Subtractive colour on screen

About subtractive colour on screen
  • Computers, TVs and phones use the additive RGB colour model to represent colour. It’s called additive because it works by adding different coloured lights together to create new colours.
  • Although all the displays on these devices use the RGB colour model, they can still be used to explore the effects of subtractive colour models such as CMY or RYB.
  • Subtractive colour models used in printing work by subtracting colours from white light to produce different hues.
  • In the CMY model, the primary colours are cyan, magenta, and yellow, while in the RYB model, the primary colours are red, yellow, and blue.
  • By using a computer, TV, or phone to explore subtractive colour models, it’s possible to visualize how colours are created by subtracting different wavelengths of light.
  • The ability to explore subtractive colour models using computers, TVs, and phones can be useful for designers, artists, and anyone working in the printing industry, as it allows for a better understanding of how colours are created and manipulated using different colour models and media.
  • Regardless of whether additive or subtractive colour is to be explored the easiest way to identify the relationship between colours is by using a colour picker.
  • A colour picker is a visual tool that allows the user to select a colour from a colour spectrum or a colour model such as RGB, HSL, or CMYK.
  • Some colour pickers include numeric input fields for entering exact colour values, or a colour palette that includes predefined colours.
  • Colour pickers may show colour relationships in the form of a grid, wheel or in-line with one another.
  • The alternative to colour pickers is to calculate the relationship between colour values mathematically but can be a time-consuming process.
Mixing CMY colours on screen
  • The primary colours in the CMY colour model are:
    • Cyan
    • Magenta
    • Yellow
  • A secondary colour is produced by mixing two primary colours of equal intensity:
    • Magenta + Yellow = Red
    • Yellow + Cyan = Green
    • Cyan + Magenta = blue
  • Mixing secondary colours produces darker versions of their common primary colour:
    • Green + Blue = dark cyan or teal
    • Blue + Red =  dark magenta or purple
    • Red + Green =  dark yellow or olive.
  • When a primary and its complementary secondary colour are mixed together, the resulting colour is the very dark version of the mixed primary colour:
    • Cyan + Red = a very dark cyan or dark teal
    • Magenta + Green = a very dark magenta or dark purple
    • Yellow + Blue = a very dark yellow or dark olive
    • The exact colour depends on the specific tints of shades of the colours being used and the proportions in which they are mixed.
  • When all the primary colours are mixed in equal intensities, the result is a dark grey or brown colour, but not true black.
  • True black is achieved by using black ink (K) in addition to the CMY colours, creating the CMYK colour model commonly used in printing.
Mixing RYB colours on screen
  • A secondary colour is produced by mixing two primary colours of equal intensity:
    • Red + Yellow = Orange
    • Yellow + Blue = Green
    • Blue + Red = Purple
  • Mixing secondary colours produces darker versions of their common primary colour:
    • Green + Purple = Dark Blue
    • Purple + Orange = Dark Red
    • Orange + Green = Dark Yellow
  • Each secondary colour is the complement of one primary colour:
    • Orange complements blue
    • Green complements red
    • Purple complements yellow
  • When a primary and its complementary secondary colour are mixed together, the resulting colour is the very dark version of the mixed primary colour:
    • Blue + Orange = Dark brown
    • Red + Green = Dark olive
    • Yellow + Purple = Brown
    • The exact colour depends on the specific tints of shades of the colours being used and the proportions in which they are mixed.
  • When all the primary colours are mixed in equal intensities, the result is a dark grey or brown colour, but not true black.
  • True black can be achieved by adding black paint or ink.