E-mail List Archives
Thread: Colour contrast and blue light filters
Number of posts in this thread: 4 (In chronological order)
From: Pat Reynolds
Date: Thu, Jan 31 2019 5:34AM
Subject: Colour contrast and blue light filters
No previous message | Next message →
Hello,
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?
With thanks,
Pat
-
*- -*
*Dr Pat Reynolds*
Executive Director
Free UK Genealogy <http://www.freeukgenealogy.org.uk/>;
A Charitable Incorporated Organisation registered in England and Wales,
number 1167484
VAT registration: 233 0105 70
+44 1723 362616 +44 7943 145387
Westwood House,Westwood, Scarborough YO11 2JD, UK
From: Patrick H. Lauke
Date: Thu, Jan 31 2019 5:45AM
Subject: Re: Colour contrast and blue light filters
← Previous message | Next message →
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
From: Jonathan Avila
Date: Thu, Jan 31 2019 7:30AM
Subject: Re: Colour contrast and blue light filters
← Previous message | Next message →
This is an interesting question and one that also comes up with invert colors as that changes the contrast ratios as well. From my experience with blue light filters is that they are a spectrum that the user can specify and typically remove blues and warm the colors with more reddish colors. So I'd imagine it would impact contrast of colors that have more blue in them -- but this only a guess since I am not an expert in color.
Testing could be difficult if the filter is applied in such a way that the contrast tools can't get the value. You may need to apply the filter values to the colors first and then run them through a contrast checker -- depending on the configuration. There are both browser and platform level blue light filters so they may work differently.
Jonathan
Jonathan Avila
Chief Accessibility Officer
Level Access
= EMAIL ADDRESS REMOVED =
703.637.8957 office
Visit us online:
Website | Twitter | Facebook | LinkedIn | Blog
Looking to boost your accessibility knowledge? Check out our free webinars!
The information contained in this transmission may be attorney privileged and/or confidential information intended for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any use, dissemination, distribution or copying of this communication is strictly prohibited.
From: Pat Reynolds
Date: Sun, Feb 03 2019 5:56PM
Subject: Re: Colour contrast and blue light filters
← Previous message | No next message
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 ADDRESS 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
> > > > >