LCD spatial noise and human observer performance

Results of physical as well as psychophysical evaluation of an LCD with respect to its spatial noise are presented. Spatial noise is determined using a high-resolution CCD camera and a method is developed to compensate for it. This compensation algorithm is based on a spatial noise map, derived from CCD camera images, and on the application of an error diffusion algorithm. This method of noise compensation reduces the spatial noise by about a factor of 2. Psychophysical evaluation is performed in order to explore the dependence of human contrast sensitivity on display spatial noise. The psychophysical evaluation uses the two-alternative forced choice (2-AFC) method of contrast threshold detection. Aperiodic Gaussian-shaped objects serve as stimuli. They simulate lung nodules. The probability of correct response obtained using the 2-AFC tests indicates that spatial noise compensation leads to a lower contrast threshold.