Ringing artifacts
Ringing is an image artifact that may appear when Doing Deconvolution under certain conditions. It produces dark and light ripples around bright features of an image.
Inverse filtering techniques like Wiener Filter suffer specifically from ringing artifacts. The Huygens software does not apply such techniques at all.
The source of ringing is usually conversion of a discontinuous signal into or out of Fourier space. A number of related issues can produce signal discontinuities and therefore contribute to ringing. Discontinuities can occur at the edges of the image or of subvolumes of the image or even at the edges of bright features (Figure 3). Another source of discontinuities is inadequate spatial sampling of the raw image or point spread function, a noisy image or point spread function, and a point spread function shape that is inappropriate to the image.
Image and quote from the deconvolution artifacts article (W. Wallace, L.H. Schaefer & J.R. Swedlow) at the Olympus Microscopy Resource Center.