| 摘要 |
FIELD: information technology. ^ SUBSTANCE: block transform-based digital media codec more efficiently encodes wide dynamic range transform coefficients in two parts: a normalised coefficient and bin address. The normalised coefficient relates to a grouping of coefficient values of the wide dynamic range into bins, whereas the bin address is an index of the coefficient value within a bin. With careful selection of the bin size, the normalised coefficients have a probability distribution roughly similar to narrow range transform coefficients, which is better suited to variable length entropy coding. The codec uses variable length entropy coding to encode the normalised coefficients in a 'core' of the compressed bitstream, and fixed length coding to encode the bin address as a separate optional layer that can be omitted. The codec further adaptively varies the bin size of the grouping based on a backward adaptation process to adjust the normalised coefficients towards a probability distribution well suited for efficient variable length entropy coding. ^ EFFECT: efficient compression of wide-range transform coefficients. ^ 29 cl, 12 dwg |
