Shooting pictures in RAW gives DSLR users the opportunity to
fine-tune their settings, by potentially controlling every step
of the RAW conversion. Users often assume that RAW images are
directly output from the sensor without any additional
processing, but is this really the case? What kind of processing
can be applied and what kind of influence does it have on the
final image? Most noise occurs at the pixel level and can be
considered as statistically white (meaning that each individual
pixel’s noise is independent from other pixels’ noise) and
identically distributed. However, there is another kind of
noise, usually less common, that violates this “statistically
white” rule. It is noise due to irregularities on the sensor,
and thus has a fixed position. Because different sizes of
transistors are shared by all the pixels in a single row or a
single column, all the pixels of a row (or column) might be
slightly too bright or too dark. This is called row or column
noise. It is often possible to correct it by l