An image processing device includes an edge strength calculation unit, and a mixing unit. The edge strength calculation unit calculates an edge strength of a pixel of interest in an input image from a stairs tone strength of the pixel of interest and a gradient of the pixel of interest, wherein the gradient is calculated from pixel values of the pixel of interest and pixels adjacent to the pixel of interest, and the stairs tone strength is indicative of differences between the gradient and a variance of the pixel of interest calculated from the pixel values of the pixel of interest and the adjacent pixels. The mixing unit calculates an illumination light component of the pixel of interest of the input image from an average value of the pixel of interest and pixel values adjacent to the pixel of interest, and a mixing ratio calculated from the edge strength.