The JPEG image format is inherently lossy. Because of
this, each edit and subsequent recompression of JPEG photos in general
purpose image editors, such as Adobe Photoshop, results in a
progressive degradation of image quality.
Fortunately there is, in most cases, a way to avoid this unnecessary
recompression. If all you need is to quickly process a group of JPEG
photos from your latest vacation - rotate, crop, remove red-eye,
correct color and brightness, imprint date or comment - you do not need
to compromise on quality of photo editing.
Better JPEG is a batch JPEG photo editor that can do all of this editing without loss of image quality.