News for hackers. Stuff that matters.

A comment on The Difference Between ‘Violet’ and ‘Purple’ (2015). Parent comment

Re:The Difference Between ‘Violet’ and ‘Purple’ (2015) by jacobolus on Tuesday April 02, 2019 @12:10PM (#19555644)
[edit: shortened this comment] I’m not trying to be “pedantic”, just not grossly misleading / confused, the way the article and most of the comments here are, including the one at top of this thread. Frankly this nonsensical article should be flagged off the front page, as it is going to lead people who read it to be misinformed.

RGB display primaries are only related to the CIE system insofar as people use the CIE system for characterizing and describing them. But it doesn’t constrain the choice of primaries. The primaries are chosen (more or less) to maximize the display gamut under the constraint that there will be 3 of them. They don’t match human cone cells per se (obviously there is some relationship between cone cell responses and maximizing the gamut, but it is not a simple one).

[ Parent | on HN ]
Re:The Difference Between ‘Violet’ and ‘Purple’ (2015) by ajross on Tuesday April 02, 2019 @12:16PM (#19555720)
We're in the weeds and I've lost you. You said "The CIE 1931 curve showing a bump in red inside the blue is misleading I think. It does not represent how the cones react"

Which I took to be a complaint that XYZ doesn't represent cone response well.

And I responded that that's silly, because (1) XYZ wasn't designed to represent cone responses and (2) the bump is there deliberately to produce a more mathemetically orthogonal basis.

If you go back to all those books you've read over that decade you spent building your expertise, I'm sure you'll find the same info.

[ Parent | on HN ]
Re:The Difference Between ‘Violet’ and ‘Purple’ (2015) by jacobolus on Tuesday April 02, 2019 @12:21PM (#19555783)
A different person said that. I thought your response to him was fine, except for the weird thing about sRGB.
[ Parent | on HN ]
Re:The Difference Between ‘Violet’ and ‘Purple’ (2015) by ajross on Wednesday April 03, 2019 @03:11PM (#19566285)
OK, makes sense. You're still being sorta oddly pedantic about this. sRGB was for sure designed to reflect a phosphor set based on red, green, and blue primaries that absolutely were chosen for their correspondence to what most people reason about as primary colors, and the reason for that is that we have three cone pigments in our retina and those three tickle them more or less orthogonally.

So I don't get your criticism. Poster above wanted a set of primaries that corresponds to how the cones react. The closest you can get to that is an RGB space like... sRGB.

Arguing about which design point (phosphor correspondence or cone correspondence) is "real" or "derived" is IMHO meaningless pedantry at this level.

[ Parent | on HN ]