Maintenance for the week of October 7:
• PC/Mac: No maintenance – October 7
• Xbox: EU megaserver for maintenance – October 9, 2:00 UTC (October 8, 10:00PM EDT) - 16:00 UTC (12:00PM EDT)
If you have an Nvidia card in the 900 series or later (maybe earlier), there is Nvidia Freestyle. This is enable in GFE under "Experimental". It supports a number of games, including ESO, with nothing extra needing to be installed.
You setup a hotkey of your choice (I use Alt-Z) to access the menu in-game and see post-process shading and changes in realtime.