Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/108118
Title: Technique of distortion correction in endoscopic images using a polynomial expansion
Authors: Asari, K.V.
Kumar, S. 
Radhakrishnan, D.
Keywords: Barrel distortion
Corrected centre
Distortion centre
Endoscopic images
L 2-norm approximation
Polynomial mapping
Issue Date: 1999
Source: Asari, K.V.,Kumar, S.,Radhakrishnan, D. (1999). Technique of distortion correction in endoscopic images using a polynomial expansion. Medical and Biological Engineering and Computing 37 (1) : 8-12. ScholarBank@NUS Repository.
Abstract: A new technique to correct non-linear distortion of endoscopic images based on L 2-norm approximation is proposed. A mathematical model is defined that maps the endoscopic images from the distorted image plane onto an undistorted image plane. A set of model parameters is defined, consisting of the image distortion centre, corrected centre and expansion polynomial coefficients representing radial distortion correction. A new method to find the image distortion centre based on a curvature criterion is also developed. The expansion coefficients are estimated on the basis of the degree of straightness of the grid lines in an image of a test grid consisting of dots in a rectangular pattern. The corrected image centre is computed by ensuring that the distances between neighbouring test dots of different grid lines in the corrected image are the same. The quantitative data providing the results and errors of the expansion characteristics are presented. The performance of the proposed distortion correction algorithm is validated with grid patterns of different orientations. The algorithm is also applied to typical endoscopic images, and the results are presented. The high-speed response of the proposed technique is a key step towards on-line camera calibration.
Source Title: Medical and Biological Engineering and Computing
URI: http://scholarbank.nus.edu.sg/handle/10635/108118
ISSN: 01400118
Appears in Collections:Staff Publications

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