[Class Assembling] Hi! Welcome to FilmmakerIQ.com - I'm John
Hess and today we'll explore Hollywood's history of visual trickery with the backstory
of modern greenscreen compositing. With cameras and computers everywhere in our
modern world, it's easy to forget that the very first motion pictures were, themselves,
essentially a special effect. It's here at the beginning of filmmaking that we'll
start our journey: the close of the 19th century with one of the world's first prolific filmmakers
- a man who spent his life studying the art of illusion - Georges Méliès. In his 1898 film "Four Haads are better
than one", Méliès employs a visual trick that is the rudimentary beginnings of what
we now think of as greenscreen compositing. The use of mattes for multiple exposures. Compositing is a technique combining different
shots and elements into one image. The matte shot was the first compositing techniques
employed by early filmmakers such as Melies. In his film, Melies would black out parts
of the frame using a piece of glass with some black paint. This "matte" made it so no
light would reach the film so it wouldn't get exposed. Then Melies would rewind the
film and this time matted out of everything else and expose only the part of the frame
that was under the matte earlier. The resulting double exposure could combine two or more
different shots into one frame all done inside the camera. This matte technique was used again on Edwin
S. Porter's 1903 The Great Train Robbery but this time not as magic trick but as a
means to create a larger more realistic world Notice the train moving outside the window
of the train station - also the open door of the mail car with the scenery in the background.
Both of these shots were done using mattes and double exposure. Now the fair question to ask here is why didn't
they just shoot it in a real train station or a real train car? The answer is it was technically impossible
at the time. Early orthochromatic film needed a lot of light and the technology for efficient
electrical lighting for film was still a decade or two away. That's not even considering
the inherent exposure problems of shooting an interior scene with a window in the shot.
Even modern day cameras have trouble with the brightness differences between interiors
and exteriors. In order to make film behave they way we experience the world, visual trickery
had to be done. As film grew up in the 1900s and 1910s more
techniques for augmenting sets and creating false realities would be developed. The Glass
shot was a technique of painting elements on a piece of glass and placing that glass
between the subject and the camera - a sort of real world compositing which was refined
by early filmmaker Norman Dawn, using it to augment sets making them look much bigger
and more elaborate without the costs of construction. But the problem with the glass shot was the
paintings had to be ready on set. Norman Dawn solved this problem by painting the glass
black and treating the shot like a matte shot. The matted film would be transfer to a second
camera where matte artists could take their time creating the matte paintings. This matte
painting concept continued seeing use in the golden era of Hollywood and continues with
us even in our digital world. The problem with mattes is the camera had
to stay perfectly still and no action could cross the matte line - the "hopefully"
invisible line between the live action and the matte painting. This is where the traveling matte came into
place. The process patented by Frank Williams in 1918 and demonstrated here in F.W. Murnau's
1927 film"Sunrise" - was a black matting process which photographed subjects against
a pure black background. The film would then be copied to increasingly high contrast negatives
until a black and white silhouette emerged. This black and white silhouette was used as
the matte - called a traveling matte because it moved throughout the frame. This "black back matte" effect which was
called the Williams Process was used quite famously by John P. Fulton in 1933 for the
film "The Invisble Man". The shots where the invisible man was taking off his clothes
were accomplished by photographing actor Claude Rains wearing a full black velvet suit standing
against a black background. This effect was so memorable and startling it was used on
follow up sequels even after more effective processes came along. The Williams Process had some issues - for
one, any shadows on the subject would be lost in the traveling matte. An alternative came
about in 1925, invented C. Dodge Dunning which would eventually be called the Dunning Process.
This process used colored lights, lighting a background screen blue and the foreground
subject in yellow. Using dyes and filters, the blue and yellow light could be split apart
to create traveling mattes. The Dunning Process would first see use on King Kong in 1933. The problem with the Dunning Process was it
only worked with black and white film. Color Film needed a new technique and it would come
in 1940 by special effects artist Larry Butler in the Thief of Bagdad. That was the first wish master Two more remain. Name them. Don't you hurry me, I've got to be careful. Two more.... you know what I wish. Tell me, where's my friend Armand? Master, to know that you must look into the all seeing eye. Then give me the eye. Master, I can take you to where it is but even I cannot steal it for you. Steal? I could do that. Little braggart what have you ever stolen? What haven't I? Key from the slot, ring from his finger, money from his purse the scent of a genie. And the tongue of a liar but he who would steal the all seeing eye from the very brow of the goddess must be neither a thief nor a braggart but a hero. I always wanted to be a hero... come on! Then catch on to my hair. Alright, but mind you, this is not my second wish yet. Now I'm rather helping you. Yes Master. Using the three strip technicolor process,
Butler shot the subject against a blue background. Blue was used because it was the farthest
away from skin tones and the blue film stock had the smallest grain. Taking the blue separation
from the three technicolor negatives, Butler was able to create a silhouette matte just
like with Williams process. Then, using an optical printer, a relatively new invention
at the time that could combine multiple film strips into one, Butler would first remove
the blue background from the foreground plate and, using the negative of the travelling
matte, remove the foreground space from the background plate and then finally combining
both foreground and background plates together. This bluescreen technique won an Academy award
for Best Special Effects for Larry Butler in 1940 but it was not without its inherent
problems. Firstly the process was extremely time consuming as it involved several steps
with an optical printer. Secondly, it still had some edge issues where a thin blue line
was almost always visible in the shots. It also couldn't handle any fine details like
hair or smoke or motion blur. Despite these limitations, the blue screen process was used
extensively including in such blockbusters as The Ten Commandments in 1956: Hollywood kept experimenting with other variations
on the bluescreen process including the ultraviolet matte as used in "The Old Man and The Sea".
