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From: Mike Osborne - AccEase
Date: Tue, Oct 16 2007 1:20PM
Subject: Colour contrast standard
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As they say - the great thing about standards is that there are so many to
choose from.

When it comes to colour contrast there appear to be two:
* W3C - colour contrast 500, brightness 125
* HP - colour contrast 400, brightness 125

Are these numbers arbitrary or is one right and the other wrong? Is 500 too
much or is 400 inadequate?

Does anyone have any reliable evidence (from studies etc.) of which standard
should be used?

Cheers
Mike

From: Alastair Campbell
Date: Mon, Oct 22 2007 7:40AM
Subject: Re: Colour contrast standard
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On 10/16/07, Mike Osborne - AccEase < = EMAIL ADDRESS REMOVED = > wrote:
> Are these numbers arbitrary or is one right and the other wrong? Is 500 too
> much or is 400 inadequate?

I seriously doubt there is a real answer to that, for most people the
HP one is fine, but I'm sure there are some who benefit from very high
contrast.

It is a sliding scale, and you could argue that those with a need for
extreme contrast should have tools (e.g. user style sheets / Opera /
system tools) that provide that regardless of what the site does.

If you look at the colour range allowed by the W3C one, it doesn't
give you a whole lot of flexibility in the design, although I'm not
sure how the WCAG 2 algorithm varies from version 1? I'm under the
impression it's not directly comparable, although I'll check with a
colleague who put together some tools based on it.

Kind regards,

-Alastair

From: tedd
Date: Tue, Oct 23 2007 7:10AM
Subject: Re: Colour contrast standard
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At 2:35 PM +0100 10/22/07, Alastair Campbell wrote:
>On 10/16/07, Mike Osborne - AccEase < = EMAIL ADDRESS REMOVED = > wrote:
>> Are these numbers arbitrary or is one right and the other wrong? Is 500 too
>> much or is 400 inadequate?
>
>I seriously doubt there is a real answer to that, for most people the
>HP one is fine, but I'm sure there are some who benefit from very high
>contrast.
>
>It is a sliding scale, and you could argue that those with a need for
>extreme contrast should have tools (e.g. user style sheets / Opera /
>system tools) that provide that regardless of what the site does.
>
>If you look at the colour range allowed by the W3C one, it doesn't
>give you a whole lot of flexibility in the design, although I'm not
>sure how the WCAG 2 algorithm varies from version 1? I'm under the
>impression it's not directly comparable, although I'll check with a
>colleague who put together some tools based on it.
>
>Kind regards,
>
>-Alastair

Excuse me for injecting my two cents, but how does contrast standards
work with the different states of links? If you study the problem,
you'll see that there's not enough range to provide sufficient
contrast between different states of links using 500 or even 400.

If there is, please tell me the combination.

Cheers,

tedd

--
-------
http://sperling.com http://ancientstones.com http://earthstones.com

From: Patrick Lauke
Date: Tue, Oct 23 2007 7:30AM
Subject: Re: Colour contrast standard
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> tedd

> Excuse me for injecting my two cents, but how does contrast standards
> work with the different states of links? If you study the problem,
> you'll see that there's not enough range to provide sufficient
> contrast between different states of links using 500 or even 400.

In part, the onus is on the user agent to work in tandem with any user settings. For instance, I'd see it as the browser's duty to - if requested by the user - clearly outline the link that currently has focus...but the line is certainly blurry.

Just looking at normal/focussed, I've tended to invert foreground/background to differentiate the two states. Visited/unvisited is certainly more problematic...again, part of me wants to say that it's really the browser's job to help out here, but of course it's wishful thinking.

One dubious approach I remember was to style visited links with a strikethrough-type styling, but that makes them very difficult to then read.

Sorry, no real answer, just throwing some more thoughts into the ideas stew...

P

From: tedd
Date: Wed, Oct 24 2007 6:50PM
Subject: Re: Colour contrast standard
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At 2:25 PM +0100 10/23/07, Patrick Lauke wrote:
> > tedd
>
>> Excuse me for injecting my two cents, but how does contrast standards
>> work with the different states of links? If you study the problem,
>> you'll see that there's not enough range to provide sufficient
>> contrast between different states of links using 500 or even 400.
>
>In part, the onus is on the user agent to work in tandem with any
>user settings. For instance, I'd see it as the browser's duty to -
>if requested by the user - clearly outline the link that currently
>has focus...but the line is certainly blurry.
>
>Just looking at normal/focussed, I've tended to invert
>foreground/background to differentiate the two states.
>Visited/unvisited is certainly more problematic...again, part of me
>wants to say that it's really the browser's job to help out here,
>but of course it's wishful thinking.
>
>One dubious approach I remember was to style visited links with a
>strikethrough-type styling, but that makes them very difficult to
>then read.
>
>Sorry, no real answer, just throwing some more thoughts into the ideas stew...
>
>P

P:

I knew there was no answer. I was simply making the statement that
the contrast requirement is not possible if one was to apply it to
different states of a link. So, in this case, the requirements are
beyond our ability to comply.

Cheers,

tedd
--
-------
http://sperling.com http://ancientstones.com http://earthstones.com