Parameters of detected sources against VIS I_E magnitude. Panel a is the concentration index C_4 − 8, which is the difference in magnitude between the aperture with a radius of 4 and 8 pixels. The parameter shown in panel b is the FWHM of the sources in arcsec, panel c is the ellipticity and panel d is the maximum surface brightness. All four parameters are derived from the ERO-Fornax catalogue and are intrinsic size parameters deconvolved with the PSF. Known GCs are shown as red symbols. The blue shaded density distribution represents all photometric sources in the Fornax FoV. The yellow, orange, red and maroon ellipses mark the levels that include 95%, 90%, 68%, and 50% of all known GCs in the Gaussian mixture output.