Image processing method for determining matching position between template and search image
View Patent ↗An inspection apparatus and method outputs an accurate matching position even if a search image contains a pattern similar to a template. An image search unit includes a relative position comparing unit which compares the relative position of a template in a template selection image with the relative position of a location currently being searched for in a search image and outputs the amount of position mismatch between the relative positions. A matching position determining unit determines a matching position by taking into consideration the amount of position mismatch in addition to search image similarity distribution information.
1. An inspection apparatus which obtains a search image and applies template matching to the search image, said inspection apparatus comprising:
a storage device storing first distribution information indicating a distribution of first similarities between a template selection image and a template;
a similarity distribution calculating unit that calculates second distribution information indicating a distribution of second similarities between a search image and the template;
a unit that calculates third similarities between similarity distributions, said third similarities indicating similarities between the first and second distribution information;
a position mismatch amount calculating unit that calculates an amount of position mismatch between the first and second distribution information
an integrated index value calculating unit that calculates, for matching candidate positions of the second distribution information, an index value based on the second similarities and the third similarities between the similarity distributions, and carries out an operation in which the smaller the amount of position mismatch is, the larger a rate of the similarities between the similarity distributions in calculating the integrated index value; and
a matching position determining unit that determines a matching position on the basis of the integrated index value.
2. The inspection apparatus according to claim 1 , wherein the position mismatch amount calculating unit calculates 1.0 minus the ratio of the area of a region for calculating the degree of similarity between normalized correlation maps to the area of each normalized correlation map as the amount of position mismatch.
3. The inspection apparatus according to claim 2 , further comprising a user interface for setting a contribution ratio of the third similarities between the similarity distributions when calculating the integrated index value of the amount of position mismatch.
4. The inspection apparatus according to claim 1 , wherein the position mismatch amount calculating unit calculates the sum of an amount of position mismatch in the x-direction and an amount of position mismatch in the y-direction as the amount of position mismatch.
5. The inspection apparatus according to claim 1 , wherein the position mismatch amount calculating unit outputs the amount of position mismatch in the x-direction or the amount of position mismatch in the y-direction, whichever is greater, as the amount of position mismatch.
6. An inspection method, in an inspection apparatus, of obtaining a search image and applying template matching to the search image; the inspection method comprising the steps of:
a high magnification imaging device acquiring a template selection image of an object;
storing first distribution information indicating a distribution of first similarities between said template in a template selection image and a template;
a high magnification imaging device acquiring a search image of a sample;
a similarity distribution calculating device calculating a second distribution information indicating a distribution of second similarities between the search image and the template;
calculating third similarities between similarity distributions, said third similarities indicating similarities between the first and second distribution information;
a position mismatch amount calculating unit calculating an amount position mismatch between the first and second distribution information;
an integrated index value calculating unit calculating, for matching candidate positions of the second distribution information, an index value based on the second similarities and the third similarities between the similarity distributions, and carrying out an operation in which the smaller the amount of position mismatch is, the larger a rate of the similarities between the similarity distributions in calculating the integrate index value; and
determining a matching position on the basis of the integrated index value.
7. The inspection method according to claim 6 , wherein the position mismatch amount calculating unit calculates 1.0 minus the ratio of the area of a region for calculating the degree of similarity between normalized correlation maps to the area of each normalized correlation map as the amount of position mismatch.
8. The inspection method according to claim 6 , wherein the position mismatch amount calculating unit calculates the sum of an amount of position mismatch in the x-direction and an amount of position mismatch in the y-direction as the amount of position mismatch.
9. The inspection method according to claim 6 , wherein the position mismatch amount calculating unit outputs the amount of position mismatch in the x-direction or the amount of position mismatch in the y-direction, whichever is greater, as the amount of position mismatch.
10. The inspection method according to claim 6 , further comprising the step of setting, through a user interface, a contribution ratio of the similarities between the first and second similarity distributions when calculating the index value of the amount of position mismatch.