I was recently at an interactive installation that had three theater lights – red green and blue shining on a white wall.
The kids were fascinated by this – especially with how the colors mixed and how they could make different colors by casting shadows on the wall.
This is a human scale representation of the red-green-blue (RGB) additive color model (the electronic screen you are looking at right now uses the exact same method to reproduce every color you’re looking at).
It also reminded me of some of the really cool applications to use photography gels to have fun with color.
The RGB Additive Color Model
Electronic screens produce colors by projecting various combinations of three additive primary colors, red, green, and blue.
The two other color models that you might be familiar with are CMYK subtractive color (Cyan, Magenta, Yellow, Key-Black) which is used for print and RYB subtractive color (Red, Yellow, Blue) which we are all familiar with from art class.
In the case of RGB additive color: Red+Green = Yellow, Green+Blue=Cyan, Blue+Red=Magenta, Red+Green+Blue=White
The reverse is also true – if you subtract colors by casting a shadow the color of the shadow is a result of the remaining colors.
In photography, we can gel our strobes to produce the exact same effect.
According to Lee Filters, the three gels to use for the RGB primary colors are: Red, Green, Blue (all special order from B&H). Alternatively, you might be able to find these (or similar) included with many of the hot-shoe strobist gel packs.
There some really fun ways to use RGB color theory in photography.
And here are two articles by photographer Glenn Norwood for using gels for creating mood and atmosphere with gelled lighting and using gelled lighting for color theory driven stories.
Give It A Try And Let Us Know How It Goes!
Have you experimented with different colors of projected light?
What is your favorite application of colored photography gels and additive color theory?
Are you interested in trying this?
Leave a comment below and let us know what you think!