<p>A screenshot for use in the tutorial <a href="//commons.wikimedia.org/wiki/Commons:Cleaning_up_interference_with_Fourier_analysis" title="Commons:Cleaning up interference with Fourier analysis">Commons:Cleaning up interference with Fourier analysis</a>.
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It's Gimp running on GNU/Linux Ubuntu, they are all free software and there is no copyright on it. I took this screenshot by myself.
No machine-readable author provided. <a href="//commons.wikimedia.org/wiki/User:Alejo2083" title="User:Alejo2083">Alejo2083</a> assumed (based on copyright claims).
No machine-readable source provided. Own work assumed (based on copyright claims).