Up: Image Analysis Tasks
This is a simple task that subtracts a plane from an image. The plane
is determined by least square fitting through all non-blanked pixels of
the original map, weighted by a weight image. The latter can be used to
account for a non uniform signal to noise ratio, but is more frequently
used to ignore some areas (typically the sources) in the fit.
It supersedes an older obsolete version (still available as PLANE_OLD)
which fitted a plane through 3 points of the input image.