Cover of Night on Panorama
#494e4f on #327a88
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
1.72:1
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 13.4
Below Lc 15: the draft treats this as not text.
Dark text on a lighter ground.
Colour difference
ΔE00 20.6
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#f0f6f7 is the nearest colour of the same hue that passes AA on #327a88, 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 1.85:1, ΔE00 17.0.
deuteranopia
Ratio 1.65:1, ΔE00 16.4.
tritanopia
Ratio 1.69:1, ΔE00 23.4.
The weakest of the three is deuteranopia, where the two are ΔE00 16.4 apart against 20.6 for a trichromat — still clearly two colours.
Both colours have pages of their own: Cover of Night ·Panorama · the same pair the other way round ·all pairs