1. An image processing apparatus, comprising at least one processor coupled to at least one memory, the at least one processor being programmed to implement operations comprising: acquiring correspondence information between a first image and a second image; acquiring information regarding a corresponding point candidate pair including information regarding a coordinate of a first point on the first image and a coordinate of a second point on the second image; calculating a matching degree of the corresponding point candidate pair to the correspondence information, using the correspondence information; and controlling to display a calculation result of the matching degree on a display unit, wherein the correspondence information differs from the information regarding the corresponding point candidate pair, and the correspondence information is information regarding a plurality of corresponding point pairs that has already been associated between the first image and the second image.