Automated photographic contact printing system

Abstract

A photographic contact printing system comprises a data base in which certain exposure parameters (e.g., spectral response, sensitivity, dot-growth factor, nominal exposure value and overlay factor) of a variety of different photosensitive recording elements are stored. Upon selection of any one of such recording elements by a printer operator, a microprocessor automatically controls an exposure source (e.g. an electrically energizable lamp) to provide a pre-programmed exposure of the selected recording element. During exposure of the recording element, a logic and control unit receives a time-varying signal representing the instantaneous spectral radiance of the exposure source. The LCU integrates the exposure produced by the source until the integrated exposure matches a nominal (or an adjusted nominal) value, at which time the exposure is terminated. Preferably, the LCU is programmed to produce an adjusted nominal exposure value based on various exposure-affecting inputs made by the printer operator, including percent dot (or line) change, source power level, number and density of overlays and filters, percent diffusion, etc. As a result of the invention, the process of determining proper exposure for a plurality of photosensitive recording elements under a variety of exposure conditions is greatly simplified.