1. A system adapted to render an image file that represents an image for output by a printing device, the printing device having a predetermined halftone, the system comprising: an input module that obtains a page description of an image to be output by the printing device; a mask detection module that detects the presence of one or more level masks in the page description, wherein each of the one or more level masks is designed to impart a corresponding transparency level to one or more objects in the page description; a level determination module that determines the one or more corresponding transparency levels of the one or more detected level masks; a custom mask module that obtains one or more custom masks that correspond to the same one or more transparency levels as the one or more detected level masks, wherein the one or more custom masks are designed based on the predetermined halftone of the printing device; and a mask replacement module that replaces the one or more level masks in the page description with the corresponding one or more custom masks.