1. ROY G BIV
The natural light that we see coming from the sun is generally perceived as white light. But we have all seen colored light in the form of a rainbow appear seemingly out of nowhere where white light used to be. Who can tell me how rainbows are formed? Water molecules in the air act as prisms. The colors of the rainbow are ROY G BIV

2. Here’s a picture of what happens to light in a water molecule
Here’s a picture of what happens to light in a water molecule. The white light is refracted as it hits the back of the raindrop and then is refracted again as it leaves the raindrop. When the light is refracted, or split apart, we see the entire spectrum of visible light.

3. White light is actually a combination of all the colors of visible light, ROY G BIV, the colors of the rainbow. Of those 7 colors, there are three primary colors which combine to make every other color of light.

4. Additive Color Mixing
So when we combine these colors of light, we create new colors in a process called additive color mixing.

5. These are the primary colors of LIGHT.
When they are mixed together, the resulting color is WHITE.
The primary colors of light are red blue and green. When they combine, they create white light. Think of it this way. A prism takes white light apart so that we can see all the colors that make up white light. When we do the reverse, and we put all the colors back together, we get white light.

6. Color Wheel for Light White Red Magenta Blue Cyan Green Yellow
I’ve tried to boil this down to what you absolutely need to know to understand lighting. By understanding the qualities of light, the mechanics of different commonly used lighting equipment and the principals of how light and color are transmitted, you will have a really solid foundation in lighting design. By knowing these things, you could walk into a situation with designers and be really well prepared.

7. So different frequencies of color come together to make the colors that we see. All the colors are a result of the blending of the three colors red, blue and green. Secondary colors are the colors that we get when the primary colors are mixed. They are yellow, magenta, and cyan (Fun fact.. those are the three colors that your printer uses to make all the colors it prints. Check your ink cartridge when you get home!)
Secondary and primary colors combine to make tertiary colors and so on.
Our eyes and brains cannot perceive any color combination that is not adjacent on the color wheel. Think about it.. Can you imagine a reddish green? Our eyes and brains cannot process that.
Complimentary colors are located across from each other on the color wheel. Mixed together, they create white light.

8. SUBTRACTIVE COLOR MIXING
These are the primary colors of PIGMENT.
When they are mixed together, the resulting color is BLACK.
You may have heard in art class the at the primary colors are red, blue and yellow. When those primary colors combine, they make black. That is true for pigment, the primary colors of light are different.

9. A pigment is a material that changes the color of reflected light by absorbing select wavelengths of light. Many materials selectively absorb certain wavelengths of light. Materials that humans have chosen and developed for use as pigments usually have special properties that make them ideal for coloring other materials.

10. Before we go any farther, we need to understand that light is made up of waves. Just like radio waves and microwaves and x-ray waves travel through the atmosphere, light also travels through the atmosphere. The different colors travel at different frequencies. Red is low frequency light and blue is high frequency.

11. Subtractive Color Mixing
Red Filter
Subtractive Color Mixing
When we use gels on light, we are using a process called subtractive colors mixing. Instead of adding colors together to make a new color, we are taking colors away to create a new color. Gels act as filters which absorb certain frequencies of light.
Because Magenta is made up of red and blue, it absorbs the other colors in the spectrum and lets through the red and blue light.
The red filter blocks out all but red and the blue filter blocks out all but blue... but there is no blue light left.. it has already been filtered out.
It's hard to actually demonstrate this theory. You would need perfect lab conditions where no other light can bleed in.
What kind of gel do you think would burn out faster? (answer – a pure color gel)
Magenta Filter
(Blue+Red)
Cyan Filter
(Blue+Green)
= No Light!

12. When colored light hits a white surface, it reflects that color
When colored light hits a white surface, it reflects that color. When color hits a colored surface it modifies that color. A colored surface absorbs all other color and reflects its own color. An actor wearing a blue costume lit by white light absorbs the red and green wavelengths and reflects the blue
One reason that this concept is important for a lighting designer, is because the color that you reflect on an object can change the color of an object.
An object that we see as blue is really just the reflection of blue light!!!
Have you ever noticed how you can be wearing an all black outfit and then you go out in sunlight and suddenly you realize that you are wearing very different shades of black?
That's because most black has some form of red or blue in it. The color of light that you shine on the costumes can effect the way they look.

13. So a gel is actually a color filter. Here's a little back story on gels. In Shakespeare's day, light was filtered by shining white light through red wine. Later in history, different kinds of colored water and very thin silks were used to filter light for the theatre. Then the first gels came out and, yes, they were actually made of gelatin. They were still making them until 1975.
Gels are now made of a mixture of polyester and polycarbonate, which longer lasting materials.

14. So here's what you need to know...
The three primary colors of light are red, blue and green
When the three primary colors combine, they make white
Two primary colors combine to make a secondary color, and a secondary color combines with a primary color to make a tertiary colors.
Complimentary colors are colors that are located across from each other on the color wheel and, when combined, they make white light.
Light is made up of wavelengths.
Additive color mixing is the combination of different colors of light.
Subtractive color mixing occurs when certain colors of the spectrum of light are absorbed by a filter and others pass through a filter.