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Re: Colour contrast and blue light filters

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From: Pat Reynolds
Date: Feb 3, 2019 5:56PM

Thanks, Patrick. Yes, the colours, etc are all meeting the standard. Yet to
be implemented, but before we do we'll have a look with a couple of blue
light filters.

We'll be re-audited by the Shaw Trust, which will pick up any mistakes.

Best wishes,

Executive Director, Free UK Genealogy

On Thu, 31 Jan 2019, 12:45 Patrick H. Lauke < <EMAIL REMOVED> wrote:

> On 31/01/2019 12:34, Pat Reynolds wrote:
> > We are working on a major overhaul of colours on all our sites, to make
> > them AA compliant. Does anyone know how these filters might impact on
> > accessibility, and what we might do to mitigate that?
>
> I'm assuming that you mean you're going to ensure the colour contrast
> ratios of all foreground/background colour combinations are AA compliant
> - minimum 4.5:1 for "regular" text / 3:1 for "large" text (and, if doing
> WCAG 2.1, also minimum 3:1 for meaningful non-text content).
>
> It will depend on the specific blue light filter used (as I don't think
> there's any particular standard way in which these work), but while
> these filters generally result in a duller/less pronounced/lowered
> contrast overall, following at least the minimum WCAG contrast ratios
> should still result in a strong-enough contrast. To be on the safe side,
> stronger contrasts (not just trying to squeak past the 4.5:1 ratio, for
> instance) will be better and safer. If it's a major concern, you can
> always run a simulated blue filter and test the contrast ratios AFTER
> the filter was applied, and tweak to ensure that they're strong enough
> even when the filter is on.
>
> Of course, with regards to WCAG, you should also ensure that color alone
> is not used as an indicator/to convey meaning, as this may also
> otherwise cause problems for users that run a blue filter.
>
> 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
> > > > >