Earlier quoted context omitted.
> The fact that PNG stores straight/unpremultiplied alpha says everything if you know anything about imaging in computer graphics. > And the fact that the updated format spec just released didn't address this tells you everything you need to know about the group in charge of that, today. What does it say? That they are naive or have the wrong priorities? Their rationale for this seems quite reasonable to me: https://…
You can't represent additive pixels (i.e. glowing pixels) with non-associated alpha. That's why this is used in exactly zero image processing software, internally. E.g. an associated pixel with the 8bit/channel RGBA value 255, 0, 0, 0 (glowing red). Because PNG can only store associated data a reader must associate before displaying. And that will give you a value of 0, 0, 0 after (black instead of additive red). See…
They do not mention precision at all in their rationale for that: “We standardized on non-premultiplied alpha as being the lossless and more general case.”
> And when 16bit PNG got introduced...
PNG has supported 16-bits per component since it was first introduced (see version 1.0 of the spec or RFC 2083).