Coding gain and spatial localisation properties of discrete wavelet transform filter banks for image coding
We consider coding gain and spatial localisation properties of DWT filters for still image compression. A high coding gain, relative to a highly correlated image source model, ensures that slowly varying image areas are coded efficiently. A low spatial width ensures that anomalies such as edges can also be coded efficiently. By considering an image model we design filters that simultaneously exhibit a high coding gain and low spatial width. Several existing filters are also examined. Several filter sets are then compared for image compression using a DWT and a JPEG type quantisation method. The filters with the best spatial width and coding gain properties outperform the other filters at low bit rates, especially with regard to ringing distortion. >