The GIF entries are probably the most practical for most webmasters' needs... PNG isn't quite universally supported, even though it can shrink the final product by around 1K, and allow you a couple extra colors in some cases.
Perhaps the most interesting thing to note in the GIF entries is that the only thing that REALLY matters with GIF size is the # of colors involved...
Compression - GIF
8 color = 10-11K
6 color = 9-10K
4 color = 8-9K
The entries below will show different levels of "preserved detail" in details like borders between countries. But the real deciding factor in which image is the "best" is of course, Liane's opinion... it is her map, after all. ;)
ENTRIES WITH OVER 4 COLORS: These folks decided to stay "true to the original" and not allow the elimination of any of the main colors in the original image...
GIF - 9300 bytes
Paint Shop Pro
reduce color depth
saved to GIF
[note - I should add that the image could be much further compressed by altering the contrast and/or changing the large heading color to black (in which case you could get the image down to 4 colors without losing significant visual quality).]
GIF - 9179 bytes
saved as 6 color GIF with Alpha Transparency
GIF - 10525 bytes
Save For Web
GIF (Adaptive color)
reduced to 8 colors
ENTRIES WITH 4 COLORS: These folks all decided that black could be sacrificed from the color palette... and all their entries came in within 800 bytes of each other. DaveN gets bragging rights for file size here, but for most webmasters' purposes, the details of execution & software used will apparently make very little difference in the size of the end result... (MacGuru gets special mention for "most appealing technique")
GIF - 8095 bytes
Fireworks - 4 color
Aww... No more details than that? C'mon Dave, everyone else spilled the beans here... How'd you do it???
GIF - 8421 bytes
Start at 8 colour gif.
Snapped all colours to websafe.
Select 'remove unused colours'.
delete non major colours (leaves 5).
Changed the black colour (borders on countries) to the same blue as labels
GIF - 8718 bytes
Ulead SmartSaver Pro 2.0
Converted to GIF
Bumped colors down to 4
Played with "weight", "engine" and "palette" settings to find best compression/quality ratio
-ended up with even weight, median cut engine, and browser safe palette
(Could have made custom palette for even better selection, but did not in the interest of time)
Turned on dithering to close in a couple country lines that were becoming more dotted than they should have been
GIF - 8728 bytes
reduced image depth to 4 colours
saved as 4 colur GIF
GIF - 8742 bytes
Save for Web command
Reduce to 4 colors
GIF - 8811 bytes
converted to .gif
limited it to 4 colors
Had a beer, scratched his nose
GIF - 8837 bytes
Converted file to 8 bit color
Reduced image to 6 color GIF automatically
Deleted two more colors by hand (4 color final)
ENTRIES WITH 3 COLORS: Taking artistic liberty to the limit, the 3 color category says, "To heck with red, who needs flashy when you can have speed?"
GIF - 8540 bytes
reduced colour depth to 16 colours using optomized octree, nearest colour
saved as a gif file
Ulead GIF Animator
compressed using 8 colours and colour diffusion
Netmechanics (online GIF compressor)
shrank it to 3 colours and saved it
(edited by: mivox at 9:35 pm (gmt) on Oct. 11, 2001)