Don't update images if not changed

[PaulWalkerUK]

For performance reasons, I have PapyrusCS output to a local directory, then use robocopy to synchronise the output to a network location. However, even though I run PapyrusCS against exactly the same world data, it looks like it's still modifying the resulting image files, or at least, stamping a new "last modified" date. This causes robocopy to see the files as updated and so needing copying over to the network storage.

If the data hasn't changed, is it possible for the image files not to be changed/stamped with a new modified date?