PDF proofs and your finished Print job
“Why doesn’t my print job exactly match the pdf proofs I viewed on my computer display?”
Great question! They actually cannot match as they aren’t ‘comprised’ of the same base colors, nor are they viewed on the same medium.
PDF proofs are viewed on computer displays which use the colors of Red, Green, and Blue to represent full color images. These images are very vibrant as the light of the display brightens everything... which is why they ‘pop’ to an extent that ink on paper cannot mimic! To make matters more challenging, pdf proofs will appear different (sometimes greatly) on each display you view them on, as each display is calibrated differently. Displays can even change the way they represent color as they age.
In contrast, the color printing process on paper uses 4 inks to reproduce full color images: Cyan, Magenta, Yellow, and Black (known as CMYK). Cyan is a bright, lighter colored blue, Magenta is a bright pink/red, Yellow is bright, and Black is just that. And naturally, when viewing ink on a paper printing project, the light source is shining down on it, and not behind it - which decreases vibrancy significantly.
The paper you choose for your project - uncoated, gloss coated, satin coated, etc. - can even further distance the color compatibility between the PDF proof and the finished piece. There are several factors causing that, but the simplest is the ability of different papers to absorb ink. The more ink absorbed into the paper, the ‘duller’ the color on the finished product.
And if you print out your pdf proof onto paper using a laser or inkjet printer, you will see yet more color variation. Each laser / inkjet printer will represent full color images via a different color profile (set by the manufacturer). And as stated above, the paper you print on will add even more variables into the mix.
So what do you do? If exacting color (dead-on flesh-tones for example) is critical to the success of your piece, the best way to ensure that is achieved is to see high-quality color proofs on paper. Then have your printer run the job to those proofs - or as close as possible. In most cases, you will be very happy with the result. If color isn’t critical, you can achieve a good result by using PDFs as your only method of proofing, and trust your printer to use their own in-house color proofs and calibration to ensure a good job.