Robust FFT-Based Scale-Invariant Image Registration with Image Gradients

We present a fast and robust gradient-based scale-invariant image registration technique which operates in the frequency domain. The algorithm combines the natural advantages of good feature selection offered by gradient-based methods with the robustness and speed provided by FFT-based correlation schemes. Experimentation with real images taken from a popular database showed that, unlike any other Fourier-based techniques, the method was able to estimate translations, arbitrary rotations and scale factors up to 6