Cover of Night on Diesel
#494e4f on #322c2b
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
1.62:1
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 -8.6
Below Lc 15: the draft treats this as not text.
Light text on a darker ground — the negative sign is the polarity.
Colour difference
ΔE00 12.7
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#8f9596 is the nearest colour of the same hue that passes AA on #322c2b, 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 1.65:1, ΔE00 11.0.
deuteranopia
Ratio 1.61:1, ΔE00 10.8.
tritanopia
Ratio 1.62:1, ΔE00 27.3.
The weakest of the three is deuteranopia, where the two are ΔE00 10.8 apart against 12.7 for a trichromat — still clearly two colours.
Both colours have pages of their own: Cover of Night ·Diesel · the same pair the other way round ·all pairs