Showing papers on "Human visual system model published in 1972"

Image processing in the context of a visual model

Abstract: A specific relationship between some of the current knowledge and thought concerning human vision and the problem of controlling subjective distortion in processed images are reviewed.

Visual Acuity and Spatial Modulation Thresholds

Abstract: Seeing shapes and patterns is the major capacity inherent in our visual system. It depends, to be sure, on the ability to distinguish differences in light intensity and color, but this is not enough; they must be distinguished more or less simultaneously and identified as belonging to different areas of the visual field. Ultimately all this raises the question of the kind of spatial divisibility or capacity for spatial partitioning exhibited by the visual system. When taken to the limit of sensory threshold, this becomes the traditional topic of visual acuity or spatial resolving power of the visual apparatus.

Interocular transfer of adaptation to spatial frequency during retinal ischaemia.

Abstract: PROLONGED inspection of a grating pattern of repetitive light and dark contours produces a transient reduction in the visibility of low-contrast gratings the spatial frequency and orientation of which are similar to that of the inspected grating. This after-effect, often referred to as adaptation, occurs even when one eye performs the inspection and its partner is tested. Certain properties of this after-effect, with other data, suggest that its locus is visual cortex1–7, but the evidence is largely indirect because of the difficulty of identifying sites of action within the stages of the human visual system. One of the few techniques available for inferentially partitioning the visual system stages is retinal pressure blinding, a heroic but effective method for functionally uncoupling the retina from higher stages8–11.

Methods for comparison of the efficiency of biological and technical systems

Abstract: In this work the methods of the communication theory for binary detection, multiple detection and extraction are applied to biological systems. It is the objective of this investigation to compare the performance of optimal and biological systems in receiving signals superimposed by noise. The required mathematical relations and methods of measurements are derived. In the second part of this work pattern recognition experiments (multiple detection) at the human visual system with stationary and time variant patterns are described. The comparison of the performance between optimal and biological system shows that the human visual system acts in a suboptimal way. From some other detection experiments it can be concluded that the recognition process is describable by spatial cross-correlation.

Study of Optical Illusions During Visual Approaches.

Abstract: : The report concerns the study of optical hazards (illusions) during visual approaches. The study was conducted primarily to develop criteria which would help to minimize the probability of accidents at certain problem airports due to illusory factors. The investigation included the psychological factors leading to the misinterpretation of visual stimuli as well as the physical conditions which constitute a proper environment for optical illusions. The topographical features, ambient lighting, visibility restrictions, manmade structures/objects, and airport/runway characteristics were assigned weighted indexes for the mathematical modeling in order to determine sites which may possess visual approach hazards. The description of the human visual system and psychology of perception are contained in the appendix, and the mathematical modeling for probability of visual hazards (illusions) is described in the main body of the report. (Author)