Multiscale Compound PDE Approach for Despeckling ofUS/SAR/OCT Images

Abstract

In this work, a compound PDE approach is proposed in multiscale for speckle reduction of diagnostic Ultrasound (US) images, Satellite aperture radar (SAR) images and optical coherence tomography (OCT) images. In denoising process, it is always difficult to preserve discontinuities in one part of the image and simultaneously recovery of smooth areas in other part of image. Hence, combining different algorithms is the only way to improve the image restoration capability. In this paper, coupled PDE, complex diffusion and second order non linear diffusion are applied to layers 1, 2 and 3 of Laplacian pyramid respectively. . In each pyramid layer, using robust median estimator, gradient threshold is estimated automatically. To limit the number of iterations, mean absolute error (MAE) between two adjacent diffusion steps is used as stopping criteria. Quantitative results on synthetic data and simulated phantom show the performance of the proposed method over state of the art methods. Results on real images demonstrate that the proposed method effectively suppresses the speckle and preserves edges & structural details of the image.