Abstract

The rms granularity values normally produced by an optical scanner are in terms of semispecular instrument density. It is shown that these semispecular values can be converted to a diffuse density basis by dividing by a quantity q that is defined as the ratio of the instrument density of the sample to the diffuse density. The q factor has been measured by two methods, one of which is convenient for use in the routine measurement of diffuse granularity with existing equipment. It has been found that, except at very low density levels, the q of a given material varies only slightly as the diffuse density changes. It does, however, increase significantly as the numerical aperture of the optical system decreases. When a range of samples is measured, maximum values of q occur at moderate values of sample granularity.

© 1970 Optical Society of America

The Measurement of rms Granularity

J. H. Altman
Appl. Opt. 3(1) 35-38 (1964)

Photographic Granularity and Graininess. VIII.* A Method of Measuring Granularity in Terms of the Scanning Area Giving a Threshold Luminance Gradient†

L. A. Jones, G. C. Higgins, and K. F. Stultz
J. Opt. Soc. Am. 45(2) 107-112 (1955)

Photographic Granularity and Graininess. VII. A Microphotometer for the Measurement of Granularity*

L. A. Jones and G. C. Higgins
J. Opt. Soc. Am. 41(3) 192-200 (1951)

Photographic Granularity and Graininess. IX. Techniques and Equipment for the Objective Measurement of Graininess*

L. A. Jones, G. C. Higgins, K. F. Stultz, and H. F. Hoesterey
J. Opt. Soc. Am. 47(4) 312-321 (1957)

Radiographic screen–film noise power spectrum: calibration and intercomparison

John M. Sandrik, Robert F. Wagner, and Kenneth M. Hanson
Appl. Opt. 21(19) 3597-3601 (1982)