Why Does CGI Look So Bad on 4K TVs?


Illustration: Mark Pernice

When I plugged in my new 4K ultrahigh-definition television for the first time, I expected more than an upgraded picture. With four times as many pixels as my old TV, plus a high-dynamic color range, I was hoping for a consciousness-expanding experience — something that felt like filling a new eyeglasses prescription while doing peyote. And at first, it delivered. On a 4K Blu-ray disc, 2001: A Space Odyssey revealed details I’d never spotted in any previous home viewing, down to the razor burn on Keir Dullea’s neck. The darkened earth tones of Back to the Future Part III made it feel less like a cartoon and more like a real western. The Blues Brothers might as well have been painted by Botticelli. I could see the texture of the film grain, which gave images a depth and character they had lacked in normal HD. It was a little like having a 35mm. projector in my living room.

I put on 2015’s The Revenant next, and it looked pristine — until the bear showed up. On my old TV, the grizzly had been photorealistic. In 4K, it looked a lot more like the digital figment it was, blurry around the edges and lighter on its feet than a real 700-pound mammal would be. The CGI wasn’t bath, just soft, especially against the sharpness of the live-action Canadian wilderness. It became distracting to the point that I could hardly enjoy Leonardo DiCaprio’s mauling.

I figured the bear was a fluke and that maybe my TV would fare better with newer VFX. That is when I began to notice — and pretty soon absolutely could not stop noticing — similar issues in other recent movies that had seemed perfectly fine on my old screen. In parts of Thor: Ragnarok, the Hulk resembled a plastic action figure. In godzilla vs. Kong, some live-action scenes and digitally rendered ones were so texturally dissimilar it was like they’d come from different movies. The green-screen jungle backdrops in this year’s The Lost City looked cheap enough to tip over and flatten Sandra Bullock. The uncanny valley spoiled any scene in which a human actor handed off stunt work to a digital body double — which is to say pretty much all the action sequences in every recent superhero movie. (Before you ask: Yes, I had turned off my TV’s motion-smoothing feature.)

Was I picking pixel-size nits that most viewers will never notice? maybe. But I wasn’t alone. Jeff Rauseo, who reviews 4K Blu-rays on the YouTube channel Films at Home, says he saw many of the same things I did when he replaced his own TV. “It’s worse in things where the CGI wasn’t done very well to begin with. Some of the new Marvel shows almost look like something from the CW,” he says. “With standard HD, it was easier to suspend disbelief: Yes, that’s Godzilla, and obviously he’s not real, but at least he blends in with the background.”

“For the most part, a movie like Mad Max: Fury Road is an example of CGI done right,” says Matthew Hartman, a critic with over 1,200 bylines at High-Def Digest. “You’re so impressed with the practical effects that you don’t notice all the computer-generated ones. But in 4K, some dodgy color grading can create a weightless appearance for effects that weren’t rendered as well. There are shots of fire coming out of the tailpipes as they speed toward the War Rig, and you’re like, Okay, that’s obviously fake.”

The problem may not be that effects have gotten worse but that TVs have gotten better too fast. When the first 4K sets debuted a decade ago, nobody wanted them. They cost $20,000, and there was barely any 4K programming. But then companies like TCL and Hisense figured out how to make 4K panels at such low prices that they became the only kind you could buy in large sizes. By March 2021, 44 percent of TV-owning US households had purchased one.

Hollywood has been slower to adapt. Even as much live-action footage is shot at 4K or higher, plenty of movie CGI is still rendered at 2K — which, somewhat confusingly, can be not just half as sharp as 4K but a quarter. Since a 2K effect in a 4K shot sticks out like a blurry thumb, most movies with lots of digital imagery resort to a work-around. All of the live-action footage is downgraded to 2K to match the digital elements and then the combined product is upscaled (enlarged and enhanced using AI) to 4K for home video. Meanwhile, most older films can simply be remastered at a single higher standard. This is why a $350 million movie like 2019’s Avengers: Endgame may get less of a boost from your new TV than older CGI-less ones like 1960’s Spartacus or even 1990’s Home Alone.