But the real challenger to blue screen was created in the late 50s and credited to one
of the giants in world of compositing Petro Vlahos. Developed by Vlahos in the mid 50s and used
extensively by the Walt Disney Studios in the 60s and 70s: The Sodium vapor process
used actors, who were lit normally, standing in front of a white screen which was lit by
powerful sodium vapor lights - those are the orange lights you see on street corners. Sodium
vapor emits light in a very specific wavelength - averaging 589.3 nanometers - and nothing
else. Using a specially coated prism in an old three
strip Technicolor camera, the very specific wavelength of the sodium vapor light was split
off and captured on special black and white film - automatically creating the black and
white traveling matte. The remaining light would be captured by regular three strip Technicolor
Film which was relatively unaffected by the yellow/orange sodium vapor lights. This technique produced some of the best travelling
mattes of the time and was used by Disney first on film The Parent Trap and then The
Absent Minded Professor both in 1961. Mary Poppins in 1964 demonstrated the capability
of the sodium vapor process winning an academy award for best special effects. There was just one problem. Only One Sodium
Vapor prism was ever made so there was only one camera that was capable of this process.
Disney owned the camera and they didn't let it rent for cheap.
Revenge of the Blue Screen In the late 50s, When MGM was ready to produce
Ben Hur in the MGM Camera 65 format (a 65mm film process) they turned to Petro Vlahos,
the inventor of the sodium vapor process for help on the compositing. They didn't want
the problems that Ten Commandments had with bluescreen but The sodium vapor process wouldn't
work as it prism it used was been made for 35mm film, not 65mm. So Vlahos was asked to
see if he could do something about trying to improve the bluescreen process. After six months of hard work, Vlahos had
a discovery. And this is where it gets pretty complicated. Most colors that aren't purely
green or purely blue have about equal amounts of blue and green in them. So when creating
a matte from bluescreen, Vlahos used a Green Cancellation separation (or positive), ran
it though with the original color negative exposing both pieces of film together under
a blue to light to create a "blue difference matte". This matte was clear where the blue
and green were the same - Then the blue separation positive was combined with the original negative
and exposed under red light to get a cover matte. This cover matte was applied back to
the original color separations except that the blue separation was replaced with a composite
of the green and the green difference mask - essentially a synthetic blue separation. This complicated process required 12 film
elements to get from the composite negative to the composite internegative but it was
remarkable in the way it single handedly solved the edge and fine detail problems that plagued
blue screen. It was so successful in fact that the process
remained in popular use for almost 40 years. Developments like microprocessor controlled
quad optical printers, employed by Richard Edlund for The Empire Strikes Back made the
process faster and more accurate but the next big change to come would be in the form of
digital. I have consciously avoided the the term "chroma
key" as historically the term applied only to video systems only. That's not the case
anymore. In rudimentary video mixers, a keyer was a mathematical process that would make
a range of colors in a video signal and make it transparent. This is, of course, a common
effect that television newsrooms all over would use weather map special effects. Blue as a screen color was still predominate
but green started to take over as films began getting the digital post production treatment
in the late nineties. Why Green? Basically Green was easier and cheaper to light than
blue, green registers brighter on electronic displays, worked well for outdoor keys (where
the blue screen might match the sky) and the bold green color was less common in costumes
than blue is. And now as digital camera are replacing film,
many digital sensors use a Bayer Pattern which have twice the number of green photosites
than red or blue to capture luminance. This makes modern digital cameras much more sensitive
to the green part of the spectrum making pulling a matte from greenscreen a little easier.
Blue is still commonly used as are other colors depending on the needs of the shot. So now with advanced software and motion controlled
cameras, Chroma Key, a term that has grown now to encapsulate much more than it's original
video technique, can be used to insert backgrounds and set extensions in ways that Georges Milies
and Norman Dawn could only dream of. There are cynics today that believe modern
film is too reliant on CGI and that we should return to a simpler form of real filmmaking.
But as I hope you learned, that era never existed - filmmakers from the very beginning
have sought to push the medium with special effects. The undeniable truth about filmmaking is the
only thing that matters is what's on that screen. From Edwin S. Porter's matted train
station window to the modern action spectacle, it's all about creating a window onto another
world. A world where each of us can find our dreams our fears and ourselves. All these
effects we have are just tools to help us get there.. And we have some fantastic tools,
so use them, and make something great. I'm John Hess and I'll see you at FilmmakerIQ.com
