Adaptive fuzzy hexagonal bilateral filter for brain MRI denoising

Abstract

Magnetic resonance image (MRI) plays a crucial role in medical applications for visual analysis and processing. Rician noise which arises from the MRI during acquisition can affect the quality of the image. This crucial issue should be addressed by denoising method. The proposed adaptive rician noise removal based on the bilateral filter using fuzzy hexagonal membership function improves the denoising efficiency at various noise variances and preserves the fine structures and edges. The fuzzy weights were obtained with the local mean (μi) and global mean (μg) by constructing hexagonal membership function for local order filter and bilateral filter. Bilateral filter is used to preserve the edges by smoothening the noises in MRI image and local filter is used to preserve the edges and retrieve the structural information. Brain MRI images are restored by multiplying its corresponding fuzzy weight with the restored image of local order filter and bilateral filter. Experiments on synthetic and clinical Brain MRI data were done at different noise levels by the proposed method and the existing methods. The result shows that the proposed method restores the image in better visual quality and can be well utilized for the diagnostic purpose at both low and high densities of rician noise.