The present techniques provide fully automated methods for quantifying the location, strength and percent of expressed target molecules or other biological markers in immunohistochemically stained biological samples. The samples may be automatically segmented, for example into subcellular compartments, from images of compartmental markers. Then, the distribution of a target molecule on each of these compartments is calculated that includes the percentage and strength of expression. This is different than existing intensity or ratio based methods where abundant low expression levels are indistinguishable from scarce high expression levels.