1. Colour Theory – Addition and Subtraction Theory
TOPIC 4.3
SNC2P

2. PART 1: Additive Colour Theory P.294-297

3. Lesson Goals Today we will learn that:
colours of light can be added together to form a variety of colours through two investigations.
Pigments can subtract colours from light.

4.
WHAT COLOURS DID YOU OBSERVE IN YESTERDAY’S ACTIVITY?
IF YOUR HAVE A CELL PHONE, PLEASE TAKE IT OUT NOW ... ITS TIME TO TEXT IN YOUR OBSERVATIONS!
TEXT YOUR RESPONSES TO

5. ACTIVITY 4.4 RESULTS (Textbook P.300)
OBSERVATIONS
FILTER COLOURS
ACTIVITY 4.4: TRICKING THE EYE
ACTIVITY: SUNLIGHT & PADDLE COLOURS
RED
RED 
GREEN
 GREEN
BLUE
 BLUE
RED + GREEN
 YELLOW
RED + BLUE
 MAGENTA (PURPLE)
GREEN + BLUE
 CYAN (TURQUOISE)
RED + BLUE + GREEN
 WHITE

6. Did you know ...
That the millions of colours on a computer monitor or TV screen are produced with ONLY ... 3
COLOURS!!

7. Recognizing Colours
Your eyes have only 3 types of cells that can recognize millions of colours.
When you observe a colour, it is because different combinations of these cells are stimulated.
A TV screen uses a system of only three colours to create the effect of many different colours, just like the cells in your eyes.

8. Primary Colours PRIMARY COLOURS:
Three colours that can be combined to create any other colour.
Can be additive or subtractive.
RED GREEN BLUE

9. Additive Primary Colours
ADDITIVE PRIMARY COLOURS ARE:
Red
Green
Blue
These three colours of light
are also known as
primary colours.

10. Additive Primary Colours
Creating different colours of light depend on the additive colour theory.
When all 3 primary colours
are combined, they make
white light.

11. Additive Secondary Colours
By combining only two of the primary colours, you will make a secondary colour.
These are:
Yellow
Cyan
Magenta

12. Complementary Colours
Colours that are directly across from each other are complementary colours.
Red & cyan
Green & magenta
Blue & yellow

13. Pigments can subtract colour from light
When an object absorbs a colour, it removes (or subtracts) it from the beam of light. The colours of most of the objects that you observe every day are the result of subtracting colours.
There are three subtractive primary colours: cyan, magenta, and yellow. A variety of combinations of these three colours can subtract light from white light to produce nearly any colour.
Magenta, cyan, and yellow films subtracting colours from white light. What do you see when these three overlap?

14. The colours produced by subtracting equal amounts of two of the three subtractive primary colours are called subtractive secondary colours.
The subtractive secondary colours are the same as the three additive primary colours (red, green, and blue).

15. When the three subtractive primary colours are added together and subtracted from white light, you get black. The “code” for black is K so as not to be confused with blue.

16. Subtractive Colour Theory of Light
If a colour is absorbed, it will not make it to your eye. You only see the reflected colours.
Paint and pigment manufacturers mix all three of the primary subtractive colours in varying degrees to make any range of colours reflect from a surface.

17. Primary pigments
Yellow
Magenta
Cyan
Black

18. Colour Wheel
The COLOUR WHEEL shows how all the colours are related.

19. Colour Wheel
Tertiary colours are formed by mixing the secondary colours. The resulting colours are yellow-green, orange, crimson, cobalt, and turquoise.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

20. Colour Wheel Relationships
The subtractive primary colours cyan, magenta, and yellow are the same as the additive secondary colours.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

21. Colour Wheel Relationships
The additive primary colours red, green, and blue are the same as the subtractive secondary colours.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

22. Colour Wheel Relationships
The colours that are directly across from each other on the colour wheel are complementary colours.
When you add complementary colours, the result is white.
When you subtract complementary colours, the result is black.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

23. Using Diagrams to Illustrate Subtractive Colours
Diagrams can be used to show how colours are subtracted from white light when it hits a film of a certain colour.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

24. ACTIVITY 4.6 (Textbook P.301) SUBTRACTING COLOUR WITH FILMS & WITH YOUR EYES
THREE parts to the activity.
Part A:
At stations.
Please record your observations on your handout.
Part B:
At your desk in groups of 2 or 3.
Pg. 301 “What To Do”. Do # 6 and 7.
Part C:
Answer the questions on the handout.
HAND-IN YOUR ACTIVITY HANDOUT AT THE END OF CLASS.
HOMEWORK: Handouts on Addition & Subtractive Colours

25. STATION 1 - YELLOW
Place the YELLOW film over the colour wheel found on page 299 of the textbook.
Beside each colour on your list (see handout), write the colour that it appears to be after the YELLOW film was placed over it.
Go to the next colour station
There are 4 colour stations to complete.

26. STATION 2 - RED
Place the RED film over the colour wheel found on page 299 of the textbook.
Beside each colour on your list (see handout), write the colour that it appears to be after the RED film was placed over it.
Go to the next colour station
There are 4 colour stations to complete.

27. STATION 3 - ORANGE
Place the ORANGE film over the colour wheel found on page 299 of the textbook.
Beside each colour on your list (see handout), write the colour that it appears to be after the ORANGE film was placed over it.
Go to the next colour station
There are 4 colour stations to complete.

28. STATION 4 - GREEN
Place the GREEN paddle over the colour wheel found on page 299 of the textbook.
Beside each colour on your list (see handout), write the colour that it appears to be after the GREEN paddle was placed over it.
Go to the next colour station
There are 4 colour stations to complete.