Lighmap density numeric value

Hi, i’m trying to play with Python scripting in ue, and what i want:

I can see the Lightmap density by alt+0 view mode, but what engine value have all of this colors? e.g.: dark blue 0.1 green 0.5 red 1 or somethig like that.
I want to compare this value with custom reference value to tweak the resolution of lightmaps.

I will be glad to any help and advice. it doesn’t matter to me to use python, it can be C++ or BP.