articles/Media/proofbeyondreasonabledoubt-page8
by Mike McNamee Published 01/10/2008
An advertisement cross-rendered to an ISO newspaper profile shows a reasonable match to the printed copy on the right. Note that by checking the 'show paper white' option, the white proofing paper has been matched to the darker, more yellow newsprint.
CONTRACT PROOFING
As we mentioned earlier this is the highest level of proofing and a contract proof is normally signed to confirm a binding contract between the printer and the client. Providing the final job matches the contract proof, all errors are down to the client from this stage forward. If he has failed to spot that an image is reversed or out of place, he carries the can! Today's contract proofs are so good that they are truly representative of the input colour, at error levels that cannot be reliably detected by the unaided eye. Two identical proofs, off machines on opposite sides of the world, should be just that, identical. One of the best examples is the IKEA catalogue. This is a 192 million copy publication made in centres all over the world and controlled by GMG proofers to known and certified standards in, we think, about 27 centres. The certification standards for contract proofing are provided by UGRA/FOGRA (for Europe) and IDEAlliance/GRACoL (in the USA). These standards are evolving and have recently been tightened yet further. To comply with the standards, the errors on a particular target have to be measured and reported on a label attached to the contract proof. The errors are tightly controlled as you will see later.
Paper Matters
Papers for proofing should be selected with care as some of them are intended merely to give an impression of what an image is going to look like ahead of committing to a large expensive piece of fine art paper. Others are specialised products made to exacting standards for contract proofing. A Google search for 'proofing paper for inkjet' returned more than 2 million hits!
Epson products such as Enhanced Matte Paper may be used for lower grades of proofing but for more specialised work there are four options as tabled below:
Paper has a profound influence on the outcome of the proofing process. The 'colour' of paper is a complex subject and has specifications and ISO Standards all to itself (as do teeth and dentures by the way!). The aim when choosing a paper is to closely match the paper that you are proofing towards, that is if you are printing to a bright-white, gloss paper you should choose a bright-white proofing paper. When a proofing paper has more brightness than the 'aim' paper, you can add ink (and colour) to match when using Absolute Colormetric rendering intent. If the paper is already too dull you cannot add any ink to make it whiter!
The four Epson proofing products are compared with the paper used for printing Professional Imagemaker in the table opposite and also graphically.
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