Noise Reduction

Record sensor temp alongside raw, apply different noise compensation depending on temp in post.

A Peltier can help build the profiles - by heating and cooling to a range of temperatures as needed.

Fixed Pattern Noise

General explanation: http://en.wikipedia.org/wiki/Fixed-pattern_noise

AXIOM Alpha measurements:

C0 + C1 * exposuretime

C0: Constant component of dark frame energy. The non-uniformity across columns is probably due to each ADC response.

C1: Exposure dependant component of the dark energy. If all pixels are read in parallel, the non-uniformity across rows might come from temporal variation of thermal noise. But why is it exposure dependant ?

Images generated by https://github.com/Matthias-Fauconneau/serenity/blob/master/calibrate.cc using http://files.apertus.org/AXIOM-Alpha/darkframe-*.raw16.xz