In liquid inkjet printing, a critical quality issue is the coalescence of ink on the media surface. This paper describes a technique for quantifying coalescence using an automated print quality analysis system. This technique measures spatial variability of reflectance caused by coalescence. Uniformity is compared in test samples printed with different printing technologies. The technique was used to study the effects of different media coatings on the magnitude of coalescence in inkjet printing. The roles of the surface tension of the ink, the surface energy of the media and the rate of ink absorption by the media are examined for insight into the mechanisms of coalescence.