ESSENTIAL
PREPRESS
do
photographers do it better?
The Creative Firm (Sydney) recently opened their digital studio to thirty or so ACMP Photographers. Owner/Photographer Leo Duyckers demonstrated a workflow familiar to many, composing and lighting an image using flash and conventional studio expertise. The major interest occurred when Leo digitally assessed his image using skills which are still largely regarded as 'prepress' skills. After Leo's demonstration, I doubt there was one person present who was not convinced that prepress knowledge is now a prerequisite for any photographer concerned with quality digital process.
Simply put, it is not possible to produce a quality digital image without being aware of its final reproductive requirements. In Leo's example, his image of a business phone was destined to be printed lithographically. Leo had set tip his system to capture the image with lithographic end points and gradation, and had the breadth of knowledge to make any additional adjustments post-capture.
As a mark of the confidence Leo has in his own studio, press-ready images are burnt to CD to prevent the originals being tampered with by prepress.
What interested me was how The Creative Firm had integrated prepress in to what was essentially a photographic workflow. For instance, Leo's approach to colour management draws from his experience as a photographic printer. So rather than pay someone to build a monitor profile, he prefers to visually calibrate his monitor himself, using only the Adobe Gamma control panel. Not extraordinary in itself, however proofs of work destined for print media are obtained from a Pictography 4000 machine. Pictographs are renowned for their high photographic finish - rather than their similarity with the lithographic press. Leo and Pati Tracy (from just Dupes etc) testify that Pictographs are a mirror- of the final work (probably has something to do with their Fiery RIP).
Graham Prichard
An image from The Creative Firm accompanies this article. It was taken on a Sinar Leaf DCB2 with Sinar lenses and Colorshop software. Colorshop is produced by Scitex, a name synonymous with high-end scanning equipment, It permits many of the prepress adjustments that scanner operators would be familiar with.
If you consider yourself to be more of a photographer than a prepress operator, the following introduction to digital prepress could be of assistance. Whether you use a camera or a scanner, the aim is to finish up with an image file which is as close as possible to the requirements of output/reproduction. The final test of any file is determined by the colour value of the dot.
DOT PERCENTAGE
Dots of ink
combine on paper to give the final representation of a photographic image.
We must prepare for the output of this dot from the very first stage of
scanning or capture. Dots can be assessed at different stages of press,
prepress and postpress. You will find that sampling pixel values is referred
to as 'looking at the dot', as is also the case in assessing film separations
and the final print.
In scanning or digital
photography, it is our job to ensure that range and colour controls are
set up to capture colour in a way which records a reproducible dot. Most
scanning software permits the measuring and adjustment of dot percentage
at preview stage. High-end camera software usually permits the. operator
to specify preferred colour levels prior to capture. Dot percentage requirements
will vary depending on printing process and stock. The most likely output
process for a commercial or magazine photographer's images would be lithographic
sheetfed on
coated stock.
On this type of stock (and with Eurostandard/Australian inks), a highlight area would typically measure Cyan 5%, Magenta 3%, Yellow 4% and no black. Note that this value reflects the first printable tone. Specular or catchlight areas would most likely be void of dot. A shadow (last printable) on the same stock would typically be Cyan 95%, Magenta 85%, Yellow 88%, Black 70%. See examples of end points in the Bonzi Cacti image.
These end point values are assigned to a scan/digital image at the first possible opportunity. This is the range function of your scanner or camera driver With any luck (and a good tranny or well-lit subject) the rest will fall into place. Of course this doesn't always happen. The skill of scanning and imaging is in being able to recognise when dot percentage values will or will not give you the desired quality of colour reproduction.
GREY BALANCE/GRADATION
Which brings us to grey balance. This is actually a compensatory measure
which accounts for imperfect inks. The previously provided endpoint values
will print as neutrals because that particular balance (or imbalance)
of ink will produce a neutral. An equal percentage of Australian inks
will not produce clean neutrals.
Your scanner/camera driver has presets which will calculate the gradation of colour values required from highlight to shadow. Tone gradation is best explained as the way a digital file interprets the latitude of an image; the transition from one printing tone to the next. Tone may need to be increased or decreased to suit particular printing conditions. Check the presets in your scanner/camera driver to see which printing conditions they are configured for.
DOT GAIN
Many photographers who have had their work reproduced on card or a similarly
absorbent stock will be aware of this phenomenon (see previous article
in ACMP News). Ink tends to spread and get sucked into the stockIncreasing
the ink (raising the dot percentage) increases the spreading. The result
is a dark, unsharp reproduction. Photornechanical variables are also to
blame.
To limit this problem, a printer will vary ink viscosity, pressure and application speed. Be sure to obtain information regarding dot values which are appropriate to the output stock. Dot gain also occurs on coated papers, and although less severe, must still be taken in to account.
COLOUR
Prepress demands
a knowledge of CMYK as well as RGB. Removing a cast digitally is similar
to colour balancing a photographic print It's a matter of knowing what
colours make up what, and whether the adjustment required is an addition
or a subtraction of colour. Prepress operators are faced with more variables
than RA4 operators - all the factors mentioned above, and more.
Many photographers have already mucked around with Photoshop and are delighted with the colours they can achieve on their monitor. The problem is that monitors give only a fair indication of the final output Assessing an image via its appearance on the monitor is fine as long as you operate within a closed loop. But most of us need to out- source our printing, so really there is no option other than to apply precise colour values as specified by the method of output Bring up the 'Info Box' (Shortcut F8) and get a feel for the numbers.
PHOTOGRAPHERS
DO IT BETTER?
Photographers have surely heard the rumours about printing houses employing
in-house digital photographers (it's true), and no doubt scanner operators
are trembling now that photographers are improving their scanning skills.
So who is going to lose their job? At the end of the day, the object is
to produce a spectacular, reproducible image. A scanner operator with
creative flair would make an excellent digital photographer. However,
the current trend is to train photographers in prepress. Perhaps the most
sensible image-making team would be a photographer and a digital prepress
person working in unison.
ACMP Photographers who toured R.T Kelly's last year will be aware of the changing relationship between printers and photographers. One of the concerns (raised by photographers) was their ability to provide digital files of a quality acceptable to printing houses. R.T Kelly's were only too keen to advise photographers on the requirements of flies they were aware of a shift in the industry and were more than willing to accommodate changes.
Thanks to Leo Duyckers and Pati Tracy (The Creative Firm, Just Dupes etc), Michael Webb and Anthony Dickinson (R.T Kelly's), Baltronics and, of course, the Digital Users Group.
Graharn Prichard
is a Sydney artist and consultant.
Email graham@gpi.com.au
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