The paper presents an approach for a robust (semi-)automatic correction of radial lens distortion in images and videos. This method, based on the Hough transform, has the characteristics to be applicable also on videos from unknown cameras that, consequently, can not be a priori calibrated. We approximated the lens distortion by considering only the lower-order term of the radial distortion. Thus, the method relies on the assumption that pure radial distortion transforms straight lines into curves. The computation of the best value of the distortion parameter is performed in a multi-resolution way. The method precision depends on the scale of the multi-resolution and on the Hough space's resolution. Experiments are provided for both outdoor, uncalibrated camera and an indoor, calibrated one. The stability of the value found in different frames of the same video demonstrates the reliability of the proposed method.
A Hough transform-based method for radial lens distortion correction / Cucchiara, Rita; Grana, Costantino; A., Prati; Vezzani, Roberto. - ELETTRONICO. - (2003), pp. 182-187. (Intervento presentato al convegno 12th International Conference on Image Analysis and Processing, ICIAP 2003 tenutosi a Mantova, ita nel Sep 17-19) [10.1109/ICIAP.2003.1234047].