Title :
Automatic estimation of the corneal limbus in videokeratoscopy
Author :
Morelande, Mark R. ; Iskander, D. Robert ; Collins, Michael J. ; Franklin, Ross
Author_Institution :
Centre for Eye Res., Queensland Univ. of Technol., Kelvin Grove, Qld., Australia
Abstract :
An algorithm for estimating the corneal limbus from videokeratoscopic images is proposed. After the image is transformed to a polar grid, a novel edge-detection procedure, suitable for the detection of the soft edge produced by the limbus, is used to locate the limbus. Outliers due to the eyelids, eyelashes, and videokeratoscopic rings are removed by taking advantage of the approximate circularity of the cornea. An ellipse which minimizes the sum of the squared algebraic errors is fitted to the remaining edge points. Comparisons between the proposed algorithm, a manual computer-based technique and an algorithm which uses conventional edge-detection techniques demonstrate the accuracy of the proposed algorithm.
Keywords :
biomedical optical imaging; edge detection; eye; medical image processing; surface topography measurement; accuracy; algorithm; approximate circularity; automatic estimation; conventional edge-detection techniques; corneal limbus; edge points; edge-detection procedure; ellipse; eyelashes; eyelids; manual computer-based technique; outliers; polar grid; soft edge; squared algebraic errors; videokeratoscopic rings; videokeratoscopy; Australia; Biomedical measurements; Cornea; Geometrical optics; Image edge detection; Optical films; Optical refraction; Shape; Surface morphology; Surface topography; Algorithms; Astigmatism; Computer Simulation; Corneal Topography; Humans; Image Enhancement; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Keratoconus; Limbus Corneae; Pattern Recognition, Automated; Quality Control; Reproducibility of Results; Sensitivity and Specificity; Video Recording;
Journal_Title :
Biomedical Engineering, IEEE Transactions on
DOI :
10.1109/TBME.2002.805481
