  The constituents of soft matter systems such as colloidal suspensions,
emulsions, polymers, and biological tissues undergo microscopic random motion,
due to thermal energy. They may also experience drift motion correlated over
mesoscopic or macroscopic length scales, \textit{e.g.} in response to an
internal or applied stress or during flow. We present a new method for
measuring simultaneously both the microscopic motion and the mesoscopic or
macroscopic drift. The method is based on the analysis of spatio-temporal
cross-correlation functions of speckle patterns taken in an imaging
configuration. The method is tested on a translating Brownian suspension and a
sheared colloidal glass.
