[CLEAN\]STATISTIC [Clean|Dirty|Residu] [Plane] [/WHOLE]
Compute some basic statistics (min, max, mean, rms,...) on the specified
buffer (default: clean) and plane (default: variable FIRST). The current
polygon (see command SUPPORT) is used to define the area on which the
pixels are to be taken into account. With option /WHOLE, the whole image
is considered.