Edit comment LC-1525 for Accessibility Guidelines Working Group

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Comment LC-1525: Comment Shortname:; Commenter: David MacDonald <Befree@magma.ca>; Message-id:; Section of the document concerned:

or; Refinement of the section concerned:; Status:
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Commenter's response (URI):; Comment:
Part of Item: Techniques
Comment Type: general comment
Comment (including rationale for proposed change):

Web safe colors, web friendly colours
The access Working group GOC has recently made a requirement for web friendly colours.
They believe that some versions of magnifiers (older) only handle web safe or web friendly colours and then they dither non friendly colours. They believe that the dithering process will affect contrast. For instance, a light background that is not safe might get dithered darker, and a dark foreground might be dithered lighter. And the combination could cause lower overall contrast in older user agents.

Proposed Change:

Discuss why or why not web safe/friendly is an issue.

Add something like:

Note: some older user agents are limited to web friendly, web safe colours. If older user agents in your baseline, use web friendly/safe colours.; Related issues: (space separated ids); WG Notes: [TEAMC] Becky - I think this is as much of a usability as an accessibility issue since non-web safe colors may render unexpectedly for all users. I'm also not sure how we would classify "older user agents" - are there certain versions we can refer to. Isn't this a non-issue if the luminosity contrast calculates properly? David - I've looked into this and there is no strong evidence that non-web safe colors cause significantly accessibility barriers. See also http://www.accessifyforum.com/viewtopic.php?t=1149 This was an issue the Canadian Government wanted me to address with the committee. They are requiring web safe colors but I don't think we should. SO I am proposing re-jecting it. There is however, one related thing we need to clear up in 1.4 contrast. When we do forground background contrast checks. If the monitor is dithering, we will get very different results based on which pixel we chose as the foreground and background. Because dithering is several colours side by side. eh. Red and yellow make orange. Some pixels might be darker than other even though they are side by side. I explore this issue with graphical demonstrations here http://www.eramp.com/david/general/dithering.htm Discussed in the 01 February 2007 telecon: Resolution: accepted by unanimous consent http://www.w3.org/WAI/GL/2007/02/01-wai-wcag-minutes.html Response: http://lists.w3.org/Archives/Public/public-comments-wcag20/2007Jun/0051.html; Resolution: The group does not have any evidence of significant accessibility issues arising from the use of non-safe web colours. The Web-safe colour palette is the 216-colour intersection of the 256-colour palettes of the Windows and Mac OS of the 1990's. Neither Windows nor Mac uses those palettes by default, nor do Unix variants, so this concern appears to have been overcome by technology advances.; (Please make sure the resolution is adapted for public consumption)