Height conversion matrices for determining heights of halftone dot convexities are generated based on raster image data. Based on the height conversion matrices and binary image data, amount-of-exposure data are generated in order to produce a printing relief plate in which the halftone dot convexities have heights at a plurality of height levels in a screen tint region, which is formed based on the binary image data. Based on the amount-of-exposure data, a printing plate material is exposed to a light beam, thereby producing a printing relief plate.