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. Author manuscript; available in PMC: 2017 Nov 11.
Published in final edited form as: IEEE Trans Image Process. 2016 May 11;25(7):3303–3315. doi: 10.1109/TIP.2016.2567072

Fig. 2.

Fig. 2

Illustration of the multi-level CCA scheme (with two levels shown as example). Filled patterns denote L-PET patches and unfilled patterns denote S-PET patches. A pair of L-PET and S-PET patches are indicated by the same color. A coarse reconstruction in the first level (top) is used to select the refined subsets of dictionaries. At this stage, the dictionary atoms that contribute more in reconstructing the test patch are selected. The estimation in the second level (bottom) is more accurate thanks to the improved mapping and reconstruction using the refined dictionaries. Best viewed in color.