Showing papers on "Human visual system model published in 1976"

On visual detection of light sources

Abstract: Experiments show that human beings are capable of detecting self-illuminating surfaces in their visual field, and that this capacity is based, to a great extend, on immediate processing by the visual system, rather than on a higher-level analysis. What are the physical parameters associated with this perception? The following factors are discussed; The highest intensity in the scene, absolute intensity value, local and global contrast, comparison with the average intensity, and lightness computation. All these factors are shown to be insufficient for explaining human's ability to identify light sources in their visual field. Finally, a method for accomplishing the source detection task in the so-called Mondrian world is presented.

Stereoscopic optical viewing system

Abstract: An optical viewing system and method is described, whose operating principles are based on two psycho-physiological characteristics of the human visual system. One of these characteristics is the time delay between the arrival of a light stimulus or image on the retina of the eye and its recognition or interpretation at the visual cortex. The other characteristic is the non-achromatism of the eye. The first of these characteristics manifests itself in the so-called Pulfrich illusion, a moving object being apparently displaced from its actual path when viewed by an observer with a neutral filter in front of one eye, as differential visual time-lag results from the difference in brightness of the two retinal images. The second characteristic manifests itself in the so-called chromostereoscopic effect which, under certain conditions, creates the illusion that differently colored objects, although actually at the same distance from an observer, are at different distances from him.

Digital color image processing and psychophysics within the framework of a human visual model.

Abstract: : A three-dimensional homomorphic model of human color vision based on neurophysiological and psychophysical evidence is presented This model permits the quantitative definition of perceptually important parameters such as brightness, saturation, hue and strength By modelling neural interaction in the human visual system as three linear filters operating on perceptual quantities, this model accounts for the automatic gain control properties of the eye and for brightness and color contrast effects A psychophysical experiment was performed, using a high quality color television monitor driven by a general purpose digital computer This experiment, based on the cancellation by human subjects of simultaneous color contrast illusions, allowed measurement of the low spatial frequency part of the frequency responses of the filters operating on the two chromatic channels of the human visual system

A Progress Report on VISIONS: Representation and Control in the Construction of Visual Models.

Abstract: : This report is an interim progress report on the evolving structure of VISIONS, a computer system for general visual perception The goal of the system is the segmentation and interpretation of a digitized color image of natural outdoor scenes The report outlines the multi-level data structures used for representing both a visual model of the scene and the semantic data base of stored knowledge about the world A flexible modular strategy controls the operation of processes which embody diverse forms of knowledge, and allows both data-directed and knowledge-directed model building A model search space is used to store a sketch of the processing history during model formation, so that limited, directed back-tracking will be facilitated

The use of spatial characteristics for the improvement of multispectral classification of remotely sensed data

Abstract: Two techniques for the classification of multispectral remotely sensed data - the image processing technique of texture features, which is modeled after the human visual system, and the ECHO (Extraction and Classification of Homogeneous Objects) numerical technique - are examined. These two spatial analysis techniques are compared using Landsat imagery of an area of Indiana as an example, and it is found that the numerical approach is superior in classification accuracy and more efficient computationally.

Bionic image analysis using lines and edges

Abstract: Intuitive and experimental evidence indicates that perceptually important pattern elements for human vision are lines, edges, and more gradual changes in contrast. These elements can be used to specify a set of basis functions for pattern description. A general processor configuration can then be derived to detect the presence of lines, edges, etc., and to estimate their positions and contrast levels. A practical constraint on the processor is that its complexity should be controlled. Taking account of this constraint, a specific system for estimation and detection of the basic elements (lines, edges, etc.) and for recognition of more complex patterns can be derived. The derived processor exhibits some characteristics that are similar to properties of the human visual system, e.g., proportional bandwidth filtering and Mach band phenomena.

Computational Techniques in Visual Systems. Part I. The Overall Design.

Abstract: : The overall goal is to define computational techniques to be used by a system in making a visual scan of a dynamic environment with which it is to interact. Here, both brain mechanisms in the visual systems of animals and humans and computer techniques for the analysis of color photographs of natural scenes are discussed. Schemes as a formalization of the system's knowledge units are presented. This notion is helpful for our work in both the BT (Brain Theory) and AI (Artificial Intellgence) approaches. Further specific studies--from their group and from elsewhere--of subsystems of both animal and computer visual systems are presented. The interaction of high-level processes with low-level systems, as part of a general emphasis on integrated system design are examined. Part II will focus on techniques for segmenting single static colored images.

Current Vision Models And Their Effect On Enhancement

Abstract: One definition of image enhancement is - a process which causes selected components of an image to be made stronger with respect to other components. Since this definition involves a measure of strength, a space in which that measure can be made is implied. Such spaces must logically involve the human visual system and its image processing characteristics.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Work of the human visual system. IV. Reverse color discrimination and anticolor. 1st series of experiments

Abstract: It is shown that in processing of visual information visual system uses not only normally visible color differences but also the color differences of opposite sign. The term "opposite color difference" implies that the sum of any given color difference and of the opposite one is equal to zero difference.

Noise Suppression in Microwave Imagery by Exploitation of the MTF Approach to Human Vision

Abstract: Optimised presentation of images from a microwave holographic system is essential, particularly the suppression of the effects of noise on the human visual system. Recent research into the human visual system has led to Fourier models of the visual cortex, and the proposition that object recognition is possible on relatively few critical low spatial frequency components. It is therefore possible to suppress interfering noise without losing essential object information by designing a suitable filtering function compatible with the human modulation transfer function, noise and object spectral distributions. A technique is described in which an unrecognizable microwave image distribution is processed to yield a clearly identifiable target shape.

Quantizer Design Using Visual Thresholds For Dpcm Coding Of Picture Signals

Abstract: Visual thresholds play an important role in the process of incorporating properties of the human visual system in encoding picture signals. They tell us how much the picture signal can be perturbed without the perturbations being visible to human observers. We describe psychovisual experiments to determine the amplitude thresholds at a single edge having a given slope. The perturbation of the picture signal caused by the encoding process should not exceed the threshold corresponding to the slope at any picture point, in order that the original and the encoded pictures be visually indistinguishable. We give methods to design quantizers for use in Differential Pulse Code Modulation (DPCM) systems, such that the quantization error is below the threshold and either a) the number ofquantizer levels or b) the entropy of the quantized output is minimized. We also disucss the structure of these quantizers and evaluate their performance on real pictures both in terms of picture quality and entropy.

Visual motion detection: a computational theory and some of the psychological data which it integrates

Abstract: In the context of a computational theory of visual motion detection some apparently conflictual psychological data about human visual motion perception are shown to be perfectly compatible The hypothesis is put forward that the human visual motion detection system is limited to considering only one visual object at a time, this visual object being however allowed to embrace any part of the observed scene, whether the chosen part consists of many physical objects, or only one, or only a small part of one