Would it be possible to have some sort of color correction shader?

[Contra-S]

I was wondering if it would be possible to have an option to color correct the screen's colors, as some GBA emulators do with shaders like "gba-color".

[profi200]

I wanted to implement this for a while but there is one huge problem. These shaders all use the fragment shader feature of GPUs but the GPU on 3DS does not have this. I won't rule out that i find a way to make it happen but for now i have no way to accurately implement this.