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Re: replaced the phrase "complex images" (technique 1.1.2)

From: Wendy A Chisholm <wendy@w3.org>
Date: Tue, 07 Mar 2000 16:12:52 -0500
Message-Id: <4.2.0.58.20000307161055.00a618d0@localhost>
To: "Chris Ridpath" <chris.ridpath@utoronto.ca>, <w3c-wai-er-ig@w3.org>
Chris,

Here is my proposed rewrite of 1.1.2. Note that I also said that the 
description or the need to provide one may be affected by the context in 
which the image is used.

<BLOCKQUOTE>
Technique 1.1.2 [priority 1] Verify that valid IMG element descriptions 
("longdesc" attribute or d-link) are provided where necessary.
Evaluation:
Element: <IMG>
Requirements:
valid "longdesc" attribute (any valid URI) or a d-link required if 
describing the image will add information not given in the text of the 
page. The amount of information in the image and the context in which it is 
used will determine how detailed the description should be.
Cases where a description is not required:
bullets - refer to Appendix J.
horizontal rules - refer to Appendix K.
Example of a message to be displayed:
If describing the image will add information not given in the text of the 
page,  you need to provide a description of the image.  The amount of 
information in the image and the context in which it is used will determine 
how detailed the description should be.
Additional actions:
Ask user if the image presents information that is not included in the page 
or in the text equivalent for the image. Allow the user to create or 
associate a description.
with the  "longdesc" attribute on an IMG element
via a D-link
If another document on the same site uses the same image and has a 
"longdesc", suggest that "longdesc" file.
</BLOCKQUOTE>

At 10:51 AM 2/25/00 , Chris Ridpath wrote:
>Wendy,
>
>We discussed:
>
> > >I thought the LONGDESC description should describe the image in relation
>to
> > >the document. It is not necessarily related to the image on its own.
> >
> > I'm not sure I understand this comment.  The description of an image is
> > very much related to the image on its own.  Here is an example from the
> > WCAG HTML Techniques document:
> > A chart showing how sales in 1997 progressed. The chart
> > is a bar-chart showing percentage increases in sales
> > by month. Sales in January were up 10% from December 1996,
> > sales in February dropped 3%, ..
>
>It may be a small thing but, an image has different meanings in different
>contexts. In your example chart what is the important information? The 1996
>sales increases were different from the 1997? Sales were up in January.
>Sales normally drop in February? The page that holds the image should
>provide context for the image and guide the writing of the LONGDESC.
>
>Chris
>
>
>----- Original Message -----
>From: Wendy A Chisholm <wendy@w3.org>
>To: Chris Ridpath <chris.ridpath@utoronto.ca>; <w3c-wai-er-ig@w3.org>
>Sent: Wednesday, February 23, 2000 5:15 PM
>Subject: Re: replaced the phrase "complex images" (technique 1.1.2)
>
>
> >
> > At 03:03 PM 2/23/00 , you wrote:
> > > > <blockquote>
> > > >...and a descriptive link...
> > > > </blockquote>
> > >
> > >I thought the D link was deprecated and we were not going to suggest
>using
> > >it??
> >
> > it is deprecated but not invalid. if someone has provided a d-link they
> > have satisfied the WCAG checkpoint 1.1.  Until "longdesc" is widely
> > supported we will have to look for D-links.  We will have to deal with
> > legacy as well - many sites use the D-link and will continue to do so
> > regardless of how many browsers support "longdesc" because they want to be
> > completely backwards compatible.  Therefore, if we find a d-link we could
> > suggest that the tool alert the author that they could use "longdesc"
> > instead.  d-link is still the most accepted technique for satisfying the
> > "long description" checkpoint - today.
> >
> > see http://www.w3.org/WAI/GL/WCAG10-HTML-TECHS/#image-text-equivalent for
> > more info.
> >
> > > > <blockquote>
> > > >The amount of information in the image will determine how
> > > >detailed the description should be.
> > > > </blockquote>
> > >
> > >I thought the LONGDESC description should describe the image in relation
>to
> > >the document. It is not necessarily related to the image on its own.
> >
> > I'm not sure I understand this comment.  The description of an image is
> > very much related to the image on its own.  Here is an example from the
> > WCAG HTML Techniques document:
> > A chart showing how sales in 1997 progressed. The chart
> > is a bar-chart showing percentage increases in sales
> > by month. Sales in January were up 10% from December 1996,
> > sales in February dropped 3%, ..
> >
> > I used the information from the National Braille Association because they
> > have been describing images in documents for decades (at least since
> > 1971).  Therefore, the description that they would provide for an image is
> > very similar to what we want in a longdesc.  If the function of the image
> > is to display a summary of information of sales from the last year, then
> > that's what the long description should provide.
> >
> > --wendy
> >
> >
> > >----- Original Message -----
> > >From: Wendy A Chisholm <wendy@w3.org>
> > >To: <w3c-wai-er-ig@w3.org>
> > >Sent: Wednesday, February 23, 2000 1:12 PM
> > >Subject: replaced the phrase "complex images" (technique 1.1.2)
> > >
> > >
> > > > On the 14 February telecon we discussed how to decide when an image
>needs
> > >a
> > > > longdesc.  previously we said when an image was "complex."  in the
>call I
> > > > read some excerpts from the National Braille Association's Tape
>Recording
> > > > Manual.  We decided to incorporate those ideas to replace the phrase
> > > > "complex image."
> > > >
> > > > This is my proposal:
> > > > <blockquote>
> > > > IMG element should have a valid LONGDESC attribute and a descriptive
>link
> > > > if describing the image will add information not given in the text of
>the
> > > > page. The amount of information in the image will determine how
>detailed
> > > > the description should be.
> > > > </blockquote>
> > > >
> > > > --wendy
> > > > --
> > > > wendy a chisholm
> > > > world wide web consortium
> > > > web accessibility initiative
> > > > madison, wi usa
> > > > tel: +1 608 663 6346
> > > > /--
> >
> > --
> > wendy a chisholm
> > world wide web consortium
> > web accessibility initiative
> > madison, wi usa
> > tel: +1 608 663 6346
> > /--

--
wendy a chisholm
world wide web consortium
web accessibility initiative
madison, wi usa
tel: +1 608 663 6346
/--
Received on Tuesday, 7 March 2000 16:09:01 UTC

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