Nonlinear Diffusion Equation for Image Denoising Based on SAR Amplitude and Gradient Information
Zhengming Wang · Journal of Astronautics · 2006
This paper discusses the problem of speckle reducing of SAR image based on nonlinear diffusion equation in order to reduce the noise of SAR image and improve the image's quality.It analyses the amplitude distribution of SAR image,and obtain the diffusivity of nonlinear diffusion equation based on this.The new equation has large diffusivity at the background region with small amplitude to reduce speckle efficiently,but has small diffusivity at the target region with large amplitude to protect targets.To avoid the effect of speckle to amplitude distribution,it uses a nonlinear diffusion equation based on gradient to pre-process the speckle in image before each iteration step,thus get a nonlinear diffusion model for speckle reducing based on SAR amplitude and gradient information.Numerical results show that the images processed by the new model have higher ENL(Equivalent Number of Looks) and higher EKI(Edge Kept Index),and it can reduce the speckle at background region efficiently and hold target feature well without the emergence of false targets.