On the Heegard-Berger problem with common reconstruction constraints

In lossy source coding with side information at the decoder (i.e., the Wyner-Ziv problem), the estimate of the source obtained at the decoder cannot be generally reproduced at the encoder, due to its dependence on the side information. In some applications this may be undesirable, and a Common Reconstruction (CR) requirement, whereby one imposes that encoder and decoder be able to agree on the decoder's estimate, may be instead in order. The rate-distortion function under the CR constraint has been recently derived for the point-to-point (Wyner-Ziv) problem. In this paper, this result is extended to the Heegard-Berger (HB) problem and to its variant with cooperating decoders. Specifically, for the HB problem, the ratedistortion function is derived under the assumption that the side information sequences at the two decoders are stochastically degraded. The rate-distortion function is also calculated explicitly for the special case of binary source and erased side information with Hamming distortion metric. The rate-distortion function is then characterized also for the HB problem with cooperating decoders and physically degraded side information.