In this paper, we propose a new methodology to proces Gel electrophoresis digital 

images automatically. This method is mainly based on an efficient acyclic graph representation of the homology (algebraic connectivity) of a grey-level digital image, also called, homological spanning forest (HSF) representation. The possibility of introducing a metric in this schema, allows the system to automatically identify the number and the location of bands on each lane of 

the image, without any intervention of the user. This method improved other methods for 

processing GEIs in the sense that no tresholding is needed here and the topological control of 

the bands is maximum.