Estimation of spatially varying illumination in hyperspectral images

While images often contain only one illumination source, objects in the scene are illuminated by varying intensities of that illuminant. We show that the illuminant can be estimated using a few known reflectances within an image taken with a hyperspectral camera. The method relies on projection to a non-convex constraint set, as well as to convex constraint sets. Simulations and tests on actual hyperspectral images show the method is effective.