Prediction of the perceived quality of streak distortions in offset-printing with a psychophysically motivated multi-channel model

AbstractThe evaluation of printing machines poses the problem of how distortions like streaks caused by the machine can be detected and assessed automatically. Although luminance variations in prints can be measured quite precisely, the measured functions bear little relevance for the lightness of streaks and other distortions of prints as perceived by human observers. First, the measurements sometimes indicate changes of luminance in regions which are perceived as homogeneous by humans. Second, the measured strength of a distortion correlates often weakly with its perceived strength, which is influenced by a variety of factors, like the shape of a streak’s luminance profile and the distribution of luminance variations in its spatial surround. We have used a model of human perception, based on fundamental neurophysiological and psychophysical properties of the visual system, in order to predict the perceptual strength of streaks (i.e. the distortion as perceived by a human observer) from the measured phys...