FIG. 2 shows a seal impression as an example of an image handled by this type of apparatus, where 101 is a registered seal impression, and 102 and 103 are seal impressions of a verification seal impression. The image will be explained below using a seal. Next, the operation will be explained.

The input device 1 scans the imprint of the registered seal stamped on the seal registration form or the verification stamp stamped on the check or bill on the grid pattern of the base, and inputs it into the pattern memory 2 as binarized digital data. . Therefore, in the pattern memory 2, a value of 1 is input for the part with the ink pad, and a value of 0 is input for the part without the ink pad. pattern·
The memory 2 normally stores each pixel formed by dividing one seal impression into 100 or more points both horizontally (x direction) and vertically (y direction). Next, the center of the seal impression of the registered seal stamp and the verification seal stamp is measured by the off-center measuring device 3.

Next, the information on the seal impression of the verification seal is rotated around its center by a small angle △θ (usually 0.5
-80) rotation. Specifically, the coordinates before rotation are (
x, y), the coordinates after rotation are (x', y'), the center of rotation is (x., y.), and the rotation angle is θ, then x'■(x
-xo)coJ+(y-yo)sinθ+X0l,, y4)y' ■(x-x.)slnθ+(y-yo)si
The coordinate system after rotation (x'
, y') is assigned the pixel value (0 or 1) in the coordinate system (x, y) before rotation to form a stamp pattern after rotation. Next, each time the seal impression data of the verification seal stamp is rotated by a small angle Δθ by the pattern rotation device 4, the degree of coincidence between the registered seal impression and the impression of the verification seal stamp is measured by the coincidence measurement device 5.

The degree of coincidence M referred to here is, for example, when the registered seal impression and the stamp impression of the verification seal are superimposed so that their centers match, and the overlap value is 1.
When the number of pixels of the registered seal impression is A, the number of pixels of the registered seal impression has a value of 1 is B, and the number of pixels of the verification seal impression has a value of 1 is C, then M=A/B - C... ...(2) Or, it is calculated by M=A/B.

After the seal impression of the verification seal has rotated once (360 degrees), the determination device 6 selects the maximum matching degree M at each rotation angle, and this M is the reference value M.

If the difference exceeds , it is determined that the registered seal impression and the verification seal impression match. Conventional image matching devices are configured as described above, so in order to match images with high accuracy, many calculations are performed during rotation, which takes a long time.
There were some shortcomings.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it uses registered images and matching images. The rotation angle formed with the image is measured using several concentric circular patterns with radii determined from the registered image at the time of registration and registered with the image, rather than the entire image, so that it can be done with a small amount of calculation. The purpose is to provide an image matching device.

Hereinafter, one embodiment of the present invention will be described based on FIG. 3. 1 is an input device, 2 is a pattern memory, 3 is a center measurement device, 4 is a pattern rotation device, 5 is a coincidence measurement device,
6 is a determination device, 7 is a concentric circle expansion device, 8 is a concentric pattern memory, and 9 is the same. Centroid pattern shift device, 10
11 is a concentric circle coincidence measurement device, 11 is a rotation angle calculation device, 12 is
is a file device.

FIG. 4 is an explanatory diagram regarding concentric circle expansion by the concentric circle expansion device 7.

In Figure 4, 102 is an example of a registration/seal imprint; 10
5 is the center of the seal impression, 106 is a circle drawn virtually on the seal impression with radius R, and 107 is also radius R. circle, 108
indicates the reference line of the angle θ when concentric circles are developed. Fifth
The figure shows an example of the pixel configuration of a concentric pattern obtained by the above-mentioned concentric circle expansion, where - portions correspond to portions with ink pads and □ portions correspond to portions without ink pads.

Note that the horizontal axis is a measure of the rotational direction and corresponds to the number of pixels. Next, the operation will be explained.

Similar to the conventional apparatus, the input device 1 registers the impression of a registered seal or a verification seal into the pattern memory 2 as binary digital data, and then the center of the seal is measured by the center measuring device 3. Next, the seal imprint of the registered seal stamp is concentrically developed by a concentric circle developing device 7 to convert the stamp pattern into a concentric circle pattern.

This concentric expansion is defined by a predetermined radius Rl, . R2
Regarding ......
: degrees), find the coordinates (x, y) R1 determined by equation 3,
Pixel value (0 to 1) of the point closest to the coordinates (x, y)
It is to calculate in order.

x=RcOs(n ・△θ)+XOy2Rsin(n
・△θ) +YO} ・・・・・・・・・(3) (However, X.

,Y. is the coordinate of the center, n is an integer, and 0<n・△θ<36
The concentric circle pattern developed by the concentric circle development device 7 is stored in the concentric pattern memory 8.

This concentric pattern memory 8 stores a number of pixels proportional to Ri for a circle with a radius Ri. Examples of concentric circle development using two circles with radii R1 and R2 are shown in FIGS. 5A, B, C, and D.

Circle 10 with radius R on the seal imprint 102 of the registered seal stamp in Figure 4
6. Radius R. The concentric patterns developed by the circle 107 are shown as developed patterns 206 and 207, respectively, as shown in FIG. 5A. Also, another set 2 of the same thing as shown in Figure 5 B.
It is shown as 08,209. Next, the concentric pattern shift device 9 moves the developed pattern 2 of the seal impression developed in a circle with radius R.
08 can be shifted by l pixels on the concentric pattern memory 8, and the operation is as follows.

