Edge Preserved Enhancement of Ultrasound Medical Images Using Multiscale Ripplet Transform Based OGS Algorithm

Edge preserved enhancement is of great interest in ultrasound medical images. Speckle is a main factor which affects the quality; contrast resolution and most importantly texture information present in ultrasound images and can make the post-processing difficult. In this paper, a new algorithm based on discrete ripplet transform (DRT) and overlapping group shrinkage (OGS)/thresholding scheme using bilateral filter (BLF) is presented. The DRT, a new efficient multiscale geometric representation with the different features of anisotropy, localization, directionality and multiscale, is employed to provide effective representation of the noisy coefficients. Bilateral filtering and OGS thresholding scheme are applied to DRT coefficients to improve the despeckling efficiency with this consideration that blurring associated with the speckle reduction should be less and fine details are enhanced properly for the enhancement of ultrasound images. The proposed algorithm helps also to improve the visual quality of ultrasound medical images by reducing the speckle significantly while preserving the edge features. Experimental results show that the performance of proposed algorithm for noise suppression, feature and edge preservation in terms of different performance measures.