I did a search, but couldn't find anything.
When I originally set the gallery up, I specified 4096MB as the max image size, and 2048 pixels as the max width/height. Unfortunately, I'm running out of space. One of the options I have is to convert all the uploaded images to jpg. The majority of them are png.
Before I decrease the max image size to something like 2048, I'd like to know if it is possible to mass convert all png to jpg.
AFAIK there isn't a way to do that in coppermine.
Edit - Sorry. I misread your post. I thought you were looking for something to resize them.
http://documentation.coppermine-gallery.net/en/admin-tools.htm#admin_tools
No problem. Seems I have to switch servers anyway for more space.