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. Author manuscript; available in PMC: 2021 Jan 1.
Published in final edited form as: IEEE Trans Comput Imaging. 2020 Sep 11;6:1375–1388. doi: 10.1109/tci.2020.3023598

Fig. 2.

Fig. 2.

Illustration of the difference between the directly calculated difference matrix Dn and the implicitly calculated basis matrix Ωn (the rank r was set as 13). (a) One frame (#13) of the normal-dose reference PCT (upper) and the low-dose simulations (lower). (b)-(c) Corresponding difference matrices of frames in (a), where D1 and D3 are obtained by directly calculating along the spatial height and temporal dimensions, respectively. (d) Illustration of two typical column vectors (reshaped to be the size of Nh × Nw for visual observation) in the basis matrix Ω1 calculated upon D1. (e) Illustration of the two typical column vectors in the basis matrix Ω3 calculated upon D3.