Modified block-matching 3-D filter in Laplacian pyramid domain for speckle reduction

The Laplacian pyramid-based block-matching 3-D filtering (BM3D) is proposed (LPBM3D) for despeckling the speckle image. For BM3D in each pyramid layer, the criterion used to collect blocks in the 3-D groups to the actual data statistics is devised. An adaptive wavelet thresholding operator that depends on both noise level and signal characteristics is proposed. The performance of the proposed LPBM3D method has been compared with the state-of-the-art methods, including the recently proposed nonlocal mean (NLM) and BM3D method. Experimental results show that the visual quality and evaluation indexes outperform the other methods with no edge preservation. The proposed algorithm effectively realizes both despeckling and edge preservation.