Patent ID: 6324305
Filing Date: 2001-11-27
Classification: G06K,H04N

Abstract:
A method of processing digital image data that is composed of multiple superimposed separations, comprising:a) dividing the image data into separations, wherein each separation is composed of light intensity signals in respective discrete locations, each of said light intensity signals having a value which indicates a magnitude of a light intensity of the image data in said separation at said discrete location;b) partitioning each separation by creating a lossless signal plane and a lossy signal plane, said partitioning including, in stated order, the steps of:1) selecting a number of consecutive discrete locations in said separation, said selected locations having respective light intensity values having magnitudes that lie within a pre-determined range;2) calculating an average value for the light intensity values; and3) replacing the values of signals in each of said consecutive discrete locations with said calculated average light intensity value;c) generating a selector map which indicates, for each discrete location in each of said separations, whether a light intensity signal previously located thereon has been placed on said lossless signal plane or on said lossy signal plane; andd) for at least one separation, separately compressing said lossless signal plane and said lossy signal plane in a manner suitable for compressing a type of data contained thereon, wherein said lossy signal plane is composed of a lossy subset of light intensity signals placed in discrete locations that correspond to discrete locations of lossy light intensity signals in said separation, and wherein the signals present in discrete locations on said lossless plane that correspond to discrete locations of lossless light intensity signals in said separation are ignored.