Technical Report Abstract: A same scene captured under different lights produces two different color images. Such a color variation is usually approximated by the von Kries model, that relates the color responses of the images by a diagonal linear map. In order to describe also image noise, diffuse lights possibly disturbing the scene or lens scattering, an offset term is often added. In this work, we compare the diagonal model and the diagonal-offset model in terms of accuracy on color correction and illuminant invariant image retrieval. Our experiments show just slight differences between the performances of the two models, that provide satisfactory results.