This work presents a local (spatially-variant) gamut reduction algorithm that operates only on the saturation channel of the image, keeping hue and value constant. Saturation is reduced by an iterative method that comes from inverting the sign in a 2D formulation of the Retinex algorithm of Land and McCann. This method outperforms the state-of-the-art both according to a quantitative metric and in terms of subjective visual appearance.