Open this image in a new tab to see it in full. This is the deriveHDRfromLDR node.
I’m not sure what makes the function special honestly, as I don’t understand it for the most part. I saw them using it in paragon and liked the way that it helped boost a materials emissive colors and feels a bit more on the realistic side to me. High emissive values will result in a blackened texture, so you’ve gotta be careful with it.
I’ve also noticed that you may get more lens flare effects when using higher HDR intensity values than your typical emissive texture, but I could be wrong about that.
Overall, not sure how the node works, but I like its results.
I’m sure there is some sort of HDR from LDR equation out there that they pulled from.