Cover of Night on Dragon’s Fire
#494e4f on #fc4a14
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
2.47:1
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 26.8
Clears Lc 15 — disabled or purely decorative text, which is not meant to be read.
Dark text on a lighter ground.
Colour difference
ΔE00 41.1
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#212526 is the nearest colour of the same hue that passes AA on #fc4a14, 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 1.66:1, ΔE00 27.0.
deuteranopia
Ratio 2.90:1, ΔE00 41.3.
tritanopia
Ratio 4.25:1, ΔE00 56.9.
The weakest of the three is protanopia, where the two are ΔE00 27.0 apart against 41.1 for a trichromat — still clearly two colours.
Both colours have pages of their own: Cover of Night ·Dragon’s Fire · the same pair the other way round ·all pairs