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Re: Accessible color and contrast for projected presentations

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From: Denis Boudreau
Date: Sep 2, 2014 6:59AM

Hello Sean,

I’d like to echo Tim’s comment. How many time have we been attending a presentation where the presenter eventually says: “you can’t 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 what’s underneath.

If you’re 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 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
>
>