High-rate quantization and transform coding with side information at the decoder

We extend high-rate quantization theory to Wyner–Ziv coding, i.e., lossy source coding with side information at the decoder. Ideal Slepian–Wolf coders are assumed, thus rates are conditional entropies of quantization indices given the side information. This theory is applied to the analysis of orthonormal block transforms for Wyner–Ziv coding. A formula for the optimal rate allocation and an approximation to the optimal transform are derived. The case of noisy high-rate quantization and transform coding is included in our study, in which a noisy observation of source data is available at the encoder, but we are interested in estimating the unseen data at the decoder, with the help of side information.We implement a transform-domain Wyner–Ziv video coder that encodes frames independently but decodes them conditionally. Experimental results show that using the discrete cosine transform results in a rate-distortion improvement with respect to the pixel-domain coder. Transform coders of noisy images for different communication constraints are compared. Experimental results show that the noisy Wyner–Ziv transform coder achieves a performance close to the case in which the side information is also available at the encoder.