CTP for Four-Color
Eric Roberts, director of graphic technologies for Lehigh Press, a book cover and jacket manufacturer in Pennsauken, N.J., the advantages of digital workflows include the following:
* reduced steps in workflow and number of personnel;
* potentially faster set-up time;
* no film, processing, chemicals, etc; and
* better registration and dot quality.
But challenges remain, namely:
* the higher prices of thermal plates and platesetters;
* a need for all-digital stripping;
* re-RIPing for changes; and
* obsolescence of previous film, proofs, etc.
While cost considerations generally take precedence in comparing digital and traditional platemaking, quality must be considered, as well. The clearest benefit of CTP in terms of production quality is the way the dot is created. Roberts explains that with CTP, the sidewalls of the dot are perpendicular to the substrate as with a cylinder. (Compare this to a conventional dot, closer in shape to a cone or anthill.) "Regardless of packing on press or other gain issues," he continues, "a thermal dot can better perpetuate a quality image on the press." For the printer, better dots mean better image quality.
How to maximize quality
Most publishers and printers agree that quality is not created at the platesetter, but earlier in the production process. For example, Robert Dainton, technical director of Citiplate, notes, "Much four-color work in books today is 133 line screen or below. This is well within the current technological capabilities of available and emerging ultraviolet platesetting equipment.
"The keys for book printers," he continues, "are getting: (a) maximum CTP speed; and (b) optimum CTP quality without paying an unnecessary premium for a CTP consumable."
Many printers emphasize the importance of accurate calibration between different components of the digital workflow. However, good calibration alone does not insure quality. Roberts cites the following example: "A calibrated proofer won't compensate for DuPont cyan toner that doesn't match what Kodak cyan toner represents."