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Thread: Accessible color and contrast for projected presentations
Number of posts in this thread: 7 (In chronological order)
From: Sean Curtis
Date: Sun, Aug 31 2014 3:18PM
Subject: Accessible color and contrast for projected presentations
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Hi all,
In addition to web accessibility we're researching the accessibility of
slide decks for conference presentations for low vision users. We have a
gap in our knowledge here, and would really appreciate any input.
Our main question - WCAG contrast checkers (
http://webaim.org/resources/contrastchecker/) give a pass / fail for the
accessibility of colour combinations on computer screen. Are they also
accurate for the visual accessibility of slides presented on a stage? That
is, if a colour combination passes WCAG AA can we assume that is it ok for
a conference presentation?
Also, which is more visible for low-vision users - dark text on light
backgrounds or light text on dark backgrounds? I've heard this might depend
on how well-lit the presentation area is. Is it possible to give a
generalisation here?
Any other input on the accessibility of conference slides for low vision
users would be greatly appreciated.
Cheers,
Sean Curtis
From: Tim Harshbarger
Date: Tue, Sep 02 2014 6:29AM
Subject: Re: Accessible color and contrast for projected presentations
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Sean,
I'm not sure that applying the same contrast ratio to slides being displayed during a presentation at a conference would work.
I took a quick look at the associated success criteria because I thought I recalled something in the calculation that might impact how well it would work for this situation:
http://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html
I believe part of the formula needs to take in account the ambient lighting and the calcuation assumes an average which might not be appropriate for such a setting. But based on the various degrees of lighting that I've experienced in the past in conference rooms, the amount of lighting could alter the calcuation. I don't know how significantly it might alter those values though. It might be inconsequential or significant.but I suppose you could try to take a guesss at common lighting scenarios for conference venues.
Thanks,
Tim
From: Denis Boudreau
Date: Tue, Sep 02 2014 6:59AM
Subject: Re: Accessible color and contrast for projected presentations
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Hello Sean,
Id like to echo Tims comment. How many time have we been attending a presentation where the presenter eventually says: you cant see it clearly on the screen, but on my laptop, the color contrasts are very clear. The lighting in the room, the quality of the projector itself and how close/far attendees are sitting from the screen are all important factors to take into consideration when trying to determine if the color contrasts used are going to be sufficient in a presentation.
As you cannot control either of those factors, my guess would be that you play it safe. You are much better off assuming that your contrasts need to meet level AAA as opposed to AA. I think this is simply common sense, That stil leaves you a lot of options, but making sure your contrasts all meet a ratio of at least 7 to 1 is just another way to avoid some issues. Also, avoid using complex background images, where the text might end up competing with whats underneath.
If youre trying to come up with requirements of some sort in order to internalize this into a standard, and your requirements need to align with existing WCAG 2.0 Success Criteria, then my recommendation would be to align to SC 1.4.6 [1], instead of SC 1.4.3 [2].
Finally, when it comes to what is most easily read, it totally varies from one person to another, so again, there is no one size fits all answer here. I think your best bet is to:
a) use large fonts (try not to go under 30 pixels),
b) keep the number of words per slide to a minimum (easier said than done), and
c) make sure the contrasts are strong enough (again, aligning to SC 1.4.6 instead of SC 1.4.3).
Hoping this helps!
[1] http://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html
[2] http://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast7.html
/Denis
On Sep 2, 2014, at 8:29 AM, Tim Harshbarger < = EMAIL ADDRESS REMOVED = > wrote:
> Sean,
>
> I'm not sure that applying the same contrast ratio to slides being displayed during a presentation at a conference would work.
>
> I took a quick look at the associated success criteria because I thought I recalled something in the calculation that might impact how well it would work for this situation:
> http://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html
>
> I believe part of the formula needs to take in account the ambient lighting and the calcuation assumes an average which might not be appropriate for such a setting. But based on the various degrees of lighting that I've experienced in the past in conference rooms, the amount of lighting could alter the calcuation. I don't know how significantly it might alter those values though. It might be inconsequential or significant.but I suppose you could try to take a guesss at common lighting scenarios for conference venues.
>
> Thanks,
> Tim
>
>
From: Olaf Drümmer
Date: Tue, Sep 02 2014 12:07PM
Subject: Re: Accessible color and contrast for projected presentations
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Hi,
On 31 Aug 2014, at 23:18, Sean Curtis < = EMAIL ADDRESS REMOVED = > wrote:
> In addition to web accessibility we're researching the accessibility of
> slide decks for conference presentations for low vision users. We have a
> gap in our knowledge here, and would really appreciate any input.
I think trying to solve issues in the setup of and apparatus used for a presentation by optimising a file is a complete waste of efforts, in many less than perfect setups there is no possibility to succeed.
A major building block of access and assistive technologies is that a user can adjust the presentation to her needs. There is no way a slide presentation presented through a video projector can be adjusted to an individual's person needs without disregarding the needs of others.
To me it seems to be a much better approach to use alternative options in the presentation setup. One such option could be to use ad hoc screen sharing in some fashion. Options to do this are VNC (screen sharing over the LAN network, available in a couple of freeware options), web meeting or webinar solutions (GoToMeeting, WebEx, or the free of charge Google Hangout On Air, etc.). Low vision users for example have essentially the same display quality as if they viewed the slides on their computer or tablet, they could for example zoom in to enlarge portions of the page/slide.
