US 12,437,446 B2
Image comparison method, image comparison device, and non-transitory computer-readable recording medium recording image comparison program
Atsushi Imamura, Kyoto (JP)
Assigned to SCREEN HOLDINGS CO., LTD., Kyoto (JP)
Filed by SCREEN HOLDINGS CO., LTD., Kyoto (JP)
Filed on Aug. 21, 2023, as Appl. No. 18/452,854.
Claims priority of application No. 2022-138973 (JP), filed on Sep. 1, 2022.
Prior Publication US 2024/0078709 A1, Mar. 7, 2024
Int. Cl. G06T 7/00 (2017.01); G06K 15/02 (2006.01); G06T 7/12 (2017.01); G06T 7/136 (2017.01); G06T 7/174 (2017.01)
CPC G06T 7/97 (2017.01) [G06T 7/12 (2017.01); G06T 7/136 (2017.01); G06T 7/174 (2017.01); G06K 15/027 (2013.01); G06T 2207/20224 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An image comparison method for comparing a first image that is a multi-valued image and a second image that is a multi-valued image, the image comparison method comprising:
a difference image generation step of generating, based on the first image and the second image, a difference image that is a binary image representing a portion having a difference between the first image and the second image, the difference image including one or more partial difference images each including one or more pixels;
a contraction step of performing contraction processing to each of the one or more partial difference images to generate a contracted image including one or more partial contracted images;
an outline image generation step of generating an outline image by removing the contracted image from the difference image, the outline image including one or more partial outline images each including one or more pixels;
a candidate image generation step of generating a candidate image by removing a partial outline image that is adjacent to the partial contracted image from the one or more partial outline images, the candidate image representing a portion as a candidate of an edge region, the candidate image including one or more partial candidate images each including one or more pixels;
an edge image generation step of generating an edge image representing an edge region based on the first image, the second image, and the candidate image; and
a comparison result image generation step of generating a comparison result image by removing the edge image from the difference image, wherein
in the edge image generation step, assuming that one or more pixels constituting the one or more partial candidate images included in the candidate image are sequentially set as a processing target pixel, and that the processing target pixel and eight pixels around the processing target pixel are set as nine comparison target pixels, the processing target pixel is determined to be a pixel constituting the edge region when a first condition is satisfied, the first condition being a condition in which a difference between a pixel value of at least one of the nine comparison target pixels in the first image and a pixel value of the processing target pixel in the second image is less than or equal to a first threshold value, and a difference between a pixel value of at least one of the nine comparison target pixels in the second image and a pixel value of the processing target pixel in the first image is less than or equal to the first threshold value.