kymarto wrote:
Jpeg is a lossy format--you lose something every time you open and resave after any adjustment. Even if your originals are jpgs, it makes sense to save in a losless format such as tiff or png, even though they will be much larger. Better yet shoot raws or tiffs and save as tiffs or png, unless the loss of quality is not an issue for you.
FWIW, I have heard that practically speaking, there is no benefit from saving jpgs in PS at a quality setting higher than 10.
And practically speaking, there is so little degrading by saving in JPG-HighQuality setting that it does not make sense to do otherwise!