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Re: Accessible color and contrast for projected presentations

for

From: Tim Harshbarger
Date: Sep 2, 2014 6:29AM

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

-----Original Message-----
From: <EMAIL REMOVED> [mailto: <EMAIL REMOVED> ] On Behalf Of Sean Curtis
Sent: Sunday, August 31, 2014 4:18 PM
To: WebAIM Discussion List
Subject: [WebAIM] Accessible color and contrast for projected presentations

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