An image processing device includes a hue calculation unit configured to calculate a hue of a pixel included in a target image; an extraction unit configured to extract a first group including a pixel, a hue of which is close to a hue of the target pixel; a chromaticity calculation unit configured to calculate a chromaticity of the pixel included in the first group and that of the target pixel; a diffuse reflection factor calculation unit configured to calculate an estimated diffuse reflection factor by using the chromaticity of the pixel included in the first group and that of the target pixel; and a separation unit configured to separate a diffuse reflection component from a pixel value of the target pixel by using the diffuse reflection factor, the diffuse reflection component representing a component in the pixel value that varies as the diffuse reflection factor varies.