>>2709250It's not. You can read the paper he put out a few years before the camera came out.
Imagine you've got rack of tubes in front of your sensor.
Each tube is pointing at its own pixel, in goups of 9, middle one pointing ahead, all the others fanned out slightly.
Only the light going straight down each tube hits that pixel, there isn't any stray light coming in from somewhere else.
This means the final image is much lower res than your sensor but you have control over what light included in the image.