amiroxx wrote:
what is true:
Apple video gamma correction value was just taken from some random value by a hired coder who doesn't understand the concept of gamma.
In my experience, as a consultant for several manufacturers and developers in the media industrie, I can tell you, that many engineers and coders really misunderstood the SMPTE or DCI specifications. The results are mistakes in the hardware video IOs and mistakes in software and mistakes in whitepapers. I helped out EIZO, SMALL HD, Dolby!!!, AJA, AVID and many more.
One problem with gamma is that the (older) SMPTE specifications are incomplete in terms of display gamma, only with the newest BT1886 there is now a concrete specification for gamma. But nearly all video displays are based on the older power gamma, not on the BT1886... that is also a new problem, cause newer consumer TVs use sometimes and more and more will do BT1886... (near to gamma 2.4 but looking different in the blacks)
filmlights correct implementation of NCLC tags is the only correct way to prevent this problem on mac systems.
Blackmagic should also implement those NCLC tags for Quicktime files...
As far as I been told Apple QT spec was written by broadcast veterans, not random programmers. It was done long time ago. It's still the most, full and advanced system related to videos (just bit outdated now).
Even if it's 'industry' problem (including crazy slow SMPTE) and taking into fact that it was written so long time ago (with just few later changes) it does work.
It's everyone else than Apple who ignores all tagging etc. which is the main reason for all this mess. Another reason are SMPTE and others who omit most important tagging in quite new technologies. I asked so many times- where is tagg for BT.1886 which is current standard for SDR videos?Filmlight has done nothing more except properly using what is already available.
BlackMagic also does it now, so you are bit outdated (for few good months now).
In general, gamma is not specified for rec709 deliveries!!
And this is the core reason of all these problems…
Well- now it's specified, but even new technologies (h265) simply forgotten about it (yet have all outdated and useless flags).
I've asked BM what is the gamma behind Rec.709 choice in Resolve. Answer was- as per Rec.709 spec. But spec doesn't specific any gamma related to monitoring
Whole problem is a "industry" problem, not Apple's.
Apple's choice for Rec.709 gamma is not from nowhere. Their 1.96 approximation is based on the Rec.709 spec itself:
"The power function of the majority of the gamma curve is 0.45, but because it is offset by the linear section the resulting equivalent gamma is more approximate to 0.50-0.53 (the inverse of which is approximately gamma 1.9-2.0 to convert back to linear)."
Problmes is that value is useless these days as no one grades to 1.96 gamma.
It's all plain and simple- just in no ones interest to fix it (same as some companies are not interested to provide proper GPU monitoring) as there is no money behind it
Whole argument that you need and will ever need dedicated card to display video accurately as oppose to just using GPU is one big bullxxx
All what you need is move forward and use properly current technology, not live by 20 years old one. Todays GPUs are more than enough to handle this task.
Print industry been using GPUs for years and they need to be as accurate as video world.