4.34.3

Mixing ColoursMixing Colours(p294-299)(p294-299)

Mixing ColoursMixing Colours(p294-299)(p294-299)

Primary Colours

• The 3 primary colours can be combined to generate any other colour:

• Red• Green• Blue

3 Colours• The millions of colours on a computer monitor

or TV screen are produced with only 3 colours. • Your eyes have 3 types of colour-receiving

cone cells that respond to colours of light.

Try this on page 295

How Do Your Eyes Work?

• Each of the 3 types of cells in your eyes that are sensitive to colour respond to certain wavelengths.

• Your brain combines the information to “see” the correct colour.

Light-sensitive cells in the retina

Mixing Colours

• Primary Colours - 3 colours that, when combined, can make any

other colour. - primary colours can be additive or subtractive

(they can be added together or taken apart).- See Figure 4.13 (p296) – ask your neighbour to

hold up your textbook

(4.3) Mixing Colours

• Additive Primary Colours - When the 3 additive primary colours are shone together, white light is produced where they overlap. - Where only 2 of the additive primary colours overlap, you see additive secondary colours.

Additive Primary Colours3 colours

Additive Primary Colours2 colours

Complementary Colours

• Complementary Colours - are a primary colour and the secondary colour created by mixing the other two primary colours.- are opposite each other in the colour chart to the right

Homework

• (4.3) Mixing Colours- WB p122-123

4.34.3

Mixing ColoursMixing Colours(p294-299)....more(p294-299)....more

Mixing ColoursMixing Colours(p294-299)....more(p294-299)....more

(4.3) Pigments

• There are 3 subtractive primary colours: cyan, magenta, and yellow.

• A variety of combinations of these 3 colours can subtract light from white light to produce nearly any colour.

• Pigments can subtract colours.

Pigments

• Printer ink consists of black, cyan, magenta, and yellow ink only. How can we print such a wide variety of colours?

Subtractive Primary Colours• The colours produced by subtracting equal

amounts of 2 of the 3 subtractive primary colours are called subtractive secondary colours.

•

Subtractive Primary Colours

• Black is produced by subtracting equal amounts of the 3 subtractive primary colours.

• The “code” for black is K so as not to be confused with blue.

colour wheel

- summarizes the relationships among additive and subtractive primary, secondary, and complementary colours.

More Colours

Diagrams illustrate how colours are subtracted from white light when it hits a material of a certain colour.

Diagrams

So, how do we actually “see” colour?

• Your eyes have three types of cone cells• One type detects red, one type detects blue

and one type detects green (due to the different wavelengths of the colours)

• Your brain combines the information to “see” the correct colour

• Colour blindness can be caused when one or more cone cells are not working properly

Can you see all of the numbers?

Homework

• (4.3) Pigments- WB p124-127- Text p299 LC #1-3

p 303 #2, 5, 8, 9Now try these!- Activity 4.6 (p301)- Activity 4.7 (p302)

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