MiRA image reconstructions as a function of the assumed chromatic parameters: the stellar-to-total-flux ratio and the dust spectral index d_env. The star is represented in red at the center of each image. The true values are and d_env = 1. Top right: χ² map of the reconstructions as a function of the chromatic parameters for reconstructions with the total variation regularization. All χ²sup3 are represented in black. The blue crosses represent the location of the images in the χ² map. We can clearly see that this map is degenerated.