MODELS OF CONTRAST SENSITIVITY IN HUMAN VISION

Eight models are examined as input-output representations of steady-st ate vision in humans at moderate to low level illumination. Three new models for visual contrast sensitivity are introduced and evaluated us ing CSF data with samples on both narrow and wide frequency ranges. Ad ditionally, five variations of previously published models are evaluat ed using the same data. A nonlinear least squares fitting algorithm pr oduced the optimal parameters for each model. The eight models are com pared on the basis of rms error in their fit to the CSF data. The thre e new models, based on second-, third-, and fourth-order filter functi ons, provided the best fit to the data. They appear to more-closely ap proximate the underlying sensory mechanisms, and thus they provide a m ore useful input-output representation of the overall human visual sys tem.