Elimination of subband-coding artifacts using the dithering technique

Subband image coding produces several types of artifacts, including contouring and ringing. We use the dithering technique to remove these artifacts. By dithering the subband signals, we can replace signal-dependent artifacts with signal-independent white noise which is less annoying to human eyes. The subjective quality of the coded images is hence improved. In addition, signal-independent white noise can be easily removed by existing noise-reduction methods. The dithering technique can also be applied to transform coding, including the discrete cosine transform, to remove the blocking artifact. Experiment results that illustrate the effectiveness of dithering are given