Method and apparatus for compression using reversible wavelet transforms and an embedded codestream
AssigneeRicoh Company, Ltd.
InventorsAhmad Zandi, Edward L. Schwartz, Michael J. Gormish, Martin Boliek
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Abstract
A compression and decompression system in which a reversible wavelet filter are used to generates coefficients from input data, such as image data. The reversible wavelet filter is an efficient transform implemented with integer arithmetic that has exact reconstruction. The present invention uses the reversible wavelet filter in a lossless system (or lossy system) in which an embedded codestream is generated from the coefficients produced by the filter. An entropy coder performs entropy coding on the embedded codestream to produce the compressed data stream.
Claims67
An encoder for encoding input data into a compressed data stream, said entropy coder comprising:
- a reversible wavelet filter transforming the input data into a plurality of coefficients;
- an ordering and modeling mechanism coupled to the reversible wavelet filter, said ordering and modeling mechanism generating an embedded codestream in response to the plurality of coefficients;
- and
- an entropy coder, coupled to the ordering and modeling mechanism, operable to entropy code the embedded codestream to produce the compressed data stream.
An encoder for encoding input data into a compressed data stream, said entropy coder comprising:
- a reversible wavelet filter transforming the input data into a plurality of coefficients;
- an ordering and modeling mechanism coupled to the reversible wavelet filter, said ordering and modeling mechanism performing embedded quantization on the plurality of coefficients to generate an embedded codestream in response to the plurality of coefficients;
- and
- a binary entropy coder, coupled to the ordering and modeling mechanism, operable to binary entropy code the embedded codestream to produce the compressed data stream.
A method of encoding input data into a compressed data stream comprising the steps of:
- transforming the input data into a plurality of coefficients using a reversible wavelet filter;
- generating an embedded codestream in response to the plurality of coefficients;
- and
- entropy coding the embedded codestream to produce the compressed data stream.
A method of decoding an encoding data stream comprising the steps of:
- retrieving coded data for a coding unit;
- modeling a bit of each coefficient with a context model and an entropy decoder;
- applying an inverse wavelet filter on the coefficients starting with the coarsest level.
A decoder for decoding encoded data comprising:
- an entropy decoder for entropy decoding the encoded data into a codestream of coefficients;
- a inverse reversible wavelet filter coupled to the entropy decoder for transforming the codestream of coefficients into reconstructed data.
Dependencies are inferred from the claim text.