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Re: colour contrast algorithm

for

From: John Britsios
Date: Sep 19, 2003 7:21AM


Dear all!

Here is a tool a found to this topic!
http://colorpro.com/info/tools/convert.htm

I have found many links to this topic and whcih I have posted them in my
forum here:
http://www.webnauts.net/phpBB2/viewtopic.php?t=52&;sid=cd52ed69455e27753d0df431c25eda43

Worth to have a look at!

My kindest regards,

John Britsios
Web Accessibility and Usability Consultant


----- Original Message -----
From: "gez" < <EMAIL REMOVED> >
To: < <EMAIL REMOVED> >
Sent: Thursday, September 18, 2003 2:09 PM
Subject: Re: colour contrast algorithm


> Hi Dey,
>
>
>
> I've been trying to find out myself if there has been any more work on the
> algorithm, but haven't been able to come up with anything.
>
>
>
> Personally, I think the suggested algorithms works well, but I think the
> threshold for the difference in colour is a bit high. I know that HP use
the
> algorithm, but instead of using a threshold of 500 for the colour
> difference, they use a colour difference of 400, which is much more
> workable. The W3C's threshold for the difference in brightness seems to
work
> OK from the tests I've done.
>
>
>
> The algorithms only really work with normal text, and don't take into
> account the weight of the font. You get the same results for bold or
normal
> text, where bold text will obviously be more distinguishable.
>
>
>
> I've implemented the algorithm on my site, so you can quickly test colours
> to see what works: http://www.juicystudio.com/services/colourcontrast.asp
>
>
>
> Best regards.
>
>
>
> Gez
>
>
>
> ----- Original Message -----
> From: "Dey Alexander" < <EMAIL REMOVED> >
> To: "Webaim forum" < <EMAIL REMOVED> >
> Sent: Thursday, September 18, 2003 9:38 AM
> Subject: colour contrast algorithm
>
>
> > The suggested algorithm for testing to see if text and background
> > colours provide sufficient contrast (as documented in the W3C's draft
> > techniques document for Accessibility Evaluation and Repair Tools at
> > http://www.w3.org/TR/AERT#color-contrast) has recently been discussed on
> > this list (between 20-26 August 2003).
> >
> > However the discussion did not lead anywhere terribly useful, and my
> > query is slightly different to the original focus of the earlier
> discussion.
> >
> > The W3C document indicates that the algorithm is a "suggested" one that
> > is "still open to change". Can anyone shed any light on whether this is
> > then a reliable indicator of colour contrast, or whether some more
> > authoritative/reliable algorithm exists?
> >
> > Reason for my question: sponsors/clients of a project I am currently
> > working on believe that the requirements are too stringent. This view
> > was expressed after I used the algorithm to generate a report on a range
> > of colour options that were being considered--very few of them passed
> > muster, as I expected.
> >
> > I would be extremely grateful for any advice or references to other
> > resources/expert opinions.
> >
> > Cheers,
> > Dey
> >
> >
> >
> >
> >
> > ----
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> > visit http://www.webaim.org/discussion/
> >
> >
> >
>
>
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