Usage: seuil in.pgm n [n2] out.pgm
Description: If n2 is not present, for each pixel x, out[x] = if (in[x] < n) then 0 else 255
If n2 is present, for each pixel x, out[x] = if (n<= in[x] < n2) then 255 else 0
Types supported: byte 2d, byte 3d, long 2d, long 3d, float 2d, float 3d
Category: arith