Abstract
Abstract: :
Purpose: The ModelFest project results have demonstrated that visible contrast energy measures can predict reasonably well the thresholds of spatial stimuli varying in size, orientation, shape, and spatial frequency content (Watson, 2000 Optics Express). Standard thresholds for visible contrast energy would be helpful for human factors engineers and others needing quick answers to the question, "Will this stimulus be detectable?" This would be possible if tables were available to help compute the contrast energy of the stimulus as well as to convert the contrast energy to visible contrast energy. Methods: To facilitate the development of such standards we have reviewed some of the theoretical and experimental literature on visual contrast detection and have converted selected results to contrast energy. Starting from the threshold luminance contrast energy threshold of 10 –6 deg 2 sec or 0 dBB (Watson, Barlow, & Robson, 1983 Vision Research), we tried to find sensible correction factors for observers, spatial frequency, orientation, and chromaticity. Results: Tables and graphs traceable to experimental results are now available to support pencil and paper estimation of contrast thresholds for a wide range of wide band and narrow band stimuli. Corrections for additional variables are still needed. Conclusions: In the past, to estimate a detection threshold, it was necessary to find a study on a target similar to the one of current interest, and extrapolate. With these graphs and tables, this search and extrapolation are no longer necessary. Even when more complex models are available, the proposed present methods should help confirm the model predictions.
Keywords: detection • contrast sensitivity • color vision