The cinema space is abuzz over The Hobbit: An Unexpected Journey, but not just over Bilbo Baggins and his ensuing adventures against the legions of Sauron. Orcs are slain and goblins lanced, yet discussion of the film has largely vectored around Peter Jackson’s unorthodox frame rate choice. While the New Zealand auteur is no stranger to innovation, his latest entry in Tolkien’s fantasy realm features one minor major technical departure: it is the first box office release both recorded and projected in 48 frames per second. Popular opinion seems to occupy one of two extremes, with its detractors the more outspoken of the bunch.

The backlash over the technical presentation did not come without warning. When Jackson debuted The Hobbit at last year’s CinemaCon in Las Vegas, the showing was met with splintered ambivalence. Some attendees cited its crisp motion compared with the legacy 24 fps format, while others dispraised its “non-cinematic” feel in concert with its rapid disintegration of the suspension of disbelief. Theater owners mostly expressed disdain over having to upgrade their 3D projection systems, a hardly trifling fee of $10,000 per screen.

In an industry which fosters innovation and traditionally greets bigger numbers with gusto, the recent friction over The Hobbit’s screening format may seem curious. After all, 48 is exactly twice the established standard, which means you are seeing double the information every second. So why is 24 fps broadly considered “cinematic” and 48 fps less so? And why are filmmakers like Jackson, Andy Serkis and James Cameron pushing for HFR (High Frame Rate) formats?

Silent Film and Beyond

With his penchant for particulars and visual flair, it’s fair to say that Jackson did not take the decision to deviate from the industry standard of more than 80 years lightly. As he details in a pre-release Facebook post, the early film era’s choice to commercialize 24 fps was one of compromise. Most people assume 24 is a magical number for film or holds some sort of psychophysical significance. Not so.

Prior to the late 1920s, there was no agreed-upon recording speed, film stock or projection speed. The first silent films were shot with variable frame rates, with some dipping as as low as 14 frame/s. Such a speed was barely enough to maintain the illusion of motion; viewers today would find the jerkiness nigh unwatchable. In the theater houses, projectionists would even alter the rate of playback to match the musical accompaniment or on-the-fly to maximize profits.

When sound film arrived, this model was no longer sustainable. Fixed image timings became necessary in order to sync picture and sound and to escape the dissonance created by mismatches in audiovisual playback. Which timing to choose hinged sensitively on the type of film stock, which is enormously expensive to buy and to process. Prior to the digital era, a film’s primary costs were a function of the width of the film stock (known as the gauge) and capture speed. All else equal, a 14 fps film was roughly 70% cheaper to shoot than a 24 fps film, while a 35mm production is roughly half as expensive as the 70mm IMAX format used in Christopher Nolan’s previous two Batman films.

As the industry convened around 35mm stock, an economic ceiling was naturally placed on capture speed. In the end it was 24 frame/s which struck a delicate equilibrium between cost-effectiveness and motion continuity. It’s likely that every movie you’ve seen at the cinema or on DVD and Blu-ray was originally recorded progressively at a rate of 24 images per second. On most playback systems, each frame is then displayed multiples times to reduce flicker.1

In a presentation on frame rate, videographer Mark Schubin tells us candidly, “There is absolutely nothing special about 24 frames per second. There is no particular psychological reason for it, no mathematical reason for it.”

The Allure of HFR

As HFR’s proponents have pointed out, none of the constraints around the 24 frame format applies to today’s world of digital ubiquity. Digital production costs do not scale dramatically with frame rate, and the latest in digital imaging allows for a variety of speeds, from 48 to 60 to 10,000 frame/s, and even speeds faster than the speed of light. Current technology is now able to capitalize on our visual system’s potential in ways that were simply not possible in the 1920s. While the human eye is unable to take in many thousands of unique images per second, 48 veers much closer to our biological limits than does 24.2

This boost in capture speed carries immediate visual improvements, namely an increase in motion resolution. If you’ve ever seen a fast-paced pan of the camera while watching a movie, you’ve likely noticed the jerkiness. This is because there are not enough frames in the source to maintain smooth motion. Filmmakers are reflexively cognizant of this (there are even tables which calculate the maximum speed of camera pans before strobing occurs) and ensure that their pans do not spill over a specified threshold. With 48 and higher frame rates, this problem goes away. With more frames to work with, camera movements are more stable, lending quick pans and the choreography of action scenes greater intelligibility.