That is, the concentric pattern shift device 9 shifts the data by l shifts as described above, and successively creates developed patterns 210, 211, etc. with a radius R, as shown in FIG. 5C and D. In other words, after shifting the expanded pattern for a circle with radius R a number of times for all pixels, the same shift is repeated for radius R2, and this operation can be performed for expanded patterns for all radii. . Next, each time the above-mentioned shift is performed, the degree of coincidence between the development pattern 206 of the seal impression of the registered seal impression and the shift pattern (208, 210, 211, etc.) of the seal impression of the verification seal impression is measured by the concentric circle coincidence degree measuring device. Measure in 10.

This degree of matching is calculated by superimposing the development pattern of the corresponding radius of the seal impression of the registered seal and the development pattern of the corresponding radius of the verification seal, and calculating the number of overlapping pixels with a value of 1 as a, and the corresponding radius of the seal impression of the registered seal. It is calculated as follows, where b is the number of pixels with a value of 1 in the developed pattern of , and C is the number of pixels with a value of 1 in the developed pattern of the corresponding radius of the stamp of the verification seal stamp.

For each shift of the concentric pattern shift device 9, the degree of coincidence m is measured by the degree of concentricity measuring device 10, thereby determining the autocorrelation function of the concentric pattern at a certain radius. This is shown in FIG. Naturally, the value of m takes the maximum value when the shift amount is O. This point is P1,
Assuming that the second peak is P2, the larger the ratio m1/M2 of the value m1 of m at P1 to the value M2 of m at P2, the easier it is to find the correct value when correlated with the development pattern of the verification seal. . For this purpose, examine the autocorrelation function of the expansion pattern at consecutive values of V around 1 using the registered seal, and set the value of v for which m1 is greater than a certain value and the ratio of m1/M2 is greater than the given value as V1 in the file. Register to the device.

Similarly, V2, V3, etc. are also determined and registered. When checking, use this 1, V2...
... from the file device, find the development pattern of the registered seal impression and verification impression at this radius, correlate the second development pattern at the same radius, and find the angle from the point where the maximum value is found. . Multiple V1, V2...
The correct angle may be one where some of the angles found in . The rotation angle calculation device 11 calculates the rotation angle d of the seal impression of the verification seal stamp with respect to the seal impression of the registered seal stamp as follows.

Assume that the shift giving the maximum matching degree m occurs at the k-th shift of radius Ri. Since the rotation angle corresponding to one shift of the radius Ri is determined in advance to be Δθ according to equation (3), d=k·Δθ . . . (5) is obtained. Next, the stamp pattern measuring device 4 measures the verification stamp pattern stored in the stamp pattern memory 2 at the corner (-
d) Rotate and measure the degree of coincidence of the seal imprints between the registered seal stamp and the verification seal stamp using the seal stamp coincidence degree measurement device 5 in the same way as the conventional device, obtain the degree of coincidence M, and set the degree of coincidence M to the reference value M by the determination device 7. .

If M>MO, it is determined that the registered seal stamp and the verification seal stamp match. In the above explanation, it is assumed that the registered seal impression and the verification seal impression are affixed by the same seal or a similar seal, but if they are affixed by different seals, the concentric circle coincidence measurement device 10 The obtained degree of matching m
gives only a low value in every shift.

Therefore, in the rotation angle calculating device 11, if the shift is less than the threshold value in all shifts, the registered seal impression and the verification seal impression are considered to be different, and the determination device 6 is notified to that effect. As described above, in the image matching device according to the present invention,
During registration, find the autocorrelation function of the concentric circle expansion pattern,
The radius where the difference between the first peak and the second peak is large is determined and registered in a file, and during verification, the angle is determined from the correlation of the concentric circle development pattern at this radius, so the correct angle can be determined with high precision. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional image matching device, FIG. 2 is a diagram showing an example of registered images and matching images, FIG. 3 is a block diagram of an image matching device of the present invention, and FIG. 4 is an explanation of concentric circle expansion. 5 is a configuration diagram showing an example of the pixel configuration of a concentric pattern, and FIG. 6 is a diagram of an autocorrelation function of the concentric pattern. 1...Input device, 2...Pattern memo 3...Center measuring device, 4...Pattern rotation device, 5... Matching degree measuring device, 6.
...Judgment circuit, 7...Concentric circle expansion device,
8... Concentric pattern memory, 9...
Concentric pattern shift device, 10... Concentric circle coincidence measuring device, 11... Rotation angle calculation device, 12
...It is a file device.

Claims (1)

[Claims] 1. Means for determining the center from the image, and means for determining one or more concentric circular patterns centered on the center, using an image matching device that digitally superimposes and matches the registered image and the matching image by matching their positions and angles. means for determining the correlation between the two concentric patterns; means for determining the positions and peak values of the first and second peaks of the correlation values indicating the correlation; A file device that registers the radii of multiple concentric circles such that the peak value and the ratio of the first peak value to the second peak value are each a given value or more together with the image, and at the time of verification, match the registered image read from the file device. Find the center of the image, take the correlation of the concentric pattern with the radius read from the file device, and calculate the first of this correlation value.
There is a means to calculate the angle of two images from the peak, a means to find the correct angle by taking the angle whose value is more similar than the angles found from multiple concentric circle patterns, and a means to calculate the correct angle by calculating the angle of the two images by this angle. An image matching device characterized by comprising means for performing matching by rotating and aligning the positions.