An Automatic Warping Points Extraction Method for Calibration of Wide Angle Camera

Radial or pincushion distortion problem of the wide angle charge-coupled device (CCD) camera is an important issue in the image calibration in case of close-up photography of real scene. We designed the auto-extraction method of the warping points in the calibration algorithm of the image acquired by the wide angle CCD camera. Proposed method extracts the distortion point by the wide angle CCD camera, using the threshold value of the histogram of the horizontal and vertical pixel lines. This processing step can be directly applied to the original image of the wide angle CCD camera output. Proposed method results are compared with hand-worked result image using the two wide angle CCD cameras having different angles (90° and 120°) with the difference value of the result images respectively. Experimental results show that proposed method can allocate the distortion-calibration constant of the wide angle CCD camera regardless of lens type, distortion shape and image type.