PROOFING "Those are fools who do not proof." Digital data are human invisible ones, ergo they has to be proofed. The wide variety of used software, color management, drivers and settings is such a big range, nobody can be experienced enough to estimate the concrete result of a digital workflow process. Only a proof can be the ceckpoint in between, between prepress and print. Although proof itsself is an complicate technical area this difficulties are no excuse to avoid an frequently used proofing through the whole workflow chain.