A method for rendering a computer image includes, for each pixel of a plurality of N×M pixels forming a tile, determining a plurality of masks for the pixel, wherein N and M denote integers larger than 1, and wherein each mask identifies a respective subset of the pixels that are equidistant from the pixel and located at a respective distance from the pixel. The method further includes: determining an active mask for the tile, the active mask identifying active pixels of the pixels, each of the active pixels being determined as having color information; based on the active mask, identifying an empty pixel of the pixels, the empty pixel lacking color information; and determining at least a first nearest active pixel that is nearest to the empty pixel. The determining includes comparing the active mask with at least one mask of the masks for the empty pixel.