Image via reduser.net

Jackson is well aware of this, having employed over two dozen RED EPIC cameras in his 3D production of The Hobbit. While HFR can give 2D exhibitions a more lifelike edge, its benefits are most palpable in 3D presentations, where artifacts like flicker, blur and crosstalk tend to be exacerbated. In the traditional 3D cinema experience, each eye is alternately sent 24 unique frames each second. For theaters capable of HFR playback, each eye receives 48 unique frames, resulting in a smoother, less headache-inducing visual experience.3 Jackson chose to release the HFR format for 3D exhibition only; all 2D exhibitions will be shown in the traditional 24-frame format. (Check here for a current list of theaters upgraded to 48-frame projection systems.)

For commercial purposes, 48 fps has the added benefit of being fully backward-compatible with legacy 24-frame playback systems.

The (Dis)Comfort Zone

Ultimately, the disfavor surrounding The Hobbit‘s higher frame rates stems not from an unrefined use of props, lighting and CGI, as some have suggested, but from our stiffly conditioned sensorium. We’re simply not used to viewing movies this way. Our lifelong familiarity with 24-frame cinema has etched its signature into our collective subconscious.

Though it might seem like the jump from 24 to 48 is not significant, it is massive in terms of how our optical system responds and adjusts. The added smoothness unshackles our suspension of disbelief we so intimately associate with low-motion content, ejecting us from the fantasy world of Middle Earth and onto the set, where props are revealed for what they really are. In short, a closer approximation of reality is exchanged for the filmic, almost surreal quality we identify with the cinema experience.

High-motion content is abundant outside of movies. Since the destination of broadcast material, including sports and news coverage and low-budget programming, is in the living room rather than the theater, this content is typically recorded on video at 30 frame/s.4 The visual flavor of this type of content seems every bit as natural to us as the flavor of film-based content. Our years of conditioning means that we subliminally associate different species of programming with their capture rates.

Those who own newer high-definition TVs have likely already experienced HFR movies, albeit in exaggerated and simulated form. Most flat panels today, especially 120 Hz and 240 Hz LCDs, come equipped with MCFI (motion compensation via frame interpolation), which synthesizes new frames from existing ones to enhance motion resolution.5 When this effect is applied to movies captured at 24 fps, the cinematic feel is upgraded to the feel of the high-motion programming described above. Commonly called the “soap opera effect”, this not only boosts the level of realism to uncomfortably high levels but distorts director intent by creating new frames not present in the film source. The core difference between The Hobbit and motion processing at home, of course, is that the high-motion in The Hobbit is not simulated; the frames are present in the source material.

Adapt or Go Home

As with any new technology, HFR will need to survive an incubation period. Sound, color, widescreen, digital projection, 3D; all have had their share of doomsayers, yet cinema lives on. Jackson’s Hobbit format provides us more sensory information and is actually closer to reality than what we’re used to, the same promises accompanying every other industry revision since silent film. Even so, perhaps none has had as dramatic an impact on the “feel” of the film as HFR. While The Hobbit‘s juiced frame rates and hyper-realism may be initially unnerving, most agree that it is an effect that wears off after the first 20-30 minutes. After all, our sensorium is highly adaptable and, over time, we may come to associate 48 fps with cinema the way we associate 24 fps now.

For several in the industry, HFR is long overdue, and they have Peter Jackson to thank for being the first to break down commercial barriers. As Cameron and others prepare their own high frame rate presentations for the big screen, time will tell whether the tide of opinion flows toward the new medium or recedes back to the familiar embrace of the legacy format.

Footnotes:

1. When movies are shown at your local theater, each frame is flashed twice or three times to compensate for flicker arising from the inter-frame black period. Thus while the movie itself was recorded at 24p, the movie projector runs at a 48 or 72 Hz refresh rate. The same is true for digital projection and flat-panel televisions; each film frame is repeated according to the refresh rate of the display.
   
