RE: MIDRANGE-L Digest, Vol 3, Issue 1776

[George Kinney <GKinney@xxxxxxxxxxxxxxxx>]

from: "Walden H. Leverich" <WaldenL@xxxxxxxxxxxxxxx>

>On the other hand, GIF and JPG are both lossy
compression schemes. GIF works much better w/long runs of the same
color, while JPG handles many colors much better -- hence for documents
GIF tends to be better while for photos JPG is better.  

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Not true. GIF is lossless. GIF uses LZW, hence the patent issues. GIF is
however an 8bit color format, so you must either palletize your image or use
dithering, both of which are ugly. (But neither is a huge problem for mostly
black and white text) You still get out exactly what you put in. Even if
what you put in was hidden from you by your graphics editor/viewer that
gleefully let you save a 24bit image to GIF. 

JPG doesn't compress anything better, it throws away a lot of data to get
those smaller file sizes. It just happens that the eye filters out a lot of
noise, so it isn't really disruptive to colorful, busy images. Even if you
crank up the quality setting, repeated save-open-save will continually
degrade the image.

TIFF is problematic because it is a very non-standard standard. There are 
*many* different compression schemes that are allowable, few viewers will 
support more than a few. And I'm not aware of any browsers that support tiff
'out-of-the-box', most require tracking down and installing a plugin of some
sort. (Quicktime includes a TIFF plugin for IE. How obvious a solution is
that?)

If you must have lossless, and it needs to be viewable by just about
everyone, go with PNG. If the lossless isn't a huge factor, then JPG is
good.