Abstract

The effect of the dependence of grain-noise level on signal level is considered for a coherent optical-processing system. It is shown that even when all spatial frequencies associated with image detail are removed by high-pass filtering, the square-law rectification of grain noise reproduces a recognizable image. A similar effect is shown to occur for halftone images. A simple explanation is provided for halftones which agrees well with experiment. A linear theory is also given for the case of granularity. Experimental results, relating macroscopic density measurements in the original and the filtered image, show argeement to the theory for fine-grain films, while results for coarse-grain films suggest minor deviations.

© 1965 Optical Society of America

Photographic Granularity and Graininess†,*II. The Effects of Variations in Instrumental and Analytical Techniques

Loyd A. Jones and George C. Higgins
J. Opt. Soc. Am. 36(4) 203-227 (1946)

Relation between Graininess and Granularity for Black-and-White Samples with Nonuniform Granularity Spectra*

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J. Opt. Soc. Am. 49(7) 693-702 (1959)

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Peter Fellgett
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Hans J. Zweig
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Properties of Granularity Wiener Spectra*

Stephen A. Benton and Richard E. Kronauer
J. Opt. Soc. Am. 61(4) 524-529 (1971)