Abstract
A new technique to correct non-linear distortion of endoscopic images based on L2-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.
Similar content being viewed by others
References
Atkinson, L. V., andHarley, P. J. (1993): ‘An introduction to numerical methods with Pascal’ (Addison-Wesley, London)
Brown, D. C. (1966): ‘Decentering distortion of lenses’,Photogramm. Eng. Remote Sens., pp. 444–462
Haneishi, H., Yagihashi, Y., andMiyake, Y. (1995): ‘A new method for distortion correction of electronic endoscope images’,IEEE Trans. Med. Imaging,14, pp. 548–555
Nomura, Y., Sagara, M., Naruse, H., andIde, A. (1992): ‘Simple calibration algorithm for high-distortion-lens camera’,IEEE Trans. Pattern Anal. Mach. Intell.,14, pp. 1095–1099
Phin, L. C., Maxted, K. J., Richardson, W., andMacleod, J. (1996): ‘Video endoscopy testbox’,Med. Biol. Eng. Comput.,34, pp. 501–502
Smith, W. E., Vakil, N., andMaislin, S. A. (1992): ‘Correction of distortion in endoscopic images’,IEEE Trans. Med. Imaging,11, pp. 117–122
Tsai, R. Y. (1986): ‘An efficient and accurate camera calibration technique for 3D machine vision’,Proc. IEEE Comput. Vision Patt. Recogn., Miami, FL, pp. 364–374
Weng, J., Cohen, P., andHerniou, M. (1992): ‘Camera calibration with distortion models and accuracy evaluation’,IEEE Trans. Pattern Anal. Mach. Intell.,14, pp. 965–980
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Asari, K.V., Kumar, S. & Radhakrishnan, D. Technique of distortion correction in endoscopic images using a polynomial expansion. Med. Biol. Eng. Comput. 37, 8–12 (1999). https://doi.org/10.1007/BF02513259
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02513259