When a single pixel is displayed by four color sub-pixels, or R (red), G (green), B (blue), and G, in a Bayer array, this invention sets the scaling rate of a scaling process to 3/2 times when executing the scaling process on image data having three color components, or R, G, and B, and then executes a color conversion process for finding four color components from the three color components; after this, a decimation process for reducing the number of pixels is carried out. Setting the scaling rate of the scaling process to an integer proportion, moirés caused by the scaling process can be made less noticeable. Note that it is desirable for the scaling rate of the scaling process to be close to √2 and for the denominator of the integer proportion to be lower.