Re: [DCP-o-matic] Rec709 vs BT1886 for DCP

Am 11.08.2017 um 01:43 schrieb Carl Hetherington via DCPomatic: I don't know if I read enough about it already, but from the document Charles quoted, it seems that what everyone is calling Rec 709, is actually Rec 709 (the color part) with BT.1886 gamma. It seems as if Rec 709 for historical reasons never had a proper gamma associated with it, as Rec 709, despite now being 'THE' digital HD color space, was conceived in the early nineties and carried the intrinsic gamma of cathode ray tube displays with it. That was, so to say, baked-in the display technology of the days, so, at the time they didn't see a need to formalize on this. Later, when displays became digital flat panels, they needed a digital representation to be compatible with existing material. And that became BT.1886, and I think that is from 2011 or so. Hardly any consumer equipment spec mentions BT.1886, but I guess, where ever the specs say Rec 709 now, it actually means Rec 709 with a BT.1886 gamma. Much of that is spec'd for broadcast, and to comply with consumer equipment ('TVs') and consumer expectations. They even take into account that typically, TVs are operated in lit or dimly lit environments, and expect that some shadow detail is lost due to these 'typical' viewing conditions, so they also assume a slight overall gamma up-shift to compensate for that. - Carsten