Tweak XDR brightness scaling for common values

[diamondsw]

Right now when adjusting brightness with hardware keys and the tweaked OSD, it appears that the native XDR brightness scale (the one that goes up to 1600 nits on my MacBook Pro) uses an internal curve for its intervals, things like 1180, 870, 642, 474, etc. Would it be possible to tweak it a bit to lock on to some common numbers? For instance, 500, 600, 1000 nits, etc.

(Honestly, this may be possible - there's an amazing wealth of settings in there, but I didn't see anything that quite scratched this itch.)

[waydabber]

Hi there - I can add an option to round the output if that makes one feel better. But what you see is how things work natively, the curve will not produce rounded nit values.

Here is how things look like with various max brightness levels for the native curve.

[diamondsw]

Not sure if we're looking at the same thing; I probably explained poorly. Or maybe I'm misunderstanding your response!

Given the curves posted above, taking the green one that maxes at 1600/1599 nits, the curve comes close to several "useful" nit values, but doesn't quite hit them. My suggestion is to slightly nudge the values off the strict curve, fixing indexes 12 through 15 at more "useful" values even though brightness would not quite increase consistently between indexes.

For instance, index 12 peg to 500, index 13 peg to 600, index 14 peg to 1000, index 15 peg to 1200. These are similar to but not quite what they're at today, but allow reaching some common brightness values quickly, and compare to other devices. If I want to quickly compare my screen to my old 500-nit Air, a 1000-nit TV, or an older 600-nit tablet or laptop, I could just change brightness rather than manually altering the max nits each time.

[waydabber]

Oh, I see. Now the problem is that with native XDR upscaling the keyboard curve matches the system curve exactly - in this case the app reports the nits value (reading the report from the display), does not directly set it - so fine-tuning the setting to match a round number would require some iterative process but that would not be very practical.

[diamondsw]

Makes total sense - thanks for the explanation. Looks like this isn't possible then, but setting the maximum nits is certainly a viable workaround. :)