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Proof Beyond Reasonable Doubt - proofing - part 3 of 1 2 3 4 5 6 7 8 9 10 11

by Mike McNamee Published 01/10/2008

Progressives enable the press operator to check the output from each part of the process and compare it by densitometer readings.

The main advantage of analogue proofing is that it reveals problems of moire fringing which occur from the interaction between the pattern of half-tone dots and the image structure. Obviously with a proofing method that does not exactly mimic the half tone structure no warning of moire will be flagged. There were a number of proofers which accommodated the need to check the half-tone structure, the most common of which was the IRIS proofer. It was the IRIS proofer which started the inkjet revolution, particularly for fine art limited edition printing. The joke at the time was that the technician who fettled the IRIS was always at the staff Christmas lunch because he was there for the rest of the year anyway, repairing the ever-petulant system!

Analogue Proofs thus use the same technology as the printing press and usually employ the same separation films and/or plates or both. Digital Proofs use a machine other than the press to mimic press behaviour, providing a cheaper and now more reliable method of predicting the outcome from the press.

Contract Proofs

A contract proof is one which is 'signed off' as representing the final output, ahead of giving permission to run the whole job. The press operator retains the contract proof and the print run is matched to it. In the case of any dispute, the contract proof provides tangible evidence of what everybody signed up to, at the outset. Contract proofs tended only to be employed on high value, high prestige or large run jobs, mainly because of the cost of making them. Today a contract proof can be made at the same speed as any other inkjet print, it is only the colour precision which differentiates it from any other inkjet proof. Because of their importance and prevalence we cover them separately later in this feature.

Scatter Proofs

If a multi-page document contains a small number of randomly placed images these are sometimes gathered together on a single sheet and proofed on their own while the remainder of the document is proofed 'for position only', ie to check text and that all the pictures are in the correct place and orientation. FPO's are often made on desktop laser prints.

Page Proofs Page proofs come in two kinds, 'Reader Spreads' which show what the reader will see in the bound document and 'Imposition Proofs'. If you take the staples out of a magazine then the single sheet of paper (usually 2xA4, printed both sides) shows you what an imposition proof looks like. Thus you will find in Professional Imagemaker that page 15 is on the same proof as say page 22, although because we are now perfect bound, all pages are trimmed. There is an additional complication that we sometimes also print both sides of a sheet at the same time. Seeing the imposition proof enables the press operator to allow for an image on one page 'robbing' ink from the picture on the same imposed page. The 'tracking' as it is called is tweaked to make the best optimisation of the two pages.

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1st Published 01/10/2008
last update 18/05/2017 12:32:26

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Updated 18/05/2017 12:32:26 Last Modified: Thursday, 18 May 2017