Comment by dcrazy
I’m 14 minutes into this 2 hour 15 minute presentation that hinges on precision in terminology, and Yedlin is already making oversimplifications that hamper delivery of his point. First of all, he conflates the actual RGB triplets with the colorspace coordinates they represent. He chooses a floating point representation where each value of the triplet corresponds to a coordinate on the normalized axes of the colorspace, but there are other equally valid encodings of the same coordinates. Integers are very common.
Secondly, Rec. 2100 defines more than just a colorspace. A coordinate triple in the Rec. 2100 colorspace does not dictate both luminance and chromaticity. You need to also specify a _transfer function_, of which Rec. 2100 defines two: PQ and HLG. They have different nominal maximum luminance: 10,000 nits for PQ and 1,000 nits for HLG. Without specifying a transfer function, a coordinate triple merely identifies chromaticity. This is true of _all_ color spaces.
On the other hand his feet/meters analogy is excellent and I’m going to steal it next time I need to explain colorspace conversion to someone.
If you watch a little further until about 20 minutes what follows is an explanation of what the primaries represent (described by you as “colorspace coordinates”) along with a reasonable simplification of what a transfer function is, describing it as part of the colorspace. I believe that’s reasonable? He merely explains Rec. 2100 as if using the PQ transfer function is innate. Definitely all seems appropriate and well presented for the target audience.