This module computes the histogram of a Fimage.
The histogram is given in the Fsignal type.
It counts the number of pixels having a value belonging to a certain
cell (interval) of a uniform grid.
The size and the position of these cells can be specified in different
ways using all combinations of the options. The \verb+-t+ option tells
whether the values outside the specified interval should be ignored or
counted on the boundary cells. A weight image can be specified with
the \verb+-w+ option; in that case, each cell will sum up the weights
of its associated pixels instead of simply counting the number of its
associted pixels. In other terms, the default behavior (no \verb+-w+
option) is equivalent to a constant weight image $w(x,y)=1$.
\index{histogram!of an image}





