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Re: img@relaxed CP [was: CfC: Close ISSUE-206: meta-generator by Amicable Resolution]

From: Steve Faulkner <faulkner.steve@gmail.com>
Date: Sat, 4 Aug 2012 18:54:35 +0100
Message-ID: <CA+ri+VmpUWhrESS_sjnH_1su-dDKvn7a4jMmHrpjs4yyz3LKMg@mail.gmail.com>
To: Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com>
Cc: "Michael[tm] Smith" <mike@w3.org>, public-html@w3.org, HTML Accessibility Task Force <public-html-a11y@w3.org>, John Foliot <john@foliot.ca>
hi ben,

>I doubt a user agent would factor the presence of an attribute such as
>@relaxed into its decision to indicate or not indicate the presence of
>a particular image without a provided text alternative. In particular,
>I doubt user agents which provide configuration for indicating or not
>indicating such images (such as VoiceOver which allows users to ask it
>to announce all images or only images "with descriptions") would
>distinguish <img> and <img relaxed> as distinct categories in their
>configuration UI.

I don't presume to make such judgements without first having defined a
proposed mechanism and sought feedback from end users and the
accessibility engineers implementing such a mechanism in user agents.

regards
SteveF

On 4 August 2012 15:29, Benjamin Hawkes-Lewis
<bhawkeslewis@googlemail.com> wrote:
> On Sat, Aug 4, 2012 at 1:01 PM, Steve Faulkner <faulkner.steve@gmail.com> wrote:
>>>The absence of @alt is an unambiguous indication that the image should
>>>have a text alternative. Doesn't necessarily mean it's key to
>>>understanding the content though.
>>
>> While you may disagree, that is what the HTML5 and HTML LS currently
>> define it as.
>
> I was talking about what developers can effectively communicate with,
> and what UAs can (and do) reasonably assume from, its absence, rather
> than merely what the spec says about it, but in any case it agrees
> with what I was saying AFAICT:
>
> "If the src attribute is set and the alt attribute is not  The image
> might be a key part of the content, and there is no textual equivalent
> of the image available."
>
> http://www.w3.org/TR/html5/the-img-element.html#the-img-element
>
> It says "might be" not "is". This is the correct inference, I feel.
>
>> When an image is the content of a figure element it is not unabiguous
>> <figure>
>> <img>
>> <figcaption>text</figcaption>
>> </figure>
>
> Yeah, I take it as read that we are using presence of @alt as a
> shorthand for presence of @alt or other (non-repair) source of text
> alternative.
>
>>> User agents (as opposed to linters) have to treat images without @alt
>>> with or without the linter flag the same,
>>
>> why? currently firefox for example does not display any visible
>> indication of an image when it has not alt attribute, why is that
>> useful for users who have images disabled?
>
> I'm not saying it is or isn't, though I do think user agents should be
> free to render as they see fit.
>
> I doubt a user agent would factor the presence of an attribute such as
> @relaxed into its decision to indicate or not indicate the presence of
> a particular image without a provided text alternative. In particular,
> I doubt user agents which provide configuration for indicating or not
> indicating such images (such as VoiceOver which allows users to ask it
> to announce all images or only images "with descriptions") would
> distinguish <img> and <img relaxed> as distinct categories in their
> configuration UI.
>
> Maybe an <img relaxed> would be less likely to be a spacer image. But
> I think there are more reliable heuristics for detecting spacer images
> than looking for the absence of @relaxed, for example looking at
> filename, intrinsic image size, color variance, repetition of the
> image, and legacy traits of surrounding code.
>
> In practice, spacer images are rare in new content where you could
> treat the absence of @relaxed as a signal. For recent content a bigger
> challenge to alerting users to key content is the abuse of CSS
> background images to speed loading of content images like news photos
> and galleries.
>
> @relaxed is such a weak signal for user agents that I doubt the value
> of pushing it into the accessibility APIs, that's all.
>
> --
> Benjamin Hawkes-Lewis



-- 
with regards

Steve Faulkner
Technical Director - TPG

www.paciellogroup.com | www.HTML5accessibility.com |
www.twitter.com/stevefaulkner
HTML5: Techniques for providing useful text alternatives -
dev.w3.org/html5/alt-techniques/
Web Accessibility Toolbar - www.paciellogroup.com/resources/wat-ie-about.html
Received on Saturday, 4 August 2012 17:55:45 GMT

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