An image processing system is provided that includes: an image data storage section that stores image data of a consecutive plurality of frames; a display section that displays image data that is stored; a region-of-interest setting section that sets a region of interest in the displayed image data; a change amount detection section that, with respect to the region of interest that is set, compares image data of adjacent frames stored in the image data storage section and detects a change amount therebetween; a change determination section that determines whether the detected change amount exceeds a predetermined threshold value; and an index storage section that stores image data of a frame that is determined to exceed the predetermined threshold value by the change determination section as an index.