Codeword orientation: an improved subband coding/vector quantization scheme for image coding
Nabil M. Akrout · Optical Engineering · 1994
A new procedure is proposed for image compression as an improvement on vector quantization of subbands. Codewords with vertical and horizontal shape are used to vector-quantize the high-frequency subimages obtained from a multiresolution analysis scheme. The codeword shapes take into account the orientation and resolution of each subband detail to preserve edges at low bit rates. Their sizes are defined according to the correlation distances in each subband for the horizontal and vertical directions.