Quantized indexing: beyond arithmetic coding

Summary form only given. Quantized indexing (QI) is a fast and space-efficient form of enumerative (combinatorial) coding (EC). The arithmetic precision, execution time, table sizes and coding delay of EC are all reduced by a factor O(n) at a redundancy below log(e)/2^g-1 bits/symbol (for n input symbols and a g-bit QI precision). Due to its tighter enumeration, QI redundancy is below that of arithmetic coding (AC). The relative compression gains increase for shorter outputs and for less predictable data. Simultaneously, QI is significantly faster than the fastest arithmetic coders, from factor 6 in high to over 200 in low entropy limit (´typically´ 10 to 20 times faster). These speedups are the result of using no coding operations on more probable symbol, fewer and simpler operations on less probable symbol and intrinsically cleaner division of labor between the coder and modeler