Pyramid median filtering by block threshold decomposition
Hongbing Zhou, Bing Zeng, Yrjo A. Neuvo · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1991
In this paper, we first introduce the block threshold decomposition (BTD) which can be regarded as a compact form of standard threshold decomposition. The proposed BTD will produce multilevel threshold signals and applies to both discrete and continuous valued signals. Based on BTD, we then introduce a new digital filtering approach, the pyramid median filtering, which consists of a group of median filters, each operating on a BTD signal, and whose window masks form some kind of a pyramid. According to prior knowledge or estimates of the detail distributions and noise characteristics in the received signal or image, it is possible to choose the form of pyramid in order to best accomplish the task at hand. Some properties of the pyramid median filters are analyzed. Application of them to image restoration in impulsive noise shows that this approach provides a better performance than standard median filters.