...systems
Some browsers like Netscape support dynamic image resizing relative to the resolution of the window that is open on the computer's screen. It is possible to have an image always show up at 90 of the window's width. This has two negative side effects: first, the displaying computer has to rescale the image, which usually leads to a loss in quality (and unreadability in the worst case), and second, users of different WWW software will not benefit from dynamic resizing.
...map'
An image map is a graphical image you can click into to make a selection.
...format
See remarks about compression on page gif
...contrasts
A picture of a tree with green leaves has lots of smooth green contrast.
...format
If you're using Photoshop, save images in Photoshop format!
...algorithms
For example, turn the sequence 'RRRRRRRRRR' into '10*R' describing the same content with less than 50 of the characters.
...codes
We are talking about GIF here! Make sure to know the GIF paragraph on page gif!
...representation
Namely: pixels of different colors.

Lothar Fritsch
Fri May 3 22:43:31 MET DST 1996