An image processing apparatus includes an instruction unit for designating one of a plurality of partial images and instructing execution of one of a plurality of processes for a classification process to determine whether the designated partial image contains a specific pattern, an execution unit for performing the instructed process for the designated partial image using parameters, and a determination unit for determining whether the classification process for the designated partial image has terminated. When the determination unit determines that the classification process has not terminated for at least one of the partial images, the instruction unit designates one of the partial images for which the classification process has not terminated and outputs a re-instruction for execution of an unexecuted process for the designated partial image. The execution unit executes, using different parameters, the instructed process for the designated partial image.