1. An image processing apparatus comprising: a processor comprising hardware, wherein the processor is configured to: acquire coordinates of feature points in an entire input image and coordinates of feature points in each of a plurality of small regions set in the input image, through image analysis; set a target point number for each small region, based on the coordinates of feature points in the entire input image, the target point number indicating the number of feature points which are to be detected during feature point detection; set an expected point number for each small region, based on the coordinates of feature points in the small region, the expected point number indicating the number of feature points which are expected to be detected in the small region during feature point detection; compare the target point number and the expected point number for each small region; set detection sensitivity during feature point detection for each small region, based on a comparison result between the target point number and the expected point number; and perform feature point detection according to the detection sensitivity set, wherein the processor is configured to acquire the coordinates of feature points in the entire input image by performing feature point candidate detection on the entire input image, and acquire the coordinates of features points in each small region by performing feature point candidate detection on the small region.