The following case study may give you insight into options for proofing offset custom printing jobs, whether they be digests, books, catalogs, magazines, or any other signature work. For that matter, I think even smaller jobs like fold-over cards, brochures, and such, might benefit from this proofing workflow.
The Job Parameters
My client is producing a book of photos of flowers. Each left-hand page is a full-page image, and each right-hand page is a quote from a famous author. You could envision this as a meditation or contemplation book, intended to provoke thought and reflection by the reader. The format is 6” x 6”. The book is 190+ pages at this point, and it will be perfect bound.
My client had initially produced eight separate fold-over notecard designs, each with a photo on the front and a quotation on the back. The cards had a short press run (500 copies of each) and therefore were best suited to the printer’s HP Indigo digital press. This job, the perfect bound print book, will need to complement the photo cards, but will be printed via offset lithography. Why? Because it is a high-page-count book with a 1,000-copy press run, thus not a good candidate for economical digital printing.
The Goal: Critical Color
Unlike many other custom printing jobs, the goal of this job is not “pleasing color” but “critical color.” Pleasing color implies more tolerance for color shifts. Critical color implies none. Critical color work would include food, automotive, and fashion photography (and, in this case, custom printing for a professional flower photographer).
Furthermore, the client had color corrected on-screen the 90 photos comprising the print book. The monitor had been calibrated. The ambient room light had been controlled. But the images had not been physically printed prior to the job. In addition, since the images had been color corrected within the RGB color space (with a larger color gamut than CMYK) and then converted to CMYK for proofing and final offset custom printing, it was especially important for the client to see repeated series of proofs until she was happy. Anything less would risk having the final offset printed product both surprise and displease her.
The First Proofing Cycle
Under the circumstances, I suggested an initial series of Epson proofs of the photos only, plus the front matter and one quotation page. The text pages would give my client the overall “look” of the book, but for this first series of proofs, the goal was really to establish the correctness of the color in the flower photos. For a 190-page print book (half photos and half quotations), this meant just under 100 pages of photo proofs at $1.00 a page, well worth the money.
The Epson inkjet printer at this particular custom printing vendor had been “fingerprinted” to their offset press. (That is, it had been calibrated to provide the closest possible color match between the proofing device and the press. It was color calibrated regularly and therefore provided a benchmark standard that was considered a “contract proof.”
My client found errors in approximately half the images. Ostensibly this was due to color shifts in the conversion from RGB to CMYK for both inkjet output and final offset custom printing. RGB colors that have no exact match within the CMYK color space (since it is a smaller color space) shift to the next closest CMYK color during the conversion process. Also, the Epson proofs were my client’s first hard-copy proofs, and there really is a difference between color produced on-screen with light and color printed on paper with ink or dyes. So having half the images correct on the first try really was quite good.
The Next Proofing Cycle
I gave my client a choice for the next proofing cycle. She could have another set of Epson proofs or an Indigo proof. The Indigo proof might look better. The color would be close to that of the final offset printed output but not quite as close as the output from the Epson proofer. However, the printer could produce a trimmed sample book on the Indigo (unbound, but exactly accurate to size, on paper comparable to the final offset custom printing output).
Unfortunately, there might be some dot gain on the Indigo. The xerographic dots of the Indigo (amplitude modulated, similar to offset press halftone dot rosettes) would be larger than the minuscule inkjet spots (dithered frequency modulated spots) of the Epson printer. Because of the Epson’s smaller dots (entailing no dot gain and hence more accurate color) and because the Epson had been specifically fingerprinted to the final offset lithographic press, I encouraged my client to request another Epson proof of the updated photos. After all, what good would it have been to get a great looking proof that did not (contractually) match the expected custom printing output?
The client chose a hybrid solution. She requested 37 new Epson proofs of the photos for approximately an additional $37.00. She also requested an HP Indigo (laser) proof of the entire book as a “position proof” to show exact placement and cropping of all elements on all pages. She got the best of both worlds. She also asked that both proofs arrive together, so she could compare the two.
Requesting F&Gs as a Final Step
I suggested F&Gs as well. These are essentially a stack of press signatures (4-, 8-, 16-, or 32-page increments of the print book), stacked and set in a cover but unbound and untrimmed. At this point the commercial printer will have printed the entire job but not yet bound it.
Getting F&Gs is a good idea for color-critical signature work (such as magazines, books, catalogs, or digests), since an error is easier to correct. If my client finds an error in three pages within one signature, for instance, the custom printing supplier can merely reprint one signature. If my client waits and finds the problems after the book has been bound, this will necessitate tearing off the covers, reprinting all copies of the individual signature, rebinding the book with the replaced signature, and retrimming the book (yielding a smaller book in the process, which might look awkward).
So the commercial printer will print all copies of the cover and all copies of all signatures. He will send my client an F&G and then wait for her approval prior to binding the print book.
This entry was posted
on Tuesday, January 31st, 2012 at 4:28 pm and is filed under Prepress, Printing, Proofing.
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