restore edited photo

I should have mentioned that you are missing something that VikingOSX hinted at. Preview has never claimed to do "lossless" editing like iPhoto, Photos or Aperture. It is a preview/viewer app with some light editing capabilities, not a DAM.

Something called a restore from a Time Machine backup prior to your edit. Out of habit, I never make revisions to the original, only copy of an image. By the way, the option key works in Preview just as it does elsewhere to provide a Save As… dialog.

Cumbersome or not, the operating systems and their user interfaces have different human interface and workflow requirements that offer an adaptation opportunity. I have never perceived Apple's Preview as suitable photo editing software…

Not as cumbersome as editing an only-copy of an image then wondering why the edits overwrote the original. I can not think of any situation where I would edit an original and only-copy of an image without first creating at least one copy of the original image. Regardless of device or app I don't understand why anyone would edit an image of which there was not at least one backup copy.

On a similar note, If you were writing a document or book and wanted to make changes, I hope you would first create a copy of the document or book prior to doing any editing. Working copies do get lost or corrupted.

Instead of "Save As", you use the "Rename" facility, or you can export it and give it a new name.