Codebook organization to enhance maximum a posteriori detection of progressive transmission of vector quantized images over noisy channels

The authors describe a new way to organize a full search vector quantization codebook so that images encoded with it can be sent progressively and have immunity against channel noise. Due to the codebook organization, the most significant bits (MSBs) of the codeword index are most important to the overall image quality and are highly correlated. Simulations show that the effective channel error rates of the MSBs can be substantially lowered by implementing a maximum a posteriori (MAP) detector similar to one suggested by N. Phamdo and N. Farvardin (1992). The performance of the scheme is close to that of pseudo-Gray coding at low bit error rates and outperforms it at higher error rates.<>