Thin-plate spline interpolation is used to interpolate the color of the incident scene illumination from an image of the scene. The algorithm can be used to provide color constancy under changing illumination conditions, and automatic white balancing for digital cameras. Thin-plate splines interpolate over a non-uniformly sampled input space, which in this case is a set of training images and associated illumination chromaticities. Tests of the thin-plate spline method on a large set of real images demonstrate that the method estimates the color of the incident illumination quite accurately.