I imagine their interest in parallel channels is partly to avoid any motion artifacts where the visible image and the mask channel would diverge between the sample intervals. I think this is why sub-pixel color filters have won out over filter-wheel cameras in general, i.e. where a monochrome sensor reads the R, G, B fields in sequence.
But given that it comes from Netflix, it is probably also constrained by wanting to work with commodity cameras and optics. It seems they would want techniques that can scale to many productions at once with low marginal cost.
you will get 'rainbow' artifacts during motion like you get in DLP projectors when you move your eyes. You'd need an incredibly high framerate to get a small enough motion between frames (and thus, a very expensive camera and a lot of light).
I don't think that is true. MKBHD just came out with a video demonstrating using a video wall that updated in sync with the camera frame rate. Allowing two cameras to see different backgrounds, e.g. two different colors or even two different images, as the demo was showing a parallax effect.
Actually, checking the paper, they tested that - reducing the shutter speed, realigning nearby frames and adding motion blur.
As a vfx compositor, while I’d be OK with this workflow, it doesn’t come without their own issues and artifacts.
Thanks for looking at the paper. It forced me to go read it:
"We address this by increasing the repeating rate of the two lighting
conditions at 72HZ, so that the lighting changes from one color to
the next every 144th of a second. The lighting then appears nearly
constant, with a remaining effect being that rapidly moving objects
leave a trail of magenta/green outlines when seen against the screen,
as in Figure 6 (bottom)."
"The remaining drawback of time-multiplexing in this manner
is that the shorter shutter angle reduces the amount of motion
blur, which is considered desirable for cinema."
Interesting that the complaint is that it reduces motion blur.
It seems like you could create 1 frame green, 1 frame magenta, and n frames normal and still pick up the data you need.