A plurality of images are input, specific regions are set for each of the inputted plurality of images, a typical size of the specific regions of each of the plurality of images is determined, and the ratio of the typical size to the size of the entire image is calculated as a typical size ratio. A typical size ratio used as a reference is selected from the typical size ratios calculated for the respective images as a reference ratio, and a candidate region upon trimming that image is determined based on the specific regions of each of the plurality of images. A trimming region for each of the plurality of images is determined based on the reference ratio, and the typical size ratio and candidate region of each image, and each of the plurality of images is trimmed according to the trimming region.