What kind of LUT is this?

Hello everyone.

This isn't strictly ReShade related but I didn't know where else to ask this.
This is a native LUT file from a game I'm trying to edit. But it's very different from Reshade's LUT texture. It doesn't contain all the colors, and it's not a 3D lut. So I'm kind of lost as to how to edit it and how to save it.



i.imgur.com/RLJ1Q1Q.png

I hope you geniuses can help me out.

Looks like it's just the first square of a normal 3d lut.

Indeed, it does look like it's part of this:




Or maybe this one?




But that's exactly how it is in the game. I haven't cropped or resized the original image at all. I wonder where the rest of the lut is or how to edit this one.

And have you tried to modify it? there's really no telling what it does just by the resource, and no point of guessing as it can be anything.