Besides changing the gamma from absolute to relative, how do I further "tweak" the gamma?
What does the black output offset do? Increase the black level?
The gamma controls don't affect the black level at all, but do influence shadow detail and the relative brightness of midtones. An output offset of 0% is equivalent to BT.1886-like (input offset), while an output offset of 100% is equivalent to a "pure power" curve.
The difference between "absolute" and "relative" is that "relative" is less influenced by the display black level (i.e. setting gamma to "relative" will give you almost exactly the set gamma value at 50%, while "absolute" will produce a lower effective gamma in most cases. How much lower depends on the black level, the lower the black level, the less difference between "absolute"/"relative" and 0%/100% output offset).
I am aware that gamma does not affect the black; what I was wondering is what "black offset" does. Are you saying that black offset is tweaking the gamma?
Thanks for explaining the absolute and relative difference!
what I was wondering is what "black offset" does. Are you saying that black offset is tweaking the gamma?
Yes. If you want to get a better idea how it affects the curve shape, you could create a few synthetic profiles with different settings (set black luminance to a value above 0) and view the resulting tone response curves in the curve viewer.