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RE: WA - background-image in CSS

From: Scarlett Julian (ED) <Julian.Scarlett@sheffield.gov.uk>
Date: Fri, 18 Jan 2002 15:18:51 -0000
Message-ID: <F9BE3B1AB649D311A573009027852E4D01896707@EDUC_MXS>
To: "'RUST Randal'" <RRust@COVANSYS.com>, w3c-wai-ig@w3.org

The whole crux of this is that Bob feels that it is he and not you that
should determine what is important information. I would say that if you feel
the background image is so much less important than the rest of the page
leave the bl**dy thing out, don't put it in in the first place. The web is
full to the brim of cr*p that isn't important; why add to it?

J.

> -----Original Message-----
> From: RUST Randal [mailto:RRust@COVANSYS.com]
> Sent: Friday, January 18, 2002 2:59 PM
> To: w3c-wai-ig@w3.org
> Subject: RE: WA - background-image in CSS
> 
> 
> Charles is MAKING MY POINT EXACTLY.
> 
> If I have an image that I, as the author of the page, deem 
> does NOT CONVEY
> CRITICAL INFORMATION, such as a picture of trees, then I 
> SHOULD FEEL FREE TO
> USE IT AS A BACKGROUND IMAGE.  If IT IS IMPORTANT, such as a map, then
> OBVIOUSLY I will include it in the HTML, and properly apply 
> the necessary
> attributes for accessibility.
> 
> That what I said in my very first post.
> 
> -----Original Message-----
> From: Charles McCathieNevile [mailto:charles@w3.org]
> Sent: Friday, January 18, 2002 9:37 AM
> To: Access Systems
> Cc: w3c-wai-ig@w3.org
> Subject: Re: WA - background-image in CSS
> 
> 
> Well, there are two ways of looking at this.
> 
> On one side, it is important for accessibility to convey the essential
> information - a page often contains lots of supplementary 
> stuff to highlight
> and reinforce its message(s), and a user can find out those 
> are there and
> look them up if they have an appropriate browser. In some 
> cases part of that
> information will be in an inaccessible form. In the real 
> world there is then
> a tension between whether someone provides more new 
> information that they
> consider it important to convey, or whether they render 
> existing information
> more accessible.
> 
> In order to meet WCAG, there is a requirement that the 
> background image (as
> part of the style) not convey critical information that is 
> not otherwise
> available. That requirement makes sense. In text form, alt="" 
> (in otherwords
> a null statement) is therefore an acceptable equivalent, for 
> the purpose of
> meeting checkpoint 1.1. In fact with the background image 
> there is no easy
> wayt to include alt information, or a description. That 
> doesn't mean there
> is
> no way of doing it at all.
> 
> If people are aware of how the Web works well - i.e. things 
> don't appear in
> multiple places, they have an identifier (URI) that can be 
> used to find
> them,
> and local services can cache the content of that identifier 
> for speed or
> offline work (browsers do this automatically to a large 
> extent, and there
> are
> ways of doing it on a wider scale), there is more that can be done.
> 
> It is possible to find out what the background image is - at worst by
> inspecting source, although some browsers give direct access, 
> and more tools
> could be made that do so - at least as far as having a URI to 
> be ableto look
> at it.
> 
> Then all that is required is that there is a way of getting 
> information
> about
> the image. Some approaches from W3C spring to mind...
> 
> Annotea:
> 
> Annotea is a service that allows anyone to annotate anything 
> with a URI - a
> page, part of a page, an image, an image as used in a 
> particular page, etc.
> The annotation can be anything else on the Web - another 
> page, a bit of text
> written for it, another image, and it has a type - comment, 
> example, test,
> seeAlso, ...
> 
> There are tools to use this in Amaya, Mozilla, Internet explorer, any
> javascript capable browser. It is also possible to do it from
> non-script-capable browsers via a Web interface. Details of 
> Annotea are at
> http://www.w3.org/2001/Annotea
> 
> RDFPic
> 
