An image processing system includes an external device including an orientation specifying unit that specifies orientation of the body-insertable apparatus, a rotation correcting unit that aligns orientations of a plurality of pieces of image data, a screen generating unit that generates a screen displaying the image data, an average color bar generating unit that calculates an average color of the image data, generates an image of the calculated average color, and generates an average color bar in which images of the generated average colors are connected, and an organ image generating unit that generates an organ image, obtained by superimposing the images of the average colors generated by the average color bar generating unit. The screen generating unit generates the screen in which the average color bar generated by the average color bar generating unit is incorporated, and incorporates the organ image into the screen.