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Re: lowsrc attribute

From: Karl Ove Hufthammer <karl@huftis.org>
Date: Sat, 23 Nov 2002 19:32:05 +0100
Message-Id: <n2m-g.Xns92CFC6B51FC85huftis@ID-99504.news.dfncis.de>
To: www-html@w3.org

Toby Inkster <tobyink@goddamn.co.uk> wrote in

> AFAIK, it's never been part of any official recommendation,
> but it was a good idea in some ways.

Well, you can achieve a similar effect by using the PNG graphics
format with Adam-7 interlacing. Then you get a low-resolution
version of the image when just 1/64 of it has been downloaded
(gradually improving when 1/32, 1/16, 1/8, 1/4, 1/2 and 1/1 of the
image has been downloaded). These low-resolution 'previews' can be
further enhanced by using resampling/interpolation. You'll find an
example of this, with images of both regular resizing and bilinear
and bicubic interpolation at <URL: http://www.its.caltech.edu/~stl/png.html >.

Most modern browsers support progressive rendering of Adam-7 PNGs
(though IE's support is a little strange), but non support
interpolation. You'll find Mozilla's bug report on this at
<URL: http://bugzilla.mozilla.org/show_bug.cgi?id=75077 >.

The JPEG format also supports progressive rendering, but it's not
as good at Adam-7 PNGs.

Karl Ove Hufthammer
Received on Saturday, 23 November 2002 13:34:41 UTC

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