CMYK - Subtractive Colour Model

• Colours on physical surfaces use subtractive colour mixing
• The more colour you add, the less light comes off the paper

Traditionally, the colours were red, yellow and blue but as printing evolved this became Cyan, Magenta, Yellow and Key (black) as it produced a wider range of colour on paper

Best model for colour on physical sources (e.g. paper)

• Can think of each CMYK Colour as subtracting the amount of RGB light reflected, e.g.
  • Cyan absorbs red and reflects green and blue
  • Yellow absorbs blue and reflects red and green
  • Magenta absorbs green and reflects red and blue

Black is necessary because CMY don’t alone quite create a pure non-reflective black

Colour Difference in Painting

Although CMY is the adopted colour format for printing, painting still uses RYB