Depth dependance of the granularity power spectrum of photographic layers
Abstract
The influence of the depth dimension of a photographic emulsion coating on the measurement of the granularity power spectrum is examined both theoretically and experimentally. For this, the emulsion is divided into elementary layers. The power spectrum of the global layer is built up as the sum of these elementary power spectra, each weighted with a different factor, which depends on the distance of the elementary layer from the plane of focus of the optical measuring system. This factor is the square of the out-of-focus modulation transfer function of the optics. A method is discussed for measuring the granularity power spectrum in dependence of the depth of the emulsion layer by successive enzymatic reduction of the upper elementary layers. Measurements on an X-ray film, which was exposed to daylight from one side, indicate equal elementary power spectra of the lower layers and an increased and flatter spectrum near the surface of the emulsion coating, due to the contribution of relatively more fine grains to the higher density of the upper layers.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1974
- Bibcode:
- 1974PhDT........46W
- Keywords:
-
- Granular Materials;
- Optical Measurement;
- Photographic Emulsions;
- Power Spectra;
- Depth;
- Surface Properties;
- Transfer Functions;
- Instrumentation and Photography