New directions in HDR


Senior Member
HDR or High Dynamic Range video will be the new battleground for the next few years as consumers remain unmoved on the resolution war.
While it is difficult to see the between 4K vs 6K vs 8K, dynamic range fidelity is much more perceptible and adds value to any production.
Improving the dynamic range of sensors will add convenience, time and cost savings to shooters. Conversely, ramping up resolution only adds to mounting cost for storage, computational power and higher resolution monitors.
With improved dynamic range, less energy, time, manpower, and gear will be required to achieve optimal exposure for each shot.
For example, in backlit situations, less light is required to fill in the shadows if there is more latitude in the sensor.
Currently, the only way to improve dynamic range is to shoot in LOG mode.This is fine for narrative, documentary work. But for today's social media, immediacy often means no time for color correction or extensive post-processing.

Enter HDR.

In the early years, Magic Lantern offered a way for Canon owners to shoot alternate frames of a movie clip at 2 different exposure values. A video processing software than separates the even numbered frames from the odd numbered frames to create 2 identical clips (but at different EVs) Computational masking then recombines the 2 clips to retain details in the shadows yet preventing blow-outs in the highlights.

This workaround, although ingenious, has it limitations. Ghosting becomes apparent when the travelling matte tries to catch up with a moving subject.
The holy grail of true HDR video is a a sensor that could selectively assign ISO to to different parts of the same scene.
The new Sony Quad Bayer sensor technology and Canon's Dual Gain Output sensor are the among world's first commercial deployment of a new HDR strategy.

Quad Bayer Sensor
Quad bayer sensors can be found in this year's crop of video devices. The Mavic Air 2 and the latest sony smartphones are some of the early adopters of Quad Bayer Sensors.
In a Quad Bayer sensor each pixel consist of 4 photosites capable of capturing at two exposures within each quad-sites. So far, the implementation of Quad Bayer sensor has been limited to sub1" sensors. But with improved imaging engine, we could eventually see full frame Quad Bayer sensors in Sony cameras in the near future.

Dual Gain Output

Canon takes advantage of the dual native ISO of older sensors in a novel way. Instead of selecting between 2 base ISOs, The new Canon C300 m3 sends data from each pixel via two different pathways with different gain. This strategy is highly processor intensive so it can only be used in a 2K Super 16mm Crop mode at up to 112fps.

Evidently, both Quad Bayer and Dual Gain Output technology are in their nascent stages throttled by limitations in processing power. But even at their current small sensor deployment status, we can still see the clear advantage of HDR over camcorder-ish aesthetics that used to plague small sensor cameras.