Image coding based on two-channel conjugate VQ

Abstract

Two-channel conjugate VQ (TCCVQ) has been recently proposed for speech coding. Compared to ordinary VQ, two-channel conjugate VQ requires less computational complexcity and less storage (memory) and is more robust against channel errors. This technique is now extended to image coding. The emphasis in this paper is on the usefulness of the TCCVQ when it is applied to image coding or is combined with a conventional image coding technique. Initial investigation confirms these advantages of two-channel conjugate VQ. For a noise-free channel the performances of both techniques are similar. However, when channel noise is injected, for the same bit rate, images reconstructed based on two-channel conjugate VQ are subjectively more pleasing (have less visible distortion) than those based on ordinary VQ. Both VQ techniques are also applied to a well-known separating mean VQ and are tested for robustness against channel errors. Computer simulations demonstrate the success of the two-channel conjugate VQ technique for image data compression at various bit rates.