An image obtained by being imaged by an imaging device and converted to color data using a color processing parameter is input and target color data corresponding to converted color data is input. Next, the color processing parameter is optimized based upon the color difference between the converted color data and target color data. When the optimization processing is executed, first optimization processing is executed for optimizing the color processing parameter using the first target color data being within a prescribed color gamut, and the converted color data corresponding to the target color data, and second optimization processing is executed for optimizing the color processing parameter using second target color data, which includes the target color data being out of the prescribed color gamut and is less than a prescribed threshold value, and the converted color data corresponding to the second target color data.