2. The human visual system’s response rate is highly dependent on the particular stimuli. For example, our sensitivity to light in dark environments is greater than our sensitivity to dark in light surrounds. Tests with Air force pilots have shown that the human eye can identify light that is flashed only for 1/220th of a second. We are capable of taking in hundreds of light emissions per second, though we vary in our ability to make distinct sense of those images as the frequencies climb higher and the stimuli change. At the end of the day, frame-based motion is merely a simulation of reality.
   
3. The figures given are for unique frames per eye. You’ll recall that for 2D theatrical presentations, each frame is flashed twice to reduce flicker. The situation is the same for 3D exhibitions. Given a 24-frame projection system, you are processing 48 total frames per eye. For 48-frame playback, this number doubles to 96 per eye.
   
4. This frame rate is easier to reproduce at home compared with 24 frame/s. Because the standard refresh cycle of televisions (in the U.S.) is 60 Hz, only a simple 2:2 pulldown is required to render 30 frame/s material. This avoids the judder which arises when 24 frame/s material is converted to 30 frame/s for proper playback on 60 Hz playback systems. This process, called telecining, is needed to make the 24-frame standard format of film compatible with video frame rates used in television and broadcast. Additionally, the economics of higher-cost film make video capture a more popular choice for low-budget programming like daytime soaps and the rest.
   
5. MCFI’s main function is to upgrade low-motion content to appear as fluid and continuous as high-motion content. The technology algorithmically creates new frames to insert between the source frames as if they were always there, thereby artificially inflating the frame rate. The quality of the results can vary broadly by manufacturer in accordance with the processor and software fitted to the display. Most HDTVs have this feature enabled by default. To annul the video-like “soap opera effect” it is the first processing feature I disable when calibrating or bringing home a new display.
   

 
 
Much confusion has arisen due to the recent ads by LG and others comparing their new 3D TVs to “conventional” 3D sets. Let’s be clear: there is absolutely a war among 3D television manufacturers, and it’s likely to intensify as more appealing 3D content hits the market. So what are the differences between the types of 3D displays, and more importantly, which one is better?

There are presently two types of mass-produced stereoscopic displays: those based on active shutter and those based on passive polarization technology. Both presentations artificially enhance the sense of depth in an image by delivering slightly differing views to each eye. Our brain then fuses the two images together, creating an illusion of depth. Note that all types of 3D content — including 3D Blu-ray, video games, and cable and satellite programs — are compatible with both types of 3D displays. While both formats can effectively convey a three-dimensional image, notable differences exist in how each format is perceived by the end user and in the glasses used for the respective technologies.

Active Shutter 3D

Active shutter-based televisions arrived on the market first, shortly following the massive success of James Cameron’s Avatar. These sets incorporate “shutter” glasses along with an active component, the mechanics of which are relatively simple. The display shows alternating L eye and R eye images in a rapid sequence that is synced to the glasses, which block one eye while leaving the other eye open (hence, its “shutter” designation). The sync between the display and glasses is maintained via either IR or Bluetooth, which also happens to be its biggest shortcoming.

Image via Digital Trends

As the 3D effect completely depends on the sync between the (emitter in the) display and the (receiver in the) eyewear, there is the possibility that the system will fail to maintain proper sync. Further, interoperability between other IR and Bluetooth 3D televisions and glasses continues to be a problem and will likely not be remedied until an official standard for 3D glasses is finalized.

Panasonic, Sony, LG, Samsung, and Toshiba produce active shutter displays in both LCD and plasma varieties.

Passive Polarized 3D

Televisions using polarized 3D technology require different eyewear called polarized glasses, which are passive in nature and, in principle, function just like polarized sunglasses. Polarized glasses use offsetting polarization filters in each lens that correspond to the filters applied to the surface of the television screen. As each eye only receives light that is polarized in the corresponding direction from the screen, each eye sees a different image. The biggest downside to this approach is that vertical resolution is halved as a byproduct of polarization. On the upside, any pair of polarized glasses will work with any polarized TV, and they’re much cheaper than active glasses.

LG, Vizio, and Toshiba market passive polarized displays for LCDs only.

Passive polarized TRON: Legacy Limited Edition by Oakley

So what are the practical differences between these two technologies? Each 3D display type has pros and cons, largely resulting from the glasses required to view the stereoscopic signals. We’ll break down the differences that involve the most salient considerations.

