Wednesday, 12 July 2017

Paper to Pixel to Paper Again: Part 21

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A guide to creating the best looking line art in print in the new digital print world

Part 21
Cleaning Up Line-up From Print Sources

Greetings!

This is the twenty-first installment of Paper to Pixel to Paper Again, a series that explains (in an overly thorough manner) the how-to's of preparing line art (and later in the series, color art!) for print.


And as always, if you have any questions, please let me know in the comments!

***
In the last installment, we left off discussing techniques for cleaning pages restored from newsprint sources. Many of the techniques I ended with in the last installment are no different than how you'd clean a line art original or production negative, albeit with a lot more to do—but now we're going to discuss something unique to newsprint originals. 

When a visual has undergone multiple generations of any kind, there's bound to be some loss of quality, as the medium imparts some of its characteristics to If you're old enough to have made cassette mix tapes for friends or boy/girlfriends or whomever, you're familiar with the phenomenon. The tape hiss and corresponding rolled-off high end, and wow and flutter imparted by the cassette significantly changes the character of the sound. Dub a song onto multiple generations of consumer-grade cassette, and you're really in trouble.

Well, printing is no different, in that multiple-generation sources have picked up characteristics/flaws from their previous printings. In the case of restoring Cerebus pages, the newsprint and web presses used to print the monthly issues present these problems quite vividly, as a side by side comparison with original artwork will tell you. The chief noticeable characteristic is the dot gain of the printing—the tendency of ink to expand and spread as it hits the page—which we won't address now, as we'll be dealing with it in a future installment. The second characteristic is called slur. 

Here's a brief description of slur written by Gordon Pritchard--
One talks of slurring whenever the geometry of the halftone dot changes. The printed image then appears to be displaced. The round halftone dot assumes an oval form. Two kinds of slurring exist – on the one hand, in the direction of printing (circumferential slurring), and on the other hand, transverse to the direction of printing (lateral slurring). These effects lead to a reduction in quality, and reflect the processing conditions within the group comprising the plate, blanket, and printing cylinders, as well as on other material influences.


The above is taken from OffsetPrintingTechnology.com, a great resource for prepress and offset print troubleshooting.

The above visual example is pretty extreme, but gives you a good idea of what we're talking about here. For a variety of reasons, the impression the negative made on the paper varies from the intended image in ways that will add to each other should you make yet another copy of this copy, especially if the art in question involves this kind of mechanical tone.

There are, however, some things you can do to help things along and try to keep the tone from clogging up more in your copy of a copy.

For the purposes of this demonstration, we're going to work from a different page than before. Here's a print scan of the second page of Cerebus ever, as printed in the first-issue file copy used to restore the new (January 2017) release.



Please put aside any general observations you might have ("What, did Deni Loubert write in the corner of every single page of your copy?" "What pressman was running this, and why didn't they notice the smeared ink on the blanket, obscuring several words on every single copy of the run??"), and focus on the figure at the bottom, and whatever it is that's going on on his snout.

And here's what this looks like nice and up close, in my in-process version of the file. 



In addition to the horizontal stretching of the dots (slur) resulting from the speed of the paper feed, and various press issues, notice how large the dots are in the highlighted areas, and how some of the dots are even connected to each other. If these are left alone and the material printed from this file as-is, these areas will only become further degraded and clogged, possibly even leaving a dark black blotch in the very tight area.

Fortunately, once you've identified these issues using your eyes and your previously-printed copy, it's pretty easy to correct using the techniques we've already learned in previous installments. Those connected dots should have their connecting areas drawn out with a brush, and the larger, expanded dots can be replaced by tone patched from another area of the figure. (see the "tone fixing" installment from before.)

So let's take a look at how it appears after the cleanup.



Wait a second. That's not just cleaned up, everything is also magically shrunk uniformly?

Yeah. We'll get to that in the next installment or two.

(Fantasy parenthetical: it sure would be nice if you could, I dunno, click a button and make all of the junky tone disappear, leaving nothing but the line art remaining, ready to be re-toned... a nice fantasy, huh? Well, I've done some messing around with some freely-available Free Fourier Transformation tools--which include source code!--and it seems like, in the hands of someone with some real programming skill, it could be a reality. Are you a programmer interested in working on such a tool with me? Email me at cerebusarthunt at gmail dot com!)

Next week: The end in sight?

Sean Michael Robinson is a writer, artist, and musician. See more at LivingtheLine.com.

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