Chroma keying is a special effect that revolutionized filmmaking. In video and film production, chroma keying on green or blue screen allows filmmakers to combine shots, change locations, fix mistakes, maximize budgets and create impossible effects. Every day, audiences see the result of chroma keying's innovative history.
Chroma Key Today
Explanation
Chroma keying is the process of shooting a subject on camera and replacing that subject in an entirely different background indiscernibly. According to Mercury TV, chroma "refers to the purity, brilliance or richness of a color and its strength and weakness...Keying cuts a hole in an image making it transparent. The resulting hole is then filled with another image." The development of color film and television allowed colors absent in human skin tone to be isolated and separated. Blue and green are the primary colors used as chroma backgrounds.
Early Beginnings
Linwood Dunn began the earliest chroma key experimentation. He used traveling mattes to create wipes in 1933's, "Flying Down to Rio." Working for RKO Pictures, Dunn designed numerous special effects with his homemade optical printer. According to Filmreference.com, "The printer consisted of a modified motion picture camera set up on a solid base with a special precision motion picture projector---both driven in synchronization while the camera photographed the film carried in the projector. Through this film-copying process, the image in the projector could be modified in unlimited ways."
Key Innovators and Major Milestones
Larry Butler invented blue screen technology. He used keying effects to create a massive genie in the 1940 film, "The Thief of Bagdad." According to Newtek, "This was a very tedious and precise process involving several layers of film which had to be precisely aligned when creating the master negative." Arthur Widmer further advanced keying techniques. In 1958, while working on "The Old Man and the Sea," Widmer developed the ultraviolet traveling matte process. According to Richard Rickett's book, "Special Effects: The History and Technique," Richard Edlund also changed keying effects. For "The Empire Strikes Back," he created a four-headed optical printer called the quad. "By using the quad...complicated shots that contained several hundred elements...could be achieved in a fraction of the time that it would take on a traditional printer." In the late 1970s, the advent of video changed chroma keying color from blue to green. According to Videomaker.com, "That's because of the detail in the green color channel that digital cameras retain." The most significant change in chroma keying resulted from the development of computer generated images (CGI). This technique uses the concepts of chroma keying, but creates the backgrounds on computer.
Past Challenges
From weather reports to film footage, past chroma keying effects presented problems. Videomaker.com reports, "The key would be imprecise, causing said weatherman in his garish plaid polyester jacket to appear to be dematerializing into his map." In chroma keying, lighting, reflective surfaces, shadows, unevenness, and crude matte lines posed challenges.
Significance
According to Trivision, chroma keying "gained wider acceptance in later years as a budget shortcut, allowing actors to be filmed in environments that would have been too costly for the studio to shoot with a full crew." Blue and green screens made impossible backdrops achievable. Videomaker.com reports, "These days, chroma key and related technologies, such as blue and green screen effects, have gotten so exact, they're the key to Hollywood blockbusters."
Tags: chroma keying, chroma keying, keying effects, Blue green, blue green, blue screen, chroma keying
