The TIFF is produced from merging 5 brackets spaced 2EV apart using HDRMerge into a DNG, then I just opened that DNG in RawTherapee, applied neutral (+ CA correction in the TIFF file I uploaded, but the JPG images use a version without CA correction therefore the CA around the lamps etc) and saved it as a 16-bit TIFF. I shot this using my old Pentax K10D which is very noisy by today’s standards, and I did not enable noise reduction in RT, and despite this there is virtually no noise.

The point of this was just to show one way of brightening shadows in a very realistic way using GIMP. I did not have to use GIMP at all to do that, I could have stayed in RawTherapee (and in fact I did for the version I sent to the client). Every shadow-brightening method tries to do the same thing, but is different… “same-same but different”.