1. A digital image processing method, said method comprising: accessing element data representing a plurality of elements belonging to a plurality of digital images; performing a similarity analysis between said elements from said plurality of elements to obtain inter-relational data results relating to said elements; and performing clustering of said plurality of elements, said step of performing clustering including incorporating in said inter-relational data results at least one hard constraint relating to elements from said plurality of elements, to obtain constrained inter-relational data results, performing a spectral analysis to obtain eigenvector results from said constrained inter-relational data results, and performing discretization of said eigenvector results using constrained clustering with a criterion to enforce said at least one hard constraint to obtain clusters.