deletions | additions       diff --git a/Introduction.tex b/Introduction.tex  index 431ff56..c5c23c1 100644  --- a/Introduction.tex  +++ b/Introduction.tex 
...
A characteristic feature of the photon counting imaging technique is the possibility of calculating the true position of a photon event that covers several pixels with subpixel accuracy - a processes termed centroiding.\cite{Suhling2002, Suhling1999, Boksenberg1985} The original centroiding algorithms, based on a simple center-of-mass calculation,\cite{Boksenberg1985} were developed for implementation in hardware. In the advent of more powerful computers, it became possible to implement increasingly complex centroiding algorithms based on fitting the photon event in software. However, some of the algorithms employed in photon counting imaging are still simple, one-iteration algorithms.\cite{Postma2011}  In the past decade, photoswitchable and photoactivatable fluorescent probes \cite{Fernandez_2008} have allowed the same centroiding principle to be employed in circumventing the diffraction limit in fluorescence microscopy. Single-molecule localisation fluorescence microscopy techniques are based on the activation of a small subpopulation of the fluorescent proteins or fluorophores used to stain the sample. They are imaged and subsequently deactivated before the process is repeated with a different subset of fluorophores.\cite{Betzig2006,Rust2006,Hess2006} The centroid positions of the fluorescent probes are calculated in each frame, typically by fitting a three-dimensional Gaussian function to the fluorophore's point spread function,  and the final image is formed by summing many frames. Single-molecule localisation fluorescence microscopy is now a well-established technique, and much effort has been put into the development and optimisation of many different types of centroiding algorithms, including iterative fitting algorithms.\cite{Small2014} We recently reported that single-molecule localisation algorithms produce good results when applied to centroiding single photon events imaged with an MCP-intensified CMOS camera.\cite{Hirvonen2015_OL} Here, we extend this work and apply super-resolution software for centroiding photon events detected with an EBCCD camera. Moreover, multi-emitter fitting analysis was used for separating overlapping photon events, an important aspect not reported before, which allows an increased count rate and shorter acquisition times.