Synopsis
		sfprestolt < in.rsf > out.rsf inv=n depth=n stack=y nh= dh= vel= pad=nt extend=4

Parameters
		bool depth=n [y/n] y: depth migration, n: time migration   float dh= offset sampling   int extend=4 trace extension   bool inv=n [y/n] y: modeling, n: migration   int nh= number of offsets   int pad=nt padding on the time axis   bool stack=y [y/n] if y: stack migrated image   float vel= constant velocity