Ring artifact reduction via multiscale nonlocal collaborative filtering of spatially correlated noise

Mäkinen, Y.; Marchesini, S.; Foi, A.

doi:10.1107/S1600577521001910

Journal of Synchrotron Radiation Journal of
Synchrotron Radiation

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Figure 8
A fragment of Z₀ of Fly and the corresponding $[{Z_{0\,}{\bigcirc\kern-8.5pt\ast}\,\,{g_{{\rm{d}}}}}]$ (top), and a fragment of Z^*₀ with the corresponding $[{Z^{\,*}_{0\,}{\bigcirc\kern-8.5pt\ast}\,\,{g_{{\rm{d}}}}}]$ (bottom). For $[{Z_{0\,}{\bigcirc\kern-8.5pt\ast}\,\,{g_{{\rm{d}}}}}]$ and $[{Z^{\,*}_{0\,}{\bigcirc\kern-8.5pt\ast}\,\,{g_{{\rm{d}}}}}]$ , 50%-gray pixel color in the figure corresponds to value 0 in the data. Note how most of the signal of the sinogram fragments is not present in the convolved arrays, facilitating the estimation of the streak noise statistics. Although $[{Z_{0\,}{\bigcirc\kern-8.5pt\ast}\,\,{g_{{\rm{d}}}}}]$ and $[{Z^{\,*}_{0\,}{\bigcirc\kern-8.5pt\ast}\,\,{g_{{\rm{d}}}}}]$ look very similar, careful visual inspection reveals slight differences similar to those between $[{\eta\! = \!\eta_{k}}]$ in Figure 1