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As toolsets have gone digital, from production through delivery, ensuring image integrity from acquisition to final display is more critical than ever. While the use of reference monitors on set is increasingly common, there is still disagreement over elements as basic as white point. How should producers be accounting for the gaps between monitor sizes, characteristics, and physical settings they’re being viewed in, when so much is still up for grabs as of this November, 2011?
As toolsets have gone digital, from production through delivery, ensuring image integrity from acquisition to final display is more critical than ever. While the use of reference monitors on set is increasingly common, there is still some disagreement over elements as basic as white point. Even more important, how should producers be accounting for the gaps between monitor sizes, characteristics, and physical settings they're being viewed in?
Not only have CRT monitors and their established standards disappeared from production and post, but today's viewers watch content on an ever-increasing number of screens, each of them with different frame rates, color space, aspect ratios. Everyone in the content creation chain, from directors and cinematographers to DI and visual effects artists' struggles with the pros and cons of current display technologies.
The Hollywood Post Alliance
(HPA) recently convened the first-ever Reference Monitor Symposium, sponsored by Walt Disney Studios, Dolby and Sony and several others, and drawing 200 attendees to the Walt Disney Studios lot in Burbank. HPA president and Disney's Digital Studio General Manager Leon Silverman welcomed the crowd inside the Fantasia Theatre, where that classic animated feature was mixed.
"It's fitting that we gather here to look at display technologies that will stand the test of time," he said. "Audiences are now viewing content on various different kinds of displays with different color spaces, frame rates, and other parameters. These choices present interesting challenges for industry professionals. We can begin, finally, to understand how we might better visualize images consistently from previsualization into the home."
Silverman stressed that the event was not a shoot-out and would not "anoint any specific technologies." "It's about how we tag-team and take better stock of where we are today and how we can learn from each other and have a common dialogue and definitions," he said. "As displays evolve, at the same time consumer displays evolve, it's important to talk amongst ourselves, which is what we're going to do today."
The day's program was curated by a Blue Ribbon panel, chaired by FotoKem Senior Vice President of Technology Paul Chapman. (For the rest of the Blue Ribbon panel, see sidebar.) Chapman explained that the group considered many types of test material. "We tried to mix both objective and subjective material," he said. "We interspersed test patterns that came from Sony, THX and Sarnoff Labs with more normal content, including actual subjective content material from theatrical/movies, and some animation."
FotoKem Senior Vice President of Technology Paul Chapman chairs the panel.
First, Chapman gave a quick survey of the existing reference display technologies:
Liquid Crystal (LCD) is the most widely deployed today and has the biggest spread of quality from excellent to marginal. The benefits of widespread consumer acceptance are economies of manufacturing scale, which make these monitors less expensive. Different kinds of LCD technology have various tradeoffs. Pros of LCD include long life, consistent performance and availability in a large range of sizes and applications. The biggest con for LCD displays is often poor black level, as well as the fact that the viewing angle can be limited.
Plasma can produce good images for a reasonable price, again benefiting from widespread consumer acceptance. It works somewhat similarly to a CRT, in which each pixel can be thought of as a very small CRT. Pros are that black levels can be quite good and images are similar to those seen on a CRT monitor. Plasma displays are also fairly inexpensive and have good colorimetry. But the cons are also significant: black level control is hard and noise in the image can be an issue. Plasma monitors are not available in smaller sizes. But the biggest problem is a bad characteristic of phosphor: image retention and burning.
OLED is the latest technology but is the most difficult to manufacture. There's little consumer penetration and therefore no economy of scale yet. (It's also worth noting that there is more than one kind of OLED.) The pros are excellent blacks, colorimetry that is close to CRT and a large dynamic range. The biggest cons are that the viewing angle is not wide, OLED monitors are currently only available in smaller sizes, they're difficult and expensive to make and that they also have a limited lifetime, similar to CRT monitors.
Projection technology offers a very good color gamut and overall image quality. But projection is very expensive and requires a dark viewing environment. Ambient light degrades monitor image quality quickly.
Chapman urged attendees to closely examine the monitors in the afternoon session, which were shown by the symposium's sponsors Boland Communications
, Dolby Laboratories
, Marshall Electronics
, Panasonic Solutions Company
, Penta Studiotech
, Sony Electronics
and TV Logic
"Try to look from various angles," he advised. "Look at some of the test patterns that show gray scale response tracks. Look at some of the content with high contrast to see how black level, flare and specular highlights are handled. Look at noise levels in the image on static shots such as test patterns. Talk to manufacturers about how they calibrate and what instruments are recommended. Look to make sure the monitor is properly handling the 10-bit signal without introducing artifacts."
"Sadly not all monitors will look the same," he added. "There is not a one-size-fits-all solution any more. You have to choose the technology to match your application. This is why we're having this symposium."
