Hi,
a pre-processed JPG (which is most likely sRGB) file from let’s say a DSLR RAW photo is not having a real benefit when you color correct it in Nuke (in float precision) and write it out again as a JPG texture. Write it out as a ACEScg EXR and at least you keep your grading changes in the highest precision.
If you can develop your RAW photo to ACEScg, then you can benefit from a bigger color gamut and a higher dynamic range that was captured by the camera. I do this with Affinity Photo, but I am not sure if the gamut is still limited to sRGB in the RAW development process.
I am not really sure what to do with values over 1.0 in this case, because a texture should not have a higher value than 1.0 if I am not mistaken. I was playing around with that here: Understanding the sRGB-Texture IDT - taking an image from the “screen” into the “scene”
Best regards
Daniel