10 Prepress Troubleshooting
Tips:
How to spot little problems
before they become big headaches
Typically, only about 15% of client-supplied
files are actually ready to output without problems. The other
85% have one or more problems - some are minor and hardly noticeable
in the final piece; others have more serious problems that will
jam your imagesetter or other output device or, worse, produce
an unacceptable print job that the client won't pay for. The
earlier you find these problems, the better. You can decide
who should fix the problems: you, for an additional fee, or
the client, and deal with them before you waste materials or
miss a delivery date.
In an earlier column I covered some popular pre-flight
software designed to auto-troubleshoot digital prepress files
and identify, but not fix, problems. These programs can be real
time-savers, but you still need to understand the most common
problems and how to fix them to avoid angry clients and wasting
time and money. With that in mind, these are the most common
prepress problems you will encounter.
The problem with fonts
This is far and away the most common trouble area.
Jobs can contain from two to a dozen or more typefaces, and
page layout or illustration programs do not automatically include
the fonts with files they create. Therefore, it's the client's
responsibility to include these fonts with the job so you can
temporarily load them to output the files. If the correct fonts
are not included, they will be missing or substituted in the
output, usually with unfortunate results. This means clients
must include the Mac or PC screen and printer font files for
all PostScript typefaces used, even if they seem like common
fonts. There are over a dozen similar, but not identical, versions
of something as common as Times or Helvetica out there, for
example.
For TrueType fonts, just the main font file is required
- it includes both screen and printer resources. Although TrueType
can be problematic, especially on older imagesetter RIPs. Adobe's
Multiple Master fonts can also be a problem - clients must remember
to include any special instances of MM fonts used in a job.
Other fixes? Well, Illustrator and FreeHand can
convert all type to outlines in their files - you won't need
the font files to output the work, but you will not be able
to edit the text. Adobe's excellent Acrobat Distiller can open
files from almost any program and convert them to PDF, embedding
font resources in the these files, solving the font problem
and other potential issues. All you need to print them is a
copy of the free Acrobat Reader, although every print shop should
own the full Acrobat package - it's a real swiss army knife
for graphic arts files.
Tricky graphic files
With the widespread use of low-cost digital cameras
and scanners - some are as low as $69, but you get exactly what
you pay for - and the availability of powerful image-editing
programs like Photoshop, many clients create and process their
own photos or other pixel-based graphic files. Predictably,
there are many things a client can get wrong, and a full discussion
of these is much too big for this article. The most common errors
are incorrect resolution (they should be 1.5 to two times the
planned output line screen; I see more and more incredibly bad
72 dpi GIF or JPEG files from the Web included in print jobs
these days), wrong colour mode (CMYK, not RGB or any other mode)
or improper file format (TIFF or EPS are best).
Other common issues are bad colour balance or contrast/density
problems (improper monitor settings and calibration are the
biggest culprits here, and not understanding what the density
numbers in Photoshop's info palette really mean), incorrect
total dot gain assumptions when processing the images (18% to
25% for sheetfed presses and 25% to 35% for web presses, depending
on paper used), incorrect CMYK separation parameters for maximum
black and total ink level settings, attaching an incorrect CIE/ColorSync
output profile to the image or doing type effects in older versions
of Photoshop (they will come out looking rough at all but the
largest sizes, because pixel-based graphic files are only about
one-tenth the resolution of real imageset type).
This is a big topic in itself, and unfortunately
it's difficult to determine the Photoshop settings a client
might have used in any given file. The best thing I can suggest
is that if a client wants to prepare his own images he should
make sure he understands your exact image requirements and gets
some professional prepress Photoshop training. Most Photoshop
courses are taught by people who know how to create cute buttons
or drop shadows but have little solid knowledge or experience
in professional prepress. Find someone who does - she'll be
expensive, but a day of her training can save a client or a
printshop a lot of time, money and trouble.
Missing graphic files
Many page layout and illustration programs allow
clients to place or import graphic files - typically EPS or
TIFF - into them, and these placed files should always be included
with the main file when sent to the print shop or output bureau.
The client should be careful to include the right version of
the file used in the layout and not change the names of placed
files. Which brings us to a related problem.
Nested graphic files
If you place an EPS illustration file done in Illustrator
or FreeHand or a pixel-based photo from Photoshop into a page
layout program, the final file you create maintains a link to
all the placed graphic files. It's also possible to place EPS
or TIFF files into Illustrator or FreeHand now, and if you then
save these files and place them into another illustration or
page layout file, you're 'nesting' all these levels of placed
graphics files. That should work in practice, but often causes
problems, especially with older RIPs. The links get dropped,
fonts get substituted or profiles get confused, and so on. Wherever
possible, tell clients to avoid nesting. If they want to put
an EPS logo into a new illustration file, open the logo and
use cut and paste to put it into the new file, rather than using
the place or import command. Also keep file names short and
organize all placed files in one folder or directory.
