Sony Releases Stacked CMOS Sensor for Smartphones with 48 Effective Megapixels

Re:Sony Releases Stacked CMOS Sensor for Smartphones with 48... by npunt on Tuesday July 24, 2018 @02:50AM (#17598660)

I forgot the specific term that describes this, but basically each pixel on a sensor is going to have a threshold for whether it activates (much like a neuron's action potential). Say its 20 photons. If it gets less than that, it is unable to see anything at all. Meanwhile a larger pixel will see something because it will be able to capture more than 20 photons in a given unit of time. On the other hand, the aggregate of several smaller pixels across many sensors will each fail to reach that threshold and thus see nothing.

The L16 has some low light and dynamic range problems, I believe owing to this very situation.

[ Parent | on HN ]

Re:Sony Releases Stacked CMOS Sensor for Smartphones with 48... by dperfect on Tuesday July 24, 2018 @03:20AM (#17598794)

I believe the term you're looking for is reciprocity failure[1] (or schwarzschild effect), though apparently it doesn't happen with digital sensors - only film. Noise becomes an issue in similar situations, but it's not affected by the number of photons hitting the sensor.

Correction: Shot noise[2] is related to the number of photons hitting the sensor.

[1] https://en.wikipedia.org/wiki/Reciprocity_(photography)#Reci...

[2] https://en.wikipedia.org/wiki/Shot_noise

[ Parent | on HN ]

Re:Sony Releases Stacked CMOS Sensor for Smartphones with 48... by theoh on Tuesday July 24, 2018 @03:22AM (#17598806)

You might be referring to the dark current, which is the noise floor for any signal coming out of the CCD. There doesn't need to be an activation threshold of a particular number of photons (maybe there is, though?) for the dark current to reduce your signal to noise ratio.

[ Parent | on HN ]