How to keep printed documents accurate color reproduction
Is there a way to widen the gamut of a CMYK print so that the darks stay dark and the lights stay light? I suspect it has something to do with color space being exported, but I don't know how to approach making changes to it. Also any other hints of workflow adjustments to help guarantee accurate colours?
I recently had some proofs done with the same Indesign generated PDF (with a few CMYK AI files and a number of photos) at two different printers on similar matte stock. I did everything I thought I should to make sure the colours are right... saving the AI and INDD files in CMYK and not doing any explicit conversion to the placed RGB photos until exporting to PDF.
One of the prints I found the colours were generally darker than what I was looking at on my screen and some of the darker areas lost some details. The other print had the opposite problem... the colours were a bit brighter, and lost some detail in the lighter tones. Generally I've noticed that things I get printed are generally a bit darker than I see on my screen at a few different places.
It really depends on what technology you rely on when printing a job.
Generally, numeric printing is a little to a lot darker than what you have on screen and there's no way to be sure your greens for example won't come out yellowish or your violets reddish. For numeric printing, I highly recommend to approve a sample of the job (press proof) before going and print it entirely.
In the case of offset printing, you can use the pantone bridge color chart to have a pretty good idea of the colors. Also adding 20% of cyan to your black will make it richer.
Also remember that anything under 10% transparency or color saturation nay not appear on print.
If you have a printer at home, I suggest you calibrate it just as you like and bring a sample to your professional printer. Let the professionals do their work and work their press may it be offset or numeric to get as close as possible to the sample you brought them.
Here is a rule. If you follow it, you will be loved by your print providers and you clients!
RULE: Always ask your printer (or magazine, poster or billboard publisher) for their PDF specifications before submitting artwork for print, and any other specs they might have for a particular type of job, and use their specs to the letter. A good prepress department will email you a .joboptions file that contains the exact specs for PDF output from InDesign, Photoshop or Illustrator.
RULE 2: If the work is color-critical, ask for a press proof (or a Matchprint or Sherpa proof) that will be your "contract proof" for the job. A contract proof is one that the printer says the job will match, and you have signed as acceptable. It's up to the printer to ensure that the job does match the contract proof.
RULE 3: For highly color-critical work, and for anything that's long run and/or expensive to produce, do a press check. That means going to the print shop when the job is run and inspecting the actual printed sheets coming off the press against your color proof. Large presses have hospitality rooms for customers' representatives waiting for their jobs to hit the press.