Contrast and vision

Every pair of your colours as text on background, in WCAG 2 and APCA; the set as three kinds of colour-blind viewer and a greyscale photocopy see it; and a fix for every pair that fails.

Colours one per line: hex, rgb(), hsl(), oklch(), lab() or a name

Contrast matrix rows are text, columns are background; pick a cell to see it as text below

WCAG 2: AA needs 4.5:1 for body text and 3:1 for large text (24 px, or 18.66 px bold); AAA needs 7:1 and 4.5:1. The ratio is the same both ways round.

APCA (0.1.9, the WCAG 3 candidate): Lc is signed, positive for dark text on light and negative for light on dark, and the direction matters. Rough floors: Lc 90 preferred for body text, 75 the minimum for body text, 60 for other content text of 24 px or 16 px bold, 45 for large headlines, 30 for non-text.

Text samples

Colour oneColour two

Contrast and vision

Contrast matrix rows are text, columns are background; pick a cell to see it as text below

Text samples

Vision Machado 2009 at full severity, and greyscale at the same L*

Hard pairs distinct for most viewers (ΔE2000 8 or more), collapsed below 8 for some

Fix it for every pair under 4.5:1, move one colour along its OKLCH ramp, hue and chroma held, until it passes