Crosshair that inverts color underneath?

[unit23]

@CleanCut;645761

I would like to make a crosshair which simply reverses the color underneath it, instead of overlaying a specific texture color. Is that possible?

Ultimately, I’m trying to make my crosshair always visible, but I have lots of bright colors, so no matter what I pick, it blends into something.

Suggestions?

Maybe put a 1 pixel border around the cross image, to have some sort of border?