“…The SIR methods incorporate the statistical noise properties of the measurements and the image priors into the reconstruction. In the SIR reconstruction framework, the image prior in the cost function plays an important role in successful image reconstruction (Wang et al 2006, Chen et al 2008, Sidky and Pan 2008, Wang et al 2009, Huang et al 2011, Tian et al 2011, Xu et al 2012, Zhang et al 2013, Liu et al 2014, Niu et al 2014, Geyer et al 2015, Sun et al 2015, Harms et al 2016, Zeng et al 2016a, Zhang et al 2016b, 2016c, 2017c, 2018, Wu et al 2017, Zeng et al 2017). Meanwhile, it is difficult to find appropriate priors for the whole image (Zoran and Weiss 2011).…”