A standardised printing condition is the final and most important
part of a fully colour managed image and page workflow. Indeed,
without the profile for the printing presses the effort put into the
rest of the workflow is completely undermined.
Profiling RGB images and establishing sound colour management
policies at the desktop (see the chapters on Colour Management,
Handling Digital Images and Monitors for more of an insight into this
area), together with accurate PDF X file production and device
calibration for soft and hardcopy digital proofs, are all fundamental
to producing files ready for print output. The press profile is the
final piece in the puzzle that can protect against nasty surprises
and, of course, unanticipated extra costs.
How press profiling works
A press profile reflects the press’ characteristics so that they can be taken
into account when a job is prepared for output.
This ensures that the printed result is more accurate.
While it’s perfectly possible to profile every press at every
printer, this has proven impractical for many markets and areas of
print. This is because very often the printer, and therefore which
press will be used for the job, is not known when the output files
are in production. Moreover, files may need to be printed at a number
of print sites, often in different parts of the world, and later on
reprints may be needed – possibly from different printers or presses.
Such is the day-to-day reality of print production, and, needless to
say, managing press profiles in this environment is extremely difficult.
In response to this difficulty, and to avoid the need for publishers,
designers and other printer clients to use differing CMYK profiles
for different printers, a number of organisations have introduced the
concept of ‘standard printing conditions’ for a range of printing
methods, presses and papers.
Standards practice in action
In the USA, the well-known SWOP (Specifications for Web Offset
Publications) is well established and used mainly for web offset
production on lightweight coated papers. SWOP is often used as a
standard USA CMYK colour profile for litho printing of all types.
Another US specification, Idealliance GRAcoL G7, covers sheet-fed litho printing.
using some innovative grey balance calibration techniques.
With the latest SWOP v3 and v5 profiles they are now, as with G7, very closely aligned to ISO 12647/2 based profiles and printing conditions.
Increasingly the international standard
ISO 12647/2-2004 is used in the UK, Europe and in parts of the Middle and Far East where it is needed for their export clients. This standard covers a
range of printing conditions, including sheet and web offset litho
printing, and various paper types. It was researched and developed
by FOGRA, the German printing research organisation, which had
recognised that profiling individual presses was not practical for
the industry’s clients and printers.
FOGRA printed colour managment tests formes on coated and uncoated papers. These test results produced
data sets that could be used to determine the standard printing
conditions for sheet fed and web offset presses on a number of
papers. Using these datasets a range of standard ICC profiles have
been produced for CMYK separations. The most widely used of these are
ISO coated v2.icc, for use with sheet and web litho on coated papers, and
ISO web coated.icc, for use with web offset on lightweight coated
papers.
Other data sets and profiles are available for uncoated papers,
newspaper printing and gravure production. In addition, other
profiles matching the standard printing
condition selected can be made from the data sets for each printing
condition and used within Adobe PhotoShop or any other ICC conversion
software.
Working with standards
Print managers who want to work with these standard printing
conditions and CMYK profiles should notify their printers to ensure
that they understand the requirements. It also means matching a
defined tone value increase curve to manage dot gain, and
increasingly – as in GRACol G7 – matching grey balance targets to
control colour appearance more accurately. It’s worth noting that
printers are becoming increasingly sophisticated in their use of both
handheld densitometers and spectrophotometers. However, the ISO
standard specifies printing conditions and targets using CIE L*a*b*
and density. As a densitometer isn’t capable of delivering colour
L*a*b* targets your chosen printer should be using a
spectrophotometer on the press.
The above can all be managed by the printer using process control
methods within the prepress workflows and on-press testing. Again, it
should be noted that testing on a web press is considered by most to
be impracticable and often a wasted exercise unless the print
condition can be reproduced again. This is unlikely, unless the press
is equipped with an inline closed loop colour measurement system,
where the data on a job is stored for future use.
Tailored press profiles
Should the job demand it, and should you wish to go further than
these standards, some printers will have profiles of their own,
specifically tailored to their own presses. It’s worth checking this
out. The same goes for their chosen digital proofing method, which
should be referenced and measured to the data set that produced the
standard printing condition. This makes it easier to match the proofs
on a press that’s been set up for the corresponding/matching print
conditions. Many proofing systems are now FOGRA and/or SWOP certified
for accuracy, when correctly used.
Improved quality and saving on cost
The benefits of all this – including the value of more predictable,
reliable and better quality printed products – cannot be
underestimated, Not least, printers using these standards and the
associated process control methods also have a systematic way of recognising and solving
potential printing problems before the cost of correcting them is too high.
The ISO 12647/2-2004 standard fits well with the rather more general
ISO 9001 quality standard as a way of controlling printed quality.
Standard printing conditions are a practical way of covering the
final, most important part of a colour managed workflow, the printing
press.
The British Printing Industries Federation (BPiF) now has a certification scheme to provide UKAS accredited certification for ISO 12647/2. This is a product certification, not based on a once a year snap shot of the performance of one press. See this link for more information:
http://www.britishprint.com/page.asp?node=727&action=view_document&tid=6334&sec=&page=1
For more information on the area of colour management, process
control and standard printing conditions also see:
www.eci.org
www.forga.org
www.swop.org
www.icc.org
www.idealliance.org
www.gmicolor.com
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