Weighted D filtering

In this paper, we have proposed a new type of filter which has the most desirable properties of an image smoothing filter. These properties are (1) Robust smoothing efficiency. (2) Edge preservation. and (3) Thin-line detail preservation. The new filter is related to Hodges-Lehman D filter, which is the median of averages of symmetrically placed order statistics. Though it has robust smoothing efficiency. D filter cannot preserve edges or thin-line details. It is shown in this paper that by incorporating a subsampling scheme derived in this paper with the robust D filtering process, the edges as well as the thin-line details can be preserved. The new filter computes its output as the median of weighted averages, instead of plain averages of symmetrically placed order statistics. One particular weighting scheme is considered in details for experiments. The experimental and comparison results are included verifying the useful properties of the proposed filter. To carry out the comparison experiments, some new measures for edge and detail preservation are also proposed in the paper.