Color and Vision

Key Question:

How do we see color?

Color and Vision

When all the colors of the rainbow are combined, we do not see any particular color.

We see light without any color. We call this combination of all the colors of

light "white light".

Color and Vision We can think of

different colors of light like balls with different kinetic energies.

Blue light has a higher energy than green light, like the balls that make it into the top window.

Red light has the lowest energy, like the balls that can only make it to the lowest window.

Photoreceptors in the eye

Cones respond to three colors: red, green and blue.

Rods detect intensity of light: black, white, shades of gray.

How we see colors

Which chemical signal gets sent depends on how much energy the light has.

If the brain gets a signal from ONLY green cones, we see green.

How we see other colors The three color receptors

in the eye allow us to see millions of different colors.

The additive primary colors are red, green, and blue.

We don’t see everything white because the strength of the signal matters.

All the different shades of color we can see are made by changing the proportions of red, green, and blue.

How we see the color of thingsWhen we see an object,

the light that reaches our eyes can come from two different processes:

1. The light can be emitted directly from the object, like a light bulb or glow stick.

2. The light can come from somewhere else, and we see the objects by reflected light.

How we see the color of things Chemicals, known as

pigments, in the dyes and paints absorb some colors and allow the color you actually see to be reflected.

If you were to mix the colors of paint you will get black, pigments are different from light

Light V.S. Pigment

How does a color TV work? Televisions give off light. To make color with a TV, you can use red,

green, and blue (RGB) directly.

The screen is made of tiny red, green, and blue dots.

The dots are called pixels and each pixel gives off its own light.

TV sets can mix the three colors to get millions of different colors.