JPEG File Format

As I mentioned earlier in this chapter, JPEG format is not a preferred graphic file format for use in high-quality printing environments. This is because saving an image as a JPEG automatically applies lossy compression, which removes data from an image. But the reality is that we often receive JPEGs from a variety of sources and are expected to print them. So our guiding principle—our graphic file Hippocratic oath—is to “do no more harm.” Here are a couple of good rules of engagement for working with JPEGs:

Never save a JPEG as another JPEG. If you do, you risk doubling the compression-related damage by recompressing an already compressed image.
Resave all JPEG images as TIFFs before you even open them. This can be accomplished easily through the use of actions through Photoshop or Adobe Bridge.