1. An image processing apparatus, comprising: extraction means configured to extract a characteristic amount of a region in which a recognition object may possibly be included from within an image of a processing object; parameter retaining means configured to retain a parameter regarding the recognition object; context retaining means configured to retain a context regarding the recognition object; and decision means configured to decide based on the characteristic amount extracted by said extraction means, the parameter retained in said parameter retaining means, and a result of arithmetic operation performed using the context retained in said context retaining means whether or not an image in the region is the recognition object, wherein said decision means decides whether or not there exists a region in which a score calculated using the characteristic amount and the parameter is higher than a predetermined threshold value, and performs, where it is decided that a region in which the score is higher than the predetermined threshold value exists, arithmetic operation regarding the recognition object corresponding to an image other than an image in the region using the characteristic amount, the parameter, and the context.
6. The image processing apparatus according to claim 1 , wherein, when a new recognition object is set, an image in which the new recognition object exists is read out from a plurality of stored images, and it is decided whether or not the read out image includes a different recognition object, and then a co-occurrence probability is calculated based on a result of the decision and a context regarding the new recognition object retained in said context retaining means is updated based on the co-occurrence probability.