[erdewit]

This is dealt with by smoothing the spectrum in a way to preserves the power density. The constructive and destructive interference then cancel each other out.

[Gracana]

What does "smoothing the spectrum" mean? What operations are being performed?

[danuker]

I'd guess: Fourier transform, a power density preserving blur convolution, then inverse Fourier transform.

But I am not familiar with the field of signal processing.