Progressive transmission of images using block wavelet transform

The progressive image transmission (PIT) allows an approximate image to be built up quickly with details to be transmitted progressively through several passes over the image. In this paper, we propose an efficient PIT scheme in which two-channel conjugate classified vector quantization (TCCVQ) is applied to the subvectors formed from the classified wavelet transform blocks. The use of these two techniques allows efficient bit-rate reduction and reduces coding artifacts (i.e., blocking effects and distorted edges) at lour bit rates. The adaptive classification technique is utilized to classify an image into four perceptually distinct categories based on their ac energies. Simulation results show that the first stage image already provides an useful approximation and reconstructed images, at the intermediate levels, preserve fine and pleasant qualities based on both subjective and mean squre error criteria compared to other schemes.