1. An image processing apparatus comprising: a unit which acquires N images sensed under N respective types of image sensing conditions; a management unit which extracts respective feature amounts from the N sensed images, and manages the extracted feature amounts as a feature amount cluster, in which each of the extracted feature amounts is in association with corresponding one of the image sensing conditions; a first specification unit which specifies a second feature amount cluster containing a feature amount similar to a feature amount of interest in a first feature amount cluster among feature amount clusters managed by said management unit; a second specification unit which specifies sets of feature amounts, each of the sets being associated with a corresponding one of the N respective types of image sensing conditions from the first feature amount cluster and the second feature amount cluster; a third specification unit which specifies a set having a largest distance between feature amounts in the set among the sets specified by said second specification unit; and a determination unit which determines an image sensing condition associated with the set specified by said third specification unit, as an image sensing condition for discriminating the first feature amount cluster and the second feature amount cluster.