Edited by author 10-09-2006 08:35 PM
Just in case someone stumbles on the term "quadrature pair" and looks here first, here's an excerpt from Freeman, 1991 (just what I happened on first when looking to refresh my memory - a pretty good tutorial on Gabor filters in general can be found at our own http://mplab.ucsd.edu/tutorials/pdfs/gabor.pdf).

"Consider two filters, identical except shifted in phase from each other by 90 degrees. The filters are called a quadrature pair..."
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