We address the problem of quantifying myocardial deformations from tagged MRI sequences. We develop a two-step approach comprising (i) a motion estimation step via a variational non rigid registration method using a novel class of generalized information measures, called exclusive f-information, and (ii) a measurement step, yielding local and segmental deformation parameters over the whole myocardium. Experiments performed on healthy and pathological data demonstrate that this approach delivers, within a reasonable computation time and in a robust and fully unsupervised way, reliable measurements for normal subjects and provides quantitative pathology-specific information