Improving the subjective quality of low bit rate subband/wavelet coded images

Distortion resulting from ringing and/or aliasing is the most objectionable subjective distortion normally appearing in low bit rate subband/wavelet coded images. This paper presents a method for significantly reducing both ringing and aliasing, while still achieving low bit rates and requiring low encoding/decoding complexity. The method employs a new signal dependent two-band filter bank system that employs short FIR filters, yet results in a relatively small loss of aliasing cancellation in its synthesis section. The signal dependent part of the filter bank is the statistical linear prediction used to decorrelate the subband signals. Experimental results indicate that this approach can achieve very good subjective quality at low bit rates