The value of _array_intensities.pixel_fast_bin_size specifies
the number of pixels that compose one element in the direction
of the most rapidly varying array dimension.
Typical values are 1, 2, 4 or 8. When there is 1 pixel per
array element in both directions, the value given for
_array_intensities.pixel_binning_method normally should be
It is specified as a float to allow for binning algorithms that
create array elements that are not integer multiples of the
detector pixel size.