Contrast sensitivity to patch stimuli: Effects of spatial bandwidth and temporal presentation

Abstract

Models of the spatial response of human vision are important for applied work, but the available contrast sensitivity function (CSF) data vary widely due to the diverse spatiotemporal stimuli used over the years. To assist selection, this paper: (1) reports measurements of the effects on the CSF of varying the spatial and temporal windows of grating patches; (2) demonstrates that the widely discrepant CSFs from previous studies can be accounted for by using these results; and (3) discusses simple criteria for choosing CSFs for practical applications. CSFs were measured for several combinations of spatial and temporal waveforms, using the same subjects under otherwise identical conditions. The CSF was measured over the range of 0.5-10 c/deg using Gabor-type patches of 1.0-, 0.5-, 0.25-, and 0.125-octave spatial bandwidths using both abrupt and gradual temporal presentations. The results were compared with the CSF obtained with a fixed aperture (4 deg x 4 deg) grating pattern. Increasing the number of cycles resulted in increased sensitivity at intermediate frequencies, changing the CSF to a narrower bandpass shape. For each patch bandwidth, the gradual presentation CSF had a narrower spatial pass band than with the abrupt presentation. The relevance of the large differences in the CSFs obtained with different stimuli to our understanding of visual performance is discussed.

The Effect of White-Noise Mask Level on Sinewave Contrast Detection Thresholds and the Critical-Band-Masking Model

“…It is known that the CSF shape lacks low spatial frequency attenuation when Gabor patch window scales with spatial frequency (Peli, Arend, Young, & Goldstein, 1993). This is the shape of the CSF obtained and used by Solomon (2000).…”

Digital enhancement of television signals for people with visual impairments: Evaluation of a consumer product

“…A normally sighted person can see gratings of spatial frequencies up to about 25 or 30 c/deg. Higher levels of contrast are required for the gratings to be seen as the spatial frequencies increase [3,4]. The inverse of the contrast detection threshold is defined as the contrast sensitivity.…”

Central and Off-Axis Spatial Contrast Sensitivity Measured with Gabor Patches

“…Briefly, as Peli et al noted (6), "extended gratings CSFs are unlikely to represent actual contrast sensitivity in free viewing of real-world images, and, therefore, may be inappropriate for vision simulation in normals." Indeed, more recent models (5,7,8) have relied heavily on results collected using Gabor patches as stimuli, i.e., spatial sine-wave gratings windowed by a twodimensional (2-D) Gaussian envelope.…”

“…The contrast of the Gabor patch gradually increased and decreased over the 1200-ms interval. A raised cosine temporal envelope to minimize temporal transients associated with stimulus presentation followed since such transients were known to selectivity affect low spatial frequency sensitivity (5,6,9). The subject's task was to press a button on a response console indicating whether the pattern appeared on the left or right side of the fixation cross.…”