Some Qualitative and Quantitative Results on Spatial Filtering of Granularity

Following O’Neill the spatial frequency filtering of granularity has been performed by using a low-pass filter. The sample is illuminated in coherent and parallel light. Qualitative and quantitative results are shown in a few examples and the effect of spatial frequency filtering on contrast, sharpness, resolving power, and granularity is pointed out. The spatial filtering of granularity appears as a powerful tool to increase the signal-to-noise ratio in the frequency band transmitted.