Design And Implementation Of Ultrasonic Image Despeckling System Based On Nonlocal Means Filtering

It is known to all that medical ultrasound imaging is one of the most popular diagnostic techniques in the modern medical system.However,due to drawbacks in ultrasonic imaging mechanism and system design,some noise will inevitably be introduced into images.Among them,the most serious noise in contaminated ultrasound images is speckle noise.The appearance of such speckle noise reduces the resolution of the image,which interferes with the doctor's correct diagnosis for the patient's disease and also limits the development of computer-aided diagnostic techniques.Therefore,removing speckle noise and preserving the edge details of the image is an important prerequisite for doctor's diagnosis or some advanced image processing tasks such as tissue segmentation and registration.Considering that non-local means filter algorithm can make full use of the redundant information of the image,this paper presents the filtering algorithms adapting to reduce speckle noise based on Bayesian model of non-local means filter.The main work is as follows:1?The Bayesian non-local means filtering model is studied in detail,and combined with the statistical characteristics of speckle noise,the mathematical form of the model is proposed,which lays the foundation for the design of iterative filtering despeckling algorithm.2?An iterative filtering despeckling algorithm is designed.The first iteration with the noisy image itself being the input of the filtering model generates an initial estimator which then further offers a better input of the filtering model.The iteration stops when the maximum number of iterations is reached,and the satisfying restored image can be obtained.The time complexity of the iterative filtering despeckling algorithm is reduced by using block pre-selection and blockwise filtering,and the time for processing an ultrasound image is controlled within a short time.3?An ultrasound image despeckling software system is developed using Visual Studio software platform and OpenCV Vision Library.The despeckling algorithm is realized in it,which can simulate speckle noise generation for any image and reduce the speckle noise,or remove speckle noise for a real ultrasonic image.