State-of-art camera calibration methods always require sharp target images for accurate feature detection. This Letter presents a novel calibration method for a defocused camera with a conventional periodic target. Two crossed phase maps are recovered from the periodic target image by Fourier transform. Instead of intensity, feature points are extracted from the phase domain, which is robust against camera defocusing. Simulations and experiments confirm that the proposed method can realize accurate camera calibration using both focused and defocused images.
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