A Study on Fast Removal Method of Impulsive Noise Using Parallel Processing with GPU

The median filter is used to remove image degradation due to impulsive noise. However, since this process is also applied to non-noise pixels, image quality deteriorates. Therefore, the Switching median filter for determining whether the pixel of interest is noise is proposed as an effective method. In addition, several improved methods have been proposed, one of which is Multi-directional Switching Median Filter developed by our laboratory. In this method, detection and removal of noise candidate pixels from four directions are performed as the first step by using a 2x2 detection operator, and density values are corrected by averaging processing of the second step, to restore the image. But, with this method, it takes time to remove noise in the high resolution image. A parallelized method to improve processing speed was developed by allocating pixels of this Multi-directional Switching Median Filter to threads of the GPU. For the difference in noise rate and image size, image denoising was performed on five test images by the proposed method and some conventional methods. In this paper, we report the effectiveness of our proposed method for in high resolution images from the results of comparative experiment.