The logic is fairly simple. You can use any size thumbnails - the only limitation is when you use larger than 128x128px with Graphic type the slidemount will turn to Simple, because its meaningless to use graphic which will be fully covered. There's no limit for the "None" or "Simple" type.
So, when selecting Large thumbs for Folders on the Chameleon/Thumbnails tab, a simple 2-pass build can be used :
* 1st pass : Create everything as normal, ie with say 120x120 thumbnails, or 180x180 etc
* 2nd pass : Re-build (use ALL) the album with the required Folder Thumbnail size (240x240, 480x480 etc) and unselect Process subdirectories. Any other changes can be added here, like setting different column/row values.
OK, this is familiar territory … a simple 2nd pass. As it used to be!!!!
An addition : Dedicated folder icon images can be used if required and named as something like !FolderIcon.jpg. Ensure they are set as the Folder Thumbnails and are excluded.
(It would appear that JAlbum v7 now allows for an image to be the folder thumbnail AND excluded at the same time, and an album built in a single pass).
IMHO I think this adds another creative element to Chameleon.
See the attached screenshot for an example of this simple technique, large folder thumbnails using dedicated images.