Patent ID: 7734105
Filing Date: 2010-06-08
Classification: H04N

Abstract:
1. A method of compressing an image block comprising multiple image elements, each image element has a respective color comprising multiple color components, said method comprising the steps of: determining a first codeword and a second codeword that are representations of properties of said multiple image elements; providing an index sequence of image element associated indices; selecting a compressing mode from a first compressing mode and a second compressing mode before, during or after determining said first and second codeword and providing said index sequence; and providing a mode index representing said selected compressing mode, wherein if said mode index represents said first compressing mode, said first codeword is a color codeword that is representation of the colors of said multiple image elements, said second codeword is an intensity codeword that is a representation of a set of multiple intensity modifiers for modifying the intensity of said multiple image elements by adding an intensity modifier to the multiple color components of a color representation obtainable based on said color codeword and said index sequence comprises, for each image element in said image block, an intensity index associated with an intensity modifier from said intensity modifier set, and if said mode index represents said second compressing mode, said first codeword and said second codeword are a first color codeword and a second color codeword that are representations of the colors of said multiple image elements, and said index sequence comprises, for each image element in at least a subset of said multiple image elements, a color index associated with said first color codeword or said second color codeword.