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Subtractive Colour Theory
Subtractive Colour Theory Additive Colour Theory - A Refresher - the primary additive colours are... - adding all three primary colours gives... - adding two primary additive colours gives a... - the secondary additive colours are... - adding a primary colour and its complementary secondary colour gives... We use Additive Colour Theory to create images on your TV: Subtractive Colour Theory Think about it...can Additive Colour Theory be used to explain these things? colour printers stage lighting silk screen printing SUBTRACTIVE COLOUR THEORY What is it? - using pigments or filters to produce a colour by removing colours from white light - pigments or filters absorb some of the wavelengths of light - the remaining wavelengths reach our eyes, which creates the colour that we see Subtractive Colour Theory How does it compare to Additive Colour Theory? Subtractive Theory Additive Theory Colours are removed from white light to make different colours or black (no light) Colours are added together to make different colours or white light How does it work? when the colour is being produced by the light source itself When do we need it? when the colour is being observed after light is reflected or transmitted by the object Examples Computer printouts, stop lights, silk screen tshirt TV, PSP, iPod Red, Green, Blue Cyan, Magenta, Yellow Primary Colours Secondary Colours Cyan, Magenta, Yellow Red, Green, Blue The Primary Subtractive Colours: Cyan: - reflects/transmits _______ and ________ - absorbs _________ Magenta: - reflects/transmits _______ and ________ Think about it... - absorbs _________ Yellow: - reflects/transmits _______ and ________ - absorbs _________ Why do we use these instead of RBG to subtract colours from white light? Subtractive Colour Theory How does it work for coloured lights? Light Source (white light) Cyan Filter Transmits: B&G Absorbs: R Primary Subtractive Colours Cyan Filter Transmits: B&G Absorbs: R Yellow Filter Transmits: G/R Absorbs: B Secondary Subtractive Colours Magenta Filter Transmits: R/B Absorbs: G Red Filter Transmits: R Absorbs: B/G Green Filter Transmits: G Absorbs: R/B Blue Filter Transmits: B Absorbs: R/G How does it work for coloured lights? Light Source (white light) Magenta Filter Transmits: R/B Absorbs: G Yellow Filter Transmits: G/R Absorbs: B Primary Subtractive Colours Cyan Filter Transmits: B&G Absorbs: R Yellow Filter Transmits: G/R Absorbs: B Magenta Filter Transmits: R/B Absorbs: G Secondary Subtractive Colours Red Filter Transmits: R Absorbs: B/G Green Filter Transmits: G Absorbs: R/B Blue Filter Transmits: B Absorbs: R/G Subtractive Colour Theory How does it work for coloured lights? Light Source (white light) Magenta Filter Cyan Filter Transmits: R/B Transmits: B&G Absorbs: G Absorbs: R Primary Subtractive Colours Cyan Filter Transmits: B&G Absorbs: R Yellow Filter Transmits: G/R Absorbs: B Magenta Filter Transmits: R/B Absorbs: G Yellow Filter Transmits: G/R Absorbs: B Secondary Subtractive Colours Red Filter Transmits: R Absorbs: B/G Green Filter Transmits: G Absorbs: R/B Blue Filter Transmits: B Absorbs: R/G How does it work for coloured lights? Light Source (white light) Cyan Filter Transmits: B&G Absorbs: R Primary Subtractive Colours Cyan Filter Transmits: B&G Absorbs: R Yellow Filter Transmits: G/R Absorbs: B Magenta Filter Transmits: R/B Absorbs: G Red Filter Transmits: R Absorbs: B/G Secondary Subtractive Colours Red Filter Transmits: R Absorbs: B/G Green Filter Transmits: G Absorbs: R/B Blue Filter Transmits: B Absorbs: R/G Subtractive Colour Theory How does CMY printing work? Primary Subtractive Colours Cyan Ink Reflects: B&G Absorbs: R Light Source (white light) Yellow Ink Reflects: G/R Absorbs: B Magenta Ink Reflects: R/B Absorbs: G Cyan Ink Reflects: B&G Absorbs: R Reflected Light Magenta Ink Reflects: R/B Absorbs: G How does CMY printing work? Primary Subtractive Colours Cyan Ink Reflects: B&G Absorbs: R Light Source (white light) Yellow Ink Reflects: G/R Absorbs: B Magenta Ink Reflects: R/B Absorbs: G Reflected Light Cyan Ink Reflects: B&G Absorbs: R Magenta Ink Reflects: R/B Absorbs: G Yellow Ink Reflects: G/R Absorbs: B Subtractive Colour Theory How does CMY printing work? Light Source (white light) Primary Subtractive Colours Cyan Ink Reflects: B&G Absorbs: R Yellow Ink Reflects: G/R Absorbs: B Magenta Ink Reflects: R/B Absorbs: G Reflected Light A few examples... Black is often added during printing because CMY together produces a grey colour, but not a pure black
