Welcome to How’d They Do That? — a monthly column that unpacks moments of movie magic and celebrates the technical wizards who pulled them off. This entry explains how they did the glowing costumes in Steven Lisberger’s groundbreaking 1982 sci-fi movie Tron.
For better or for worse, it was Tron that unleashed Computer Generated Imagery on Tinseltown. The 1982 Disney movie is privy to a remarkable number of firsts: the first feature-length film to combine CGI and live-action; the first talking and moving CGI character; the first film to combine a CGI character and a live-action one; the first fully CGI backgrounds… The list goes on and on.
It is deliciously fitting that a film of CGI milestones is also, narratively speaking, explicitly concerned with both the potential and danger bound up in our relationship with technology.
Tron follows Kevin Flynn (Jeff Bridges), a former software engineer whose lazy days running a video game arcade are upended when he attempts to hack into the Master Control Program (MCP) of his former employer, ENCOM, on the suspicion that his old boss plagiarized his video game ideas.
Flynn teams up with a handful of former co-workers who have grown concerned that the MCP may have mutated into a power-hungry AI. But when the group infiltrates ENCOM, the MCP uses an experimental laser to digitize Flynn into cyberspace. After getting his bearings, he attempts to locate the security measure called TRON, the last hope at freeing “The Grid” from the MCP’s tyrannical rule.
The glowing costumes in Tron
Inside cyberspace, Flynn finds a world populated by programs bearing the likeness of their human creators. Each program (as well as the digitized Flynn himself) is covered in sleek, form-fitting circuitry: glowing catsuits, and crash helmets that bind them aesthetically to the flickering digital space and to each other.
Each character, from the Shakespearean MCP second-in-command Sark (David Warner) to the kind-hearted input/output program Yori (Cindy Morgan), glows like neon. Light permeates their electronic bodies, illuminating the geometric wiring that clings to their thighs, ribs, and foreheads.
So, how did they do it? Was this yet another CGI innovation applied at great duress by pioneering digital artists? Was it just a practical lighting source? Or is something a little more … old school… happening here?
How’d they do that?
Long story short:
The costumes in Tron achieved their iconic glow through a traditional animation trick known as “backlight animation.” By shining colored light through transparent mattes of specific screen elements, the filmmakers could give the costumes their glowing effect.
Long story long:
While Tron is often discussed in the context of contributions to computer animation, the film is also one of the greatest examples of a traditional animation process known as “backlighting.”
Before we get into how backlighting was used on Tron, it will be helpful to look at how backlight animation is typically used. Namely: 2D animation. If you’re a fan of traditional animation, especially from around the time of Tron’s release, you’re familiar with the visual concept of backlighting: it’s that warm and often diffuse glow that makes you think “huh, how the heck did they hand-draw that lighting effect?”
Well, the cool thing is that they didn’t!
First, the animated shot is photographed normally, but the “glow areas” are (usually) painted black. Then, the camera is rewound to the beginning of the shot and a counter-matte is placed down. Now, the originally blacked-out glow placeholders are transparent. (Fun fact: if your shot has multiple glowing elements, each requires its own counter-matte. To boot: shots with multiple colors require repeating the whole process multiple times).
Next, a light source is shone through the transparency, and colored gels can be applied in addition to any exposure shifts or filters (for sharpness, fuzziness, etc.). The result is a very tactile and magical lighting effect, complete with tapering fringes and unique liveliness that cannot really be simulated by hand (or digitally, for that matter).
Because it’s tricky to add texture to a glow, backlight animation is principally reserved for simulating lightning strikes, flames, or (as with Tron) energy. Given that the computer world of Tron is chiefly composed of light, just about every permutation of the process appears in the film, flanked by airbrushed backgrounds and the occasional CGI. What makes the use of backlit animation so notable in Tron, apart from the sheer scale of its use, is how it was used to apply animated elements to live-action performances.
This finally brings us to the glowing Tron costumes.
As cited in “The Making of Tron” by Richard Patterson in the August 1982 issue of American Cinematographer, originally, the cyberspace sequences were going to be entirely animated. However, discussions between the film’s VFX supervisor, Richard Taylor, and director Steven Lisberger gave birth to the idea of using live-action photography as the basis for backlit animation in the “computer sequences.”
