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Re: Color contrast of text on variable color background

From: David Woolley <forums@david-woolley.me.uk>
Date: Wed, 05 Sep 2012 21:37:47 +0100
Message-ID: <5047B81B.2030200@david-woolley.me.uk>
To: w3c-wai-ig@w3.org
Gregg Vanderheiden wrote:
> Since it is not good to post text over a pattern -- or photo -- the best 
> would be either to not do it or to halo the text with white/very light. 
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.

The other reason I think it is done, is as a copy protection measure, 
but again that is to avoid people copying the editorial and distributing 
it without the advertising.

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;

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.

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

David Woolley
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Received on Wednesday, 5 September 2012 20:38:16 UTC

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