22.3 Using Colorpp. 487 - 491

Mr. Richter

Agenda

Warm-Up Review HW Notes:

How We See Objects Mixing Pigments (The Subtractive Color Process)

Objectives: We Will Be Able To… Describe how humans see specific colors. Explain the subtractive color process. Determine what color of light will be reflected if a

colored light is shined on a certain object.

Warm-Up:

Leaves are green. What makes them green? That is, why do we perceive them to be green?

Discuss at your table and we will discuss as a class in a few minutes.

How We See Objects

How We See Objects

An object will appear to be the color of the light that it reflects.

Green leaves appear green because they absorb all wavelengths of light except green, which they reflect.

If a red light shines on a green leaf, what color will the leaf appear to be? Black!

How We See Objects

Green objects only reflect green light.

When white light shines on green objects (white light contains green), green light is reflected

When red light shines on green objects (red light contains no green), the light is absorbed, and the object appears black.

What color does the leaf appear if green light shines on it? Green, of course!

Mixing PigmentsThe Subtractive Color Process

Mixing Pigments

To make objects a certain color, pigments (little specks of colored material) are mixed together.

For an object to reflect a certain color, all other colors of light must be absorbed.

This is called the subtractive color process.

Mixing Pigments

The subtractive color process is also called the CMYK process: Cyan Magenta Yellow blacK

These colors are the subtractive primary colors.

Mixing Pigments

How do you make green paint?

Mix cyan (which absorbs red)

With yellow (which absorbs blue)

If red and blue are absorbed, only green is reflected!

Mixing Pigments

If pure yellow light shines on a magenta t-shirt, what color will the t-shirt appear to an observer?

Yellow light = green + red light Magenta = reflects red + blue Yellow shining on magenta reflects only red light

Expert

http://www.youtube.com/watch?v=gtgBHsSzCPE

Wrap-Up: Did we meet our objectives?

Describe how humans see specific colors. Explain the subtractive color process. Determine what color of light will be reflected if a

colored light is shined on a colored object.

Homework

p. 495 #8-11