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Re: do vector graphics enhance our concept of self?

From: Charles McCathieNevile <charles@w3.org>
Date: Mon, 29 Jul 2002 08:27:06 -0400 (EDT)
To: jonathan chetwynd <j.chetwynd@btinternet.com>
cc: Danny Ayers <danny666@virgilio.it>, Jon Hanna <jon@spin.ie>, "WAI List (E-mail)" <w3c-wai-ig@w3.org>
Message-ID: <Pine.LNX.4.30.0207290816150.30977-100000@tux.w3.org>

I think the situation is a bit more complex than you seem to suggest.

There are technical reasons why jpeg doesn't have transparency, although it
does have good compression for photograph type images. GIF and PNG, on the
other hand, have transparency, but very poor compression for photographs (by
comparison). Essentially using these types of technology you have to make a
trade-off - you get one or the other.

In some cases SVG should be used to replace PNG, JPEG or GIF images
(perhaps most cases where png or gif are a good choice SVG is a better
technical choice, and as user agents and authoring tools become more common
will be a better overall choice).

In other cases SVG allows you to combine the best features of SVG with the
best features of JPEG (its compression for certain types of image) or PNG/GIF
(Hmmm. The more I think about it the more I wonder what you really gain by
keeping those formats. I am sure there are relevant cases though).

I am not familiar with all the SVG authoring tools. However, to create a tool
which allows you to trace a section of a jpeg and say "show me just that
section" isn't hard. Jim Ley has such a tool available, in an online version
written in SVG. (He uses it for providing more useful searchable information
about the bit of the image that you trace, but it can also provide a clipped

This thing can be animated or scripted to move around, and again Jim has
demos. (Because these are things he works on for a bit of fun, the script
changes from time to time. But I believe that he is happy for people to use

It is possible to use this to create a complete user interface, but it takes
some programming time - generally available at the whim of a programmer or by
paying for it.

Technically, following the approach Jim has taken is the best method I can
think of. In terms of getting a tool that makes it easy, it also seems the
best approach I can think of. If you want something that a person with
relatively basic programming skills can work on, it is perhaps also the best
option. I you want me to program it for you then all you need to do is find
me the time ;-)

Seriously, I appreciate that you want better tools. Me too. And world peace.
I think the best approach is to follow the mixed SVG/JPEG method, especially
if you want to do animation.



On Sat, 27 Jul 2002, jonathan chetwynd wrote:

>Yes Chaals,
>but the unfortunate fact is that with a gif one can just choose a 'magic
>wand tool' and the job is kind of done.
>whereas for svg, one remains in a kind of fantasy land, ie highly work
>intensive, and only partially meeting the needs*.
>as far as png files go, as far as my limited (ie one file) test showed there
>was a 5-10% compression saving on gif, hardly comparable with ~300% for
>Surely it must be plain that with all the open source productivity available
>a concerted effort to either get the jpeg source released, reverse engineer,
>or create a new source is a reasonable project?
>SVG is not intended to replace jpeg or gif as I understand it, or did I get
>this wrong to?
>thanks again
>On degredation, transparency is lost, so all the tracing goes to waste.
>Transparency is fairly fundamental to sprites.
>Its this degredation, that is the concern, or more significantly, the
>attitude to it, for meta-freaks.
>----- Original Message -----
>From: "Danny Ayers" <danny666@virgilio.it>
>To: "Charles McCathieNevile" <charles@w3.org>; "Jon Hanna" <jon@spin.ie>
>Cc: "WAI List (E-mail)" <w3c-wai-ig@w3.org>
>Sent: Friday, July 26, 2002 7:27 PM
>Subject: RE: do vector graphics enhance our concept of self?
>> <clippath d="[[here you need a path around the bit of the image that
>> >you want - this can be generated quickly by tracing out the image,
>> Amaya's good for that...

Charles McCathieNevile    http://www.w3.org/People/Charles  phone: +61 409 134 136
W3C Web Accessibility Initiative     http://www.w3.org/WAI  fax: +33 4 92 38 78 22
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Received on Monday, 29 July 2002 08:27:10 UTC

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