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Image processing for improved eye-tracking accuracyVideo cameras provide a simple, noninvasive method for monitoring a subject's eye movements. An important concept is that of the resolution of the system, which is the smallest eye movement that can be reliably detected. While hardware systems are available that estimate direction of gaze in real-time from a video image of the pupil, such systems must limit image processing to attain real-time performance and are limited to a resolution of about 10 arc minutes. Two ways to improve resolution are discussed. The first is to improve the image processing algorithms that are used to derive an estimate. Off-line analysis of the data can improve resolution by at least one order of magnitude for images of the pupil. A second avenue by which to improve resolution is to increase the optical gain of the imaging setup (i.e., the amount of image motion produced by a given eye rotation). Ophthalmoscopic imaging of retinal blood vessels provides increased optical gain and improved immunity to small head movements but requires a highly sensitive camera. The large number of images involved in a typical experiment imposes great demands on the storage, handling, and processing of data. A major bottleneck had been the real-time digitization and storage of large amounts of video imagery, but recent developments in video compression hardware have made this problem tractable at a reasonable cost. Images of both the retina and the pupil can be analyzed successfully using a basic toolbox of image-processing routines (filtering, correlation, thresholding, etc.), which are, for the most part, well suited to implementation on vectorizing supercomputers.
Document ID
20040089544
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Mulligan, J. B.
(NASA Ames Research Center Moffett Field CA United States)
Watson, A. B.
Date Acquired
August 21, 2013
Publication Date
February 1, 1997
Publication Information
Publication: Behavior research methods, instruments, & computers : a journal of the Psychonomic Society, Inc
Volume: 29
Issue: 1
ISSN: 0743-3808
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Space Human Factors
NASA Center ARC

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