Digital Path Approach Despeckle Filter for Ultrasound Imaging and Video.

Marek Szczepański,Krystian Radlak

doi:10.1155/2017/9271251

Marek Szczepański, Krystian Radlak

Open Access

https://doi.org/10.1155/2017/9271251

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Abstract

We propose a novel filtering technique capable of reducing the multiplicative noise in ultrasound images that is an extension of the denoising algorithms based on the concept of digital paths. In this approach, the filter weights are calculated taking into account the similarity between pixel intensities that belongs to the local neighborhood of the processed pixel, which is called a path. The output of the filter is estimated as the weighted average of pixels connected by the paths. The way of creating paths is pivotal and determines the effectiveness and computational complexity of the proposed filtering design. Such procedure can be effective for different types of noise but fail in the presence of multiplicative noise. To increase the filtering efficiency for this type of disturbances, we introduce some improvements of the basic concept and new classes of similarity functions and finally extend our techniques to a spatiotemporal domain. The experimental results prove that the proposed algorithm provides the comparable results with the state-of-the-art techniques for multiplicative noise removal in ultrasound images and it can be applied for real-time image enhancement of video streams.

Highlights

Medical ultrasound is an imaging technique widely used in the diagnosis and assessment of internal body structures, and it plays a key role in treating various diseases
Speckle noise is a signal-dependent and non-Gaussian multiplicative image distortion. Such noise is generally more difficult to remove than additive noise [23]. This type of distortion appears in sonar, laser, and synthetic aperture radar (SAR), and it depends on the structure of the material being imaged and various acquisition parameters [24]
Previous research has demonstrated that the best results are obtained in the presence of impulsive Gaussian as well as of mixed-type noise for the self-avoiding path (SAP) model, but our experiments suggest that in the case of ultrasound images, the greatest results are achieved for the so called escaping path model (EPM); the new filter will be denoted as the escaping path filter (EPF)

Summary

Introduction

Medical ultrasound is an imaging technique widely used in the diagnosis and assessment of internal body structures, and it plays a key role in treating various diseases. An accurate analysis of ultrasound images and an appropriate diagnosis are difficult due to the fact that the images are contaminated with characteristic granular structures called speckle noise, which deteriorates contrast and hinders the identification of important image details [1]. The main aim of image denoising is to remove the noise, while preserving the important details. According to the works presented in [3,4,5], one of the most promising results for ultrasound images was obtained with algorithms based on anisotropic diffusion techniques [6] and the idea of nonlocal means [7,8,9,10,11]. Majority of them were designed for static images, and not much attempt has been made to video by considering temporal coherence

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