The optimum tone-reproduction characteristics were determined for a high contrast, a low contrast and a controlled contrast scene, by subjective analysis of the resulting prints. From this, mathematical models of the optimum film characteristic curves and fractional gradients were derived. Optimal system gamma (filmT x paper 7 ) was determined to be between 1.2 and 1.4, however, the gradient contrast was determined for the film so that contrast is defined over the entire toe and straight line regions. Luther's equation and its derivitive were used as the models in this study, and it was found that these can be used to describe a given film's characteristics over a wide range of development times.
Imaging Science (BS)
Department, Program, or Center
School of Photographic Arts and Sciences (CIAS)
Dowling, William R., "Derivation of the Optimum Film Contrast Gradient in Photographic Tone-Reproduction Systems" (1982). Thesis. Rochester Institute of Technology. Accessed from
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