1. A method, comprising: receiving in a computing device an image comprising a plurality of cells; fitting in the computing device a Gaussian mixture model to an intensity distribution of the image, wherein the model comprises one or more Gaussian distributions and a background distribution; identifying in the computing device a first Gaussian component G g associated with a first Gaussian distribution of the one or more Gaussian distributions corresponding to nuclei of the plurality of cells; and defining in the computing device a nuclei mask as a binary matrix based at least in part on the first Gaussian component G g , wherein the nuclei mask comprises one or more putative nuclei associated with the plurality of cells.