TV’s pioneers could never have imagined the extent to which greenscreen — the technique of melding a foreground image with a different background — would become so integral to production. But now, with advances that have proven both economical and time-saving, the technology, called “chroma key” in TV antiquity, has become ubiquitous.

From news and weather reporting to visual effects-laden shows such as “Game of Thrones,” the technique, which largely relies on computer-generated backgrounds, often is cheaper and easier than shooting on location.

Greenscreen for TV got a major boost from the technology developed for use on “Avatar.” In the past, anyone directing actors against a such a matte background had to wait until post-production to see if and how the actors blended with the background. On the set of “Avatar,” real-time compositing enabled helmer James Cameron to see his actors in the computer-generated environments while he directed. It’s a leap that has unlocked greenscreen’s potential for increased use for broadcasting — even for sports, where live action is front and center.

“We started with a virtual monitor in ‘Sports Center’ that came down from the ceiling,” says ESPN vice president of emerging technology Anthony Bailey. “We’ve expanded into our ‘EA Virtual Playbook’ and moved to virtual logos, graphics and analysis tools. Shows like ‘Sports Nation’ are now based on virtual sets. It allows for us to have more in a smaller space and make it feel like it’s much bigger. Virtual is the way for us to grow.”

John Gross, creative director/vfx supervisor at Eden FX, which provided greenscreen services for NBC’s recently cancelled “The Playboy Club,” points out that greenscreen offers producers more bang for the buck.

“If you go on location, you need location permits, you need to clear the streets and you need a whole crew,” Gross says. “It’s always much cheaper to shoot on set.”

TV shows interested in greenscreen don’t need to look far to find companies that offer it as a service, at TV prices. Zoic Studios’ Zeus (Zoic Environmental Unification System) was first used on ABC sci-fi show “V,” says owner/visual effects supervisor Andrew Orloff. “It was a technique born out of necessity, because they needed us to create an environment that couldn’t be physically or economically built,” he says.

This season, Zoic is using Zeus technology on two ABC shows in production: “Once Upon a Time” and “Pan Am.” “This is a whole new paradigm for productions,” says Orloff. “It changes the way that departments interact with each other. We work directly with directors and cinematographers to match the lighting they want. Before we shoot, we have a fully rendered version of the set.”

Stun Creative, an L.A.-based advertising agency that specializes in network branding, series launches and content creation, relied on Light Craft Technology to provide real-time compositing for its work on the recent “Summer by Bravo” promo campaign. “In the past, we would have had to seriously (weigh) the advantages,” say principals Brad Roth and Mark Feldstein. “Now it’s a viable option.”

Advancements in greenscreen are enabling TV’s top shows to create the kind of sophisticated effects that were once found only in blockbuster features. On HBO’s “Game of Thrones,” the men of the Night’s Watch guard the ramparts of the Wall, a 700-foot-high ice barrier with a fortress on top, all of it generated in the computer and composited with the actors.

“We were trying to create this fantastical world that was digital greenscreen territory through and through,” says Lucy Ainsworth-Taylor, visual effects producer at BlueBolt in London, which created the digital environments for the show. “Ten years ago, I don’t know if (these kinds) of visual effects could have been done … certainly not for the budget we had.”