PNG in Windows IE: The ProblemHome | The Problem | The Solution | How To Use | More Info
Consider a standard GIF image with the halo problem. GIFs only allow one colour for background transparency, so a GIF placed over the intersection of another colour looks ghastly:
Compare the above GIF to the same image below saved as a PNG. On modern browsers (Firefox, Opera etc), the halo problem is solved - but not in Windows Internet Explorer prior to version 7. IE 6 and under render the image with an ugly background which looks even worse than the GIF halo.
Finally, here is the same PNG right-aligned to this paragraph using the very common (deprecated) img align="right" construct. The PNG can be positioned in the same way as JPGs or GIFs, but the transparency issue remains a problem.