A recent question from a client:
“I am still a bit confused on the whole ‘don’t save a jpeg to a jpeg thing’ when before I switched to RAW, my files are all jpegs, so if I want to save an image for the web, it will be a jpeg from a jpeg. Is this still OK? Can you help me with this?”
“In this case, you have no choice, so don’t worry about it. After your editing is done, go ahead and resave your derivative JPGs from the original JPG captures.
Saving a new, derivative JPG from a JPG master probably won’t be a problem if you only do it once and use high quality settings on the re-save (quality 80 or higher). But you don’t want to keep saving a single JPG over and over, because each time data is lost.
So if you’re opening your original JPGs into Photoshop to work on them, immediately do a Save As first, and save the new master file as a TIF. Going forward, all work should be done to this TIF, and all derivatives saved from it. In this case the original JPG capture is no longer the working master and is only saved for archival purposes.
Save your new, final JPGs only after all your editing/processing work is done on the new master TIF, and when you need to generate JPG derivatives for specific purposes.
And of course, from now on, only capture RAW.”