Storage medium storing program and image processing apparatus

A non-transitory computer-readable storage medium storing a set of program instructions for a computer comprising a processor, the set of program instructions, when executed by the processor, causing the computer to perform:

• acquiring a two-dimensional captured image of a particular surface of a target object;
• and
• determining whether the particular surface of the target object has an abnormality by comparing the two-dimensional captured image with a two-dimensional normal image representing a normal particular surface, the determining whether the particular surface of the target object has an abnormality including:
• acquiring, from the two-dimensional captured image, N (N is an integer greater than or equal to two) first type partial images including different portions of a first type particular surface, the first type particular surface being a particular surface represented by the two-dimensional captured image;
• performing keypoint matching between a first type partial image and a second type partial image associated with each other, each of N combinations including the first type partial image and the second type partial image associated with each other, N second type partial images including different portions of a second type particular surface, the second type particular surface being a particular surface represented by the two-dimensional normal image, the first type partial image and the second type partial image associated with each other including a common portion;
• calculating N homography matrices in accordance with N results of the keypoint matching;
• calculating a degree of difference between an identity matrix and each of the N homography matrices;
• and
• determining whether the particular surface of the target object has an abnormality by comparing each of N degrees of difference with a reference for the degree of difference.

An image processing apparatus comprising:

• a processor;
• and
• a memory storing instructions, the instructions, when executed by the processor, causing the image processing apparatus to perform:
• acquiring a two-dimensional captured image of a particular surface of a target object;
• keypoint matching between the two-dimensional captured image and a two-dimensional normal image representing a normal particular surface;
• generating a transformed image by performing homography transformation on a first image in accordance with a result of the keypoint matching, the first image being one of the two-dimensional captured image and the two-dimensional normal image;
• and
• determining whether the particular surface of the target object has an abnormality by comparing a second image with the transformed image, the second image being an other one of the two-dimensional captured image and the two-dimensional normal image.