This (Basic Color Theory) is a great little primer on color and offset printing published by the University of Arkansas. I encourage clients to download the PDF when they schedule a press check. It helps explain why we make adjustments on press the way we do.
To achieve our color goals we must remember that ink is a filter. Magenta filters out green, cyan filters out red, and yellow blue. So, if we want to make a picture look less red, we increase the cyan ink on press. The more cyan we print the more red it filters out.
Confused? Not to worry. That’s why we’re here. We do this stuff all day every day, and our press operators know the ropes.
If you’d like a more detailed explanation, call Nate direct (949) 862-7482.