Good day Ron!
Is this energy at frequencies above nyquist?
For discrete Fourier transformations the planes must be imagined on a torous or periodically repeated.
Your image data isn’t correctly sampled (Shannon theorem).
This happens if the objects you’ve imaged contain high frequencies and your imaging device doesn’t provide the necessary lowpass.
It may also happen in case of synthetic images that are most often not correctly bandlimited. Think of an image consisting of a single pixel different from zero. Such an image has an infinitely extending Fourier-spectrum.
What you see “spectrally folded in” are so-called alias-components that generally can’t be removed post hoc.
I must admit that I can’t reproduce the Fourier spectrum of the provided image (looks like a photograph of a rotating grating)!
What I get as the log Power Spectrum is: