Spectra retrieved by GMCA in our third and fourth toy models with a total number of counts corresponding to a 100 ks observation. Left: spectra retrieved by a GMCA with inpainting step of the two Gaussians in our toy model 3, with a first line emission-to-continuum ratio of 5.93 and a thinner binning (14.6 eV). Right: spectra retrieved with an inpainting step of the two thermal emissions in our toy model 4, with a first thermal emission-to-continuum ratio of 2.64. To compare both error estimation methods, we added the error bars and the kT given by 100 MC realizations, and those given by 100 block bootstraps resamplings of a single MC realization.