Thumbnail Help

[dickh]

I want to make a thumbnail size image (120X100, 24KB max.) from a standard 1600X1200 image.
When I simply reduce it, it becomes all "jaggies". Have tried several suggestions from another forum,
like "change to .TIF, then change" and "do it in steps", but nothing seems to work.
The thumbnails on pbase look great and they are only 5KB or so. How are they made?