1. An image processing device comprising: an image sequence acquisition section that acquires an image sequence that includes a plurality of constituent images; and a processing section that performs an image summarization process that deletes some of the plurality of constituent images included in the image sequence acquired by the image sequence acquisition section to generate a summary image sequence, the processing section selecting a reference image and a determination target image from the plurality of constituent images, detecting an unnecessary area from the determination target image, calculating a loss area based on deformation information about the reference image and the determination target image, and the unnecessary area, the loss area being an area that is lost when the determination target image is deleted, and determining whether or not the determination target image can be deleted based on the calculated loss area.