New finite state vector quantizers for images

Two finite-state vector designs are introduced, namely, side-match vector quantizers (SMVQ) and overlap-match vector quantizers (OMVQ). The underlying ideas of SMVQ and OMVQ are simple and intuitive, and so are their design procedures. They try to avoid large grey-level transitions across pixel block (vector) boundaries which cause the annoying `blockyness´ effect in memoryless VQ. Experimental results show that when they are applied to 512×512 grey-level images, SMVQ and OMVQ can achieve communication-quality reproduction 33.5 dB peak-signal-to-noise ratio (PSNR) at the average rate of 1/2 bit per pixel per image frame and acceptable quality reproduction (30 dB PSNR) at 1/4 bit per pixel. These performances are superior to those of ordinary VQ by more than 3 dB in PSNR. Further, because block boundaries are less visible, the perceived improvement in quality over ordinary VQ is even greater