What is the Center of the Image?

Abstract

To model the way that cameras project the three-dimensional world into a two-dimensional image we need to know the camera's image center. First-order models of lens behavior, such as the pinhole-camera model and the thin-lens model, suggest that the image center is a single, fixed, and intrinsic parameter of the lens. On closer inspection, however, we find that there are many possible definitions for image center. Most image centers do not have the same coordinates and, moreover, move as lens parameters are changed. We present a taxonomy that includes 15 techniques for measuring image center. Several techniques are applied to a precision automated zoom lens, and experimental results are shown.