Using wavelet for filtering speckle and extracting edge from ocean SAR image

摘要

Due to the SAR generates images with coherent processing of the scattered signal, producing the images usually highly susceptible to speckle effects, a new mother wavelet function was constructed and further formed a wavelet function family. It possesses the narrow band in the low-pass and its wave shape distributes on the symmetry of impulsion response coefficient in time domain, which enable it has an excellent performance in dealing with wave signal. With the original ocean SAR image that its size is 1024*1024, the Wiener filter algorithm was adopted and the new wavelet filter was applied in order to suppress speckle and then to exact the edge information with the Prewitt filter algorithm. Compared several popular mother wavelet functions with the created wavelet function as the same processing method and uniform image, the result shows that the new mother wavelet function is better than other ones in the preserving image's edge information, though its performance is not good as well as compared ones in the suppressing speckle. Based on the above discussion, it is obvious that the wavelet filter is a very effective method in speckle filtering and the constructed mother wavelet function plays an important role in extracting SAR image edge feature information.