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Re: image links and (text)boxes

From: David Woolley <david@djwhome.demon.co.uk>
Date: Sun, 15 Dec 2002 11:42:04 +0000 (GMT)
Message-Id: <200212151142.gBFBg4207260@djwhome.demon.co.uk>
To: w3c-wai-ig@w3.org

> the outlines of image links are helpful for identification,

I mis-read this at first as being a plea not to turn off the (typically)
blue border on images within anchors (which would certainly reduce the
hunt the link problems on many pages), but I think what is really being
talked about here is using the profile of an image, rather than its
internal structure, to recognize it.  Note that HTML has no concept
of an image link, only an image with an associated link; certainly no
concept of icons (icons are essentially a presentational concept, or
an alternative - ideographic - language version).

> Can we make a guideline that image links* should ideally have 
> transparent backgrounds, and non-rectangular** outlines?    (W3C please 
> note)

If these help recognisability, commercial web sites will do it anyway;
they are the sorts of things that marketing departments do ask for.
In fact, particularly on youth market sites, they are the sorts of thing
I would expect to see over used.

Howver, the reality is that good transparent backgrounds on all but the
simplest icons requires full alpha channel support, in practice PNG at
the moment.  PNG has generally been ignored by commercial designers++,
who don't care about the patent issues, and probably don't have the
technical understanding to see benefits over GIF.  If you are preparing an
apparently transparent company logo using GIFs, you can only anti-alias
it - necessary for images that are not specifically designed to be
pixelised - if you do so against a background that nominally matches the
target background.  Such logos, although having transparent borders,
show a halo of the nominal background colour when shown against a
different background.

Obviously SVG vector graphics should suffer this problem as they have
edges that are not pixellated.

> and failing on transparency have backgrounds that are easily changed?

The background may well be part of the corporate image.  Actually, the
fact that the background colour is likely to be part of the overall
design is probably the main reason why there is no incentive to move
to image formats that support anti-aliasing of transparency.

> *presumably most sites are happy to be linked to, so why is it that so 
> few images used as links are appropriate for sharing?

Most commercial sites are not happy with arbitrary linking.  In particular,
most do not like deep linking (I think you may be getting away with
deep linking entertainment sites only because you are not taking away
an audience that they want, and taking legal action against charities
always risks bad press==).  Even for linking to home pages, many sites
would rather only be linked from reputable sites.  When it comes to
icons, these are trade marks.  Companies are very jealous about
guarding their trade marks, as use by other site can imply some
level of approval.  Most big companies have legal documents explaining
when trade marks can be used, and exactly how they can be used.

(Generally, trying to emulate a trademark is even worse an offence
than using the official design without permission.)

> **wondering what others feel about the rather heavy handed cartesian, 
> or western imperialist insistence on boxes?

Most strokes in Chinese characters are horizontal or vertical, often
forming boxes.  The whole of each character is expected to fill a, 
constant sized, square box.  I'd hardly say that boxes and rectilinear
structures were a western cultural imperialism thing.  (I'd be more
concerned that Chinese language web sites use on the text as graphics,
tiny fonts, poor colour contrasts, and generally bad markup, of western
sites, indicating that they are cut and paste coding such sites in the
same way that most Western authors cut and paste code.)

Rectinlinear structures are used because they are technically easier to
support (general accessibility) and because they introduce an element of
order into the design that helps people find their way around.

++ Support in major browsers has been broken and partial, as well, which
more or less guarantees that they will be ignored by designers.  In particular,
I don't think that original implementations included the alpha channel.

== You mentioned the BBC; they are probably exceptional, as they still
retain some level of public service ethic - most entertainment sites are 
just vehicles for advertising.
Received on Sunday, 15 December 2002 06:42:39 GMT

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