1. A system for formatting data for a printhead, comprising: a. a system data store for storing: i. a raster image, ii. a source data address for indicating a location within the system data store where a portion of the raster image is stored, iii. a first shift amount, iv. a mask for specifying which pixels within the raster image should be printed, and v. a mask shift amount; and b. a system processor coupled to the system data store, wherein the system processor performs the steps of: i. storing in the system data store a first portion of the raster image located at the source data address, as offset by the first shift amount, ii. storing in the system data store a masked version of the first portion of the raster image, using the mask offset by the mask shift amount, and iii. outputing the masked version of the raster image to the system data store.