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Re: Intrinsic size of jpeg images

From: Ian Hickson <ian@hixie.ch>
Date: Fri, 28 Jan 2005 10:28:42 +0000 (UTC)
To: "Grant, Melinda" <melinda.grant@hp.com>
Cc: www-style@w3.org
Message-ID: <Pine.LNX.4.61.0501281027400.11312@dhalsim.dreamhost.com>

On Thu, 27 Jan 2005, Grant, Melinda wrote:
> When no size information is provided for an image in the html/css 
> markup, and the intrinsic size of a jpeg image is used, it appears that 
> Mozilla, IE, and Opera all ignore the resolution information when it is 
> provided in the exif or jfif wrapper; in this case, Mozilla renders at 
> about 150 dpi and IE and Opera at about 96 dpi.
> Is this correct?  If those in the know could explain why the resolution 
> information associated with jpeg images is ignored, it would be greatly 
> appreciated.

It's probably because most JPEG images have incorrect resolution data, and 
so actually doing this correctly (i.e. taking the real dimensions of the 
image based on the image's theoretical resolution) would break many pages 
on the Web.

But that's just a guess.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Friday, 28 January 2005 10:28:45 UTC

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