Incorrect line screen
Photoshop, Acrobat Distiller and most illustration
programs allow the user to specify an output line screen in
the EPS, DCS or PDF files they create, complete with dot shape,
frequency and screen angles. Unless they know your requirements
and understand how line screens work, this can be a big problem.
It's usually best for the client to leave these settings blank
and let you set them just before you output the file.
Setting parameters
You'd think that few would get this wrong, but I
see it all the time - people using the wrong page size, orientation,
border, trim or bleed when they send a file out. Often, this
is because they proofed the file on a small inkjet or laser
printer and forgot to change the settings. This can result in
a lot of wasted film or strange page breaks. Just make sure
your staff always checks for this one. It's very easy to fix,
but you have to catch it first.
Trapping violations
Unless your shop uses automatic trapping software
or a recent PostScript RIP that creates its own traps, you will
periodically run into this problem with client files, primarily
with spot or process colour illustration elements (pixel-based
files rarely require trapping). Page layout programs like QuarkXPress
and InDesign can be set to automatically create basic trapping,
but this does not apply to graphic files imported into them,
and the default auto-trap settings are not usually enough. Illustration
programs like FreeHand and Illustrator allow users to manually
or semi-automatically create traps, but they must know which
elements need trapping and how to do it. The best thing for
the print shop is to communicate the recommended trapping for
its various presses to clients and encourage them to get a little
training in this topic.
48-colour jobs
This can be a real problem. Unless a client knows
exactly what he's doing, it's quite possible to get into big
trouble when defining spot or process colours. For example,
they may unknowingly create custom spot colours instead of the
process colour mixes they intended, winding up with a 48-colour
job that would be rather expensive and time-consuming for you
to output. Or they may choose spot colours or process mixes
based on how they look on an uncalibrated monitor, only to be
disappointed or angry when you print exactly what they specified.
You should recommend that all clients use printed spot and process
colour guidebooks so they know what they're likely to get. Many
print shops - especially those with web and flexo presses, screen
printing or other high-dot-gain systems - also hand out printed
samples of popular mixes and spot colours created on their presses
to give customers some good process mixes or spot-colour choices.
Naturally, you'll also want your own employees to watch for
those 48-colour jobs.
Complex clipping paths
As RIPs get more memory and power each year, I see
this less and less, but it still comes up from time to time.
When creating illustration files in FreeHand, Illustrator or
any other PostScript-based drawing program, it's possible to
create very long and complex individual lines and paths that
can cause fatal limitcheck errors, especially on older RIPs.
This is particularly easy to do if they use the auto-trace tools
on complex placed images or a tracing program like Adobe StreamLine.
Most of the better drawing programs have a preference setting
that can automatically divide overly complex paths into manageable
segments, but the client needs to know how to use this feature.
Remember that a file that prints without problem on a 600 dpi
laser printer can often choke a 2,400 dpi imagesetter. A related
problem can occur in Photoshop files saved as EPS or DCS with
a clipping path to hide the background of the image - complex
or multiple clipping paths in a file like this can also create
RIP errors.
Valiant attempts
Some clients try to create imposed multi-page printer's
spreads for you, ready for output. While this is a noble sentiment,
it can be an absolute disaster in practice. Unless a client
knows your exact plate requirements (trim size, bleed, punch,
creep, orientation, work and turn, and so on) you can waste
a lot of film, plates and time, especially for impositions larger
than 4-up. Trust only your most highly knowledgeable customers
to do this correctly, and even then, check their work often.
Well, that's the top 10. Another problem is the
unfortunate tendency of some clients to use programs not well-suited
for professional prepress, including MS Word, WordPerfect, Lotus
Notes, older versions of CorelDraw, Ventura Publisher, Harvard
Graphics (they're still out there!) or PC PageMaker and various
accounting, database, graphing or spreadsheet programs. Images
or text from these sorts of programs should probably be placed
into a recent page layout program for use.
These days, clients have the power - and responsibility
- to handle the work that used to require many different well-trained
graphics and prepress professionals all by themselves on a typical
PC or Mac. That's a big responsibility for them, and when their
files land on your doorstep you need to protect yourself and
your clients from disappointment and/or cost/delivery problems.
The bottom line? Have a well-thought-out electronic file submission
guide done and distributed to your clients to help them. Finally,
encourage them to get proper training for their people.
above article written by Bob Atkinson
June
2007 Newsletter
