Images of the Fe spatial structures in our first toy model as found by GMCA without fixing the Fe spectral shape (on top) and by an interpolation method (below) for the three Fe line-to-synchrotron ratios marked by arrows in Fig. 2). The SSIM coefficients are written on top of the images. Coefficients under 0.75 describe images where the Fe structures are not recognizable, but the SSIM is still high because of the similarities between intrinsic Fe and synchrotron distributions.