Camera Response Function Recovery from Auto-Exposure Cameras

A robust method of camera response function estimation applicable to auto-exposure cameras is presented. The method uses the superposition property of light to solve for the response function directly using superposition constraints imposed by using different combinations of two (or more) lights that illuminate the same subject matter in varying proportions. An iterative optimization is utilised to simultaneously recover the exposure ratios of the images and the camera response function. Previously published multiple exposure methods that simultaneously estimate exposure ratio and response function suffer from a fundamental ambiguity. The use of the proposed superposition constraints solves this problem. We introduce a simple method for combining both superposition and homogeneity (from multiple exposure techniques) to accurately recover the response function from auto-exposure cameras.