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Biomedical subjects

P Koczorowski

Publications and source records attributed to P Koczorowski.

7 recordsLinked to original sources
PubMed1994

Resolving power to narrow and extended light sources and its influence on legibility of the optotypes.

The resolving power of the human visual system has been found to depend on the sizes of the light sources. The sources used in this experiment were two rectangular white fields separated by a vertical black bar. The minimal angle of resolution measured on five subjects decreased by about 10-20 times while the light sources were extended up to the effective range of spatial summation. For larger sources no significant changes of spatial resolution were observed. The experimental data revealed biphasic dependence of the minimal angle of resolution on the sizes of the light sources and permitted estimation of the effective range of spatial summation for 3-9 min arc. This range encompasses the angular diameters of typical optotypes recognized by normal observers (visual acuity greater than 1, optotypes smaller than 5 min arc), therefore we show how the spatial arrangement of the lines and strokes of optotypes determines their legibility.

Adult↗
PubMed1994

Minimal angle of resolution in monocular, single-colour vision and the TAIS model.

The mathematical model TAIS simulates visual perception of single-colour or black-and-white, non-moving objects. It makes an analysis of the luminance spatial distribution in an optional direction and describes it in linguistic terms. The model comprises three modules that successively convolve the luminance distribution with a spatial filter (a normalized Gaussian function), calculate the second derivative of the convolution and, with use of context-free and context-sensitive grammars, generate a string of symbols. The string of symbols contains the information, simplified in form and rectified from visual noise, about perceived spatial changes of brightness. The model simulates various visual phenomena, e.g. edge detection and spatial resolution, and it predicts the resolving power dependence on the light source size. The model-generated dependence of minimal angle of resolution on the light source width fits the experimental data with linear correlation coefficients in the range 0.70-0.94. The diagram consists of decreasing and constant parts, its shape adjusted to experimental data through selection of the Gaussian filter parameter and second derivative threshold.

Adaptation, Ocular↗
PubMed1994

Resolving power of the human visual system to monochromatic stimuli.

The resolving power in monocular, foveal vision was found to depend on the size of a white light source made of two white rectangles separated by vertical black bar. The question arises whether the wavelength of light influences this dependence. An experiment was done on three subjects using six monochromatic lights the range 450-625 nm, and white light for control measurements. The diagram of the dependence of the minimal angle of resolution on the source size takes the shape of a biphasic curve, i.e. decreasing and constant function. The wavelength was found to have no impact on the curve shape or values. The data points obtained for white light coincide with those for monochromatic lights. The results confirm a thesis that all three colour mechanisms in the human visual system are stimulated and are active in spatial summation processes, but to a degree conditioned by a spectral sensitivity of the particular colour apparatus. It was confirmed that all colour mechanisms have potentially the same acuity but the axial chromatic aberration causes observed reduction of acuity.

Adult↗
PubMed1986

Stereopsis angle in relation to proximity and induced refractive errors.

Dependence of stereoacuity (SA) angle on the reciprocal of the test distance with positive, negative, and zero values of induced refractive errors is demonstrated with the three-rod test and the mean errors statistical method. Two male emmetropes and one hyperope showed linearly increasing dependence of SA angle on the reciprocal of the test distance within the subject's range of clear vision extended at both ends by 1 D. Linear regression coefficients were not influenced by the value of induced refractive error within +/- 2 D. Correlation coefficients in the case of corrected refractive error were about 0.90, but their mean value in the case of induced refractive errors was 0.83.

Adult↗