lentil.detector.dark_current

lentil.detector.dark_current(rate, shape=1, fpn_factor=0, seed=None)[source]

Create dark current frame

If applied, dark current fixed pattern noise (FPN) is modeled by a log-normal distribution [1], [2] with mean = 1.0 and sigma = fpn_factor where rate = rate * FPN.

Parameters

  • rate (int) – Dark current rate in electrons/second/pixel

  • shape (array_like or 1) – Output shape. If not specified, a scalar is returned.

  • fpn_factor (float) – Dark current FPN factor. Should be between 0.1 and 0.4 for CCD and CMOS sensors [1].

  • seed (None, int, or array_like, optional) –

    Random seed used to initialize numpy.random.RandomState. If None, then RandomState will try to read data from /dev/urandom (or the Windows analogue) if available or seed from the clock otherwise.

    Warning

    Be aware that if fpn_factor is nonzero and a seed is not provided, the fixed pattern noise will be different each time dark_current is called.

Returns

dark – Dark current frame

Return type

ndarray

References

[1] Log-normal distribution - Wikipedia

[2] Janesick, J. R., Photon Transfer, Vol. PM170, SPIE (2007)