Image compression scheme for network transmission

In this thesis a scheme is proposed for still image compression for realtime transmission over a packet switched network. A layered image compression scheme based on the quad tree decomposition technique (QTD) is developed. The image is decomposed into three layers, where layers are added to a base image to incrementally improve the quality of the reconstructed image. The performance of the QTD is enhanced by adding a DCT algorithm with adaptive bit allocation and a region of interest methodology. The quad tree is then extended to a nona tree whereby pixel blocks of size 3 x 3 are processed instead of 2 x 2. Results are presented to provide a visual subjective perception of the proposed scheme. Depending on the number of layers transmitted, the compression gains range from 60:1 to 16:1. It is shown that the proposed scheme exhibits graceful degradation of the reconstructed image and some error tolerant capabilities. http://archive.org/details/imagecompression109457538 Singapore Ministry of Defense author (civilian).