Hand rehabilitation, following stroke or hand surgery, is repetitive and long duration and can be facilitated with the assistance of complex, heavy and cumbersome haptic gloves based on sensors. The present paper describes a virtual glove, software based, which tracks hand movements by using images collected from webcams and numerical analysis. Finger forces are calculated from the deformations impressed to some objects (of known elastic coefficient) grasped by the patient hand. The presented system is notable for simplicity, generality and low cost. Implementation and results of the proposed virtual glove will be the objects of a future paper.