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P P Nikolaev

Publications and source records attributed to P P Nikolaev.

12 recordsLinked to original sources
PubMed1975

[Physiologic mechanisms of the constancy of color perception].

The color constancy is the ability to recognize correctly the colours of the objects under different illuminations. For this purpose the visual system must identify the character of illumination and estimate the colour of the object, using the light reflected from this object according to the spectrum of illumination. The behavioral experiments with fishes showed that they possess the colour constancy. The electrophysiological studies on colour-coding ganglion cells showed that the simplest mechanisms of estimating the colours of objects according to illumination exist at the retinal level. The presence of colour vision facilitates the recognition of the volume form of the objects. The generally accepted view on the place and role of colour vision in the general function of the visual system of animals has to be changed on the basis of these facts.

Animals↗
PubMedDate not supplied

[Perception of color and volumetric shape of objects].

The problem of recognition of coloration of volume objects, illuminated simultaneously with bright point ans weak diffuse sources (having arbirary and previously unknown spectra) is considered. A mathematical model, in which a process of recognition of coloration is accompanied by determining orientations of surface elements relatively the point source is described. The information on orientation allows in many cases to calculate the volume shape of objects of the external world form their monocular ""retinal"" image.

Color Perception↗
PubMedDate not supplied

[Trichromatic model of the constant perception of the color of objects].

A description is presented of a trichromatic model of colour constancy (MCC) of objects with concavities: folds, holes and so on. MCC involves the system of algorithmically independent processing blocks of the image heterarchically interacting and creating at its outlet a triparametric estimation of surface reflectance of each object of the picture. This estimation little depends on changes in the illumination colour. Results are presented and discussed of a computer experiment with MCC simulating the scene in which a plane with differently coloured regions and a conic hole in each are illuminated with a single chromatic light source.

Algorithms↗
PubMedDate not supplied

[Mono-ocular color differentiation of three-dimensional objects in different illumination conditions].

General methods are described for calculating some functions of spectral parameters of illumination sources invariant to illumination changes within the limits of uniformly colored non-plane surface. Relation is shown between the number of linearly-independent acceptors of the system necessary for plotting such invariant and the complexity degree of illumination of the picture observed.

Algorithms↗
PubMedDate not supplied

[A model of constant color perception for continuous spectral functions].

A trichromatic model is proposed of constant pattern of colour perception (MCCP) for scenes with a single illumination source. In MCCP functions of the source emission, surface reflection, photoacceptor sensitivity are approximated by the normal distribution curves. MCCP characteristics "colour tone", "cleanness", and "lightness" organize its output colour metric by the human's pattern, and in a wide range of spectral composition of illumination they are invariant under these changes. Special colorimetric regime of MCCP work which estimates the colour of visual stimulus permits a comparison between the efficiencies of two proposed algorithms of visual information processing for MCCP.

Color Perception↗