Chinese Journal of Magnetic Resonance

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An Edge Enhancing Scheme for Non-Local Means Denoised MR Images

YAN Xu, ZHOU Min-Xiong, XU Ling, LIU Wei, YANG Guang*   

  1. Shanghai Key Laboratory of Magnetic Resonance, Physics Department, East China Normal University, Shanghai  200062, China
  • Received:2012-06-04 Revised:2012-07-09 Online:2013-06-05 Published:2013-06-05
  • About author:Yan Xu(1984-),male,born in Hubei province,PhD student,specializing in MRI.*Corresponding author: Yang Guang,Tel: +86-21-62233873,E-mail:gyang@phy.ecnu.edu.cn.
  • Supported by:

    Supported by Science and Technology Commission of Shanghai Municipality (08DZ1900700).

Abstract:

Non-Local Means (NLM) is an excellent filter for noise removal and has been applied successfully to MR images. However, just like every other denoising filters, it inevitably blurs fine structures in images to certain extent. In this paper, we propose to combine high frequency components (HFC) extracted from the original image with the NLM-denoised image to recover the lost details. High frequency components, which contain rich edge information, are extracted with a multiresolution method based on Laplacian Pyramid. Then the HFCs are combined with the image denoised by NLM using a continuous edge map produced by an edge detector which is based on SUSAN operator and modified to be more robust to noises. The experiment showed that the proposed scheme achieved good suppression of noise in smooth regions while preserves or even enhances image details. Furthermore, images were enhanced subtly without artifacts that are typical in enhanced images.

Key words: Magnetic Resonance Imaging(MRI), Image enhancing, Multi-resolution enhancing, Edge-Detector, Non-Local Means, Image denoising

CLC Number: