PSD2

fft_psd_tools.PSD2(image, image2=None, oned=False, fft_pad=False, real=False, imag=False, binsize=1.0, radbins=1, azbins=1, radial=False, hanning=False, wavnum_scale=False, twopi_scale=False, **kwargs)

Two-dimensional Power Spectral Density. NAN values are treated as zero.

image2 - can specify a second image if you want to see the cross-power-spectrum instead of the

power spectrum.

oned - return radial profile of 2D PSD (i.e. mean power as a function of spatial frequency)

freq,zz = PSD2(image); plot(freq,zz) is a power spectrum

fft_pad - Add zeros to the edge of the image before FFTing for a speed

boost? (the edge padding will be removed afterwards)

real - Only compute the real part of the PSD (Default is absolute value) imag - Only compute the complex part of the PSD (Default is absolute value) hanning - Multiply the image to be PSD’d by a 2D Hanning window before performing the FTs.

Reduces edge effects. This idea courtesy Paul Ricchiazzia (May 1993), author of the IDL astrolib psd.pro

wavnum_scale - multiply the FFT^2 by the wavenumber when computing the PSD? twopi_scale - multiply the FFT^2 by 2pi? azbins - Number of azimuthal (angular) bins to include. Default is 1, or

all 360 degrees. If azbins>1, the data will be split into [azbins] equally sized pie pieces. Azbins can also be a numpy array. See AG_image_tools.azimuthalAverageBins for details

radial - An option to return the azimuthal power spectrum (i.e., the spectral power as a function

of angle). Not commonly used.

radbins - number of radial bins (you can compute the azimuthal power spectrum in different annuli)