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Re: Opacities

From: David Woolley <david@djwhome.demon.co.uk>
Date: Mon, 17 May 2004 07:34:02 +0100 (BST)
Message-Id: <200405170634.i4H6Y2f01234@djwhome.demon.co.uk>
To: www-style@w3.org

> large bulky PNG files when it could be done with a tiny jpeg and opactiy 

There isn't really any such thing as a tiny jpeg.  JPEG images have a 
significant overhead and they need to be large enough that most pixels
are very similar to adjacent pixels before they achieve good compression.

JPEG is good for reasonable size photographs, and to a lesser extent for
ray traced images.  However, it is often used by people who hear that
it produces small images and only want to use one image format.
Much of the decorative images on web pages are closer to line art than
to photographic in nature.

(The most obvious misuse, I find, is for screen shots.  Unless the 
screen has a lot of images on it that are good for JPEG (as, unfortunately,
you might get with a lot of a modern wallpaper showing) JPEG tends to
produce the largest screenshot image and makes things worse because the
JPEG artefacts are particularly bad on text.  This includes reduced 
images.)
Received on Monday, 17 May 2004 02:35:29 GMT

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