Speckle noise reduction in ultrasound images using modified hybrid median filter

Abstract

Ultrasound imaging is a widely used in medical diagnosing imaging techniques. Because of following: low cost, painless and considered harmless to the patients. However, the main problem facing ultrasound images is speckle noise, which is inherent multiplicative noise that reduces the overall quality of the images in term of resolution and contrast. Edge detection in medical image is an important task for object recognition of the human organs, and it is an essential pre-processing step in medical image segmentation and 3D reconstruction. Successful results of image analysis extremely depend on edge detection. Up to now many edge detection methods have been developed. But, they are sensitive to noise. So, this thesis proposes, a new method of speckle noise reduction with ability to enhancing image edges, i.e. a modified version of hybrid median filter, it works in sub-windows and it is divided it vertical, horizontal and diagonal regions. Then it computes the mean and the median value of diagonals element, and maximum of vertical and horizontal elements in a moving window. After that the two values are compared with the central pixel and the median value of the three values will be the new pixel value. Ultimately six edge detection techniques were applied using Proposed Method and hybrid median filter images. The experimental result shows that by modifying the hybrid median filter, and combining it with Roberts edge detection operator this gives better edge preserving characteristics than hybrid median filter, edge detection helps in extracting useful features for pattern recognition. and the proposed method is highly effective in noise separation on compression other filters using image quality evaluation metrics.