Gradient color correction [solved]

Hi.

I'm in search for a shader to solve a specific problem. With my main display (a fairly expensive LG G3) I lost the OLED panel lottery, with the result of it having an annoying color tint; magenta in the middle, and green at the sides (see imgur.com/ZxEdvQL ). Since LG's support isn't very helpful, I thought about trying to solve the issue (at least for gaming) with a simple shader. My problem: All color correction shaders I found so far work on the whole picture, but I would need some kind of gradient based solution.

Does anybody know such a shader? And if not, would it be hard to build one myself (I am a software developer, but never worked with any graphics programming whatsoever)? I thought about some grayscale texture that defines how much of two configurable color values (in my case magenta and green) should be added or subtracted from each pixel on the screen, or I dunno.

Many thanks in advance!

Edit:

Do you know that when as soon as you try to describe something to others, you think about it from a new perspective, and only minutes later you find the solution yourself. 😆

Turns out I needed to combination of two shaders: qUINT_lightroom.fx to fix the magenta tint in the middle, and ArtisticVignette.fx (which allows custom vignette shapes, in my case "Left/Right") to fix the now even more greenish sides.
For calibration I used Monochrome.fx to get something that in the end should resemble a neutral gray picture, and my iPhone screen as reference (with TrueTone disabled of course).