Originally Posted by Baertram
I think you cannot apply this to the GuiRoot itself so you might need to overlay the whole screen with 1 control, which is MouseEnabled false, and you could add the saturation effect etc there. There was once an addon adding blood drop textures at the screen edges as your health was low, search for blood and you might use it to spy what was done how.
I think I have a limited knowledge of XML then, because I've only used 'Backdrop' and 'Texture' controls before (neither of which work for what I'm doing). I've looked through ESO XML documentation and found some other options that have saturation headings listed under them, like 'PolygonControl' or 'TextureControl'.
Problem is, even with looking online I can't find examples of people using either of those controls, so I don't actually know how they're used in practice or what they do. (I've found the blood mod you're talking about, but the author didn't use any XML in the mod. They only used lua and called on the blood textures from within the lua file itself).