Data string compression using arithmetic encoding with simplified probability subinterval estimation

摘要

An improved method of generating a compressed representation of a source data string, each symbol of which is taken from a finite set of m+ 1 symbols, a.sub.o to a.sub.m. The method is based on an arithmetic coding procedure wherein the source data string is recursively generated as successive subintervals within a predetermined interval. The width of each subinterval is theoretically equal to the width of the previous subinterval multiplied by the probability of the current symbol. The improvement derives from approximating the width of the previous subinterval so that the approximation can be achieved by a single SHIFT and ADD operation using a suitable shift register.