  We propose a dot-tracking methodology for processing Background Oriented
Schlieren (BOS) images. The method significantly improves the accuracy,
precision and spatial resolution compared to conventional cross-correlation
algorithms. Our methodology utilizes the prior information about the dot
pattern such as the location, size and number of dots to provide near 100%
yield even for high dot densities (20 dots/32x32 pix.) and is robust to image
noise. We also propose an improvement to the displacement estimation step in
the tracking process, especially for noisy images, using a "correlation
correction", whereby we combine the spatial resolution benefit of the tracking
method and the smoothing property of the correlation method to increase the
dynamic range of the overall measurement process. We evaluate the performance
of the method with synthetic BOS images of buoyancy driven turbulence rendered
using ray tracing simulations, and experimental images of flow in th exit plane
of a converging-diverging nozzle.
