I'm producing contract proofs for product catalogs with product shots and when I output Epson proofs they look great and gets approved. Once on press some images show strong posterization on press. I have to fix these using blur, noise after upping to 16 bit. Is there a way to catch these images at the proofing stage before plates are made? What could be the cause of this posterization in the customer supplied images. Out of hundreds it seems this occurs only in one or two images. The customer did tell me that one of these images was re-res-ed prior to being supplied to us.