The Evaluation of the Modulation Transfer Function of Photographic Materials. The Interaction of the Modulation Transfer Function of the Instruments, and of the Characteristic Curve

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Abstract
The smaller the signal-to-noise-ratio can be kept in the measurement of the modulation transfer function (MTF) of photographic material. the more care must be taken to eliminate systematic errors. Exact knowledge of the spatial exposure distribution in the sample (the so-called aerial image) and of the optical properties of the microdensitometer are essential. Four methods (including two-beam interferometry) of the measurement of the aerial image are presented and discussed. The rigorous method of correcting the interference of the optical transfer characteristic of the microdensitometer is presented taking into account the non-linearity of the photographic process. and the range of validity of a commonly applied heuristic method is investigated. Finally twa methods of eliminating the characteristic curve in order to find the effective exposure are compared and examples of their application are given.