Back to the Future: 4K Technologies Produce Better High Definition
4K/Ultra HD makes for great buzz at trade shows, and the debate around its full arrival to consumer homes is solid water-cooler fodder. What’s often overlooked, however, is just how much 4K technologies are already improving current HD.
To understand its true impact, one needs to trace back to the advent of HD, when camera manufacturers made some compromises in image resolution in developing acquisition devices. Even though a 1080-line HD TV has 1920 pixels across the line, HD cameras captured only 1440 pixels, effectively throwing away one-third of the image resolution.
How were they able to get away with such a massive cutting of pixels? According to Mark Schubin, a technology consultant and writer of the popular media-technology blog The Schubin Café, it was a sharpness issue. Major loss in resolution does not equal a loss in sharpness of the image.
“Nobody watches a television and says. ‘Oh, what wonderful resolution that has,’” said Schubin during a panel discussion at Content & Communications World earlier this month. “But they might say, ‘Oh, that’s a sharp picture.’ Sharpness, like any word that ends in -ness is subjective, and it’s proportional to two things: both the resolution and the contrast ratio.”
Fast-forward to today, and 4K cameras and lenses have brought those lost pixels back into the HD environment, greatly increasing contrast ratio. Larger sensor sizes have paid dividends for major content creators that have invested in 4K acquisition gear.
Turner Sports is one of many sports broadcasters that have toyed with 4K tools, not just in isolated live tests but as active pieces of their primary HD broadcasts in postproduction.
“When HD came about and we all wholesale went over to the 2/3-in. sensor, our creative people really felt the loss of that,” said Tom Sahara, VP, operations and technology, Turner Sports. “They like the look of having a large format. 4K has brought that back. When you see the video, it really does have that look again of film, and the subtle details are captured in the larger sensor.”
In production of feature pieces, Sahara’s Turner teams have used Sony and Canon cameras and have found that the extra pixels give the ability to pan and scan within the image during editing. It frees the editor from being locked in to just what the camera operator feeds.
“Our DPs are told to shoot a little looser,” he said. “Because of the big sensor, we get very shallow depth of field so we can get a very cinematic look, which was very difficult to get with 2/3-in. So now we’re back to Super 35mm, and we get a nice, big image. The sensitivity is good, so we can shoot in a lot more light with good contrast ratio and really bring back that film look.”
Although 4K elements in live production are still very limited, broadcasters like Fox Sports have found a valuable place for the greater resolution in super zooms and slow-motion replays.
“No matter how great your cameraman is, he’s never going to have everything framed perfectly in something like football, which is very high motion,” said Clyde Smith, SVP, new technology, Fox Network Center. “So the ability to extract and zoom and see that puff of chalk when the foot touched the line that in hi-def just wasn’t there, that really makes a difference.”