US 12,243,286 B2
Pattern image detection method
Jong Hyun Song, Gyeonggi-do (KR); and Kang Cho, Seoul (KR)
Assigned to Fourth Logic Incorporated, Gyeonggi-do (KR)
Filed by Fourth Logic Incorporated, Gyeonggi-do (KR)
Filed on Apr. 21, 2022, as Appl. No. 17/726,485.
Claims priority of application No. 10-2021-0075951 (KR), filed on Jun. 11, 2021.
Prior Publication US 2023/0005242 A1, Jan. 5, 2023
Int. Cl. G06V 10/74 (2022.01); G06T 7/00 (2017.01)
CPC G06V 10/761 (2022.01) [G06T 7/001 (2013.01); G06T 2207/30148 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A pattern image detection method in which a template image is compared with a target image and a pattern included in the template image is searched for from the target image, as to determine a location in the target image where a chip placement or other operations at the determined location is to be performed, the pattern image detection method comprising:
(a) receiving the template image and the target image by a receiving module;
(b) receiving a reference similarity that is a criterion for determining whether there is a similarity, a reference skip distance that defines a distance to a next comparison reference pixel in the target image, and detailed search criteria that defines a range in which a detailed search is performed in the target image, by the receiving module;
(c) dividing the template image into a plurality of regions having the same size by a template region module;
(d) summing a square of a brightness value of each of pixels in each region of the template image and setting the sum as a brightness value for each region, by the template region module;
(e) selecting a comparison reference pixel of the target image by a target region module;
(f) selecting a comparison target area having the same size as the template image on the basis of the comparison reference pixel of the target image and dividing the comparison target area into a plurality of regions having the same size as the regions of the template image, by the target region module;
(g) summing a square of a brightness value of each of pixels in each region of the comparison target area of the target image and setting the sum as a brightness value for each region, by the target region module;
(h) performing a normalized cross-correlation calculation according to Equation 1 in units of regions on the brightness value for each region of the template image and the comparison target area of the target image to calculate a similarity between the template image and the comparison target area, by a similarity calculation module;

OG Complex Work Unit Math
where, u: a position of the target image in a horizontal axis, v: a position of the target image in a vertical axis, X: a position of a region of the template image in the horizontal axis, Y: a position of a region of the template image in the vertical axis, W: a horizontal length of the template image, H: a vertical length of the template image, BX: the number of regions of the template image in the horizontal axis, BY: the number of regions of the template image in the vertical axis, T: the entire region of the template image, Du,v: the entire comparison region of the target image, IT(x,y): a brightness value of an x, y position of the template image, ID(x,y): a brightness value of an x, y position of the target image,

OG Complex Work Unit Math
(i) comparing the similarity calculated in operation (h) by the similarity calculation module with the reference similarity, setting the comparison reference pixel as a point of interest when the similarity is greater than the reference similarity, and updating a position of a next pixel adjacent to the comparison reference pixel as the comparison reference pixel, by a similarity determination module;
(j) comparing the similarity calculated in operation (h) by the similarity calculation module with the reference similarity, and updating a position of a pixel spaced apart from the comparison reference pixel by the reference skip distance as the comparison reference pixel when the similarity is less than the reference similarity, by the similarity determination module;
(k) repeating operations (f) to (j) for the comparison reference pixel updated in operation (i) or (j); and
(l) performing a similarity calculation of Equation 1 in units of regions or pixels having a size smaller than that of the region obtained in operations (c) and (f) within a distance range that is set by the detailed search criteria around the point of interest set in operation (i); and
(m) identifying a pixel having the largest similarity around the point of interest from the target image, by a position determination module, wherein a position of the identified pixel in the target image is where the pattern to be searched for is located.