Processing jpgs question.

It is irrelevant, as Aperture does a non-destructive editing, saving development changes into a sidecar file. I don't use Aperture, but as far as I know, every development software does this in a non-destructive way (even open source Darktable does).

What I would do is keeping the original jpg's in one folder tree, enhance them in Aperture and then bulk-save them as jpg's in a different folder tree. Then it's up to you to remove the old ones.

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"When I get a little money I buy books; and if any is left I buy food and clothes" - Erasmus.