Belladonna on Castro
#220011 on #44232f
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
1.42:1
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 9.6
clearly different
Between 5 and 10 — nobody would call these the same colour.
What the text colour has to become
#b8859a is the nearest colour of the same hue that passes AA on #44232f, 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 1.38:1, ΔE00 9.1.
deuteranopia
Ratio 1.44:1, ΔE00 9.9.
tritanopia
Ratio 1.47:1, ΔE00 14.5.
The weakest of the three is protanopia, where the two are ΔE00 9.1 apart against 9.6 for a trichromat — still two colours, but a closer call than it looks to you.
Both colours have pages of their own: Belladonna ·Castro · the same pair the other way round ·all pairs