July 08, 2013 9:49am PT by Adrian Pennington
Arri's Managing Director: HD Is 'Dumbed Down' to Make 4K Look Good
Arri's managing director Franz Kraus has called into question the industry's inexorable push toward 4K by suggesting that HD content displayed on HD screens at equipment trade shows is not being shown at its optimum quality in order to compare unfavorably with 4K displays.
“What annoys me, more than being asked about whether we are launching a 4K camera, is that at trade shows, HD quality is often being dumbed down, or not presented to its optimum quality, in order to make Ultra HD 4K look good,” Kraus said. “This is a bad trick because consumers will buy 4K displays based on the false expectation that the image is really that superior to HD.”
He argued, “The perception of picture quality has a lot to do with the physical performance of the display. For example, a 2K image displayed on an HD OLED monitor looks incredible because the active light source shows far higher contrast ratios in the picture.”
Arri, maker of the popular Alexa digital cinema camera that has been used to shoot features from Skyfall to Life of Pi, has long questioned the value of 4K photography to cinematographers who it says view exposure latitude, highlight handling and natural skin tones as more important than just resolution. “Resolving fine detail is a quality attribute which we do not deny, but we want to develop a camera that continues to deliver high dynamic range as well as greater resolution,” Kraus said.
The successor to the Alexa, which is in Arri's labs, will feature at least 4K resolution, at least 14 stops of dynamic range, and high-frame-rate capability, according to Kraus. “We are working on technology that will offer a higher spatial resolution but also pushing hard in terms of a higher temporal resolution, without sacrificing the dynamic range we can already deliver,” he said. “We don't want to produce one camera that has high contrast and another with high detail.”
The technical challenge is attempting to get all the attributes into the same product without trading off one against another.
“I believe [Japanese broadcaster] NHK has done quite a good job in developing Super Hi-Vision [an 8K format] at 120fps so it is possible to capture the finest detail in motion without decaying the image,” Kraus said.
“If you produce very high resolution images with no motion blur, it is then possible to apply extremely efficient compression technology, so in distribution you end up with decent data rates. The problem is transporting and processing the massive amount of data from the camera and throughout post.”
Nor is there a need to remain wedded to a 35mm-size sensor, which is used with numerous existing digital cinema cameras.
“With a larger sensor you can use 35mm cine lenses and need only expose a smaller portion of the image, but you can capture more information through the lens. There are so many options, but none of them come for free,” Kraus said.
Kraus declined to give a release date on the company's new camera, but he did reveal that Arri's original roadmap for the Alexa contained an upgrade to 4K that was sidelined in favor of concentration on dynamic range.
“The Alexa camera family concept had initially included a 4K-plus sensor version to be launched approximately one year after the introduction of the first Alexa. But the outcome of an intensive feasibility study more than two years ago showed that we would sacrifice dynamic range for resolution, so we decided not to proceed,” he explained.
He added: “There are products and companies leaning more toward spatial resolution. This offering was available already, so we chose to go for greater dynamic range rather than detail at that time. We believe that the most distinctive image characteristic is contrast, and after that it is really a question of whether we need to increase temporal resolution if we aim for higher spatial resolution than 2K.”