> RDFPic is an example of a tool that incorporates information 
> directly in an
> image - the open source demo tool does it for jpeg images, 
> and allows you to
> save the image (using HTTP PUT - a standard that is sadly still not
> widely-enough implemented) including the information. The 
> Jigsaw server (for
> which the demo was written) allows you to retrieve the 
> information instead
> of
> the image, or it can be extracted from the image itself with 
> a bit of a
> hack.
> More about RDFPic at http://www.w3.org/TR/photo-rdf which 
> includes links to
> online demos
> 
> SVG
> 
> A lot of browsers don't yet handle SVG. On the other hand we are only
> talking
> about a background image, so that may not trouble some people. In SVG
> including a descriptionis trivial - consider the following two images:
> 
> <?xml version="1.0" standalone="no"?>
> <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20010904//EN"
>   "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
> <svg width="100%" height="100%"   xmlns="http://www.w3.org/2000/svg">
>   <desc>A washed out background colour with spots on it</desc>
>   <image xlink:href="http://example.com/spots.png" width="100%"
>     height="100%"/>
> </svg>
> 
> (which shows how to use a bitmap image within an SVG)
> 
> or
> 
> <?xml version="1.0" standalone="no"?>
> <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20010904//EN"
>   "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
> <svg width="8cm" height="4cm" viewBox="0 0 800 400"
>      xmlns="http://www.w3.org/2000/svg">
>   <desc>A colour gradient - red on the left blending to yellow on the
>     right</desc>
>   <g>
>     <defs>
>       <linearGradient id="MyGradient">
>         <stop offset="5%" stop-color="#F60" />
>         <stop offset="95%" stop-color="#FF6" />
>       </linearGradient>
>     </defs>
>     <rect fill="url(#MyGradient)" width="800" height="400"/>
>   </g>
> </svg>
> 
> Which is a complete image in itself - compressed this uses a 
> very small
> number of bytes indeed.
> 
> Both images above include a description, which can be easily 
> extracted.
> 
> There are other image annotation systems available of course, 
> which can do
> the same kinds of things as RDFPic or annotea via a Web 
> Query: as an example
> see http://swordfish.rdfweb.org/discovery/2001/08/codepict/ (an
> implementation designed for collecting pictures of multiple 
> people, and thus
> finding out who has been in the same place as whom, ...)
> 
> cheers
> 
> Charles
> 
> 
> 
> On Fri, 18 Jan 2002, Access Systems wrote:
> 
>   On Fri, 18 Jan 2002, RUST Randal wrote:
> 
>   my opinion only ! (well maybe not just me but I do not 
> speak for others)
> 
>   > blind user gets the same ESSENTIAL CONTENT as the user 
> who can see the
> page.
> 
>   users with disabilities or other reasons for using 
> alternative screen
>   display
>     DESERVE AND ARE ENTITLED TO ALL THE CONTENT, who are 
> "you" to determine
>   what is "essential" content to me
> 
>   THIS IS ONE of the major complaints of almost all people 
> with disabilities
>   in all areas of access.  NO ONE!, period, has the right to 
> determine my
>   needs and priorities.
> 
>   Bob
>   *you and me as used is generic and not intended to mean any 
> one individual
>   ** really one of my major peeves!
>   *** shouting is intentional and needed
> 
>      ASCII Ribbon Campaign                        accessBob
>       NO HTML/PDF/RTF in e-mail                   
> accessys@smartnospam.net
>       NO MSWord docs in e-mail                    Access 
> Systems, engineers
>       NO attachments in e-mail,  *LINUX powered*   access is 
> a civil right
>  
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> 
> 
> 
> -- 
> Charles McCathieNevile    http://www.w3.org/People/Charles  
> phone: +61 409
> 134 136
> W3C Web Accessibility Initiative     http://www.w3.org/WAI    
> fax: +1 617
> 258 5999
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> 
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Received on Friday, 18 January 2002 10:20:58 GMT

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