Lack of Covariation of the Effects of Luminance and Eccentricity on Contrast Sensitivity

Ma, García-Pérez; Peli, Eli

doi:10.1097/00006324-199901000-00030

Cited by 3 publications

(3 citation statements)

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“…The first experiment found significant individual differences in contrast sensitivity among participants. This is in line with prior research that has found that individual performances varies widely as a function of luminance and eccentricity ( Garcia-Perez & Peli, 1999 ). Individual contrast levels have been shown to be more reliable than group averages in visual experiments as the threshold of sensitivity can greatly affect recognition ( Baker, 2013 ; Pelli & Bex, 2013 ).…”

Section: Discussionsupporting

confidence: 92%

Evaluating integration of letter fragments through contrast and spatially targeted masking

Zhang,

Morrison,

Sun

et al. 2024

Journal of Vision

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Section: Discussionsupporting

confidence: 92%

Evaluating integration of letter fragments through contrast and spatially targeted masking

Zhang,

Morrison,

Sun

et al. 2024

Journal of Vision

View full text Add to dashboard Cite

“…Given the empirical constraints provided by (a) the shape of the acuity versus illuminance curve and (b) the shape of the high-illuminance CSF, the DeVries-Rose law can only hold with sine-wave gratings of low spatial frequency. Yet, at low frequencies, empirical data indicate that there is a further range of decreasing sensitivity beyond the Weber range (see García-Pérez & Peli, 1997), and this decreasing range is also observed at higher frequencies in some subjects (García-Pérez & Peli, 1999). At intermediate and high frequencies, the increase in sensitivity with illuminance cannot be linear, and the average slope of this nonlinear increase must often be much larger than 0.5.…”

Section: Resultsmentioning

confidence: 98%

Is the DeVries-Rose to Weber Transition Empirically Possible with Sine-Wave Gratings?

Garcı́a-Pérez

2005

Span. J. Psychol.

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Visual functioning at various retinal illuminance levels is usually measured either by determining grating acuity as a function of light level or by determining how sensitivity to sine-wave gratings changes with retinal illuminance. The former line of research has shown that grating acuity follows a two-branch relationship with retinal illuminance, with the point of discontinuity occurring at the transition from scotopic to photopic vision. Results of the latter line of research have summarily been described as a transition from the DeVries-Rose law to Weber's law, according to which log sensitivity increases linearly with log illuminance with a slope of 0.5 over a range of low illuminances (the DeVries-Rose range) and then levels off and does not increase with further increases of illuminance (the Weber range). This paper aims at determining the compatibility of the results of these two lines of research. We consider empirical constraints from data bearing on the shape of the surface describing contrast sensitivity to sine-wave gratings as a function of spatial frequency and illuminance simultaneously, in order to determine whether they are consistent with a summary description in terms of DeVries-Rose and Weber's laws. Our analysis indicates that, with sine-wave gratings, the DeVries-Rose law can only hold empirically at low spatial frequencies. Keywords: Weber's law, DeVries-Rose law, contrast sensitivity, retinal illuminance, visual acuity Con frecuencia se ha medido la función visual a distintos niveles de iluminancia, bien determinando la agudeza visual para enrejados sinusoidales en función del nivel luminoso o bien determinando la forma en que la sensibilidad a enrejados sinusoidales cambia con la iluminancia. La primera vía de acercamiento ha revelado que la agudeza varía con la iluminancia de acuerdo con una función de dos ramas y un punto de discontinuidad en la transicion de visión escotópica a visión fotópica. Los resultados obtenidos a través de la segunda vía se han resumido aludiendo a una transición de la ley de DeVries-Rose a la de Weber, según la cual el logaritmo de la sensibilidad aumenta linealmente con pendiente 0.5 a medida que aumenta la iluminancia (para niveles bajos de iluminancia que comprenden el llamado rango de DeVries-Rose) pero luego permanece constante e invariante ante sucesivos incrementos de iluminancia (dentro del llamado rango de Weber). Aquí se evalúa la compatibilidad de los resultados obtenidos en estas dos líneas de investigación. Se parte de las restricciones empíricas impuestas por datos que revelan la forma de la superficie de sensibilidad a enrejados sinusoidales en función de la frecuencia espacial y la iluminancia, y se determina si esas restricciones son compatibles con la descripción que ofrecen las leyes de DeVries-Rose y Weber. El análisis muestra que la ley de DeVries-Rose sólo es posible empíricamente para enrejados sinusoidales de baja frecuencia.

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“…However, it is known that the bandwidth varies between channels [35]. It is also the case that the contrast sensitivity function, which represents the envelope of all the channels, varies between observers [37] and, thus, both center frequencies and channel bandwidth probably vary across observers. It was, therefore, of interest to examine, for the sake of the vision model and for the sake of the implemented algorithm, the effect of variation in these parameters on the performance of the algorithm.…”

Section: Robustness To Variations In Filter Parametersmentioning

confidence: 99%

Feature detection algorithm based on a visual system model

Peli

2002

Proc. IEEE

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An algorithm for the detection of visually relevant luminance features is presented. The algorithm is motivated and directed by current models of the visual system. The algorithm detects edges (sharp luminance transitions) and narrow bars (luminance cusps) and marks them with the proper polarity. The image is first bandpass filtered with oriented filters at a number of scales an octave apart. The suprathreshold image contrast details at each scale are then identified and are compared across scales to find locations in which the signal polarity (sign) is identical at all scales, representing a minimal level of phase congruence across scales. These locations maintain the polarity of the bandpass-filtered image. The result is a polarity-preserving features map representing the edges with pairs of light and dark lines or curves on corresponding sides of the contour. Similarly, bar features are detected and represented with single curves of the proper polarity. The algorithm is implemented without free (fitted) parameters. All parameters are directly derived from visual models and from measurements on human observers. The algorithm is shown to be robust with respect to variations in filter parameters and requires no use of quadrature filters or Hilbert transforms. The possible utility of such an algorithm within the visual system and in computer vision applications is discussed.

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Lack of Covariation of the Effects of Luminance and Eccentricity on Contrast Sensitivity

Cited by 3 publications

References 0 publications

Evaluating integration of letter fragments through contrast and spatially targeted masking

Evaluating integration of letter fragments through contrast and spatially targeted masking

Is the DeVries-Rose to Weber Transition Empirically Possible with Sine-Wave Gratings?

Feature detection algorithm based on a visual system model

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