Figure 12
Comparison of two sinograms of Fly after different denoising procedures. Top to bottom: noisy sinogram Z; Münch et al. (2009); Vo et al. (2018); proposed procedure based on BM3D denoising. Although Vo et al. (2018) is very effective at removing streaks, it also considerably affects the sinogram features; note, for example, the considerably weaker bold diagonal line (indicated by the first arrow) compared with the other algorithms. Both Münch et al. (2009) and Vo et al. (2018) also distort larger areas of the sinograms, as pointed out by the second arrow; these problems are absent from the BM3D-based result. Although not visually obvious here, the differences cause severe artifacts in the tomograms, as can be seen in Figure 13. |