Program sflight | Apply 2-D directional high-pass to highlight data.
[SYNOPSIS]
sflight < in.rsf > out.rsf ax=1. ay=1. eps=0.
[PARAMETERS]
float   | ax | =1. |   | 	x direction 
float   | ay | =1. |   | 	y direction 
float   | eps | =0. |   | 	highpass filter parameter; if eps=0, apply derivative 
[DIRECTORY]
user/gee
