Speckle Noise Reduction of Ultrasound Images Based on an Undecimated Wavelet Packet Transform Domain Nonhomomorphic Filtering

In this paper, we describe a speckle noise reduction method for ultrasound images based on the undecimated wavelet packet transform (UWPT). Recent wavelet domain despeckling methods always assume speckle noise of ultrasound images as oversimplified distributions and use logarithmic transformation to suppress speckle noise in a homomorphic filtering framework. The proposed method avoids that unnatural assumption and applies a nonhomomorphic filtering function combining the generalized likelihood ratio (GenLik) method and local wiener filter technique to suppress speckle noise in UWPT domain. Experimental results of simulated and clinical images show that this method outperforms several powerful speckle reduction methods in terms of speckle reduction as well as in terms of image detail preservation.