Incorporate a background subtraction step

[gsganden]

E.g. cluster empty images, and for each new image identify the closest cluster and apply standard background detection techniques. Could use as a preprocessing step for a classifier or to highlight areas for manual inspection in a GUI.

[gsganden]

One challenge is that the cameras sometimes get jostled and the background sometimes changes, e.g. because a tree falls down. Clustering may or may not address these issues. Image stitching techniques could also be useful.