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RGB versus CMY colour model

Short answer

RGB is additive, used in displays, combining red, green, blue light; CMY is subtractive, used in printing, combining cyan, magenta, yellow inks. They are complements: C=1-R, M=1-G, Y=1-B.

Differentiate between the RGB colour model and the CMY colour model, with example.

RGB is an additive colour model that makes colours by adding red, green and blue light. CMY is a subtractive model that makes colours by removing (absorbing) parts of white light using cyan, magenta and yellow inks.

PointRGBCMY
Full formRed, Green, BlueCyan, Magenta, Yellow
TypeAdditiveSubtractive
Based onLight emitted by a sourceLight reflected from a surface after absorption
Starting pointBlack (no light)White (paper)
All components at maximumWhiteBlack (in theory; real inks give dark brown)
All components zeroBlackWhite
Primary coloursR, G, BC, M, Y
Secondary coloursCyan, magenta, yellowRed, green, blue
Used inMonitors, TV, scanners, cameras, mobile screensPrinters, painting, photographic printing
Device typeInput and display devicesOutput/hard-copy devices

Relation between them

The two models are complements. With values normalised from 0 to 1:

C = 1 - R, M = 1 - G, Y = 1 - B

Example

  • Pure red in RGB is (255, 0, 0), or (1, 0, 0) normalised. In CMY this is C = 1 - 1 = 0, M = 1 - 0 = 1, Y = 1 - 0 = 1, i.e. (0, 1, 1), or (0, 255, 255) on a 0-255 scale: magenta ink plus yellow ink absorb green and blue, leaving red.
  • Yellow is (255, 255, 0) in RGB and (0, 0, 255) in CMY.
  • White is (255, 255, 255) in RGB and (0, 0, 0) in CMY.
 RGB (add light)          CMY (subtract light)
  R + G = Yellow           C + M = Blue
  G + B = Cyan             M + Y = Red
  R + B = Magenta          C + Y = Green
  R + G + B = White        C + M + Y = Black

✓ Answer checked by Claude Opus 5.5 (high effort)

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