Re: Accessibility UAWG: contrast control

Thanks Jonathan;

I don't have examples in SVG as yet, but was commenting more on interactions
seen with users using other graphical based applications, and when using
diagrams without the use of a computer.

I agree that changing the colors of bitmaps wouldn't be useful for some
users, but for some low vision users, changing specific colors can eliminate
some problems.  This option is provided by the leading three magnification
products, but as meaning can be conveyed through color, would changing the
color of certain portions of an image alter the meaning from that intended?
For example. say a blue circle represented entry and other colored circles
represented other meanings, would changing the circle's color from blue run
the risk of altering the meaning?  Quite probably.

So, I think uas need to offer a user three things:
1. the ability to alter contrast
2. The ability to change specific colors, which is useful for some low
vision users
3. Some textual output to identify what the color is set to within the SVG
mark-up, regardless of how it's displayed on screen.  As Philippe mentioned,
getting an exact color value, or it's textual equivalent would be useful for
"normal" users as well.

Will
----- Original Message ----- 
From: "Jonathan Chetwynd" <j.chetwynd@btinternet.com>
To: "Will Pearson" <will-pearson@tiscali.co.uk>
Cc: "SVG (www) list" <www-svg@w3.org>
Sent: Tuesday, November 16, 2004 1:52 PM
Subject: Re: Accessibility UAWG: contrast control


> Will,
>
> 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
> native
>
> 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:
> http://www.peepo.co.uk/temp/gui-schema
>
> 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.
>
> regards
>
> Jonathan Chetwynd
> http://www.peepo.co.uk     "It's easy to use"
> irc://freenode/accessibility
> 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
> useful
> feature, and one I do think ua's should implement.  I'm just wondering
> what
> 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
> don't
> cater for everyone.  Some people may have preferences outside of those
> catered for by any default schemes, so maybe some advanced options to
> allow
> a user to select their own scheme would also be necessary.
>
> As an aside, I think user selectable color schemes are useful, not just
> user
> 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.
>
> Will
> ----- 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 18:04:19 UTC