Prepress proofing

A contract proof usually serves as an agreement between customer and printer and as a color reference guide for adjusting the press before the final press run. Most contract proofs are a prepress proof.

The primary goal of 'proofing' is to serve as a tool for customer verification that the entire job is accurate. Prepress proofing (also known as off-press proofing) is a cost-effective way of providing a visual copy without the expense of creating a press proof. If errors are found during the printing process on press, correcting them can prove very costly to one or both parties involved.

Press time is the most expensive part of print media. The main objective of proofing is to produce either a soft or hard copy of what the final product will look like on press. Hard-copy proofing usually involves ink-jet printing or other technologies (i.e. Laminate Proof) to produce high-quality one-off copies of the production artwork. Soft proofing usually involves highly color accurate wide-gamut computer displays.

"The printed proof is a dispassionate simulation of the ultimate output - a CMYK press sheet. The mission of a proofing system is to create accurate predictions, not pretty pictures." In the best conditions the proofing process will actually try to emulate the effects of the printing press through color management and screening techniques, which can be quite challenging because proofing devices may behave and operate quite differently from press devices.

Since the first days of Johannes Gutenberg, proofing has just been press proofs - one makes a short run on the press in order to verify what is to be done on a production run. As technology evolved to lower the per-copy cost of a printing job, the cost of starting a production run continued to rise. Today, it can be very costly to start up a production press, and thus it is cost-prohibitive to run a press proof. While some people may think a press proof is the ultimate proof quality, this is not necessarily so, especially if the production run is done days or weeks later when press conditions may have changed, or the production run is done on a different press than the press proof.

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