Efficient Image Transmission using Transform-based Compression Techniques

A. Alasaad, H. Behairy, and M. Khorsheed (Saudi Arabia)

Keywords

Image Transmission, Image Compression, Channel Cod ing, ErrorControl Coding, DCT, DWT, Wavelets, PCGC.

Abstract

We present a system for still image transmission over noisy satellite channels. The system couples image compres sion together with error control codes to improve the re ceived image quality while maintaining its bandwidth re quirements. In this paper we extend our previous work on Discrete Cosine Transform (DCT) based image compres sion in noisy channels. We evaluate the performance of Discrete Wavelet Transform (DWT) based image compres sion and compare it to its equivalent DCT-based. We show how DWT-based image compression outperforms DCT based both in noise-free and noisy channels. We also show how using a class of Forward Error Correction called Parallel Concatenated Gallager Codes (PCGC) can signifi cantly improve the quality of the transmitted image in noisy channels. Despite the bandwidth expansion caused by in troducing PCGC, the protected image occupies a smaller bandwidth now by compressing the image before applying PCGC. Evaluation results show improvement in the over all system including bandwidth requirements compared to similar systems with different coding schemes.

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