Figure 2

The frequency expanded process. (a) The Fourier intensity with Nyquist size, (b) the Fourier intensity of the rectangular window with Nyquist size, (c) the normalized Nyquist frequency, (d) the preliminary expanded Fourier frequency, (e) the Fourier intensity of the rectangular window with 3 times Nyquist size, (f) the final expanded Fourier intensity.