During the life of a print job, there may be more than one proofing cycle.
The first proofing cycling is for judging color and content long before printing.
So usually, an individual page of a project, or certainly an ad,
will be proofed to check the content before sending it to imposition.
It's also sent for customer approval, and
then if there had been any corrections made
and this is the second round of proofing, that second proof is to help confirm
that any corrections that were requested have been made.
Here you can see an individual page proof coming out of an inkjet printer.
Now keep in mind, this is not like your desktop inkjet printer, this is
highly calibrated and color profiled so it
gives faithful color rendition of this job.
Once a job has been imposed, that imposed flat will be proofed, to make
sure that the pages are in correct position and that no errors have crept in.
And, a proof
like this is printed from the RIPped data, that's going to actually make the plates.
And again, remember, RIP is a good thing, it means raster image processor.
So this gives them an opportunity to check the text on multiple pages, check
all the images, and any other content, to make sure there aren't any problems.
They want to check the crops and bleed, make sure that nothing's cropped out
that shouldn't be, make sure that there's
adequate bleed, and to check something called back-up,
because it's going to print on both sides of the sheet.
You want to make sure that the pages align as they should.
Usually, something like this is trimmed and
then supplied to the customer for approval.
Often we'll create a mock-up of the job based on this proof
from an imposed flat, and it really looks like a finished piece.
But that way, you get to judge crossovers,
make sure that everything's where it should be.
Here the prepress supervisor is looking at a proof from an imposed flat, and he's
making sure that everything, like takeoff bars and color bars, are in place.
He's making sure that the job backs up correctly, making sure that
everything trims out like it should, that there's adequate bleed, and so forth.
So this is one last chance to take a really good look at this
imposed flat before the next step, which is sending it to the plate setter.
So, on that imposed proof, all the pages for that flat are in position.
A flat is just an
assembly of pages that's meant to burn a plate.
It represents exactly what's going to image on that plate,
and includes things, as I mentioned, like take-off bars,
and take-off bars help on the press, they're sort
of a mechanical aid to ensure even ink coverage.
And then color bars, which are important
because they are read by computerized controls or
by handheld devices in order to ensure that the press is running as it should.
The solid bars
that you see are what are called take-off bars, and
they are used to ensure that there's even press coverage.
Sort of a long story, why they're handy,
but it's something that a pressman really appreciates.
And then the very small blocks that you see here are what are called color bars.
And those enable handheld devices or computerized
controls to monitor the way ink coverage is
behaving on press, making sure that everything's in
register, and that the press is running as
it should.
As you might expect, it's important that those proofs be reliable.
After all, they're used to judge both color and content,
they're used as a reference when the job goes to press.
So, there are color patches that are
printed, and then those color patches are read
and analyzed, and these serve as a
quality control patch for the proofing device itself.
These quality control patches are printed by the proofer, and then they're
read with a handheld device or a computerized reader, and
that information is fed back into the proofer, so that
it can auto-correct and ensure that it's outputting correct color,
so that it can be used as a reliable proof.