A position of a pixel serving as an extraction subject is determined by using first image data photographed under a first light source. An extraction range corresponding to the determined position is also determined, by using a color value of the pixel at the determined position and a color value of a pixel at a peripheral position around the determined position in the first image data. A first representative color value is calculated from the first image data and a second representative color value from second image data photographed under a second light source, on the basis of the position of the pixel serving as the extraction subject and the extraction range. A color correction condition for converting a color value depending on the first light source into a color value depending on the second light source is then generated.