- Introduction Overview
- Take the Picture
- Remove Background
- Refine the Mask
- Replace Background
Green screen photography, or chroma key as it's called in the broadcast industry, has been around for a long time. The technique was originally developed by feature film producers in the 1930s, but you're probably most familiar with it from nightly news and weather reports. Green is the most commonly used background color, but blue is also used in some situations. The most important criteria is that the background color doesn't appear anywhere else in the image.
The use of green screen replacement is fairly new in still photography. In the past, the most common photo studio background replacement technique was front projection, where a 35mm slide was projected through a splitter exactly aligned in front of the camera. You could produce pretty believable results, but the technique required an expensive reflective backdrop, a dark camera room, and very careful control of the lighting. Lighting was also restricted to hard, directional light sources with grids to prevent any light from spilling onto the backdrop. Soft window light and softboxes were out of the question.
Now, with digital capture and readily available digital darkroom tools, green screen replacement is within the range of every photographer. Mastering the tools opens up new possibilities for special effects, and also provides a very cost effective way to expand the variety of backgrounds you can offer to clients. As an added benefit, you can freely change the color of the background to fine tune the background to best complement the subject.
With still photography, the biggest challenge is to cleanly cut out the subject. (A digital photo is typically much higher resolution than video or HDTV, which has about the same resolution as a 4 X 6 inch print.) The process normally involves three steps; first you need to remove the green background by creating a mask around the subject, then you normally need to fine tune the mask, and lastly you will drop in a new background. Most of the steps are similar whether the starting point is a green screen, blue screen, or any other background.
All of the steps can be done effectively in Adobe Photoshop, which is the focus of this tutorial. There are also a number of dedicated programs that specialize in green screen removal. such as Green Screen Wizard and Primatte. You can also buy kits that bundle a green backdrop with software, such as the Westcott Digital Green Screen Kit.
Next: Taking the Picture