  In this paper the use of Random Sprays Retinex (RSR) algorithm for global
illumination estimation is proposed and its feasibility tested. Like other
algorithms based on the Retinex model, RSR also provides local illumination
estimation and brightness adjustment for each pixel and it is faster than other
path-wise Retinex algorithms. As the assumption of the uniform illumination
holds in many cases, it should be possible to use the mean of local
illumination estimations of RSR as a global illumination estimation for images
with (assumed) uniform illumination allowing also the accuracy to be easily
measured. Therefore we propose a method for estimating global illumination
estimation based on local RSR results. To our best knowledge this is the first
time that RSR algorithm is used to obtain global illumination estimation. For
our tests we use a publicly available color constancy image database for
testing. The results are presented and discussed and it turns out that the
proposed method outperforms many existing unsupervised color constancy
algorithms. The source code is available at
http://www.fer.unizg.hr/ipg/resources/color_constancy/.
