On several occasions I have had to delete all my images and re-add them through the admin panel. Mainly, this is because I have updated most of the descriptions or keywords, or saved the images at a different Jpeg quality or size and FTP'd them to the folders again. The only problem with this is that the ratings, comments, etc., get deleted as well.
It would be great if someone could come up with a mod for the admin control panel where you could choose to update image fields. It would only have to update fields that can be defaulted from iptc data (like checkimages) and possibly any image size fields if those are stored anywhere. If easier, maybe this could be a plug-in that you would need to customize like the batch upload.
