An image processing apparatus includes a reducing unit that reduces an input image chronologically input as moving images and accumulates a reduced image of the input image as a first reduced image in a predetermined memory. The image processing apparatus further includes a generating unit that generates, as a second reduced image, one reduced image from multiple first reduced images accumulated in the memory. The image processing apparatus further includes a smoothing unit that smooths level values of a pixel included in the second reduced image and pixels surrounding the pixel with respect to each of multiple ranges set according to the width of level values of pixels. The image processing apparatus further includes a synthesizing unit that synthesizes multiple range-by-range results of the smoothing on the basis of the input images. The image processing apparatus further includes an output unit that outputs a synthesized image as an output image.