Using a flash with a CMOS image sensor: ERS and GRR modes
by Oleg Dzhimiev
Operation modes in conventional CMOS image sensors with the electronic rolling shutter
Flash test setup
Most of the CMOS image sensors have Electronic Rolling Shutter – the images are acquired by scanning line by line. Their strengths and weaknesses are well known and extremely wide usage made the technology somewhat perfect – Andrey might have already said this somewhere before.
There are CMOS sensors with a Global Shutter BUT (if we take the same optical formats):
- because of more elements per pixel – they have lower full well capacity and quantum efficiency
- because analog memory is used – they have higher dark current and higher shutter ratio
Some links:
- CCD and CMOS Sensor Architecture and Readout Modes (nice pictures)
- Image sensors and shutter related artifacts
- Rolling Shutter (Wikipedia)
So, the typical sensor with ERS may support 3 modes of operation:
- Electronic Rolling Shutter (ERS) Continuous
- Electronic Rolling Shutter (ERS) Snapshot
- Global Reset Release (GRR) Snapshot
GRR Snapshot was available in the 10353 cameras but ourselves we never tried it – one should have write directly to the sensor’s register to turn it on. But now it is tested and working in 10393s available through the TRIG (0x14) parameter.