Olaf
From: Sean Curtis
Date: Tue, Sep 02 2014 5:24PM
Subject: Re: Accessible color and contrast for projected presentations
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Thanks all for the information. I'll be recommending we improve contrast to
at least AAA levels, and that we try to move away from Keynote/Powerpoint
in favour of an accessible, HTML based solution. Using HTML will allow
people to follow along on their own device, thus allowing them to benefit
from whatever assistive technologies they have set up for themselves.
Cheers,
Sean Curtis
On Wed, Sep 3, 2014 at 4:07 AM, Olaf Drümmer < = EMAIL ADDRESS REMOVED = > wrote:
> Hi,
>
> On 31 Aug 2014, at 23:18, Sean Curtis < = EMAIL ADDRESS REMOVED = > wrote:
>
> > In addition to web accessibility we're researching the accessibility of
> > slide decks for conference presentations for low vision users. We have a
> > gap in our knowledge here, and would really appreciate any input.
>
> I think trying to solve issues in the setup of and apparatus used for a
> presentation by optimising a file is a complete waste of efforts, in many
> less than perfect setups there is no possibility to succeed.
>
> A major building block of access and assistive technologies is that a user
> can adjust the presentation to her needs. There is no way a slide
> presentation presented through a video projector can be adjusted to an
> individual's person needs without disregarding the needs of others.
>
> To me it seems to be a much better approach to use alternative options in
> the presentation setup. One such option could be to use ad hoc screen
> sharing in some fashion. Options to do this are VNC (screen sharing over
> the LAN network, available in a couple of freeware options), web meeting
> or webinar solutions (GoToMeeting, WebEx, or the free of charge Google
> Hangout On Air, etc.). Low vision users for example have essentially the
> same display quality as if they viewed the slides on their computer or
> tablet, they could for example zoom in to enlarge portions of the
> page/slide.
>
> Olaf
>
> > > >
From: Whitney Quesenbery
Date: Tue, Sep 02 2014 6:36PM
Subject: Re: Accessible color and contrast for projected presentations
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Back in the day, one of the conferences where I presented used to send out
very strict guidelines for presentation templates. They wanted large text
and high contrast. They preferred black text on a light background for
consistency among speakers.
They weren't (strictly speaking) accessibility advocates, but they pointed
out they they ran a professional updating conference with fairly long
rooms, so people at the back were 20 rows of seats (maybe 60 feet) away
from the screen. And, people wanted to take notes which, back before the
days of tablets, meant writing on paper. On the handouts they provided. So
there was light in the room.
My point is that there is every reason in the world to think about the
context in which your slides will be shown. And if you plan to make a
presentation, I assume you want people in the room to be able to see what
you project. Unless, of course, it's just wallpaper to make a design behind
you, in which case none of this matters. But if you want people to see
what's on your slides:
- High contrast (I'd suggest at least AAA, if not 10:1)
- Large text - the guideline for signage is to make your text 1.75 inches
larger for every 50 feet of viewing distance (1.75" at 50' to 5.25" at 150'
to 8.75" at 300')
- No distracting backgrounds behind the slides
and you might think about
- most important information in the top half of the slide to take into
account rooms with flat floors, where heads block the bottom half.
On Tue, Sep 2, 2014 at 7:24 PM, Sean Curtis < = EMAIL ADDRESS REMOVED = > wrote:
> Thanks all for the information. I'll be recommending we improve contrast to
> at least AAA levels, and that we try to move away from Keynote/Powerpoint
> in favour of an accessible, HTML based solution. Using HTML will allow
> people to follow along on their own device, thus allowing them to benefit
> from whatever assistive technologies they have set up for themselves.
>
> Cheers,
>
> Sean Curtis
>
>
> On Wed, Sep 3, 2014 at 4:07 AM, Olaf Drümmer < = EMAIL ADDRESS REMOVED = > wrote:
>
> > Hi,
> >
> > On 31 Aug 2014, at 23:18, Sean Curtis < = EMAIL ADDRESS REMOVED = > wrote:
> >
> > > In addition to web accessibility we're researching the accessibility of
> > > slide decks for conference presentations for low vision users. We have
> a
> > > gap in our knowledge here, and would really appreciate any input.
> >
> > I think trying to solve issues in the setup of and apparatus used for a
> > presentation by optimising a file is a complete waste of efforts, in many
> > less than perfect setups there is no possibility to succeed.
> >
> > A major building block of access and assistive technologies is that a
> user
> > can adjust the presentation to her needs. There is no way a slide
> > presentation presented through a video projector can be adjusted to an
> > individual's person needs without disregarding the needs of others.
> >
> > To me it seems to be a much better approach to use alternative options in
> > the presentation setup. One such option could be to use ad hoc screen
> > sharing in some fashion. Options to do this are VNC (screen sharing over
> > the LAN network, available in a couple of freeware options), web meeting
> > or webinar solutions (GoToMeeting, WebEx, or the free of charge Google
> > Hangout On Air, etc.). Low vision users for example have essentially the
> > same display quality as if they viewed the slides on their computer or
> > tablet, they could for example zoom in to enlarge portions of the
> > page/slide.
> >
> > Olaf
> >
> > > > > > > >
> > > >
From: Mallory van Achterberg
Date: Wed, Sep 03 2014 12:44AM
Subject: Re: Accessible color and contrast for projected presentations
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On Tue, Sep 02, 2014 at 08:36:20PM -0400, Whitney Quesenbery wrote:
> and you might think about
>
> - most important information in the top half of the slide to take into
> account rooms with flat floors, where heads block the bottom half.
The heads get me regularly, being short.
_mallory