A single exposure method and a double exposure method for reducing mask error factor and for enhancing lithographic printing-process resolution is presented. The invention comprises decomposing a desired pattern of dense lines and spaces in two sub patterns of semi dense spaces that are printed in interlaced position with respect to each other, using positive tone resist. Each of the exposures is executed after applying a relative space-width widening to the spaces of two corresponding mask patterns of semi dense spaces. A factor representative for the space-width widening has a value between 1 and 3, thereby reducing mask error factor and line edge roughness.