A standard model for foveal detection of spatial contrast

Abstract

The ModelFest data set was created to provide a public source of data to test and calibrate models of foveal spatial contrast detection. It consists of contrast thresholds for 43 foveal achromatic contrast stimuli collected from each of 16 observers. We have fit these data with a variety of simple models that include one of several contrast sensitivity functions, an oblique effect, a spatial sensitivity aperture, spatial frequency channels, and nonlinear Minkowski summation. While we are able to identify one model, with particular parameters, as providing the lowest overall residual error, we also note that the differences among several good-fitting models are small. We find a strong reciprocity between the size of the spatial aperture and the value of the summation exponent: both are effective means of limiting the extent of spatial summation. The results demonstrate the power of simple models to account for the visibility of a wide variety of spatial stimuli and suggest that special mechanisms to deal with special classes of stimuli are not needed. But the results also illustrate the limited power of even this large data set to distinguish among similar competing models. We identify one model as a possible standard, suitable for simple theoretical and applied predictions.

Use of a cubic phase plate as solution for moderate astigmatism: preliminary study

“…con valores: f0=33.3573 f1=5.37916 y a=0.923853 γ= 3.48 ciclos/grado y λ = 13.57 ciclos/grado [14,15].…”

A Wavelet-Based Model for Foveal Detection of Spatial Contrast With Frequency Dependent Aperture Effect

“…Spatial contrast sensitivity as Watson & Ahumada [43] defined, is the ability to see alteration of light intensity in spatial patterns. Since spatial contrast sensitivity is the first stage of seeing, it has been the focus of many studies.…”

“…Later on, another improved model was introduced by Watson & Ahumada [43]. We will return to this model for more investigation in latter sections.…”

“…ModelFest dataset consists of 43 grey scale stimuli ( Figure 1) and Stimuli's properties are comprehensively described in [43]. It was gathered in two phases, first for nine observers and second for seven more and four trials for each observer.…”

Objective Video Quality Assessment — Towards Large Scale Video Database Enhanced Model Development

“…Most research activities have focused on the first part and significant progress has been obtained, notably concerning the modeling of the human visual system in specific con-ditions. Psychophysical experiments have been conducted, for example to measure and model the spatial contrast sensitivity function [1], [2], to learn about the influence of nonfluent playback conditions [3], or the sensations due to visual discomfort while watching moving objects in 3D video [4]. This selection is meant to illustrate the narrow scope that may be covered in psychophysical studies and may give a hint about the difficulty to model the human response as a whole.…”