Syntax:
set terminal imagen {<fontsize>} {portrait | landscape} {[<horiz>,<vert>]}
where fontsize defaults to 12 points and the layout defaults to landscape.
horiz
and
vert
are the number of graphs in the horizontal and
vertical directions; these default to unity.
Example:
set terminal imagen portrait [2,3]
puts six graphs on the page in three rows of two in portrait orientation.