The look of the costumes was conceptualized by the great French cartoonist Jean “Mœbius” Giraud, who consulted on Tron for three months.
The live-action cyberspace sequences were shot in Los Angeles, including on sound stages on the Disney lot. In an original two-minute feasibility test, an actor in a gray suit was placed against a white background. At the behest of cinematographer Bruce Logan (who worked on the visual effects of both Star Wars: A New Hope and 2001: A Space Odyssey), a white background just wasn’t feasible.
As Logan puts it in the 2002 documentary The Making of Tron, there wouldn’t be “enough lights in Hollywood” to properly light an all-white set. And so, the all-white void was swapped out for an all-black one. The result: actors in white costumes with black vector lines shot against a pitch-black stage. In the same making-of documentary, Jeff Bridges remembers feeling “bombarded by color” every time he’d exit the soundstage.
Even with the void swap, per American Cinematographer, the production was using so much current to bounce light on-set that the City of Burbank supposedly called the studio to complain. One other takeaway from the feasibility test was the realization that they would have to shoot on a large format negative because even a 35mm anamorphic wouldn’t be able to handle the demands of compositing. At Logan’s behest, they switched to 65mm. The computer segments of the film were shot in black-and-white because, per Logan, this was the most “elegant” way to do it.
This footage was then enlarged for blow-ups (~ 20” x 12”) and then transferred into large format, continuous tone, high-contrast Kodalith transparencies that only contained opaque and transparent elements. Clear cels were then laid over each sheet and all portions of the figure (except the areas that were going to be exposed) were manually blacked out. Next, the sheets and overlays were placed over a lightbox while an above-mounted camera made passes for different elements: teeth, the whites of eyes, faces, etc.
One part of this process would be to expose carefully cut-out segments to light sources to create the impression of a neon glow that was simultaneously tied to both the live-action photography and the CGI elements.
In the end, there’s a reason that Tron is the only live-action feature to heavily rely upon backlight animation. To begin with, the resulting “cell sandwiches” of transparencies, mattes, etc., were very thick and difficult to flatten. Per an estimation in the aforementioned American Cinematographer article, Tron contained between 400,000 and 500,000 animation elements. Which is, and I believe this is the technical term, absolutely bananas.
Backlight animation is very, very labor-intensive before you add a live-action element into the mix (indeed, a good portion of this work was ultimately outsourced to a studio in Taiwan). Backlight animation tends to be relegated to static elements, since tracking a moving target with cut-out transparencies is asking for a migraine. But, as Lisberger puts it in the making-of doc, backlight animation was “at the time, the solution to the design problem.”
What’s the precedent for the illuminated Tron costumes?
While backlighting (which also went by the names “underlighting” and “bipack glow”) has a long tradition within 2D animation, the notion of applying the technique to live-action was wholly unique to Tron.
Indeed, before he and his team migrated to California, Lisberger’s studio created an early concept for a backlit character (named “Tron,” for “electronic”). As Lisberger describes in Tron‘s making-of documentary: “Everybody was doing backlit animation in the ‘70s … it was the disco look. And we thought: what if we had this character that was a neon line? And that was our Tron warrior.”
The resulting 30-second animation was used to promote both the studio and a series of rock radio stations. “People weren’t doing backlit characters. They were using it as an effect to make things glow and pulse and logos. What we did was we tried to do a character that was backlit.”
It was a germ of an idea, but nevertheless: it was the first step towards what would ultimately become Tron.
There are pieces of animation history that you can’t help but feel nostalgic for. And the vibrant glow of backlight animation is certainly one of them. Digital technologies are now able to replicate light sources with relative ease. But something is lost in the emulation: a key part of the tactile spark that made backlighting effects feel alive and magical.
While Tron’s story warned of the tyranny of rogue AI, its filmmakers were inadvertently laying the groundwork for the greenscreen Imaginarium that has since become a blockbuster standard.
And yet, within all these inklings of where cinema was headed, the Tron filmmakers committed to an old-school animation practice that was, for all its headaches and foolhardy spirit, old school and absolutely gorgeous.