An image processing apparatus classifies a variation of a target object included in an image from a specific state as one of a plurality of types of attributes, and holds, for each variation attribute, a correction parameter for spatial transformation that corrects the target object to the specific state. The image processing apparatus generates an input image vector by vectorizing at least a partial region of the input image, and determines a variation attribute by detecting a variation of the target object from the specific state in the input image. Then, the image processing apparatus generates a transformed image vector by performing the spatial transformation on the input image vector, using a correction parameter selected based on the determined variation attribute from among the correction parameters held for respective variation attributes.