The nandb package gives functions for calculation of molecular number and brightness from images, as detailed in Digman et al. 2008. It comes with an implementation of the novel 'automatic detrending' technique.

References

Digman MA, Dalal R, Horwitz AF, Gratton E. Mapping the Number of Molecules and Brightness in the Laser Scanning Microscope. Biophysical Journal. 2008;94(6):2320-2332. doi: 10.1529/biophysj.107.114645 .