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Frequency Based
These commands perform Fourier and inverse Fourier transformations of
images. By default, the transformations will automatically convert
images between Fourier to natural orders as expected. For example, 2-D FFT
will transform the points into natural order after the Fourier transform.
Similarly the inverse, 2-D IFFT, will reorder the points from
natural order to Fourier order before applying the inverse Fourier transformation.
As you would expect, images that undergo frequency filtering will be complex-valued
after than filtering. Only the real component is shown by CTSim. However, CTSim does
have options for converting a complex-valued image into a real-valued image via
the Magnitude and Phase filtering commands.
The available frequency-based filtering commards are:
-  2-D FFT
-  2-D IFFT
-  FFT Rows
-  IFFT Rows
-  FFT Columns
-  IFFT Columns
-  2-D Fourier
-  2-D Inverse Fourier
-  Shuffle Fourier to Natural Order
-  Shuffle Natural to Fourier Order
-  Magnitude
-  Phase