4 ms·

I've wondered if rolling shutter could be (ab)used as a poor man's one-dimensional high speed camera. Depending on the framerate, resolution and exposure time,

by kmm 6y ago

I've wondered if rolling shutter could be (ab)used as a poor man's one-dimensional high speed camera. Depending on the framerate, resolution and exposure time, wouldn't you be able to get hundreds of thousands of frames per second, at the cost of having no vertical resolution. I'm not sure what it'd still be useful for with those limitations. Maybe estimating the speed of fast moving objects, or global phenomena like vibrations.

jacobush 6y ago
Definitely. There are programs for the Raspberry Pi cameras which do just that. Up to 1000fps IIRC
- detaro 6y ago
  I don't think they really make use of rolling shutter, they just configure the camera differently? (which is basically limited by the rate of pixels transferred - if you reduce the resolution, more images per second fit down the data transfer channel)
  - jacobush 6y ago
    I think they make use of the fact that individual lines are updated on the camera by the light and can subsequently be read out. If it were a camera with global shutter, chances are it could not be configured to update lines as fast indivually. A global shutter design copies each pixelsite or line into an indiviual buffer when the "shutter" signal is triggered. This happens in parallell. I'd say these high framerates on Raspi cameras definitely is an artefact of the rolling shutter design in these cameras. Maybe one could get even higher framerates by hooking the analog part (or very close thereafter) of the rolling shutter camera up to something else, but I don't see how.
  - blattimwind 6y ago
    Correct, a CMOS sensor with a rolling shutter looks and handles a lot like a piece of DRAM. Pixels are arranged in rows and colums; capturing a frame works just like a sequential read through a DRAM array. The nominal frame-rate at a given resolution is set by the read-out speed of the array, so reducing resolution increases speed almost linearly.

by kmm 6y ago

jacobush 6y ago

Definitely. There are programs for the Raspberry Pi cameras which do just that. Up to 1000fps IIRC

detaro 6y ago
I don't think they really make use of rolling shutter, they just configure the camera differently? (which is basically limited by the rate of pixels transferred - if you reduce the resolution, more images per second fit down the data transfer channel)
- jacobush 6y ago
  I think they make use of the fact that individual lines are updated on the camera by the light and can subsequently be read out. If it were a camera with global shutter, chances are it could not be configured to update lines as fast indivually. A global shutter design copies each pixelsite or line into an indiviual buffer when the "shutter" signal is triggered. This happens in parallell. I'd say these high framerates on Raspi cameras definitely is an artefact of the rolling shutter design in these cameras. Maybe one could get even higher framerates by hooking the analog part (or very close thereafter) of the rolling shutter camera up to something else, but I don't see how.
- blattimwind 6y ago
  Correct, a CMOS sensor with a rolling shutter looks and handles a lot like a piece of DRAM. Pixels are arranged in rows and colums; capturing a frame works just like a sequential read through a DRAM array. The nominal frame-rate at a given resolution is set by the read-out speed of the array, so reducing resolution increases speed almost linearly.