Browse Prior Art Database

Arithmetic Compression Code Control Parameter Approximation

IP.com Disclosure Number: IPCOM000052052D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11

Publishing Venue

IBM

Related People

Authors:
Helman, DR Langdon, GG Rissanen, JJ [+details]

Abstract

This invention relates to a method for ascertaining the nearest integer value of a control parameter k (skew parameter) used in arithmetic compression coding as derived from the counts of the ones and zeros of an input bit stream. This approximation starts with the observation that the ratio of the number of counts of the least probable symbol (lps) to the total symbol count is approximately equal to 2/-k/. It is desired that the count be converted into k without actual division. In contrast, the prior method [*] used a difference in leading zeros between the count of the number of the zeros and the count of the number of ones in order to approximate k. The method of this invention is to initially approximate k and utilize it as a running incrementable/decrementable parameter.