When trying to edit a picture in Mac OS X Preview, you may receive an error message that you don’t have permission to edit the file. This seems to be a bug in Preview.
You don’t own the file “” and don’t have permission to write to it.
You can duplicate this document and edit the duplicate. Only the duplicate will include your changes.
The quick fix is to click cancel, close the file, and re-open it. You should be able to make edits to the file in Preview again.