Background-Peak-Background integration.
Originally from one dimensional profiles with a peak in the
middle and background at the left and right side of the peak.
The bpb method is used in eval14 for determining the quality of
the background. The available data are stored in a box with
dimensions Nhor,
Nver and Nrot.
Now one could do a bpb integration along Nrot on all
Nhor*Nver rows of pixels.
And in a similar way along Nhor and
Nver.
Every row can be considered as a one dimensional profile. For each of
the directions we determine the Nleft,
Nright
and Npeak as well as
Sleft, Sright and
Speak.
If BgQuality exceeds the value of badbg the
reflection will be flagged B to signal a suspect background.
Sometimes the values of Nleft or
Nright are zero. The one-dimensional profile
has no head or tail. The net-intensity cannot be determined. The
number of such one-dimensional profiles will be printed between
brackets. If the number of missing profiles exceeds the value
of badbgallowedmis the intensity of the
corresponding intensity is not used in the determination of the
background quality. If only one projection can be evaluated, the
background quality cannot be determined. The reflection will be
flagged UnknownBackground.
The procedure for the plane intensity
is used to determine the net intensity. What about sigma?
One way is to use the formulae given in the bpb
paragraph (assuming the pixel values are real counts (and this
assumes the gain in the boxfile
is correct)).
The value thus calculated is called SigmaPoisson.
If pixels are excluded from the background, you probably
should remove some pixels from the peak (you would
actually see those pixels if the intensity of the peak was zero).