This paper describes a new method for extracting the individual contributions to the diffracted intensity of subsets of atoms in the crystal structure. The periodic perturbation of the scattering process, required for untangling the scattered intensity, is provided by altering the resonant contributions. The theory of modulation enhanced diffraction (MED) is briefly recalled in the context of resonant scattering. A periodic variation in the atomic form factor has been achieved by changing the X-ray energy in such a way that the MED theory holds. Simulated results and experimental data are presented, together with necessary corrections. Two data analysis schemes are presented, both illustrating the advantages and drawbacks of the novel modulation technique.