I'm having similar issues understanding the relationship between full well capacity and gain as shown in this question here: Reconciling gain (e/ADU), full well capacity and ADC bit depth

The difference here is that rather than having 'extra electrons' being accumulated after saturation, I seem to have more gray levels available.

My camera is a FLIR Blackfly 200S6M, the EMVA 1288 performance is found here: http://softwareservices.flir.com/BFS-U3-200S6/latest/EMVA/EMVA.html

According to the specs, the system gain is 0.24 (e^-/ADU). Given the 12-bit ADC, I calculate that it takes 17,062.5 electrons to reach full well.

The listed saturation capacity in electrons, however, is listed at 14,837, quite a bit fewer than ADC saturation.

Am I overlooking something?

  • What photographic problem are you trying to solve? That is, what kind of photo are you attempting to produce? – Michael C Sep 12 '20 at 21:32
  • There's no rule that says every single 12-bit value must be used. If one desires more discrete digital values than what 11-bit would allow, one must use 12-bit with twice as many discrete values available. That doesn't mean one must use every single one of those available 12-bit numbers. – Michael C Sep 12 '20 at 21:41
  • I'm trying to model the image chain of this camera. I'm struggling to follow your example. I've played around quite a bit with this camera and certainly run the gamut of the 12 bits, from ~0 to 4095. – B. Erickson Sep 12 '20 at 23:43

The datasheet states that the sensor has a DR capability of 11.93bit which is less than the 12bit accuracy/capability of the ADC. I.e. it is not using all of that 12bit conversion, but 12bit is required. And it will be stuck into a file format that can accept 16bit because that is also required; but it will still be 11.93bit (max).

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