User:ArnoldJWilkins/sandbox

Visual stress is a term that is now frequently used to describe the discomfort and perceptual distortions experienced when viewing certain visual stimuli, most usually text. The visual stimuli that provoke discomfort and perceptual distortions have certain spatial characteristics in common. These characteristics are rarely found in images from nature. In natural images, the spatial variation in contrast decreases with decreasing spatial scale according to a simple mathematical law. Images that do not conform to this law are generally rated as uncomfortable to look at, particularly if there is an excess of contrast at spatial scales at which the human visual system is generally most sensitive.