1. A computer readable medium encoded with an image data structure for facilitating the rendering of an image by an image processing device, comprising: a first data field operable to store opaque data, the opaque data indicating whether image data is transparent or opaque; and one or more pixel data fields associated with the first data field, the one or more pixel data fields operable to store first pixel data in each pixel data field when the opaque data indicates an image is opaque, and operable to store second pixel data and transparency data in each pixel field when the opaque data indicates that the image is transparent.