- From: David Woolley <forums@david-woolley.me.uk>
- Date: Thu, 06 Sep 2012 21:06:38 +0100
- To: w3c-wai-ig@w3.org
Lea Verou wrote: > On Sep 6, 2012, at 14:48, Marc Haunschild wrote: > >> Hi Lea, >> >> now I got it, I guess - its about how to calculate it, to change the semitransparent layer automatically to produce a satisfying contrast ratio? > Kind of. Think of it this way: > - We know the text color > - We know the (semi-transparent) background color > - We DON’T know what's going to be under that. > I think you are missing a factor here. The standard colour contrast rules assume a background with no high spatial frequencies. If you overlay on an image, without using alpha 1 for both the text and a halo, any high spatial frequencies in the image will make it more difficult to read the text, so you need a higher minimum contrast. > -- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work.
Received on Thursday, 6 September 2012 20:07:10 UTC