Elphel Development Blog

Using a flash with a CMOS image sensor: ERS and GRR modes

Operation modes in conventional CMOS image sensors with the electronic rolling shutter

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.

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Elphel presenting at ORCONF 2016, An open source digital design conference

On October 8th, 2016 Andrey will be presenting his work on VDT – Free Software Environment for FPGA Development at an open source digital design conference, ORCONF 2016. ORCONF 2016