Patent ID: 7305138

Claim:
An image encoding apparatus for encoding an image signal according to a JPEG2000 standard, comprising: a wavelet converter which acquires a plurality of conversion coefficients by performing wavelet conversion on said image signal; a modeling unit which generates a plurality of symbols representing said plurality of conversion coefficients and a plurality of contexts by performing a modeling process on said plurality of conversion coefficients obtained by said wavelet converter; and an arithmetic encoder which performs arithmetic encoding using said plurality of symbols and said plurality of contexts generated by said modeling unit, wherein said arithmetic encoder discriminates whether each of said symbols is an MPS (More Probable Symbol) or LPS (Less Probable Symbol), executes CODEMPS in a case where it is discriminated that said symbol is an MPS and executes either CODEMPS or CODELPS according to a predetermined condition in a case where it is discriminated that said symbol is an LPS, and wherein the predetermined condition is based on a probability of occurrence of an LPS corresponding to a current context.