Provided is an image combination method that can represent the texture of a drawing medium such as paper without causing a foreground fading problem. The image combination method includes a step of acquiring an illumination-light component and a reflectance component from an input image, a step of generating a texture-combined image by combining the reflectance component or the corrected reflectance component and a texture image representing a desired texture, and a step of acquiring a combined image by combining the illumination-light component or the corrected illumination-light component and the texture-combined image.