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Re: Accessibility UAWG: contrast control

From: Jonathan Chetwynd <j.chetwynd@btinternet.com>
Date: Tue, 16 Nov 2004 13:52:22 +0000
Message-Id: <BD5D9457-37D6-11D9-BD86-000A95C7D298@btinternet.com>
Cc: "SVG \(www\) list" <www-svg@w3.org>
To: "Will Pearson" <will-pearson@tiscali.co.uk>


at this stage it's really important to gather evidence, so if you have 
examples, let's see them.

traditional schemes such as white on black tend to be used for text.
(where text flows over graphics this may not always be helpful)
But do we have good examples of how illustrations and photographs can 
be made more accessible by changing contrast?

my particular interest is symbols, so stroke width and opacity are 
options supplied. 2 examples:
http://www.peepo.co.uk/launch/index.svg  change settings using the 
hammer icon  asv3
http://www.peepo.co.uk/style/contrast.svg switch style sheets  mozSVG 

RDF GUI schema should be helpful in defining what purpose the author 
intended the content for, which should help guide the user.  for 
instance as a default, borders or highlights should probably be 
included in basic contrast changes such as white on black, whereas 
illustrations or jpegs should not. try: 

OS systems may also offer some contrast controls. however the current 
mac beta complements all colours in white on black mode, which may not 
be that helpful.

I use style sheets with classes as well as script sliders for finer 
user control.
This seems to be forbidden in SVG, advice is not to try.

there is further info on the svg-developers thread which may be helpful.


Jonathan Chetwynd
http://www.peepo.co.uk     "It's easy to use"
On 16 Nov 2004, at 12:46, Will Pearson wrote:

     Hi Jonathan;

What sort of levels of contrast would you have?  Contrast is a really 
feature, and one I do think ua's should implement.  I'm just wondering 
your views on the best method for the user to select the contrast level
would be?  Generally, I tend to think default schemes, such as black on
white, white on black, etc. are the easiest for users to use, but they 
cater for everyone.  Some people may have preferences outside of those
catered for by any default schemes, so maybe some advanced options to 
a user to select their own scheme would also be necessary.

As an aside, I think user selectable color schemes are useful, not just 
selectable contrast.  I know that some dyslexics find changing the white
background of text based documents, to another color, usually some 
shade of
pink, enables them to read the document better.  This has also been 
found to
assist "normal" users in addition to those with dyslexia.

----- Original Message -----
From: "Jonathan Chetwynd" <j.chetwynd@btinternet.com>
To: "SVG (www) list" <www-svg@w3.org>
Cc: "chris Lilley" <chris@w3.org>
Sent: Monday, November 15, 2004 7:00 PM
Subject: Accessibility UAWG: contrast control

> Chris and members of the UAWG,
> it has been asserted by a number of people that a contrast control for
> an SVG user agent is 'trivial' to implement*.
> UA and AT guidelines would without doubt encourage adoption of this and
> other accessibility solutions.
> Please could a draft be published?
> regards
> Jonathan Chetwynd
> http://www.peepo.co.uk     "It's easy to use"
> irc://freenode/accessibility
> * 37 minute exchange:
> http://svg.jibbering.com/svg/2004-11-15.html#T15-45-41
Received on Tuesday, 16 November 2004 13:52:55 UTC

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