One reason movie studios have been reluctant to spend on 4K effects is that on many of the biggest screens, nobody can tell the difference. In 2009, James Cameron lobbied theater chains to install digital projectors to show Avatar in 3-D. Those projectors, most of which are still in service and will be for a while, are capable of only 2K. “With a 2K projector throwing a bunch of photons across a theater, what you could get away with in CGI was fairly forgivable,” says Jeroen “J.” Schulte, the global imaging supervisor for Lucasfilm and Industrial Light & Magic. “With 4K televisions, though, that stuff is really in your face.”

Unlike movie studios, major streaming services typically demand the CGI for their original shows and films be delivered at 4K, but that’s not always an improvement. “It takes four times as long to render,” says Angela Barson, co-founder of the VFX studio BlueBolt. “You might be able to increase your budget by 15 or 20 percent, but that doesn’t remotely cover all the additional time.” Corners are cut, and a half-assed 4K effect can look worse than a decent 2K one. Barson posits that one of the best things about 4K TVs — HDR, which expands the contrast between lights and darks — might also be the reason CGI is now more noticeable. “It can throw up more issues,” she says. “You have to make sure the CGI matches its surroundings completely throughout the full color gamut. It’s an art form, and not everybody can do it. It requires experts, and there are not enough of them in the world.”

Erik Winquist, a visual-effects supervisor at Weta FX whose credits include Avatar and the latest Doctor Strange, is a 4K skeptic. “One of the Marvel movies I just finished very recently was at 2K. The movie I’m prepping right now is going to be in 2K. And these are big tentpole films, not low-budget indies or anything,” he says. “With the distance that typical audiences sit from their TVs, the benefit of 4K is debatable. I’ve sat through dailies where we’re zooming in 16 times on somebody’s cheek and analyzing whether the pore detail is everything it can be. Part of me wondersIs anybody even seeing that?At home, Winquist watches movies with an HD projector.

I explain my own 4K CGI problem to Robert Eggers, who directed this year’s Viking revenge saga The Northman. “I totally know what you mean,” he says. Eggers has a reputation for period-realistic production design and largely avoided digital effects in his first two features. (When location scouts were unable to source a suitable 1800s lighthouse for The Lighthousehe had one built.) For a $90 million movie like The Northman, though, Eggers often had no choice. “There was a lot more CGI than I would have liked,” he says. “In 4K, there are certain things that I think look super-jarring, and it makes me want to close my eyes.”

The Northman was shot on 35mm. movie, but its CGI was rendered at 2K. “Much to my shock and horror, it’s easier for an indie movie” — that is, one without much CGI — “to be finished in 4K than a big movie,” Eggers says. He’s mostly happy with how The Northman turned out for home viewers. “The 4K version has a better, more specific, dialed-in color grade than the theatrical version,” he says. “The digital versions of movies that are screened in most theaters don’t have true blacks.”

Blu-ray.com’s review backs him up, saying that the 4K disc is “wonderful, razor-sharp, and perfectly cinematic.” That may be because most of the CGI is so subtle. In the climax, Alexander Skarsgård and Claes Bang engage in a naked sword battle at the base of an erupting volcano. During the shoot, the actors wore thongs to protect their genitals, but in the finished frames, “every now and again, there’s a little flash of computer-generated scrotum,” says Eggers, “just so they didn’t look like complete Ken doll.” (Barson, who supervised the movie’s VFX, says rendering digital sex organs is no small task: “I knew everyone was going to look, so you wanted to sell it enough that they looked properly naked but not so much that you’re going, Whoa, what’s that flapping around?”)

Other effects are more prominent, especially to the director. Eggers cites the second shot of the movie, in which a fleet of computer-generated Viking crafts approaches the Icelandic shore. “I think it’s really strong, but I only buy it 97 percent,” he says. “When those ships come in, that doesn’t totally work for me.”

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