Q) What if your original is stored as a high-quality (low-compression) JPEG and you never actually resave it? For example, start with the original image stored as JPEG. Open it for editing. Save the edited image as a separate file in whatever format you choose. Close the file. As I understand it, that sequence leaves the original intact with no loss of quality. Is that true?
A) You're correct as long as you don't resave the file over your original file; in other words, you never hit the Save button.