  We discuss imaging sources from low relative-velocity correlations in
heavy-ion reactions. When the correlation is dominated by interference, we can
obtain the images by Fourier transforming the correlation function. In the
general case, we may use the method of optimized discretization. This method
stabilizes the inversion by adapting the resolution of the source to the
experimental error and to the measured velocities. The imaged sources contain
information on freeze-out density, phase-space density, and resonance decays,
among other things.
