Optical RGB image (top) of an inactive galaxy (left) and a low-redshift X-ray detected AGN (middle) and a QSO (right). Second row: Azimuth profile of the sources, with over-plotted available model profiles (PSF, REX, EXP, DEV, and SER). Third row: Apertures within which ap_flux[band] is measured. Fourth row: the residual image after subtracting the best model. Bottom row shows, within each aperture, all the colors computed; the figures show how the profiles of the colors change with the distance from the center, depending on the source type (see more details in the main text).