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Uniform apparent contrast noise: A picture of the noise of the visual contrast detection systemA picture which is a sample of random contrast noise is generated. The noise amplitude spectrum in each region of the picture is inversely proportional to spatial frequency contrast sensitivity for that region, assuming the observer fixates the center of the picture and is the appropriate distance from it. In this case, the picture appears to have approximately the same contrast everywhere. To the extent that contrast detection thresholds are determined by visual system noise, this picture can be regarded as a picture of the noise of that system. There is evidence that, at different eccentricities, contrast sensitivity functions differ only by a magnification factor. The picture was generated by filtering a sample of white noise with a filter whose frequency response is inversely proportional to foveal contrast sensitivity. It was then stretched by a space-varying magnification function. The picture summmarizes a noise linear model of detection and discrimination of contrast signals by referring the model noise to the input picture domain.
Document ID
19840021387
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Ahumada, A. J., Jr. (NASA Ames Research Center Moffett Field, CA, United States)
Watson, A. B. (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
September 4, 2013
Publication Date
July 1, 1984
Subject Category
Behavioral Sciences
Report/Patent Number
NASA-TM-85867
NAS 1.15:85867
A-9574
Accession Number
84N29456
Funding Number(s)
PROJECT: RTOP 505-35-31
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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