Master Chief on Out of the Blue
#507d2a on #1199ee
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
1.58:1
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 14.5
Below Lc 15: the draft treats this as not text.
Dark text on a lighter ground.
Colour difference
ΔE00 55.2
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#193300 is the nearest colour of the same hue that passes AA on #1199ee, at 4.50:1. Only the lightness moved, and some chroma was given up to stay inside sRGB — which is the point: your colour stays recognisably your colour.
And to someone missing a cone
protanopia
Ratio 1.64:1, ΔE00 55.0.
deuteranopia
Ratio 1.55:1, ΔE00 55.6.
tritanopia
Ratio 1.30:1, ΔE00 12.2.
The weakest of the three is tritanopia, where the two are ΔE00 12.2 apart against 55.2 for a trichromat — still clearly two colours.
Both colours have pages of their own: Master Chief ·Out of the Blue · the same pair the other way round ·all pairs