WebAIM - Web Accessibility In Mind

E-mail List Archives

Re: Contrast Checker for rgba Color Values (and hello from anew list subscriber)

for

From: Patrick H. Lauke
Date: Aug 25, 2014 2:22AM

> The website I'm looking at is http://worldnpa.org and the color contrast I'm
> looking at is a font color of rgba(0,0,0,0.7) on a background color of
> #7EBEC5

Having a quick look, it seems that those links are actually set to
rgba(0,0,0,0.5).

> I had to search around a bit for a color contrast checking tool that would
> work with rgba, and found one on github by Lea Verou at
> http://leaverou.github.io/contrast-ratio/. The tool returns a 10.1 contrast
> ratio for this color combination which it claims passes a AAA level for any
> size text.

I think you may have entered those values incorrectly in Lea's tool.
Even using rgba(0,0,0,0.7) it returns a contrast ratio of 5.8 (not
10.1). Entering the actual rgba(0,0,0,0.5) returns 3.3, so well below
the minimum for AA.

P
--
Patrick H. Lauke

www.splintered.co.uk | https://github.com/patrickhlauke
http://flickr.com/photos/redux/ | http://redux.deviantart.com
twitter: @patrick_h_lauke | skype: patrick_h_lauke