To determine the modulation transfer function requirements for optical systems used in reproducing typewritten documents, sample reproductions were made with apparatus set for different modulation transfer functions in the negative-to-positive steps of the reproduction system. The ninety-six samples were presented in random order to thirty evaluators, who were asked to rate them as acceptable or not acceptable, in order to establish the relationship between objective and subjective image quality. Data are given showing the influence of negative-to-positive image quality degradation on the acceptability of document reproductions.
M. E. Rabedeau and A. D. Bates, "Image Quality Requirements in Optical Systems for Reproducing Typewritten Documents," Appl. Opt. 4, 439-443 (1965)