re: HSLuv, I don't know much of it but I've heard it mentioned several times, so it must be helpful. This comment[1] goes into more detail, but TL;DR the core to me seems to be having L* and whatever H and S measurement works for you, so I'd say HSLuv is spot on.
I love APCA, Myndex (Andrew Somers, APCA author) was an absolute inspiration to me for getting interested in color, I wouldn't have known 1% of what I do or have done 1% of it without his deep dives showing how to work in this space.
It has an interesting effect on the community in that the general language around it is read too strongly: it is an important and crucial advance, getting science-backed data on exactly the right contrast in multiple scenarios is _absurdly important_ in a world of Ambient Computing™.
The mistake that's made is reading into this too heavily as _the previous spec or WCAG aren't based on data at all_.
Yes, the calculation is based on absurd stuff -- 100 nit monitor, you can't track down a source for every bit of it.
But there's a _whole separate field_ that spatial frequency comes from and it is _very_ well known and understood.
Most importantly: the APCA predictions for contrast were only about 5-7 L* different last time I checked. This is important, thats a _lot_ --- but it also isn't a lot, that's on a scale of 100. What we have today isn't completely utterly alienly different and broken.
Comparing the difference in T will be enough as long as the luminance measure APCA relies on is monotonic to RGB (HSL's lightness is hilarious, its the max of RGB minus min of RGB)
I love APCA, Myndex (Andrew Somers, APCA author) was an absolute inspiration to me for getting interested in color, I wouldn't have known 1% of what I do or have done 1% of it without his deep dives showing how to work in this space.
It has an interesting effect on the community in that the general language around it is read too strongly: it is an important and crucial advance, getting science-backed data on exactly the right contrast in multiple scenarios is _absurdly important_ in a world of Ambient Computing™.
The mistake that's made is reading into this too heavily as _the previous spec or WCAG aren't based on data at all_.
Yes, the calculation is based on absurd stuff -- 100 nit monitor, you can't track down a source for every bit of it.
But there's a _whole separate field_ that spatial frequency comes from and it is _very_ well known and understood.
Most importantly: the APCA predictions for contrast were only about 5-7 L* different last time I checked. This is important, thats a _lot_ --- but it also isn't a lot, that's on a scale of 100. What we have today isn't completely utterly alienly different and broken.
Comparing the difference in T will be enough as long as the luminance measure APCA relies on is monotonic to RGB (HSL's lightness is hilarious, its the max of RGB minus min of RGB)
[1] https://news.ycombinator.com/item?id=37314700