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Usually I know at least some of the answers, but this
time I am all questions... :(

A thread over in alt.html got me thinking and doing a bit
of research about the different ways of constructing a
favicon.ico file -- specifically, including multiple
sizes, resolutions, and color depths.  There is a large
amount of conflicting information on the web about this.

From what I have read it looks like even a 256256x32-bit
(24 bit RGB, 8-bit alpha channel) compressed PNG could
end up being used if a Vista user creates a shortcut to
a webpage on the desktop and then uses the zoom feature.  
As for color, see
http://www.informationgift.com/ud/faviconic /
for a taste of what a mess this is on different browsers.

Just to confuse the issue further, there is talk about
non-square favorites icons on some old (As in Window
95/98 old) sites, but nothing about it on newer sites,
and I remember seeing some double-wide bookmark icons
on one system -- perhaps on NT server? Don't know if
they would display on newer OSs/browsers.

There is also a lot of confliction information on what
mime-type to use: I have seen the following (many of
which are surely bogus):


The first one is correct according to the standards, -- see
-- but I keep hearing about many browsers not supporting it.

Another area where there is a lot of conflicting information
is on the subject of wheter to use link rel="Shortcut Icon",
link rel="icon", or both, with some comments claiming that
it matters which comes first.

Then there is http://www.xvsxp.com/interface/icons.php , which
talks about the differences beween XP icons and OS X icons.
it doesn't mention favicons; are they different as well?

And what about Vista?  Look at "Windows Vista Icons Support" in
http://www.codeproject.com/KB/cs/IconLib.aspx and see how
different they are.

Part of me says to just create a single 16x16x4-bit favicon
using web-safe colors.  Another part of me says to make
a multi-image file with every size, resolution and color
depth combination that I can verify is used by some browser
or in some OS destop/directory shortcut. What say you?

Guy Macon


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