Diesel on Black Sabbath
#322c2b on #220022
Body text at this size
And the smaller size most interfaces actually use for paragraphs — the size that decides whether a pair is usable.
Caption text, which almost nothing passes.
WCAG 2.1
1.40:1
Fails AA
Not AAA (7:1). Swapping the two colours gives the same number — the ratio does not know which is the text.
APCA
Lc 0.0
Below Lc 15: the draft treats this as not text.
Too close to call.
Colour difference
ΔE00 19.1
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#807978 is the nearest colour of the same hue that passes AA on #220022, at 4.50:1. Only the lightness moved — which is the point: your colour stays recognisably your colour.
And to someone missing a cone
protanopia
Ratio 1.44:1, ΔE00 17.5.
deuteranopia
Ratio 1.39:1, ΔE00 15.7.
tritanopia
Ratio 1.34:1, ΔE00 10.2.
The weakest of the three is tritanopia, where the two are ΔE00 10.2 apart against 19.1 for a trichromat — still clearly two colours.
Both colours have pages of their own: Diesel ·Black Sabbath · the same pair the other way round ·all pairs