Chromakey Basics

What Is Chromakey?

Chromakey is a technique which merges two or more images together by creating transparency from a selected color. It typically works by first taking a photo of an object or person against a green or blue backdrop, then using software to create transparency from the selected color. Then, another image is inserted in the background. When you watch the local news, the weatherman isn't really standing in front of a map. He's standing in front of a green screen! The map is "keyed in" to replace the green areas of the screen, creating a virtual environment. This technique is used by Hollywood effects studios and professional photographers to place people in virtual environments quickly and easily. Chromakey is also used for novelty photos at amusement parks, fairs and events. Caricature Studio Green 4.0 includes built-in chromakey functionality for static images and a variety of novelty backgrounds to create fun "head-on-body" caricatures. Imagine all of the creative things you can do!

How Chromakey Works:

1. Typically, a person or object is photographed against a green backdrop. Actually, in Caricature Studio Green 4.0 you can key out any solid color. Green is the choice of professionals because it is the furthest away from natural skin tones. Blue is also a popular choice. Just remember that the key to success is choosing a background color that is not the same color as clothes or skin. Black and white, for instance, would not be good choices! Anything within a small range of the color will be replaced by the background image, so it is extremely important to use an appropriately colored background.

2. The green area is keyed out and replaced with a background image. In the example below, chromakey is used to create a novelty photo.

You can select virtually any image to use as your background! Put yourself on the moon, or surfing a wave with a few of our included templates!

Where Can I Find A Green Backdrop For Photos?

You can visit your local fabric store! With a few yards of cloth you can create a sufficient, inexpensive backdrop. Brighter green is better. Avoid fabric that has any kind of reflective properties because it will be harder to get good, consistent lighting. Also avoid cloth that wrinkles easily. Wrinkles create shadows, and shadows to a camera lens are essentially a different color, or a darker shade of color, which will be harder to key out. Always roll your backdrop loosely when storing. Never fold! Creases, like wrinkles, create shadows. You can also iron the cloth for a nice, flat surface. If you want to key full body images (example: our surfer background), use a screen large enough to fold onto the floor at least a few feet. A popular size is 10 x 12 feet. Hang on a flat wall, or use a backdrop stand. You can actually create a stand fairly easily using plastic PVC pipe available at your local hardware store!

Want the best results? Professional green screen backdrops are readily available and fairly inexpensive. They are usually made of muslin cloth or similar, which is well-suited to get great results with the proper use and care. Do a web search for green screen.

How Do I Take Green Screen Photos?

Frame your subject or object so that it is fully framed within the green screen area. Remember that anything outside of the screen color will not be keyed out, so you'll want to fully surround the person or object with the screen.

Any digital camera can produce sufficient results. Good pictures will depend more on preparation and lighting than what kind of camera you use. Choose a resolution suitable for high quality photos.

The Most Important Factor: Lighting!

Consistent lighting is the single most important aspect of getting good results with chromakey. The screen must be well lit to create a consistent shade of color. A bright room yields the best results. Experiment with placing a light source on each side of the screen, far enough away that it does not create a spotlight area on the backdrop. Avoid too much light. If the light source is too bright it will wash out areas of the backdrop. Your camera will interpret this as white space, and it will not be keyed out properly. Ambient lighting is not ideal because it creates lots of shadows. Your subject should stand at least 5 feet from the screen if possible, so that the light hits the screen entirely. If your subject is too close, a shadow will result. It may take a little trial and error, but anyone can get good results.

See the Help section Chromakey Function for instructions to use the tool within Caricature Studio.