Weight

Most of the cons of shutter glasses can be traced to its active attributes. The receiver, along with the batteries required to power the glasses, add weight. This may grow uncomfortable during the span of a full-length movie and may be of considerable concern for those already wearing prescription glasses. On the other hand, polarized glasses are no heavier than standard sunglasses.

Charge Time

Active shutter glasses come in the non-rechargeable (30 – 80 hours) or rechargeable variety (2 hours). Rechargeable glasses typically top out at two hours, so it’s best to have a backup pair ready to go. Polarized glasses are entirely passive and thus have a theoretically infinite “charge time.”

Cost

Active glasses range from $50 – 250, depending on whether you buy your TV manufacturer’s glasses or 3rd party glasses (all of which vary in performance). Polarized glasses are cheap by comparison; they can be found for as low as $5. Note that polarized glasses are the same ones that are used for 3D movies in the large majority of theaters. If you’re able to make out with a pair, they’ll work just fine with your passive 3D display at home. As market saturation occurs, expect retail prices of active shutter glasses to drop considerably.

The price difference between the televisions themselves is quite small. The polarizer coating applied to passive displays adds significant cost to its production, so don’t expect passive TVs to be bargain-priced relative to its active shutter counterparts.

Picture Quality

While active shutter TVs maintain full picture information in the horizontal and vertical direction, polarized displays reduce vertical resolution by half. This effectively means a 1080p signal will be perceived as 540p per eye from a polarized display, while an active shutter system delivers full 1080p per eye. Depending on how far you are seated from the screen, this may be a noticeable or negligible trait. This is also content-dependent, as sharper content (e.g., CGI and digital animation) tends to look softer on passive displays. Eagle-eyed viewers who are familiar with good and bad image reproduction will likely notice the drop in resolution when comparing the two technologies side by side, and the disparity becomes more appreciable at suboptimal screen size-viewing distance scenarios. Note that the polarization effect does not affect 2D viewing; full 1080p is maintained in 2D mode.

Crosstalk

Crosstalk – the imperfect separation between the L/R eye images – occurs when one eye sees parts of an image intended for the other eye. This happens due to limitations or deficiencies existing in the display, the glasses or even in the source itself. If it’s present in the movie’s encoding itself, for example, it will be visible with every pair of glasses. Crosstalk can occur in LCDs if the liquid crystals do not switch quickly enough from bright to dark or vice versa and in plasma panels if the phosphor compounds have an afterglow that lasts too long.

While both display types can exhibit this artifact, generally, higher quality displays and glasses will mitigate crosstalk that is otherwise not present in the source. For active shutter implementations, plasma has been shown to exhibit less crosstalk than LCD.

Viewing Angles

While both active and passive possess wide horizontal viewing angles—meaning you and all your friends on the couch can see a coherent 3D image—only active boasts equally accommodating vertical viewing angles. All this means is that if you choose passive, you must ensure the television screen is angled toward your head. If mounting your screen, ensure it’s tilted down toward the viewing positions. Otherwise, the image will break apart and your friends will go home. Keep in mind that fairly marked differences exist among glasses. Crosstalk and brightness can vary along with horizontal viewing angles depending on which glasses you use.

Light Attenuation

The eyewear associated with both technologies reduces light output significantly. Total light loss is as much a function of the display technology as the specific glasses used; each combination of television and glasses is unique. Some 3D displays will auto-adjust brightness when engaging 3D mode. Thus, there is no clear winner here. If you notice the image is too dim when slipping on the glasses, you should boost the brightness on your television. Optimally, you’d have separate settings for 3D and 2D viewing to avoid constantly manipulating your display settings.

Those are the facts. Polarized 3D is lighter, thinner, cheaper and less error-prone, but cuts resolution in half. Active 3D preserves full picture detail, resulting in an overall higher quality 3D picture, but can have syncing and interoperability issues. If you’re a plasma fan, then active shutter is your only choice at this time. Remember, all 3D TVs can also be used to view standard 2D material. But in case you decide to watch some 3D content down the road, be sure to choose the technology that best suits your viewing environment, preferences and budget.

Image courtesy of Panasonic Viera

For those who would like even more in-depth information, Raymond Soneira has a top-rate feature at 3D TV Display Technology Shoot-Out.

Who has a 3D TV and what type? For potential buyers, which type more appeals to you?

Feature image via Cnet