Colours were shaped in HSV, whose "value" is not perceived brightness:
at one pinned value the hues spread across relative luminance 0.10 to
0.45, straddling the black/white ink crossover at 0.179. So the ink was
decided by hue — red and purple took white, orange and blue took black —
and the fills nearest the crossover were the mid colours that contrast
badly with either ink.
Shape them in Oklch instead, where lightness matches what the eye calls
brightness, and split the two jobs one colour was doing: a container
sits behind text and must contrast with its ink, an accent is a mark on
a surface and must contrast with the surface. Nine call sites that were
painting marks now ask for the accent.
Colours go to whichever pole they already sit nearer rather than all
being forced deep — a dark orange is brown and a dark yellow is olive,
so the warm, naturally light hues keep their character and take dark ink
while the rest go deep and take white. Either way they land clear of the
middle, which was the fault. White ink is now 5.6-6.3:1 on every deep
hue and dark ink 11:1 on the light ones, against 2.7-8.2:1 before.
Picker curation now calls the same eventTone the picker paints with,
instead of a copy of the shaping kept in step by hand, and drops its CIE
Lab helper for Oklab distance. Renames the setting to "harmonise", since
it no longer softens anything.
Jean-Luc Makiola
9287b7b0da