Automatic Brain Magnetic Resonance Image Denoising Using A GPU-Based Trilateral Filter

Noise removal is one of the fundamental and essential tasks within image processing. In medical imaging, finding an effective algorithm that can remove random noise in magnetic resonance (MR) images is important. This thesis proposes an effective noise reduction method for brain MR images. The proposed is based on the trilateral filter, which is a more powerful method than the bilateral filter in many cases. However, the computation of the trilateral filter is quite time-consuming and the choice of the filter parameters is also laborious. To address these problems, the trilateral filter algorithm is implemented using parallel computing with GPU. The CUDA, an application programming interface for GPU by NVIDIA is adopted, to accelerate the computation. Subsequently, the optimal filter parameters are selected by artificial intelligence techniques. Artificial neural networks and support vector machines associated with image feature analysis are proposed to establish the automatic mechanism. The best feature combination is selected by the t-test and the sequential forward floating selection (SFFS) methods. Experimental results indicated that not only did the proposed GPU-based version run dramatically faster than the traditional trilateral filter, but this automatic system also effectively removed the noise in various brain MR images. We believe that the proposed framework has established a general blueprint for achieving fast and automatic filtering in a wide variety of MR image denoising applications.