  Wide-field (> 100 deg$^2$) hard X-ray coded-aperture telescopes with high
angular resolution (< 2') will enable a wide range of time domain astrophysics.
For instance, transient sources such as gamma-ray bursts can be precisely
localized without assistance of secondary focusing X-ray telescopes to enable
rapid followup studies. On the other hand, high angular resolution in
coded-aperture imaging introduces a new challenge in handling the systematic
uncertainty: average photon count per pixel is often too small to establish a
proper background pattern or model the systematic uncertainty in a time scale
where the model remains invariant. We introduce two new techniques to improve
detection sensitivity, which are designed for, but not limited to high
resolution coded-aperture system: a self-background modeling scheme which
utilizes continuous scan or dithering operations, and a Poisson-statistics
based probabilistic approach to evaluate the significance of source detection
without subtraction in handling the background. We illustrate these new imaging
analysis techniques in high resolution coded-aperture telescope using the data
acquired by the wide-field hard X-ray telescope ProtoEXIST2 during the
high-altitude balloon flight in Fall, 2012. We review the imaging sensitivity
of ProtoEXIST2 during the flight, and demonstrate the performance of the new
techniques using our balloon flight data in comparison with simulated ideal
Poisson background.
