Image transmission over noisy channels with variable-coefficient fixed-length coding scheme

A variable-coefficient fixed-length coding scheme is proposed for wavelet-based image transmission over noisy channels. Multiple subband coefficients are grouped into an extended source symbol and coded as a fixed-length code word such that the extended source symbols have almost the same probabilities. Part of the codebook is fixed based on the observation of the coefficient spatial distribution patterns in each subband to alleviate the transmission of the codebook. The remaining code positions within the fixed-length codebook can be utilized to combat channel errors by carefully arranging the code positions or be filled with other frequently appearing coefficient sequences to achieve higher compression ratio.