Reflectance based microfilming process

Abstract

A process is described for preservation microfilming in which variations in the 'fade' or background coloration of materials to be recorded is accommodated for. In particular, the process initially develops a characteristic of the camera based workstation itself which relates an exposure meter output with a select sequence of variations of the light source used with the workstation. A pseudo background target of constant hue such as a beige color is used for this purpose. A sample card also is utilized which carries a sequence of color samples each generally within a pertinent range of the spectra associated with the general coloration of the work to be recorded. Reflectance densitometer readings are taken for each of the samples on this card and the card, itself, is recorded on microfilm. The images of the samples on that test microfilm then are evaluated utilizing a transmittance densitometer. The resultant data then are compiled in a program which permits exposure to be set by the operator based upon a reflectance densitometer reading of the background of the materials being filmed. Thus, as the tone or hue of these materials alter during the course of microfilming, the operator may re-evaluate background hue with the reflectance densitometer and adjust exposure accordingly on a substantially objective basis.