Modeling Corneal Surfaces With Rational Functions for High-Speed Videokeratoscopy Data Compression

High-speed videokeratoscopy is an emerging technique that enables study of the corneal surface and tear-film dynamics. Unlike its static predecessor, this new technique results in a very large amount of digital data for which storage needs become significant. We aimed to design a compression techniq...

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Veröffentlicht in:IEEE transactions on biomedical engineering Jg. 56; H. 2; S. 493 - 499
Hauptverfasser: Schneider, Martin, Iskander, D. Robert, Collins, Michael J.
Format: Journal Article
Sprache:Englisch
Veröffentlicht: United States IEEE 01.02.2009
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Schlagworte:
Algorithms
Biomedical measurements
Biomedical optical imaging
Cornea
Cornea - physiology
Corneal Topography
Data compression
High speed optical techniques
Humans
Image Processing, Computer-Assisted - methods
keratrometry
Least-Squares Analysis
Mathematical functions
Models, Biological
Nonlinear optics
Optical refraction
Polynomials
Predictive models
rational functions
Surface fitting
Surface Properties
Surface topography
Tears - physiology
Zernike polynomials
ISSN:0018-9294, 1558-2531, 1558-2531
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Zusammenfassung:High-speed videokeratoscopy is an emerging technique that enables study of the corneal surface and tear-film dynamics. Unlike its static predecessor, this new technique results in a very large amount of digital data for which storage needs become significant. We aimed to design a compression technique that would use mathematical functions to parsimoniously fit corneal surface data with a minimum number of coefficients. Since the Zernike polynomial functions that have been traditionally used for modeling corneal surfaces may not necessarily correctly represent given corneal surface data in terms of its optical performance, we introduced the concept of Zernike polynomial-based rational functions. Modeling optimality criteria were employed in terms of both the rms surface error as well as the point spread function cross-correlation. The parameters of approximations were estimated using a nonlinear least-squares procedure based on the Levenberg-Marquardt algorithm. A large number of retrospective videokeratoscopic measurements were used to evaluate the performance of the proposed rational-function-based modeling approach. The results indicate that the rational functions almost always outperform the traditional Zernike polynomial approximations with the same number of coefficients.
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ISSN:0018-9294
1558-2531
1558-2531
DOI:10.1109/TBME.2008.2006019