1. A method for biometric acquisition, comprising: acquiring, by a sensor, an image of the iris comprising a reflection of a predefined geometrical shape; determining a value of deformation or magnification of the geometrical shape in the reflection; comparing the determined value to a value of deformation or magnification expected for a reflection occurring off a live eye; and determining that the image of the iris is acquired from a live eye if the determined value is consistent with the expected value.