Patent ID: 6278801
Filing Date: 2001-08-21
Classification: H03M,H04N

Abstract:
An image coding method in which variable length coding process is performed to transform coefficients by referring to a variable length code table comprising a plurality of reference events, consisting of Last, Run, Level, paired with reference variable length codes, wherein the variable length coding process comprises:obtaining an input event consisting of Last, Run, Level, corresponding to said transform coefficients,comparing said input event with a reference event in said table, and if said input event accords with said reference event, outputting a variable length code corresponding to said reference event,obtaining a first transformed input event, if said input event does not accord with any reference events in said table, by transforming the Level value of said input event using a predetermined function,comparing said first transformed input event with a reference event in said table, and if said first transformed input event accords with said reference event, outputting a control code and a second mode code followed by a variable length code corresponding to said reference event,and if said first transformed input event does not accord with any reference events in said table, obtaining a second transformed input event, by transforming the Run value of said input event using a predetermined function,comparing said second transformed input event with a reference event in said table, and if said second transformed input event accords with said reference event, outputting a control code and a third mode code followed by a variable length code corresponding to said reference event,and if said second transformed input event does not accord with any reference events, outputting a control code and a first mode code followed by a fixed length code corresponding to said input event by referring to a fixed length code table.