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An Idl/Envi Implementation Of The Fft Based Algorithm For Automatic Image Registration, Hongjie Xie, Nigel Hicks, George R. Keller, Haitao Huang, Vladik Kreinovich

Departmental Technical Reports (CS)

Georeferencing images is a laborious process so schemes for automating this process have been under investigation for some time. Among the most promising automatic registration algorithms aare those based on Fast Fourier Transform (FFT). The displacement between the two given images can be computed by computing the ratio F1*conj(F2)/|F1*F2|, and then applying the inverse Fourier transform. The result is an impulse-like function, which is approximately zero everywhere except at the displacement that is necessary to optimally register the images. Coverting from rectangular coordinates to log-polar coordinates, shifts representing rotation and scaling can be also determined to complete the georectification process. …