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RE: do vector graphics enhance our concept of self?

From: Charles McCathieNevile <charles@w3.org>
Date: Fri, 26 Jul 2002 13:17:12 -0400 (EDT)
To: Jon Hanna <jon@spin.ie>
cc: "WAI List (E-mail)" <w3c-wai-ig@w3.org>
Message-ID: <Pine.LNX.4.30.0207261306380.25823-100000@tux.w3.org>

I don't have time tonight to write the example, but the information in the
SVG spec should be a combination of using opacity for the image with a
clipped image

This is sort of the idea, and about the size of your resulting SVG, but
probably has bugs in it <grin/>

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20010904//EN"
<svg width="12cm" height="3.5cm" viewBox="0 0 1200 350"
  <desc>Example opacity01 - opacity property</desc>

  <rect x="1" y="1" width="1198" height="348" opacity="0" />
  <g> <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, and using
that path]]">
    <image src="yourface.jpg">


On Fri, 26 Jul 2002, Jon Hanna wrote:

>> my point was really that jpegs are quite a few years old, and bar
>> the silly
>> copyright issue, surely someone (in scandinavia?) could bring out a mark 1
>> version with transparency?
>> this might degrade quite nicely from SVG.
>IIRC the last JPEG standard was published in 2000, I'm not sure if it can be
>used in JFIF though.
>I imagine that it would be quite difficult to reliably provide transparency
>information along side JPEGs though. Certainly the mechanism GIF employs
>wouldn't be applicable. The only way I can think of right now would be to
>provide a transparency (or alpha if you want to go for bonus credit :) mask
>with the photograph, and then use a lossless form of compression (presumably
>gzip would be preferred over LZW :) on the mask. JFIF allows for
>application-specific data to be included, so you could do this in a
>backwards compatible manner.
>Just the use of two very different compression formats in the one file
>format begins to feel kludgy.
>If someone wants in the US wants to smuggle a Spec that does this across the
>Iron Curtain to me here in the Free World I'll publish it on a
>you-can-only-patent-inventions-here-so-stick-your-lawsuit webserver, but I
>think I'd just use 24-bit PNGs instead.

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 Friday, 26 July 2002 13:17:17 UTC

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