  We demonstrate an approach to obtaining near quantum-limited far-field
imaging resolution of incoherent sources with arbitrary distributions. Our
method assumes no prior knowledge of the source distribution, but rather uses
an adaptive approach to imaging via spatial mode demultiplexing that
iteratively updates both the form of the spatial imaging modes and the estimate
of the source distribution. The optimal imaging modes are determined by
minimizing the estimated Cram\'er-Rao bound over the manifold of all possible
sets of orthogonal imaging modes. We have observed through Monte Carlo
simulations that the manifold-optimized spatial mode demultiplexing measurement
consistently outperforms standard imaging techniques in the accuracy of source
reconstructions and comes within a factor of 2 of the absolute quantum limit as
set by the quantum Cram\'er-Rao bound. The adaptive framework presented here
allows for a consistent approach to achieving near quantum-limited imaging
resolution of arbitrarily distributed sources through spatial mode imaging
techniques.
