Checksumming JPEG files is not that useful (to me, at least). There are lots of cases where the file checksum doesn't match but the image is still the same, for

Checksumming JPEG files is not that useful (to me, at least). There are lots of cases where the file checksum doesn't match but the image is still the same, for some definition of "same." Examples: EXIF/IPTC/etc metadata changes (sometimes this matters; sometimes it doesn't). Image has been rotated (this almost never matters). Image saved with different compression parameters (usually this matters but not always). Image saved with different resolution (ditto). Image has been slightly edited. The point here is that with images, data identity does not always equal file identity.