Thumbnail Backup

[Jummy]

I have a DS211+ running RAID1 on which I have uploaded roughly 350GB of pictures. I have decided to use the disk independently and maybe use iSCSI but that will, as for as I am aware, require a format of the disks. Is it possible to backup only the thumbnails and then upload them to the NAS again together with the pictures (placed on my PC) to circumvent the recreation of the thumbnails?