question: Why is it that, in cinematography, the color green is used for special effects?
comment: The idea is to pick a color which isn't going to be shared by anything else in the scene. Bright neon green isn't going to be part of any of the actors or the sky so it is a good color to isolate those parts of the video. Other times a vivid blue can be used, but in concept any color would work as long as it is unique.
passages: In theater and film, green was often connected with monsters and the inhuman. The earliest films of Frankenstein were in black and white, but in the poster for the 1935 version "The Bride of Frankenstein", the monster had a green face. Actor Bela Lugosi wore green-hued makeup for the role of Dracula in the 1927–1928 Broadway stage production.
  
  Section::::Symbolism and associations.:Poison and sickness.
   BULLET::::- Rose (variations: Rose Doreé, Peachblow, Candleflame) - Similar to lavender, sometimes used for low-key lit night interiors.
  
  BULLET::::- Green Tint (variations: Verdante, Aqua Green) - Scenes tinted in green were generally mysterious or seafaring scenes. Green tone, achieved by processing through vanadium ferrocyanide solution, was commonly used in jungle and nature scenes.
  
  Section::::Process.
   At the Big Five major film studios in the United States and the mini-majors, green-light power is generally exercised by committees of the studios' high-level executives. However, the studio president, chairman, or chief executive is usually the person who makes the final judgment call. For the largest film budgets involving several hundred million U.S. dollars, the chief executive officer or chief operating officer of the studio's parent conglomerate may hold final green-light authority.
   In an interview column for the Golden Globe Awards, Greenwood stated that green arsenic was used in the corridors for the film "Atonement", but the director, Joe Wright, wanted Irish green for the dress that Keira Knightley was going to use in the movie. Sarah decided to give priority to dress and change the colour she had planned for the corridors, because the dress had a risk of losing visual emphasis. She said, "Sometimes you have to be strong to win battles, and sometimes you have to know when to let go." She was not entirely convinced with the color that the director wanted, but there are decisions that an art director must make to get the message to the viewer.
   Bubbles's original body colour was blue and white, but the BBC engineers decided that green was also needed within the scene as the other two television primary colours, red and blue, were already shown. A green wrap was made to cover his body and this can be seen in Test Card J and Test Card W, along with more of his body shown in the photograph — revealing the fact that he is actually holding a piece of chalk, which was not previously visible.
   Green is used as a backdrop for TV and electronic cinematography more than any other colour because television weathermen tended to wear blue suits. When chroma keying first came into use in television production, the blue screen that was then the norm in the movie industry was used out of habit, until other practical considerations caused the television industry to move from blue to green screens. Broadcast quality color television cameras use separate red, green and blue image sensors, and early analog TV chroma keyers required RGB component video to work reliably. From a technological perspective it was equally possible to use the blue or green channel, but because blue clothing was an ongoing challenge, the green screen came into common use. Newscasters sometimes forget the chroma key dress code, and when the key is applied to clothing of the same color as the background, the person would seem to disappear into the key. Because green clothing is less common than blue, it soon became apparent that it was easier to use a green matte screen than it was to constantly police the clothing choices of on-air talent. Also, because the human eye is more sensitive to green wavelengths, which lie in the middle of the visible light spectrum, the green analog video channel typically carried more signal strength, giving a better signal to noise ratio compared to the other component video channels, so green screen keys could produce the cleanest key. In the digital television and cinema age, much of the tweaking that was required to make a good quality key has been automated. However, the one constant that remains is some level of color coordination to keep foreground subjects from being keyed out.
   For the fantasy sequence in the pilot, in which her character appeared as an "Orion slave girl", Oliver was covered in green makeup all over her body, and a dark brunette wig. A still of her with green skin is frequently seen in the end credits of the TV series, and it became an iconic image of "Star Trek". Hence the documentary about Susan Oliver's life in 2014 was titled "The Green Girl".
   Some examples of late 1960s Green Sheet ratings include:
  
  BULLET::::- "Chitty Chitty Bang Bang" - C
  
  BULLET::::- "Oliver!" GA
  
  BULLET::::- "Star!" Y-MY-A
  
  BULLET::::- "Anzio" MY-A
  
  BULLET::::- "Birds In Peru" A
   Greensman
  
  A greensman or greensperson or greenskeeper is any production personnel on a film set who is responsible for obtaining and taking care of anything "green" or natural used in the film production. This may include plants, grass, trees, flowers, and other various landscaping materials like rocks, gravel, sand, etc. She or he is considered part of the art department. This includes artificial forms of these materials such as simulated rocks and items representing greens, such as camouflage netting. 
   BULLET::::- Green emergency lighting is also used by private security agencies securing certain government buildings and establishments where terrorist organizations may also target. However, in the State of Florida, green is allowed for use by all private security vehicles only in combination with amber lights. (Florida state legislation is pending to also allow flashing clear/white lights in combination with amber/green security patrol lights for added visibility.)
  
