The History of Green Screen Part 1
Green screen technology, as well as the amazing special CGI film-making effects we have today, had their precursors all the way back in the early 19th century.
French filmmaker, George Melies, in his classic 1898 film, “Four Heads Are Better Than One” invented an effect which foreshadowed modern green screen compositing.
He used a mixture of matte shots and multiple exposures to create amazing effects that dazzled the audiences of the time. The process was fascinating. He would place a black box over the lens. The front of the box was a glass plate partially painted black. He would expose the shot then rewind the film and replace the blackened glass with another glass plate with the black paint in different places. Then, he would expose the film a second time.
Sometimes, for more elaborate effects, Melies would repeat this process of partially blackened glass and rewinding and re-exposing the film over and over again to spectacular effect.
“The Great Train Robbery” in 1903 was one of the early film classics that relied heavily on the Melies technique of multiple exposures. At that time, it was not possible to shoot a scene inside a moving train with the camera photographing the scene within the car interior as well as the moving exterior landscape in the same shot. Then, as now, the motion picture film stock did not have the latitude of the human eye. One needed to expose for the interior of the train car. It would have to be brightly lit, enough to compensate for the bright sunlight outside which had a much higher color temperature. Early film stock and, indeed, even today’s advanced film emulsions are challenged by this problem.
By the first decade of the new century, the most popular special-effects technique was the “glass shot”. This was the relatively simple technique of painting part of the scene on a large piece of glass and placed directly in front of the lens. Because film is two dimensional, the forced perspective matte painting on the glass could be made to perfectly blend into the real background shot through the clear portions of the glass. Sometimes, instead of glass, a small forced perspective model would be placed close in front of the camera. This might be something like a miniature castle made to look like it was sitting on the top of a distant hill. Live actors could then be photographed in the foreground of the scene giving a sense of reality to the shot with the fake castle.
This technique is so basic and so effective that The American Movie Company used it in its award-winning children’s musical TV show “The Quest” in the late 1980’s.
A popular variation on the glass shot came about because the basic technique required the painting on the glass to be finished before you could film the shot. The issue was resolved by painting the area on the glass that was to be matted out a flat black. Then this area would be shot with a second time on the rewound film later after the matte artist had time to create a perfectly blended painting. This way the artist could see the actual framing of the shot, the lighting conditions, etc. and thus could produce a more realistic matte shot.
The next big advance came in 1918 when Frank Williams invented the travelling matte. It was used on many films, most notably, in the famous film “Sunrise” by German director F.W. Murnau at the sprawling UFA studios in Berlin.
Williams’ travelling matte technique had the subject filmed against a pure black background then the EFX cameraman would recopy the footage with increasingly high contrast with the negative until a black and white pure silhouette emerged. The silhouette was used as a travelling matte because it moved frame by frame to perfectly match the live footage.
Another example of the Frank Williams matting technique was its use by John Fulton in the 1933 classic, “The Invisible Man”. In the memorable shots of the film you would see the actor, Claude Rains, slowly and dramatically unwinding the bandages around his head and taking off his clothes revealing that he's invisible beneath. Mr. Rains wore a black velvet suit and was shot against a flat black background. The VFX effect amazed audiences and was used on multiple sequels to “The Invisible Man”.
A problem with the Williams’ process was shadows. If there were any, they could be lost in the travelling matte process. Luckily, an alternative solution came about in 1920. This effect, later became known as the “Dunning process”. It used various colored lights on the background with a small blue screen in the foreground. It was lit with yellow light. Then using special filters and various dyes, the yellow and blue light could be separated to create the travelling matte. This process was complicated but was used in 1933 with spectacular results in the classic film, “King Kong”.
Author: Bill Milling