The intermediare picture is
normal_image.jpg, the thumnails is
thumb_image.jpg and the full size (pop up) is
image.jpg.
orig_image.jpg is created only when you use the watermark. Is a backup for you when you decide not to use the watermark anymore.
If you still have all the
orig_image.jpg on your server then:
1) Co to config - Image watermarking - Watermark images and disable it.
2) Go to Files - Admin tools - click Update thumbs and/or resized photos - click one of the option (example Only resized pictures if you watermarked only the intermediare picture) - Select Album - choose an album from the drop down menu - click sumbit.
You can choose All Albums, but if you have too many photos in your gallery Admin Tools won't work. Will time out during the process.
I don't know if you watermarked all images including thumbnails and intermediare picture or just the full size image (pop up image)
3) I don't know what version of coppermine you use. If you use the latest version 1.5.36 then you need to apply this
http://forum.coppermine-gallery.net/index.php/topic,78212.msg378656.html#msg378656.
There is an error in util.php and Admin Tools don't work.
Make sure to update first to cpg 1.5.36 for Admin Tools to work then apply
http://forum.coppermine-gallery.net/index.php/topic,78212.msg378656.html#msg378656.
You also should update for security reasons.