Magenta lines show the radial flux profile (for one side of the disc) at 2500 Å (as seen at infinity) when the disc is illuminated by an X-ray corona at h = 20 R_g and R_tr = 3R_ISCO for BH with a^* = 1. All other model parameters are the same as in Fig. 2. Dotted and solid lines indicate the profile for a NT disc and when we assume the colour correction factor of Done et al. (2012), respectively. The black lines are the same as the black lines in Fig. 2, and are shown for comparison. The vertical dashed lines show the location of R_1/2, mod for each radial profile.