How do I make a vignette effect?

[fataIobsession (fatal)]

Hi, I’m making a dark academic library homestore and was wondering if anyone knew how to make a vignette effect. I’m unsure which topic this belongs in so my apologies if this is the wrong one and any solution helps, thanks!

[mc7oof (oof)]

GUI overlay.

Here is a post that might help:

How do you make a transparent circle vignette transition?

How do I implement the popular black transparent circle vignette transition? Where the screen is black and then a transparent circle(revealing the world) grows from the middle of the screen. I know how to script UI, but the actual effect of this stumps me.