Choice of the μ parameter and its influence on the fit of the chromatic parameters. χ² map of the reconstructions as a function of the chromatic parameters for reconstructions with the smoothness regularization. Black represents χ²> 3. The blue crosses represent the location of the images of Fig. 3 in the χ² map. The four figures represent μ = { 10⁷,10⁸,10⁹,10¹⁰ } respectively. The χ² does not change significantly with the μ hyper-parameter, but the degeneracy is always strong.