Adjust selected area of screen's gamma

[Yata]

Hello,

I have the correct UDF to adjust the gamma of my screen as I wish, but the downside is it, of course, changes the gamma of everything on screen. I'm looking for a way to take an on screen coordinate (x1 y1 x2 y2 system probably) and only adjust the gamma of that area. Is that at all possible?

If it's not, I do have an idea for something that could work. Could you take a 1x1px .png with an alpha value of 1 (or any other transparency level( and overlay it over the area, whilst still being able to fully interact with the stuffs under it? this would give the ability to lighten the screen without actually adjusting any gamma/brightness levels.

Any help here?