Chroma Key Processes, Animation

Today in animation we have learned about the various chroma key processes that have been created over the past century or so, for film makers. Ever since the 1930's filmmakers have used various techniques to create visual illusions and other special effects. In order to help learn, we were given questions to answer in a blog post.

The Chroma Key Processes

1. Magician’s Medium: The magicians medium is basically film effects. The first filmmaker to use effects was in fact a magician, and spent his life studying illusion: Georges Méliès. He used glass to cover stuff up and was able to film over film and fill in holes made by the glass.
2. Williams Process: The problem with the glass, or "matte", was that it was static and could not move. This is when a "Traveling matte" became a thing. The process was patented by Frank Williams, hence the name. The process itself involves photographing subjects against a pure black background. The film then was copied to increasingly high contrast negatives until a black and white silhouette emerged. This silhouette was used as the matte-called a traveling matte because it was able to move around.
3. Dunning Process: An alternative to the Williams process came around in 1925 by C. Dodge Dunning. The process used colored lights, lighting a background screen blue and the subject in yellow using dyes and filters. The different light could be split apart to create moving mattes. It's only issue was that it only worked with black and white film. 
   
4. Yellow Screen: In the late 50's, another alternative to the blue screen emerged: the yellow screen. Using sodium vapor to light powerful lights on a white screen, and a specially coated prism, wavelengths and SCIENCE automagically created a black and white traveling matte. The remaining light from non-sodium-vapor lights was unaffected. This technique created the best traveling mattes of the time.
5. Color Matte Difference: This was a complicated process using multiple colors and a blue screen. It requires 12 film elements to get to the final product but was remarkable in that it solved the fine detail issue with blue screens. It was so successful that it was in use for 40 years.
6. Digital Process: The digital process is the birth of the green screen. Green was better overall because most peole didn't wear green, and green is cheaper/easier then blue. It worked especially well for outdoors, where the sky isn't green.