1. An image processing apparatus comprising: a feature extraction unit adapted to extract a plurality of predetermined features in an object from input image data; a supplementation unit adapted to supplement, when there are features which are not extracted by said feature extraction unit, of the plurality of features, the unextracted features based on information of the features extracted by said feature extraction unit; and a recognition processing unit adapted to execute recognition processing of the object based on the unextracted features supplemented by said supplementation unit and the features extracted by said feature extraction unit, wherein when there is a feature which is not extracted by said feature extraction unit, said supplementation unit supplements the unextracted feature based on information of a feature which is extracted by said feature extraction unit and is located at a position symmetric to the unextracted feature about a specific axis of the object.