Multi-Pass Unsymmetric Trimmed Median Filter for Salt-and-Pepper Noise Removal

摘要

Restoration of original image corrupted with high density salt-and-pepper noise is still a challenging task. In this letter, we propose here a new method; Multi-Pass Unsymmetric Trimmed Median Filter (MPUTMF) [versions 'a' and 'b'], to restore an image affected with high density salt-and-pepper noise, with better edge preservation. The MPUTMF_a can do the restoration within two passes over the noisy image using the preprocessed pixels obtained in the same pass, where as MPUTMF_b can take up to six passes over the noisy image for restoration without using the preprocessed pixels. MPUTMF_b is computationally efficient on single core processor systems where as MPUTMF_b is well suited to be implemented on parallel processing systems or GPUs to achieve higher computational efficiency. The proposed methods are compared with conventional as well as advanced algorithms like Median Filter (MF), Adaptive Median Filter (AMF), Efficient Decision Based Algorithm (EDBA), Improved Decision Based Algorithm (IDBA) and Modified Decision Based Unsymmetric Trimmed Median Filter (MDBUTMF). The experimental analysis (visual and quantitative) shows that our method gives better results on images affected with high density salt-and-pepper noise. Peak Signal-to-Noise Ratio (PSNR) and Image Enhancement Factor (IEF) are used for quantitatively evaluating the results of proposed algorithm(s).