A system includes an internal combustion engine, an exhaust conduit fluidly coupled to the internal combustion engine and an SCR catalyst, and a reductant doser operationally coupled to the exhaust conduit at a position upstream of the SCR catalyst. The method further includes selecting image objects from the set of image objects whose metadata satisfy filtration criteria so as to exclude those selected image objects from processing and processing a rest of the image objects in the set of image objects. An apparatus for recovering a vascular filter from a blood vessel is also provided that includes a sheath and a retrieval member deployable from the sheath.