1. Colour Theory

3. Additive Colour Theory
White light is composed of all the colours of light
White colour can be created by combining the three PRIMARY colours (red, green, and blue) of light in equal parts

4. SECONDARY Colours are created by combining only two of the three primary colours of light in equal parts
Red light and blue light produces magenta
Red light and green light produces yellow
Blue light and green light produces cyan

5. The additive colour theory applies to SOURCES of light

6. Subtractive Colour Theory of Light
When light hits an object some wavelengths of light are reflected and others are absorbed, or subtracted
The colour that you see when you look at an object is the colour of the light that object reflects
A pigment is a chemical that absorbs some colours of light and reflects other colours of light

7. Black objects absorb all colours

8. White objects reflect all colours

9. Blue objects reflect blue and absorb all other colours

10. Subtractive Colour Theory
PRIMARY subtractive colours are cyan, magenta, and yellow
The opposite of the additive colour theory of light

11. Subtractive Colour Theory of Light
Secondary colours are red, green, and blue
The subtractive colour theory applies to pigment and dyes and the colours they absorb

12. How subtractive colours reflect light
We see the colour cyan because red light is absorbed and green and blue are reflected to produce cyan

13. How subtractive colours reflect light
We see the colour magenta because green light is absorbed and red and blue are reflected to produce magenta

14. How subtractive colours reflect light
We see the colour yellow because blue light is absorbed and green and red produce yellow

15. Red and Green light is reflected, therefore flower appears YELLOW
White Light (R+ G + B)
Yellow absorbs Blue (B)

16. Red light is reflected, therefore flower appears RED
Magenta Light (R+ B)
Yellow absorbs Blue (B)

17. Green light is reflected, therefore flower appears GREEN
Cyan Light (G + B)
Yellow absorbs Blue (B)

18. NO light is reflected, therefore flower appears BLACK
Cyan Light (G + B)
Red absorbs Green and Blue

19. Red light is reflected, therefore flower appears RED
Yellow Light (R + G)
Red absorbs Green and Blue

20. Green light is reflected, therefore flower appears GREEN
Yellow Light (R + G)
Green absorbs Red and Blue

21. Green light is reflected, therefore flower appears GREEN
Cyan Light (G + B)
Green absorbs Red and Blue

22. NO light is reflected, therefore flower appears BLACK
Yellow Light (R + G)
Blue absorbs Red and Green

23. Blue light is reflected, therefore flower appears BLUE
Magenta Light (R + B)
Blue absorbs Red and Green

24. Blue light is reflected, therefore flower appears BLUE
Cyan Light (G + B)
Blue absorbs Red and Green

25. Red and Green light is reflected, therefore T-shirt appears YELLOW
White Light (R+ G + B)
Yellow absorbs Blue (B)

26. Blue light is reflected, therefore T-shirt appears BLUE
Cyan Light (G + B)
Blue absorbs Red and Green

27. NO light is reflected, therefore T-shirt appears BLACK
Cyan Light (G + B)
Red absorbs Blue and Green

28. Additive Colour Theory
Subtractive Colour Theory

30. Primary and Secondary ADDITIVE Colour Theory in a nutshell
Primary and Secondary SUBTRACTIVE Colour Theory in a nutshell

31. Learning Checkpoint
Utilize pp. 386 to 388 to answer the following questions p. 388 # 1, 2, 3, 4, 5

32. Learning Checkpoint Answers
The wavelength or frequency determines the colour.
Red, orange, yellow, green, blue, and violet are six general categories of colour.
The visible spectrum is the part of the electromagnetic spectrum that the human eye can see – it goes from red through violet.

33. Learning Checkpoint Answers
Each of the visible colours of light can be approximated by an appropriate mixture of red, green, and blue light.
Each of the visible colours of pigments can be approximated by an appropriate mixture of magenta, cyan, and yellow pigments.