A region of interest extracting section automatically extracts regions of interest from within original images by obtaining the degree by which the features of portions within the original images differ from the features of surrounding portions, based on the colors of the original images, brightnesses of the original images, and the orientations of linear components that appear in the original images. A partial image generating section generates partial images by cutting out images of predetermined sizes that include the regions of interest, which are extracted by the region of interest extracting section, from the original images. The generated partial images are displayed.