Image Coding System - A Single Processor Implementation

In this paper we present the design of a still image coder. The system is built around the TNS320 digital signal processor, and is based on the Adaptive Cosine Transform Coding (ACTC) algorithm presented by Chen and Smith [1]. The algorithm is simplified in order to overcome the TMS320 hardware limitations, and computational shortcuts are introduced to speed up coding and decoding processing time. The effect of these modifications on the image quality is discussed. We will also discuss an algorithm for achieving an improved quality on predefined areas of the image while preserving the image compression rate. The system is user-interactive, and it allows the selected output bit rate to be as low as 0.1 bits/pixel.