Evaluation Of Order Statistic Filters Using A Modified Signal To Noise Ratio
Renee L. J. Martens, A.N. Venetsanopoulos · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1989
One major problem in evaluating image filters is the lack of a quality measure that is objective and quantitative yet reflects the demands of the human visual system. This study will use two new quality measures that will attempt to address this problem. The peak-to-peak signal-to-noise ratio (PSNR) for edge areas will demonstrate how the edge areas are affected by the different filters while the PSNR for the homogeneous areas will similarly demonstrate the effect in the homogeneous areas. In some applications the edge areas are more important then the homogeneous areas and vice-versa. The results of the research, therefore, contribute to the study of filter effectiveness in terms of specific applications. In addition the paper demonstrates the effect of different image types on the performance of order statistic filters. The study compares the following: 1) the adaptive trimmed mean filter [1], 2) the signal adaptive median filter [2], 3) the adaptive double window modified trimmed mean filter [3], 4) the adaptive window edge detecting median filter [45], 5) the median filter [6], 6) the a -trimmed mean filter [7], and 7) the contraharmonic mean [8]. The seven filters are compared using the PSNR, the PSNR for edge areas and the PSNR for homogeneous areas. The edge areas and homogeneous areas is determined through the use of a simple range edge detector on the original noise free image. Four different images are used for comparison: 1) 'Lenna', 2) 'Geometrical', 3) 'Harbor' and 4) 'Jones'. Three noise types will be used: 1) impulsive, 2) additive and 3) a mixture of impulsive and additive noise.