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[OM] OT: Progressive jpegs [was: critique my macros]

Subject: [OM] OT: Progressive jpegs [was: critique my macros]
From: "Daniel Mitchell" <danmitchell@xxxxxxxx>
Date: Thu, 10 Jul 2003 13:51:16 -0600
Wim Verheyen wrote:
> Select Progressive to create an image that displays progressively in
> a Web browser.
> The image will display as a series of overlays, enabling viewers to
> see a low-resolution
> version of the image before it downloads completely.
> The Progressive option requires use of the Optimized JPEG format.

 Oh, apologies, you're right. I've just never seen one of these in the
flesh, but I have seen the equivalent for GIFs.

 Testing, if I try and open a progressive JPEG in IE (6.0), it appears all
at once, which could explain why I've never seen these before.

 Mozilla 1.4 (once it's finally started up), on the other hand, does the
right thing, Netscape 7 ditto. Netscape 4.08 sort of does, but it's really
ugly; every time it steps up a resolution, it replaces the entire image with
white then fills in at the next res up.

 Opera 7.11, good. Opera 3.62 doesn't seem to even show the image at all,
unless it somehow takes ten times longer to download files than everything
else.

 When it works nicely, though, it is pretty cool.
www.danielmitchell.net/watch.jpg is a progressive jpeg (and an example of
why you might still want your normal non-film scanner) -- if you have a
sufficiently slow link, you can check it out.


 That said, it seems like it's only really worthwhile for, let's see, ~10%
of people (http://www.epistemelinks.com/Info/Browsers.aspx) and, for the 90%
of people that use IE, it actually makes things worse (as, ironically,
non-progressive jpegs appear progressively from the top down..)

 -- dan


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