Removal of statistical redundancy

Redundant information may be removed by reversible or lossless coding, that allows for perfect restoration of the original data in the decoder.

Exploitation of the results obtained by the information theory: Removed is redundant information that may be restored from other transmitted information available in the decoder.

Entropy coding

where H is entropy, p_i - relative frequency of occurance of value i, summing is performed for all possible signal values i.

Entropy coding techniques

Using entropy coding we can not achieve bpp ratio lower than entropy.

Huffman coding - shorter codewords are assigned to the more frequent symbols.

Golomb-Rice coding - special version of variable length coding optimum for variables with exponential probability distributions.

Arithmetic coding - more complicated coding that assigns bitstreams to sequences of symbols.