Susan Westland

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Visual search for an edge or line element differing in orientation from a background of other edge or line elements can be performed rapidly and effortlessly. In this study, based on psychophysical measurements with ten human observers, threshold values of the angle between a target and background line elements were obtained as functions of(More)
We investigated the blur tolerance of human observers for stimuli modulated along the isoluminant red-green, the isoluminant yellow-blue, and the luminance (black-white) direction in color space. We report the following results: (i) Blur difference thresholds for red-green and luminance stimuli (of equal cone contrast) are very similar and as low as 0.5 min(More)
A line-element target differing sufficiently in orientation from a background of line elements can be visually detected easily and quickly; orientation thresholds for such detection are lowest when the background elements are all vertical or all horizontal. A simple quantitative model of this performance was constructed from three processing stages: (1)(More)
The response of the human visual system depends on a multitude of image features, such as the wavelength (colour) of the visual stimulus and its spatial frequency content. Hence we need to take into account the spatial and chromatic sensitivity as well as spatio-chromatic interactions to properly characterize visual sensitivity. In this paper we report two(More)
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