The morning sessions were a series of "myth busters," starting with ICG President Stephen Poster, ASC, and Technicolor senior DI colorist Dave Cole talking about monitoring on-set. Poster stressed the importance of good on-set monitoring, noting that currently it's "almost impossible" to do. Cole agreed. "That implies there's a consistency from on-set to post, and that's nothing we've seen previously," he said.
Steven Poster, ASC and Technicolor senior DI colorist Dave Cole talking about monitoring on-set.
Poster noted that the International Cinematographers Guild
has trained 400 to 500 people across the country to become DITs to aid in the process; he also pleaded with people not to call these professionals "dits" but, instead, "D.I.T.s." "The goal is end-to-end device independent color management," Poster said. "We're still not there but it's still the Holy Grail. We cinematographers have to be the master of the image. We have to know what it's going to look like on the screen and the only way to do that is proper on-set calibration."
Poster also pointed out that irony that, after so much care given to the integrity of the images, those same images are ultimately judged off of uncalibrated monitors in less than ideal viewing conditions. "Properly calibrated on set monitoring is the foundation for image control," he concluded.
Cole pointed out that although people are used to editing off a monitor, shooting for the big screen is adversely affected if the footage is not viewed on the big screen earlier in the process. "If you're projecting in P3 but monitoring in 709, you need to have a good translation so that when you're seeing in either of these color spaces, it represents the same image," he said. "Otherwise, gamma, white space and the other parameters will be off. The translations between those color spaces must be correct."
Next, Technicolor VP of Imaging Research & Development Josh Pines and Technicolor Senior DI Colorist Jill Bogdanowicz busted the myth of Digital Cinema. With his typical sense of humor, Pines listed the white point of the working color spaces thusly:
Rec 709 = white point is D65;
P3 = white space varies;
Film = white point is D55;
ACES = white point is D60.
And for DCIP3, he joked that the white space was "ugh."
"None of these is inherently digital cinema color space," he said. "There is a transform from each of these working color spaces into XYZ, the color space in which digital cinema content is distributed. And XYZ is not a good working color space. It's a great space for packaging and delivering but not for working in."
Gamut is defined as "the whole series of recognized musical notes," and has come to mean an entire range or series, he continued. "So gamut means unlimited, running the full range," said Pines. "[But] in color science, all of a sudden it means a limit. The ACES gamut encompasses the entire spectrum; no one will come out with anything more encompassing. XYZ is also all encompassing. Both of these are encompass the entire visible spectrum, although the ACES one is more aligned to what we think of as RGB."
Can video display or "emissive" monitors be used for Digital Cinema mastering? Pines touched on the Stevens effect (that perceived contrast decreases at lower luminance), Hunt effect (that perceived colorfulness also decreases at lower luminance) and display flare characteristics. "The same content has to look good in a normal surround (office), dim surround (living room) and dark surround (theatrical)," said Pines. "People will disagree with me, but the way you do that is different display gammas, from 2.2 to 2.4 to 2.6 for each of the above."
Colorist Bogdanowicz described her experiences coloring the first DI, O Brother Where Art Thou
. "We were looking at a really small monitor and then we projected it and it didn't look the same," she said. "A lot of things happen perceptually that change contrast, and that's still a big problem. There is a lot of confusion among directors and cinematographers about what it means to work in different color spaces, and this is all important for a colorist to understand." Her conclusion? That she could make a first DI pass using an emissive monitor but would have to finish with the material projected.
Landmark CEO Ron Williams and Warner Bros' Jan Yarborough focused on busting Rec. 709 myths.
Williams noted that his presentation would contradict some of the previous discussion. "Rec.709 is just a recommendation and doesn't really pertain to a display," he said. "It's a production standard and has nothing to do with display." What does specify display, he added, is ITU-R BT.1886, which was just recommended in March 2011.
"For the first time, ITU Rec.1886 specified a reference electro-optical transfer function for flat panel displays used in HDTV studio production," he said, noting that while the U.S. and European standards bodies wanted a gamma of 2.35, Japan insisted on 2.4. "So 2.2 never really existed in anything, although some presentations mentioned it," he said. "People apply camera specs to a monitor, but that doesn't work."
"Critical elements for display image interchangeability include color gamut, contrasts, black/cutoff, and picture size," Williams said. "Screen size matters when comparing images. A larger screen appears to be brighter at the same fL [foot lamberts]." How bright is the right bright? Even here the numbers varied wildly: SMPTE documents specifies 35 fL; CRT monitors varied from 28 to 33 fL; HD CRT monitors run to 19 to 21 fL; plasmas vary between 18 to 24 fL; and computer monitors are between 19 to 26 fL.
Last, THX Image Technology Director Kevin Wines busted home display myths, with some photos of how people actually watch TV at home. "People in this room are spoiled," he said. "We have the rare privilege of seeing TV/film images in the most pristine way and in the best viewing environments. If I'm to bust any myth, it's the occasional misconception that when these perfect images leave our grasp that they'll ever look the same way again."
