Koninklijke Philips Corporation N.v.

Brian Gibson

David E Penna

Nikolaos Economidis

A technique for encoding pixel color values for a full or partial digital video image frame has each different color within the image being assigned a color value. The most common one of the colors ( ) within the frame or frame segment is identified, and runs of at least three successive pixels of that predominant color are encoded as a first code ( ) indicating a run and a second code indicating the run length (LL). Runs of successive pixels having a color ( ) other than the predominant color ( ) are encoded as successive iterations of a code containing only the respective color value when the run length is less than or equal to a threshold value and as a first code indicating a run ( ), a second code indicating a run length (LL), and a third code (CC) identifying the color value when the threshold value is exceeded.

Pixel color value encoding and decoding

In an image processing system for providing two-dimensional pixel images comprised of a purality of polygonal image primitives and a background, the polygonal image primitives representing a three-dimensional object, a Z buffer and a color buffer are cleared by the steps of rendering image primitives relating to foreground in the color buffer ( ) and the Z buffer ( ); and subsequently scanning the Z buffer and for each pixel, if the Z value is a predetermined background value such as zero ( ), clearing the corresponding location in the color buffer to background color ( ), and if the Z value is not the predetermined background value, clearing the Z buffer to that predetermined background value ( ). In the method, either a Z buffer or a color value is written during the buffer clearing process, but never both. The pixels may be read from cache in groups, the size of a group being selected to maximize the possibility of all consecutive pixels in a group being either foreground or background pixels. Further bandwidth saving may be achieved by the use of a tile buffer and two output buffers.

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Forest Row, United Kingdom

Brian Gibson