This paper deals with the automatic evaluation of the illuminant from a color photography. While many methods have been developed over the last years, this problem is still open since no method builds on hypotheses that are universal enough to deal with all possible situations. The proposed approach relies on a physical assumption about the possible set of illuminants and on the selection of grey pixels. Namely, a subset of pixels is automatically selected, which is then projected on the Planckian locus. Then, a simple voting procedure yields a robust estimation of the illuminant. As shown by experiments on two classical databases, the method offers state of the art performances among learning-free methods, at a reasonable computational cost.