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Recovery of motion parameters from distortions in scanned imagesScanned images, such as those produced by the scanning-laser ophthalmoscope (SLO), show distortions when there is target motion. This is because pixels corresponding to different image regions are acquired sequentially, and so, in essence, are slices of different snapshots. While these distortions create problems for image registration algorithms, they are potentially useful for recovering target motion parameters at temporal frequencies above the frame rate. Stetter, Sendtner and Timberlake measured large distortions in SLO images to recover the time course of rapid horizontal saccadic eye movements. Here, this work is extended with the goal of automatically recovering small eye movements in two dimensions. Eye position during the frame interval is modeled using a low dimensional parametric description, which in turn is used to generate predicted distortions of a reference template. The input image is then registered to the distorted template using normalized cross correlation. The motion parameters are then varied, and the correlation recomputed, to find the motion which maximizes the peak value of the correlation. The location and value of the correlation maximum are determined with sub-pixel precision using biquadratic interpolation, yielding eye position resolution better than 1 arc minute. This method of motion parameter estimation is tested using actual SLO images as well as simulated images. Motion parameter estimation might also be applied to individual video lines in order to reduce pipeline delays for a near real-time system.
Document ID
19980236600
Document Type
Conference Paper
Authors
Mulligan, Jeffrey B. (NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 18, 2013
Publication Date
November 1, 1997
Publication Information
Publication: Image Registration Workshop Proceedings
Subject Category
Computer Programming and Software
Funding Number(s)
PROJECT: RTOP 505-64-53
PROJECT: RTOP 548-60-12
PROJECT: RTOP 199-06-12-39
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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