Viper bites electronic cinema
Thomson Broadcast camera system adds another option to the tape-or-film debate
By Ken Kerschbaumer -- Broadcasting & Cable, 4/7/2002 8:00:00 PM
Tape or film, tape or film. To date, that has been the decision facing television episodic and movie producers deciding on a medium. But, this week, Thomson Broadcast Solutions is introducing the Viper FilmStream camera, a system that will add another option to the debate: data.
Expected to be available in July, the new camera, in an effort to help electronic cinema more accurately reflect the dynamic range and nature of film, sends data information to a disk recorder. Today's HDTV formats, though making gains and offering cost savings, fall short of bringing all of the qualities of film to electronic production. The camera—minus lens, support gear and recording capability—is expected to cost around $110,000.
"What we're trying to do is map this new digital technology into a similar process that film people are comfortable with," says Jeff Rosica, vice president, worldwide strategic marketing and technology. "And we're trying to give them the same latitude and versatility that they have in film."
The technology was born out of the work done on Thomson's LDK-7000 camera. Rosica says the camera uses three 9.2 million-pixel dynamically managed CCDs, which give the user the flexibility to easily "remap" the sensors to different aspect ratios or resolutions. Typically, such changes are made in signal conversion.
In designing the 7000, though, Thomson's team realized something else.
"It was possible to generate 4:4:4 RGB images that are uncompressed, unfiltered and unencumbered by video processing or other video artifacts," says Rosica. And, by generating 4:4:4 RGB log images, he adds, the camera could more accurately replicate film's dynamic range of blacks and whites (as well as colors) than the HD video formats can.
"At best, those formats are 4:2:2 color-space resolution," he says. "In most cases, they're less than that because of compression, prefiltering and other tricks being done."
Shooting indoors on HD tape and trying to capture action outside a window where it's bright, he says, would be impossible with HD, which would not be able to resolve the extremes in range. But, shot with film, those extremes would be visible, and, in post-production, color correction could be adjusted to make the scene usable. The same capabilities are possible with the Viper.
The camera works by grabbing all the picture information available at the sensors that can fit within the boundaries of the 4:4:4 signals. That 12-bit 4:4:4 linear signal bypasses the video circuitry that typically adds artifacts to the digital images and is sent through digital signal-processing circuits, where it is transformed into a 10-bit log. FilmStream technology then lays that 10-bit log information on a dual-link HD/SDI signal that is sent to the tethered disk recorder. It's recorded there in an uncompressed form.
According to Mike D'Amore, vice president, Thomson Multimedia marketing and business development for Americas and Pacific Rim, the use of 10-bit logarithmic signals instead of 12-bit linear signals allows sampling that puts the bits where they are needed most, giving finer granularity and detail to blacks and highlights.
"You want to be able to put more bits in the black and whites, so sampling is done logarithmically," he says. "The number of bits from 12-bit linear to 10-bit log is the same, and some people say it's equal to 14-bit linear."
Rosica adds that the 10-bit log signal also gives a lot more latitude in post-production.
"Once you set your iris and colorimetry in a video camera, you've pretty much set it," he says. "What we're trying to do is get closer to the film look and performance. You set the f-stop or iris properly and capture information based on that setting, and then, in post, you'll have much more creative latitude than with an HD camera."
The camera offers three operating modes besides FilmStream: an HD RGB signal, an RminusY/BminusY signal, and a straight HD/SDI signal.
The names of the manufacturers of the disk recorders will be announced during NAB. Rosica says the first generation of the camera will be for tethered applications like television episodics or movies.
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