A comparison of vector quantization subband and transform coding of imagery

Transform image coding using scalar quantization, pyramid vector quantization (PVQ), and generalized Lloyd algorithm vector quantization (VQ) and subband image coding using scalar quantization and pyramid vector quantization are considered. In a simulation study at low bit rates (0.5 bit/pel) the transform VQ coder generally provided the largest peak-signal-to-noise ratio (PSNR), although the PVQ subband coder was superior for some images. At larger encoding rates (for which, because of complexity, the generalized Lloyd algorithm VQ was not considered) the scalar-quantizer subband coder generally yielded larger PSNR than did the scalar-quantizer transform coder. The PVQ transform and subband coders provided similar values of PSNR, but the subband coded image had less blockiness than the transform-coded image