IFDL is meant to be used by people with some knowledge of digital filters and Digital Signal Processing.
IFDL is built into Igor 8.
Adding IFDL to Igor 7 or earlier
IFDL 4 can be added to Igor 7 or earlier by purchasing IFDL separately. Contact firstname.lastname@example.org to purchase this additional software.
IFDL 4 is compatible with Igor Pro 5 or later.