Simple zoom-lens digital camera calibration method based on EXIF

Abstract

This paper presents a simple method to calibrate the intrinsic parameters of zoom-lens digital cameras. This method combines the classical calibration algorithm using a planar pattern and the Exchangeable Image File Format (EXIF) metadata of image files captured by digital cameras. The EXIF metadata records many information about the camera’s setting such as the focal length of zooming lens. So we can use the focal length from EXIF to know the zoom lens setting. Firstly, a pre-calibration should be done to know the relationship between zoom lens settings and the intrinsic camera parameters. We take some sample lens settings from the minimum focal length to the maximum one by changing the lens zooming positions, and perform the mono focal calibration for each lens setting configuration. Then we get the coefficients of the polynomial function through curve fitting. After that we can get the intrinsic parameters correspond with the zoom lens setting of new image files shoot by this digital camera. Our experiments show the proposed method can provide accurate intrinsic camera parameters for all the lens settings continuously.