Is there any way to have Black Color on Post Process materials?

[Mrbear99]

So i’m trying to create a square vignette effect Post Process Material the problem is that black turn invisible.

The image is a black square and its invisible on the middle, but after some testing and changing the color of the square it turns out that if it’s white (255,255,255) its compleatly visible, so the visibility of the square depends on the color of the square.

(i’ve tried many colors but the closer to black the less visible it gets until its compleatly invisible)
Also it cant be a Widget or something because i want it to be affected by another distortion Post Process Material.

Anyways here’s the material blueprint :

[Detach789]

For just black screen you could do this:

I’m not sure if that is helpful because you only want it around the edges, but maybe if you play with it a bit you can do something with it.