MR images are mostly used for clinical diagnosis for their accuracy. Even though the resolution, signal-to-noise ratio and acquisition speed have been increased, the MR images are still getting polluted. Thus, denoising is needed to be done in order to improve the accuracy of both the manual and computer aided diagnostic process. There are number of noises in digital images caused based on the nature of image acquisition or transformation. Rician noise is the kind of noise occurs in MR images. Numerous denoising techniques have been proposed to denoise Rician distribution in MR images. In this paper a survey about noises in digital images, non-local means (NLM) filtering and wavelet based MRI denoising techniques have been done. Finally, a Rician denoising method is proposed using wavelet thresholding and Rician NLM and compared with the existing methods. The PSNR values show that the proposed method yields better results.

Noises, Rician noise, MRI, Non local means, wavelet thresholding, PSNR.

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Authors Profile
T. Kalaiselvi is currently working as an Assistant Professor in Department of Computer Science and applications, Gandhigram Rural Institute, Dindigul, Tamilnadu, India. She received her Bachelor of Science (B. Sc) degree in Mathematics and Physics in 1994 & Master of Computer Applications (M.C.A) degree in 1997 from Avinashilingam University, Coimbatore, Tamilnadu, India. She received her Ph. D degree from Gandhigram Rural University in February 2010. She has completed a DST sponsored project under Young Scientist Scheme. She was a PDF in the same department during 2010-2011. An Android based application developed based on her research work has won First Position in National Student Research Convention, ANVESHAN-2013, organized by Association of Indian Universities (AUI), New Delhi, under Health Sciences Category. Her research focuses on MRI of human Brain Image Analysis to enrich the Computer Aided Diagnostic process, Telemedicine and Teleradiology Technologies.

N.Kalaichelvi received her Bachelor of Sciences (B.Sc) degree in Physics in 2007 and Master of Computer Science & Applications in 2010 from Gandhigram Rural University, Dindigul, Tamilnadu, India. She received her Master of Philosophy (M.Phil) degree in Computer Science in 2013 from Madurai Kamaraj University, Madurai, Tamilnadu, India. She was working as Assistant Professor from July 2010 – May2012 and from July 2015 – March2016 in the Centre for Geoinformatics, Department of Rural Development, Gandhigram Rural Institute – Deemed University, Dindigul, Tamilnadu, India. She was working as Assistant Professor from June – 2014 to June -2015 in the Department of computer Science in Prince Shri Venkateshwara Arts and Science College, Gowrivakkam, Chennai, Tamil nadu, India. Currently she is pursuing Ph.D. degree in Gandhigram Rural Institute – Deemed