The case against computer-to-plate

Folio: The Magazine for Magazine Management, August 1, 1995 by Dan Segal

No one questions the lure of direct computer-to-plate technology. In its ideal state, everything that should be on an eight-page printing form would exist in a digital state, easily gathered, and then be passed through to the platemaker, Color separations, tints, advertisements and type would be imaged directing to the printing plate as imposed pages. The workflow would be direct, fast, simple - or so it seems on cursory inspection.

Computer-to-plate (CTP) is coming. However, for many publishers, there are still major obstacles between this technology and its use. There are risks as well.

To begin with, most ads are still supplied to publishers as negatives and are proofed using conventional means. We know how well the proofing materials predict the final product; if the agency claims we haven't printed what they asked for, there is demonstrable, hard evidence at hand.

With digital media, we would have no such evidence. There are a variety of problems here, both technical and otherwise. Let's take them one at a time.

* The problem of standards: There are still no standards for ads supplied as digital media, and setting standards means resolving political as well as technical issues. Until then, there is no sure way of knowing how the file will transfer to the printed image. Even if the supplied file is fine, there's enough variation between imagesetters and screening algorithms to create significant differences. But it is still the publisher's responsibility to match the supplied proof - wherever and however it originated.

* The problem of editing: One of the greatest strengths of digital media is also one of its hazards. Digital files are high-one editable. If the ad does not print light, some advertisers will claim that the file was altered. Others will claim that the publisher should have known there was a problem and corrected it before printing. But who pays for the proop? Who pays for the edit? Who makes the determination, and when?

* The problem of scanners: Advertisers supplying ads as film have higher expectations for fidelity in the printed product than advertisers supplying digital media. Good scanners exist for digitizing the supplied negatives. But they must interpret the negatives' dot patterns into non-halftone pixels that will be reinterpreted into halftone dots at the platesetter. The angles, shapes and frequencies of those dots will not match those in the film. The ad may reproduce the same - or it may not.

And these scanners are neither inexpensive nor fast. Prices run in the $75,000 range. Processing time can run from 15 minutes to an hour per ad. The costs and the turnaround times don't come close to comparing with a four-color strip for the same ad.

So where are the savings?

For the sake of argument, let's assume that editorial, which is all digital, will be the only segment of the book to go direct to plate. What do you save?

You save film. That seems to be about it. Proofs still need to be made before imaging the plates, and the cost and time needed for digital proofs is higher and longer. The files still need to be RIPped and the plates still need to be imaged. The savings in film is significant, however. Figure $24 to $48 per page, $1,200 to $2,400 for 50 pages of editorial.

But that may not really save any money - not until the cost of the equipment comes down. Imagesetters that handle large plates cost around $700,000. Time on such equipment costs much more than time on a $100,000 film imagesetter. And digital plates have lifespans of about 100,000 impressions. If significantly more books need to be printed, additional plates are required - along with the cost of a new makeready.

Digital proofs also show less. Virtually all color analog proofs show halftone dot structure and, therefore, trap, undercolor, overprinting, moire and more. And printers know how closely familiar high-end proofs will match the printed sheet.

With the exception of one, all the digital proofs now on the market are contone proofs. They show no dot structure, and aren't accurate for color. Running direct to plate with such proofs means printing blind in all aspects except vague color indication and element placement. If there is a problem, add the cost of the press downtime and a new makeready. Maybe $1,500 to $2,500 to correct, replate and get running again. (The one digital proofer that shows dot structure uses a resolution and screening patterns that are different from those used by most film imagesetters or any platesetters. But the structure it shows doesn't match what ends up on the plate.)

Of course, the plates would be inspected thoroughly before they are mounted. But think about this: Next to the inspection station of any prepress facility is a barrel filled with rejected film. Small, silly problems can make film unusable: The wrong printer font might cause a headline to bitmap, or a file may come in using spot instead of process color. Plates cost five times what film does. A barrel filled with rejected plates represents a huge investment. With plates, eight pages are imaged at a time: One page rejected is eight pages rejected. Has it offset the cost of the film yet?