Recent results from high resolution solar granulation observations indicate the existence of a population of small granular cells on scales below 600 km in diameter, located in the intergranular lanes. We studied a set of Hinode SOT images and high resolution radiation hydrodynamics simulations in order to analyze small granular cells and to study their physical properties. An automated image segmentation algorithm specifically adapted to high resolution simulations for the identification of granules was developed. The algorithm was also used to analyze and compare physical quantities provided by the simulation and the observations. We found that small granules make a distinct contribution to the total area of granules. Both in observations...