Leaves exist in many different forms, presumably reflecting the variety of evolutionary strategies to cope with different environments. Although our understanding of the molecular mechanisms that control the final leaf shape has been significantly advanced, methods for the precise quantification of leaf shape have often not been implemented. Almost by definition, when considering leaf shape the leaf edge is very important. Here we introduce a new software package, LeafProcessor, which allows precise quantification of the complexity of leaf edge by calculating Bending Energy. Bending Energy can be calculated for part of the leaf margin as well as at the whole leaf margin. In addition to Bending Energy, LeafProcessor provides a number of commonly used single metric parameters, such as such as length, width, L/W ratio and leaf area in a semi-automatic manner. Based on the data provided by LeafProcessor, we have quantified the dynamic change of the leaf edge complexity during Arabidopsis leaf development. Furthermore, we have observed that increase in cell division at the whole leaf level disturbs the dynamic changes of the leaf margin complexity, resulting in the formation of a smoother final leaf shape. Our current attempt at modelling of the manipulation of local growth which is expected to affect the final leaf shape will also be discussed.