1. An image processing apparatus comprising: receiving means for receiving a plurality of target candidate images; dividing means for dividing each of the plurality of target candidate images, which are assigned as candidates of a target image, into blocks by dividing the target image into the blocks and replacing each of the blocks of the plurality target candidate images with a raw image selected from a plurality of raw images; block classification means for placing each of the blocks of each of the plurality of target candidate images and each of the plurality of raw images into a class selected from a plurality of classes defined by a characteristic associated with color; comparing means for comparing, for each of the classes, the number of blocks of each of the plurality of target candidate images in a class and the number of raw images in a same class; and selecting means for selecting a first target candidate image among the plurality of target candidate images to be assigned as the target image to create a photo-mosaic image on the basis of comparison results of the plurality of target candidate images obtained by the comparing means, wherein the block classification means places each of the blocks into one of the classes on the basis of a distance from a characteristic value of each of the blocks to a predetermined center value that is used for classification and represents a characteristic value of the characteristic of each of the classes.