Masking Effects of Fine and Coarse Grain Pictorial Noise

摘要

In order to evaluate the potential gain of noise suppression techniques, visual detection of sine wave gratings in images with fine and coarse grain pictorial noise was investigated. Threshold modulations were measured psychophysically as a function of spatial frequency. An important part of the threshold elevations caused by pictorial noise can be explained as masking by same spatial frequency components in the noise. This masking effect can be reduced by intelligent image processing according as a-prior knowledge of signal and noise is available. The fraction of information utilized can possibly be increased from 10% to nearly 100%. The detection of lower spatial frequencies can be moderately improved by blurring of the image, whereas, the detection of higher spatial frequencies can be improved by differentiation of the image.