  We implement a general imaging method by measuring the complex degree of
coherence using linear optics and photon number resolving detectors. In the
absence of collective or entanglement assisted measurements, our method is
optimal over a large range of practically relevant values of the complex degree
of coherence. We measure the size and position of a small distant source of
pseudo-thermal light, and show that our method outperforms the traditional
imaging method by an order of magnitude in precision. Finally, we show that a
lack of photon number resolution in the detectors has only a modest detrimental
effect on measurement precision and simulate imaging using the new and
traditional methods with an array of detectors; showing that the new method
improves both image clarity and contrast.
