An adaptive BTC-VQ image compression algorithm operating at a fixed bit-rate

Abstract

Block Truncation Coding-Vector Quantization (BTC-VQ) is a simple, fast, non-adaptive block-based image compression technique with a moderate bit-rate of 1.0 bit/pixel. By making the algorithm adaptive it is possible to further lower the bit-rate. In this paper we show how the algorithm may optimally adapt itself to the local nature of the picture while keeping the bit-rate fixed at a given value. Examples are given of image compressions down to 0.65 bit/pixel. We further show how the adaptation process may be carried out in a fast and efficient manner.