Colorimetric calibration of images of human skin captured under hospital conditions

Abstract

In this paper we study the problem of acquiring colorimetrically-calibrated images of human skin under hospital conditions with uncontrolled multiple illuminants. The application domain is diagnosis of skin burns based on the measured colour. To give some control over illumination we have experimented with xenon flash in an attempt to dominate the ambient illumination. We have used a Macbeth DC Color Checker as a test target to make measurements of observed colour using a digital camera under various illumination conditions. We present an iterative colorimetric calibration algorithm which determines both a spatial image correction profile and a transformation matrix to convert measured pixel values into calibrated CIE XYZ values. We have obtained a colorimetrically calibrated burn photograph database by applying this method.