Using LUT to create a stimulus without Monitor Center

I would like to create the stimulus (Gabor patches) using the LUT obtained from a spectroradiometer which is not available to me anymore (if that makes a difference). I have the luminance values of 256 pixels. However, I cannot find a direct application of such a functionality. I am fairly new to PsychPy and coding in general. As I understand some languages inherently have a built in function to use lookup tables. The problem is that I would like to do this within the code and not in the monitor center.
In short, I would like to be able to create a grating with the wanted luminance.

All help is welcome, thanks