In the article of Maxim Shatsky et al. entitled "A Method for the Alignment of Heterogeneous Macromolecules from Electron Microscopy" (J Struct Biol. 2009, 166(1): 67–78. doi:10.1016/j.jsb.2008.12.008.), the authors show that pure noise images aligned to a reference image give an average image resembling the reference. This is a perfect example of the model bias occurring during the 2D classification step. Let's do it!!!
