Create a new bbc image tag. [imglarge] Forum bots find large images and retag them as such. They also create a small thumbnail and include that in the tag as well.
Then when the bbc is displayed, it checks to see if users have thumbnailing enabled or not. If not, then the image is displayed as usual. If they do have thumbnailing enabled, then the thumbnail is displayed. Clicking it will swap images and load up the full sized one.
If an [imglarge] tag is in a quote, it'll always start off as the thumbnail. If a regular image tag is quoted, it is resized to a thumbnail but not actually downsampled into a new image.
The reasoning behind this is to keep bandwith low for users, and to keep the forum compact when larger images are quoted.
