The present invention provides a new image processing device that is robust against a change in capturing conditions. An image processing device 100 has an acquisition unit 110 for acquiring an image, a smoothing unit 120 for smoothing the acquired image with a prescribed smoothing level, a binarization unit 130 for binarizing the smoothed image, and a control unit 140 for making the smoothing unit 120 execute multiple sessions of smoothing differing in the smoothing level.