1. An image processing apparatus, comprising: a processor comprising hardware, wherein the processor is configured to: estimate imaging distances to a subject shown in pixels within an intraluminal image; set a plurality of rectangular examination candidate regions in the intraluminal image; and set at least one of the plurality of rectangular examination candidate regions as an examination region based on a determination that a distribution of the imaging distances to the subject shown in the pixels within the at least one of the plurality of rectangular examination candidate regions is within a predetermined range; identify whether or not a microstructure of the subject shown in the examination region is abnormal, by using texture feature data that enables identification of an abnormality in the microstructure of the subject shown in the examination region, the texture feature data being specified according to the examination region; and generate a processed image for display, the processed image showing a result of the identification of the abnormality in the microstructure of the subject shown in the examination region.