"The home is the most challenging environment in the world," he continued. "In 2010, 263 million plasma displays were sold into the consumer market. How many of those ended up in an environment where anyone observed proper light levels and viewing distance? Maybe a couple of hundred. The rest?"
The viewing quality of video is dramatically affected by room lighting conditions, he pointed out. "We have no control over what direction the windows face, and sunlight changes color and intensity throughout the day," Wines said. "Seldom is the light at that ideal level when we're finishing it in post production. No one is suggesting we change the standard for post production. But you do have to be ready to adjust playback for the environment. You may be better lowering the gamma to get the perception back, as opposed to less sophisticated behavior with adjusting brightness or contrast."
What's Coming Next?
A Futurist Panel featured ETC founder/President Loren Nielsen; Dolby director, Product Marketing Bill Admans; Sony Senior Product Manager Gary Mandle, Sr; Curtis Clark, ASC, Modern VideoFilm President of Studio Services Mark Smirnoff and Deluxe VP of Color Technologies for Broadcast/Senior Colorist Pankaj Bajpai discuss creative requirements and technology drivers, including wide gamuts, more bits, higher spatial and temporal resolution, and more brightness.
From left to right: ETC founder/President Loren Nielsen;
Curtis Clark, ASC; Modern VideoFilm President of Studio Services Mark Smirnoff;
Dolby director, Product Marketing Bill Admans;
Sony Senior Product Manager Gary Mandle, Sr; and
Deluxe VP of Color Technologies for Broadcast/Senior Colorist Pankaj Bajpai discuss creative requirements and technology drivers, including wide gamuts, more bits, higher spatial and temporal resolution, and more brightness.
Smirnoff reported that Modern VideoFilm is "looking for the highest resolution and the best monitor possible." "We're in the midst of staying on top of high frame rates, especially for 3D," he said. For Clark, one of the most exciting developments is the release of the Sony F65 in January. "We need to pay attention to spatial resolution," he said. "Instead of choosing the right film stock for each project, as we once did, we'll now be picking which digital camera we want to use. The Sony F65 raises the bar with greater sensitivity and low noise."
With regard to wider gamut choices, Bajpai also praised the F65. "At HBO, it was de facto that you shot on 4 perf 35mm, the best in color fullness," he said. "With the loss of film as an acquisition format, we're finally coming full circle. The F65 will let you get very close to film. We won't have to struggle with the limitations we've had before [with digital cameras]." Sony's Mandle noted that, "we're stretching as far as we can to reach P3." "There are huge advantages to XYZ, but it'll be tough to do and take time," he said. "It's a lot of very small steps to get to that point."
Dolby's Admans noted that consumer displays are capable of much brighter content than the devices that produce that content. "At Dolby, we've started working on higher dynamic range," he said. "If you shoot with 14+ stops, it helps to switch to HDR to see you've got details in the black...even though there are no standards." Clark noted that, "because of HDR, we need something on-set to see what we're creating and set a look." "Creatively, we have an expanded palette," he said. "If we're shooting blind...we're not working with 4K versions of the waveframe. We've moved into uncharted territory and it's exciting and scary."
Glassworks Amsterdam have just purchased the cutting-edge 42" Dolby PRM-4200 professional reference monitor for their Baselight grading suite.
Mandle and Admans discussed how it's no longer efficient to devote the entire Digital Intermediate process for output to Digital Cinema, since the content will also end up on the rapidly growing number of tablets, smartphones and other devices. That brought the conversation to the fact that there is no standards for home viewing. Should that be changed?
"That's a conversation over beer," joked Admans. "Content creators work by standards set by SMPTE and EBU. The consumer then watches it in a very different way. There are standards groups working towards a standard, but we're a ways out."
In the audience, cinematographer Bob Primes, ASC praised the Dolby monitor as "emotionally more powerful than a 2K projector." Admans acknowledged that, "recorded and shown with a native 12-bit display, you see an incredible amount of dynamic range and a wide color gamut."
"It's the best of what the Dolby monitor can do within the IIF/ACES structure," said Clark. "But we don't really have a standard to work with. We want to move it higher. Ultra HD (4K broadcast) is being pushed." Mandle noted however, that there has to be a business reason before Ultra Definition will come to fruition.
One important aspect that the symposium highlighted was the different opinions about what it will take to achieve a workable reference monitor. Color space, it appears, is as much an art as a science--and the science behind the parameters to be considered is complicated enough to elude many in the industry.
As a first step towards laying out all the issues, the participants were fascinating, the issues frustrating and the event itself was timely. The bad news is the multiplicity and complexity of the challenges in finding a solution to the reference display conundrum. The good news is that a group of great color scientists, engineers and golden eyes are hard at work on it.