NDLI: Unwrapping Hartmann-Shack images of off-axis aberration using artificial centroid injection method

Content Provider	IEEE Xplore Digital Library
Author	Yuwono, M.
Copyright Year	2011
Description	Author affiliation: Faculty of Engineering and Information Technology, University of Technology, Sydney, Sydney, New South Wales, Australia (Yuwono, M.)
Abstract	As the degree of aberration and noise increases, particularly for off-axis aberration, wavefronts of Hartmann-Shack images become so distorted that special care needs to be considered in order to successfully and gracefully unwrap the images. This paper proposes an alternative algorithmic approach called the artificial centroid injection method. Initial centroid extraction is done using Laplacian of Gaussian (LoG) and dynamic thresholding. Outlier centroids are filtered using ensemble of weak classifiers boosted with Adaboost algorithm. Observing the nature of the vertical and horizontal centroid sequences using Kalman Filter, multiple General Regression Neural Networks (GRNN) are then trained to approximate centroid sequences. Artificial centroids are generated by taking the intersection points of approximated vertical and horizontal GRNN sequences that occurs inside an elliptical Region of Interest optimized with Regrouping Particle Swarm (RegPSO). These artificial centroids are injected to the intial centroid vector to predictively recover missing and previously unrecognized spots. Wavefront algorithm is then applied to correspond detected centroids to their appropriate lenslet centers. This algorithm has successfully unwrapped 29 different off-axis aberration HS images, −50° Temporal plane to +50° Nasal plane up to zero pixel prediction error, with no false correlations in any of the tested images.
Starting Page	560
Ending Page	564
File Size	1435464
Page Count	5
File Format	PDF
ISBN	9781424493517
e-ISBN	9781424493524
DOI	10.1109/BMEI.2011.6098352
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2011-10-15
Publisher Place	China
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Adaptive Boosting Kalman Filter Heuristic algorithms Noise Vectors Dynamic Thresholding Classification algorithms Bright Spots Detection Particle swarm optimization Least squares approximation Wavefront Algorithm Hartman-Shack image unwrapping Regrouping Particle Swarm Optimization General Regression Neural Network Kalman filters
Content Type	Text
Resource Type	Article

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