1. An image processing device comprising: a candidate abnormal region determining unit that determines a candidate abnormal region from an image using a first determination criterion; a bubble region determining unit that determines a bubble region from the image; a bubble inside determining unit that determines whether the candidate abnormal region is present inside the bubble region based on a determination result of the bubble region; and an abnormal region determining unit that determines whether the candidate abnormal region is an abnormal region using a second determination criterion different from the first determination criterion when the candidate abnormal region is determined to be present inside the bubble region.