Fourier Tansform Resources

http://homepages.inf.ed.ac.uk/rbf/HIPR2/fourier.htm

NASA !
http://idlastro.gsfc.nasa.gov/idl_html_help/Transforming_Between_Domains_with_FFT.html

Paul Bourke
http://paulbourke.net/miscellaneous/imagefilter/

"...We have some news to share with you about our plans for introducing fixes faster, but that will have to wait a month or so..." Autodesk.