  BULLET::::- Green and blue emergency lighting is used by some counter-terrorism agencies whilst responding to terrorist incidents, so as to distinguish the specialist agencies from other emergency departments.
   Difficulties emerge with blue screen when a costume in an effects shot must be blue, such as Superman's traditional blue outfit. In the 2002 film "Spider-Man", in scenes where both Spider-Man and the Green Goblin are in the air, Spider-Man had to be shot in front of the green screen and the Green Goblin had to be shot in front of a blue screen. The color difference is because Spider-Man wears a costume which is red and blue in color and the Green Goblin wears a costume which is entirely green in color. If both were shot in front of the same screen, parts of one character would be erased from the shot.
   It is commonly used for weather forecast broadcasts, wherein a news presenter is usually seen standing in front of a large CGI map during live television newscasts, though in actuality it is a large blue or green background. When using a blue screen, different weather maps are added on the parts of the image where the color is blue. If the news presenter wears blue clothes, his or her clothes will also be replaced with the background video. Chroma keying is also common in the entertainment industry for visual effects in movies and video games.
  
  Section::::History.
  
  Section::::History.:Predecessors.
   Derrickson was fascinated by color schemes. He chose blue-green and orange as the primary colors for "The Day the Earth Stood Still". The missile silo converted by the military for experimenting on Gort emphasized gray and orange, which was inspired by an image of lava flowing through a gray field. Derrickson opted to shoot on traditional film, and rendered the colors in post-production to make them more subtle, for realism.
   There is also a form of color keying that uses light spectrum invisible to human eye. Called Thermo-Key, it uses infrared as the key color, which would not be replaced by background image during postprocessing.
  
  For "", an ultraviolet light matting process was proposed by Don Lee of CIS Hollywood and developed by Gary Hutzel and the staff of Image G. This involved a fluorescent orange backdrop which made it easier to generate a holdout matte, thus allowing the effects team to produce effects in a quarter of the time needed for other methods.
   Section::::In history and art.:Modern history.:In the 20th and 21st century.
  
  In the 1980s green became a political symbol, the color of the Green Party in Germany and in many other European countries. It symbolized the environmental movement, and also a new politics of the left which rejected traditional socialism and communism. (See section below.)
  
  Section::::Symbolism and associations.
  
  Section::::Symbolism and associations.:Safety and permission.
   Her first work in film was as a researcher and associate art director for "American Years" (1976, 48min) directed by Francis Thompson and Jan Kadar for the City of Philadelphia celebrating the US Bicentennial. At 48 minutes long, this was one of the earliest features produced in the IMAX 70mm format.
  
  Section::::Kiss.
   One of the more notable uses of this meaning is found in "The Wonderful Wizard of Oz". The Emerald City in this story is a place where everyone wears tinted glasses that make everything appear green. According to the populist interpretation of the story, the city's color is used by the author, L. Frank Baum, to illustrate the financial system of America in his day, as he lived in a time when America was debating the use of paper money versus gold.
  
  Section::::On flags.
   In order to create an illusion that characters and objects filmed are present in the intended background scene, the lighting in the two scenes must be a reasonable match. For outdoor scenes, overcast days create a diffuse, evenly colored light which can be easier to match in the studio, whereas direct sunlight needs to be matched in both direction and overall color based on time of day.
   Section::::Plot.:In the Characters' Past.
   In a black and white pre-credits opening sequence in the 2006 Bond film, "Casino Royale", a young James Bond (played by Daniel Craig) gains his licence to kill and status as a 00 agent by assassinating the traitorous MI6 section chief Dryden at the British Embassy in Prague, as well as his terrorist contact, Fisher, in a bathroom in Lahore. The remainder of the film starting with the opening credits is shown in color.
  
  Section::::Contemporary use.
   Bulletins of the Green Sheet were initially for internal use only and exclusively included films approved by the PCA, but beginning in 1962 it appeared regularly in the periodical "The Hollywood Reporter", while beginning in 1963 the Sheet began including films that didn't receive MPAA seals, which beginning in 1958 had made up a majority of all films released in the United States, which led many states to consider adopting mandatory ratings systems.
   A chroma key subject must avoid wearing clothes which are similar in color to the chroma key color(s) (unless intentional e.g., wearing a green top to make it appear that the subject has no body), because the clothing may be replaced with the background image/video. An example of intentional use of this is when an actor wears a blue covering over a part of his body to make it invisible in the final shot. This technique can be used to achieve an effect similar to that used in the "Harry Potter" films to create the effect of an invisibility cloak. The actor can also be filmed against a chroma-key background and inserted into the background shot with a distortion effect, in order to create a cloak that is marginally detectable.
   Green-light
  
  To green-light is to give permission or a go ahead to move forward with a project. The term is a reference to the green traffic signal, indicating "go ahead". In the context of the film and television industries, to green-light something is to formally approve its production finance and to commit to this financing, thereby allowing the project to move forward from the development phase to pre-production and principal photography.
   The film was shot in colour but director Coiro and her cinematographer ultimately wanted it to be shown in black and white. The film had a successful festival run in black and white but Coiro ultimately decided to release the movie in colour so as not to limit her potential audience.
   Note that some of these functions must be prioritized over others; for example, color grading may be done to ensure that the recorded colors match those of the original scene, whereas other times, the goal may instead be to establish a very artificial stylized look.
  