Semi-implicit scheme based nonlinear diffusion method in ultrasound speckle reduction
Because of the presence of speckle noise in ultrasound image, the image resolution is not so desirable. Recently, a class of anisotropic diffusion based methods has been developed, which can reduce the speckle noise, and at the same time, preserve and enhance the edge/borders. speckle reducing anisotropic diffusion (SRAD) is an important representative of these methods. It is an explicit scheme based method with very slow processing speed due to the severe restriction in time step size (TSS), and it is sensitive to noise due to its small window size to calculate ratio of mean and variance. Using semi-implicit scheme (e.g., additive operator splitting AOS) method to discretize SRAD (called ASRAD), we could use large TSS for speed-up. However, artifacts brought by ASRAD degrade the image. In this paper, we aim to solve above problems. Our method could be generalized to solve other explicit scheme based nonlinear diffusion speckle reduction methods.