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RE: Color contrast of text on variable color background

From: John Foliot <john@foliot.ca>
Date: Wed, 5 Sep 2012 14:54:29 -0700
To: "'David Woolley'" <forums@david-woolley.me.uk>, <w3c-wai-ig@w3.org>
Cc: <lea@w3.org>
Message-ID: <00f201cd8bb1$089cabd0$19d60370$@ca>
David Woolley wrote
> In my experience, when text is overlaid in pictures, in print, it is
> done when the publisher doesn't really care about the text except as a
> way of getting people to the advertising.

Perhaps in print, but we are talking about the web. My experience is that this is the case "some" of the time, but that there are other instances when text is laid over imagery that is NOT advertising and thus critical content of the page. It's 2012, and we need to accept that for many, if not most, the web is very much a visual (and thus design prone) medium.

> I would suggest that:
> 1) unless the designer can guarantee meeting the colour contrast
> everywhere within say about 1 en around the characters, they should not
> put text intended to be read over pictures;

I for one could not even contemplate that kind of suggestion. 

We have a balance that needs to be met here: on one hand we have a requirement to meet the needs of as many users as we possibly can (sadly accepting that it will never be a complete 100% - long-tail effect being what it is). On the other hand we have visual designers who are mandated with crafting web content that is compelling and motivating. They can try and make it accessible, but if we are too demanding on what that means, then we run the risk of them not even trying: if we set the conditions that more-often than not they will fail, they will stop trying as they already know what the outcome will be - failure.

After more than a decade of trying to move the ball forward, this would be yet another plank on the (mostly false) assertions that to be accessible is to be ugly.

> 2) unless the image is lacking in high spatial frequencies, the
> required
> colour contrast should be significantly larger than for flat colours -
> text over forest leaves is much more difficult to read than over a
> constant tone of a similar colour to the leaves.

Greg's recommendation of "haloing" the text with a high-contrast halo effect is an effective (for the most part) technique that works well in these kinds of circumstances. Is it perfect? Not by a long shot, but neither is the world we live in.

> Basically, if this usage is developing, the colour contrast rules need
> enhancing, rather than having exceptions made.

I think Lea's attempts at better codifying this should be appreciated and received as such. The "just don't do it" response is to me a non-response.

Received on Wednesday, 5 September 2012 21:55:10 UTC

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