Live FFT

Get interactive fast Fourier transform (FFT) from a subset of a Signal2D using RectangularROI.

import hyperspy.api as hs
import numpy as np

Create a signal:

s = hs.data.atomic_resolution_image()

Add noise to the signal to make it more realistic

s.data *= 1E3
s.data += np.random.default_rng().poisson(s.data)

Create the ROI, here a RectangularROI:

roi = hs.roi.RectangularROI()

Slice signal with the ROI. By using the interactive function, the output signal sliced_signal will update automatically. The ROI will be added automatically on the signal plot.

s.plot()
sliced_signal = roi.interactive(s, recompute_out_event=None)

# Choose the second figure as gallery thumbnail:
# sphinx_gallery_thumbnail_number = 2

Get the FFT of this sliced signal, and plot it Apodization is used to smoothen the edge of the image before taking the FFT to remove streaks from the FFT - see the Fast Fourier Transform (FFT) section of the user guide for more details:

s_fft = hs.interactive(sliced_signal.fft, apodization=True, shift=True, recompute_out_event=None)
s_fft.plot(power_spectrum=True)