SAR Image De-noising Based on Dual-tree Complex Wavelet Transform
Yu He · Journal of Zhengzhou Institute of Surveying and Mapping · 2007
The advantages of wavelet transform are that it can analyze signal in time domain and frequency domain respectively and the multi-resolution analysis is similar to Human Vision System(HVS).And now it is well used in de-noising and restoration of SAR images.But there are two disadvantages of DWT,lack of shift invariance and poor directional selectivity for diagonal features.Dual-tree Complex Wavelet Transform(DT-CWT) is a dual-tree biorthogonal DWT with approximate shift invariance,good directional selectivity and perfect reconstruction.DT-CWT is superior to DWT used in image de-noising.In this paper,the decomposition and reconstruction of DT-CWT have been constructed,and the real and imaginary parts of decomposed image have been filtered with local non-linear soft-threshold.Experiment results demonstrate that DT-CWT can filter more speckles and keep edges feature smooth.