  We describe a scheme into which a camera is turned into an efficient tunable
frequency filter of a few Hertz bandwidth in an off-axis, heterodyne optical
mixing configuration, enabling to perform parallel, high-resolution coherent
spectral imaging. This approach is made possible through the combination of a
spatial and temporal modulation of the signal to reject noise contributions.
Experimental data obtained with dynamically scattered light by a suspension of
particles in brownian motion is interpreted.
