Résumé. 2014 Abstract. 2014 Many image processing and image analysis problems, in two or three dimensions, can be addressed and solved by methods and tools developed within the graph theory. In this paper, an image representation based on graphs is proposed: a data structure, together with methods for attributing and weighting the graph, methods to merge nodes, etc. In order to demonstrate the interest of the approach, two applications dealing with 2D-images of cellular microscopy are described and discussed.