A client recently contacted me regarding a book printing job, a perfect-bound textbook for high school students. The 312-page book has black-only ink for the text, while the cover is 4-color plus one PMS ink. The online printing company manufacturing this book for my client has recently installed a new virtual proofing system called Rampage Remote.
I personally have used this technology before (and another vendor’s remote proofing technology called InSite). In both cases, the business printing service provides a virtual link on the computer to a proof of the preflighted, imposed, press-ready files from which the final plates will be burned. The actual product the designer or print buyer will see is a PDF of each individual page on his or her computer monitor.
Which to choose?
My client wanted advice on what to do: request a virtual proof or a hard-copy proof from the custom printing service.
First of all, I noted that the virtual proof would be produced from the actual, final files from which plates would be burned. This all but assured my client that no errors could creep into the process. Since the file used to produce an inkjet proof and the file used to produce a press-ready plate are usually slightly different, an error not visible on the proof occasionally will show up on press. By using a Rampage Remote proofing workflow, the online printing vendor would eliminate this chance.
I also noted that the price would be the same either way, for hard-proof or soft-proof, and the schedule would be the same as well. That said, it was possible that not needing to send the proof both ways by courier or UPS would save a little time.
I encouraged my client to ask the book printer for a hard-copy inkjet contract proof for the textbook cover and a Rampage Remote virtual proof for the text.
Why did I offer this advice?
Color on an LCD, CRT, or TFT display is composed of the additive primaries: red, green, and blue. In contrast, color on a digital inkjet proof is composed of the same subtractive primary colors used on an offset printing press: cyan, magenta, yellow, and black. Granted, algorithms have been devised to coordinate these two color spaces, but they do not always exactly match. Color presented on a monitor may be slightly different from the same color on an inkjet proof. In addition, even if the digital information driving the color monitor is accurate, an improperly calibrated monitor will display inaccurate color. I felt that since my client had the time for an inkjet proof of the 4-color cover, it would be prudent for her to request one.
The text of the book printing job was another matter. Since the book was to be all black ink inside, there would be no potential color shift to address, so there was no reason not to request a Rampage Remote proof. My client would get the soft proof a day earlier than a hard-copy proof (i.e., no courier), and she could print out a copy of the text on her laser printer to facilitate proof review prior to the book printing.
Avoiding moire patterns
One thing that bears repeating here, however, is that the color inkjet hard-copy proof of the cover would not show the actual halftone dot structure of the final press job produced by the book printer. For that matter, neither would the hard-copy laser proofs she could have received for the text. Both inkjet proofs and laser proofs have their own halftone screening algorithms. If you look at a laser print under a high-powered loupe, you will see a dot pattern (but it won’t be the same as a PostScript halftone pattern on a platesetter). If you look at an inkjet proof under a loupe, it will appear to be almost continuous tone (actually, it’s made up of “dithered” color, also known as FM screening–minuscule spots of ink distributed randomly rather than in a regular AM screening pattern). The halftone screening patterns visible in an enlarged view of your digital printing service’s Rampage Remote PDF might actually approximate the dot pattern of the final printed piece more accurately.
Why is this “technospeak” relevant to you? In some cases, if the halftone grids conflict with regular patterns in the images themselves (for instance, with a checkerboard pattern or a Scottish tartan), undesirable moire patterns may be visible in the business printing vendor’s final book printing run. The only way to catch this prior to printing is with a true PostScript halftone dot proof, such as the Kodak Approval, which is rare and expensive these days. If you think this may happen to your job, point out the potential patterns and screen conflicts to your custom printing supplier, and ask for his advice.
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on Monday, August 22nd, 2011 at 10:41 am and is filed under Prepress, Printing, Proofing, Soft Cover Book Printing.
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