Analysis of a patch highly contaminated at small scales. Top panel: sky patch selected with high contamination at small scales. The patches represent from left to right all the emission, the CMB label, the neural network output, and the residual map computed as the difference between the second and third columns. The frequency for all patches is 217 GHz, and their temperature (in µK_CMB) is shown in the right vertical bars. Bottom panel: CMB power spectrum comparison computed over the patch shown in the top panel. The true CMB is represented in the top panel as a blue line, and the output from CENN is shown as a red line. The corresponding uncertainties (i.e. the standard deviation) are shown as blue and red areas, respectively. The difference between input and output is plotted in the middle panel as a black line, and its uncertainty is the grey area. The power spectrum of the residual map is represented as a green line in the bottom panel. The green area is its uncertainty (also the standard deviation).