Abstract
We consider passive imaging tasks involving discrimination between known candidate objects and investigate the best possible accuracy with which the correct object can be identified. We analytically compute quantum-limited error bounds for hypothesis tests on any database of incoherent, quasi-monochromatic objects when the imaging system is dominated by optical diffraction. We further show that object-independent linear-optical spatial processing of the collected light exactly achieves these ultimate error rates, exhibiting superior scaling than spatially-resolved direct imaging as the scene becomes more severely diffraction-limited. We apply our results to example imaging scenarios and find conditions under which super-resolution object discrimination can be physically realized.