Imaging science reference
Signal to noise
When a defensible mean signal-electron count is already known, ideal photon shot noise follows Poisson statistics.
shot-noise standard deviation = √SS is the mean signal in electrons. If independent RMS read noise R is also known, the simplified combined noise is:
The corresponding linear signal-to-noise ratio is:
SNR = S / combined noisePhotoelectrons
If mean incident photon count and quantum efficiency are both defensible inputs, mean photoelectrons can be approximated as photons multiplied by quantum efficiency.
Model limits
These primitives do not derive photon counts from arbitrary images and do not model dark current, fixed-pattern noise, quantization, clipping, demosaicing, denoising, or a full commercial sensor pipeline.