Layout & Pre-press
Key question
Why does the same colour look different on screen compared to print?
Screens blend colours from light, while printing presses mix them from ink on paper. In between, colour profiles do the translation. Without a profile, the software just guesses, and the result is a matter of chance.
Learning objective: You can distinguish between RGB, CMYK, and spot colours, select the correct profile, and set up black properly.
Every colour needs its colour space.
3.1 / RGB, CMYK, spot colours
Three systems, three purposes.
RGB is for screens, CMYK is for four-colour printing. Special colours such as Pantone (spot colours) are pre-mixed before printing and match brand colours more accurately, but require an additional printing plate.
01
RGB
Light, for screens. Wide colour gamut, vibrant colours.
02
CMYK
Cyan, magenta, yellow, black, for printing.
03
Spot colour
Pre-mixed colour, e.g. Pantone, for exact brand colours.
Large format and inkjet often display colours more vividly than offset. Deep blacks can fill in, and gradients should be tested in advance.
RGB for light, CMYK for paper.
3.2 / Colour profiles
The profile describes paper and machine.
A colour profile describes how colours appear on a specific type of paper using a specific printing method. Coated paper requires a different profile to uncoated paper or newsprint.
The profile is defined in the document, not just upon export. Linked images are converted to the profile in Photoshop or Illustrator (Edit > Convert to Profile).
Profile in the document, not in the export.
3.3 / Black and Overprinting
Not all blacks are the same.
Black text should be set to 100% K only and set to overprint. Otherwise, even the slightest misregistration will cause coloured fringes. Rich black, such as C40 M30 Y30 K100, is intended only for large areas.
Overprinting means that one colour is printed directly over the underlying colour rather than knocking it out. Small coloured text should be knocked out, while large areas may be slightly trapped. Avoid critical combinations such as yellow on cyan.
Text in 100% K, areas in rich black.
Exercise
Transfer a colour safely
Task: Define the colour scheme for the programme.
STEP 1
Defines two primary colours in RGB, CMYK, and Pantone.
STEP 2
Select the profile using the colour profile finder.
STEP 3
Correctly sets up black for text and areas.
STEP 4
Prints a colour chart on the selected paper.
Evaluation: Which colour has changed the most, and why?