Patent ID: 7184599

Claim:
A computer implemented method of compositing a plurality of graphical objects according to a predetermined compositing operation, at least one of the graphical objects being in the form of a compressed representation, the compressed representation comprising one or more coded pixel runs each representing one or more pixel difference values, each of the coded pixel runs having an associated byte code indicating a type for the associated coded pixel run, said method comprising the steps of: decompressing at least one coded pixel run of the compressed representation by: examining the byte code associated with the coded pixel run to determine the type of the coded pixel run; and determining pixel values for the coded pixel run, depending upon the type of the coded pixel run, using the pixel difference values represented by the coded pixel run; and compositing at least a portion of the pixel values determined for the compressed representation with pixel values for at least another one of the graphical objects, in accordance with the predetermined compositing operation, to determine one or more runs of composited pixel values representing the composited graphical objects.