Enhancement of Medical Ultrasound Images using Non-Linear Filtering Based on Rational-Dilation Wavelet Transform
Deep Gupta, Barjeev Tyagi · 2012
Abstract— Feature preserved enhancement is of great interest in medical ultrasound images. Speckle is a main factor which affects the quality, contrast resolution and most important texture information present in ultrasound images and can make the post-processing difficult. This paper presents a new computationally efficient enhancement approach which is based on the rational-dilation wavelet transform (RADWT) and non-linear bilateral filter. RADWT, a new family of the discrete wavelet transform for which frequency resolution can be varied, is employed to provide effective representation of the noisy coefficient. Bilateral filter and different thresholding schemes are applied to the noisy RADWT coefficient to improve the denoising efficiency and preserve the edge features effectively with this consideration that blurring associated with speckle reduction should be less and fine details are enhanced properly for the visual enhancement of ultrasound images. The proposed approach helps also to improve the visual quality of the ultrasound images. Experimental results demonstrate the ability of proposed method for noise suppression, feature and edge preservation in terms of different performance measures.