American Cinematographer - February 2010 - 63

This illustration details a small section of a Bayer pattern, which the Red One’s Mysterium sensor utilizes to derive its color information. Note that for every square fourphotosite cluster within this scheme, there are two green photosites for every single red and blue photosite. De-Bayer processing is therefore required to derive RGB data values. Bayer-pattern imagers incorporate a unique system to derive RGB color information in order to form an image. In this chip architecture, the sensor is laid out with groups of four adjacent color receptors: two green photosites are arranged diagonally and are flanked by individual red and blue photosites. This sort of checkerboard pattern is repeated across the entire sensor. (See illustration above.) Color information for a specific region of the image must therefore be interpreted by de-Bayer-processing the green “pixel” photosites group with their adjacent red and blue photosites to calculate a cumulative RGB value. Put more plainly, with a Bayer pattern, each photosite on the sensor does not represent an individual RGB value of color information. Just how this color-receptor scheme translates into effective resolution can lead to confusion when comparing it to other sensor technologies with different resolution designations. For this reason, it is difficult to compare resolution properties of a 4K Bayer-pattern camera to a camera that derives data from oversampled pixels or from a sensor that utilizes co-sited photosites, individual photosites that feature separate RGB “co-sites” to yield a true one-to-one pixel-to-RGB value. It’s true that the Bayer-pattern “In the real world, the only way the Mysterium could deliver true 4K resolution would be if the sensor were used as a monochrome chip.” information that comes from the Red One’s sensor is technically 4K data, but in the real world, the only way the Mysterium could deliver true 4K resolution would be if the sensor were used www.theasc.com as a monochrome chip, delivering a black-and-white picture. In that scenario, each photosite sample would be discrete and would not be averaged with any adjacent photosite data; every photosite would contribute discretely to the overall resolution. Unfortunately, with a Bayer-pattern imager, each photosite on the sensor does not generate an RGB value. And because a Bayer-pattern sensor must use color information from at least four adjacent photosites to derive a single RGB value, it is necessarily true that the effective resolution derived from the 4K Bayer data is less than 4K. The cinematographer’s goal with any format is to use it to the best of its capabilities and capture as much information and latitude as possible. With that in mind, I state that the Red One should only be used in the highestresolution setting possible for a given shooting scenario. The system does allow you to record in a number of lower resolutions, and with different degrees of compression, but to do so is to step onto a very slippery slope. Let’s suppose for a moment that you’re hired to shoot a job whose end result is standard high-definition February 2010 63

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American Cinematographer - February 2010

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