for multiple persons
Yanni Yang, Jiannong Cao, Xiulong Liu, Xuefeng Liu "Multi-Breath: Separate Respiration Monitoring for Multiple Persons with UWB Radar" in Proc IEEE 2019
L. Xu, C. Lu, Y. Xu, and J. Jia, “Image smoothing via l0 gradient minimization,” ACM Transactions on Graphics (TOG), vol. 30, no. 6, p. 174, 2011.
(https://github.com/gionuno/l0_gradient_minimization)