Contrast plays a crucial role in pattern vision. Loss of contrast hampers vision in may ways. This proposal deals with the influence of suprathreshold contrast in human vision. The research has three main purposes: to study the spatial properties of visual mechanisms that code contrast, to use what we have learned about contrast coding to enhance images for people with low vision, and to link work on the sensory coding of contrast to perceptual processes of object recognition. We will use psychophysical and image processing methods in four series of experiments. In the first, we will use a new """"""""yoked-contrast"""""""" procedure to distinguish between two models of contrast coding. In the second series, we will use a new variant of the simultaneous detection/identification paradigm to study spatial-frequency and orientational selectivity as a function of contrast. In the third series, we will apply principles of contrast coding to the design of image-enhancement algorithms based on gray-scale histogram flattening. We are particularly interested in the potential value of such techniques for those people with low vision who suffer from attenuated retinal contrast (e.g. cataract) or reduced contrast sensitivity (e.g. central-field loss). In the fourth series, we will use the concept of an """"""""ideal observer"""""""" from signal-detection theory to measure how efficiently subjects code and use stimulus information to understanding the difficulties experienced by people with low vision on object recognition.
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| Kallie, Christopher S; Schrater, Paul R; Legge, Gordon E (2007) Variability in stepping direction explains the veering behavior of blind walkers. J Exp Psychol Hum Percept Perform 33:183-200 |
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