Speckle noise filtering for restoration of coherent shear beam images

Shear beam imaging is a coherent reflective imaging technique, which inherently contains signal-dependent speckle noise with characteristic glints. The removal of the speckle using a minimal number of frames while preserving the glints is the major concern of this paper. In the past, several methods have been used to eliminate this noise. The complexity of the algorithms ranged from a simple nonlinear median filter to complex linear and nonlinear models. Here, fast morphological and wavelet filters are proposed and are shown to remove speckle better than the previous methods. The morphological filters are nonlinear in nature and computationally efficient, thus making them quite attractive. The glint is preserved by its segmentation from each frame prior to speckle removal. This paper describes the morphological, wavelet, and segmentation techniques used and discusses the current results.