IMAGE PROCESSING APPARATUS, METHOD OF CONTROLLING THE SAME, AND NON-TRANSITORY COMPUTER-READABLE STORAGE MEDIUM THAT EXTRACT PERSON GROUPS TO WHICH A PERSON BELONGS BASED ON A CORRELATION

An image processing apparatus includes a first obtaining unit to obtain a number of images in which a pair of a first person and a second person simultaneously appears, out of a plurality of images. A detection unit detects whether the pair appears in a target image group, which is one of a plurality of image groups into which the plurality of images is classified. In determining whether the pair appears in the target image group, it is determined that the pair appears in the target image group not only in a case when the target image group includes an image in which the first person and the second person simultaneously appear, but also, in a case when the target image group includes images in which the first person and the second person appear separately.