1. Additive Primary Colors and Subtractive Primary Colors
Parkland Junior High School

2. Color and Vision
When all the colors of the rainbow are combined, we do not see any particular color. All we see is light without any color.
We call this combination of all the colors of light "white light”.

3. How we see color
The retina of the human eye contains two types of cells that respond to light.
Cells called Rods detect the presence of light.
Cells called Cones detect color.
There are 3 types of cones, each type of cone responds to a different color.

4. How we see color.
The cones in the human eye respond mainly to red, green, and blue light. This is why the eye can be tricked into thinking that a beam of light is white when it contains only those three colors. This is also why all other colors are seen by the eye in terms of the relative amounts of red, green, and blue light sensed by the cones.
Signals form all 3 types of cone cells and rod cells travel along the optic nerve to the brain. The brain interrupts the shape and color of an object you see.

5. Color Blind?
If a person has defective cone cells. They have difficulty detecting some colors. This is know as colour blindness.

6. Color blind impressions

7. Additive Colors
We see with our eyes the colors created by the natural light in the world. These colors are known as additive colors. The term "additive" refers to the mixing of light.
First described by James Clark Maxwell in the mid 1800s, the Color Additive Theory describes how we perceive color and how they are created.

8. Additive Primary Colors
Essentially white light is a combination of many different colors, a continuum of wavelengths organized into “bands” which we label with names (blue, green, red, etc.)
When equal amounts of red light, green light, and blue light are mixed together they produce white light. Because you add the colors together to get white the colors that are added are known as the Additive Primary Colors.

9. Additive Primary Colors
Red, green, and blue (RGB) are known as the additive primary colors of white light.
The light of two additive primary colors will produce a secondary color.
The secondary colors are yellow, cyan, and magenta. These are the “additive” combinations.

10. The use of additive primary colors in everyday life, e. g
The use of additive primary colors in everyday life, e.g. computer monitors, televisions, and human vision.

11. Subtractive Primary Colors
So, if one of the additive primaries are removed, the color of the light changes. For example, if the red light were removed, equal amounts of blue and green light would make cyan light. Equal amounts of green and red light would make yellow light, and equal amounts of red and blue light will make magenta light.

12. Subtractive Primary Colors
Yellow, cyan, and magenta (CMY) are called subtractive primary colors because some portion of white light has been removed in order to produce each color.
When all 3 subtractive primary colors are combined they produce black

13. The use of subtractive primary colors in everyday life, e. g
The use of subtractive primary colors in everyday life, e.g. color printers and printer color ink

14. Answer the following...
The three initial colours used are called the primary additive colours. What are they?
What secondary colours were created when only two of the primary colours were blended?
What colour was created when all three primary colours were combined?
What colour was created when all three secondary colours were combined?

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Answers...
(blue, red, and green)
(magenta, cyan, yellow)
(white)
(black)
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