A new method for boundary artefact reduction in JPEG 2000

It is well known that tile boundary artefacts occur in wavelet-based lossy image coding. However, until now, their cause has not been well understood. We show that boundary artefacts are an intrinsic feature associated with the common method used to choose the tile size and the type of symmetric extension employed in wavelet-based image decomposition. A novel method of reducing tile boundary artefacts is presented. This method has recently been adopted as part of the JPEG 2000 verification model. In this technique, odd tile sizes of 2/sup N/+1 are chosen rather than the conventional even tile sizes of 2/sup N/. We show that, for the same bit-rate, an image compressed using odd tile length and low pass first convention (OTLPF) has significantly fewer boundary artefacts than an image compressed using even tile sizes.