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Old 8th February 2019, 15:08   #54629  |  Link
Warner306
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Join Date: Dec 2014
Posts: 1,127
Quote:
Originally Posted by ryrynz View Post
Anyone created a HDR test file to assist with setting target nits? Ideally madVR could have something built in?
A test file might be possible, but the result seems to vary per movie, possibly to due to other factors such as the amount of pixels near black. After tone mapping, movies with a low black floor can get quite dark because tone mapping will make many of the lower values even darker after tone mapping. This mostly occurs when raising the target nits above the actual brightness of your display by a large amount. The AvgFALL (Frame Average Light Level) can help in judging the overall brightness of the movie, but even it seems to fail sometimes in predicting a movie that is too dark after tone mapping.

I have been using HDR profile rules very similar to Manni's to match the target nits to the movie's measured AvgFMLL (Average Frame Maximum Light Level):

if (hdr) and (AvgFMLL < 1) "General HDR" else
if (hdr) and (AvgFMLL <= 100) "200 nits" else
if (hdr) and (AvgFMLL <= 160) "225 nits" else
if (hdr) and (AvgFMLL <= 190) "250 nits" else
if (hdr) and (AvgFMLL <= 225) "275 nits" else
if (hdr) and (AvgFMLL <= 250) "300 nits" else
if (hdr) and (AvgFMLL <= 270) "325 nits" else
if (hdr) and (AvgFMLL <= 300) "350 nits" else
if (hdr) and (AvgFMLL <= 380) "375 nits" else
if (hdr) and (AvgFMLL <= 550) "400 nits" else
if (hdr) and (AvgFMLL <= 700) "425 nits" else
if (hdr) and (AvgFMLL > 700) "480 nits"

You have to measure your files for profile rules like these to work. This approach focuses more on preserving the dynamic range of the source, but it also gets the brightness/contrast right much of the time. I haven't tried to optimize them any further, only simplify them, but it does a decent job of selecting a curve most of the time. Manni's original rules also incorporate the AvgFALL and I removed that bit.

This all could become a moot point if Soulnight's approach to changing the target nits dynamically during the movie ever works smoothly.

Last edited by Warner306; 8th February 2019 at 18:27.
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