  Under weak illumination, tracking and imaging moving object turns out to be
hard. By spatially collecting the signal, single pixel imaging schemes promise
the capability of image reconstruction from low photon flux. However, due to
the requirement on large number of samplings, how to clearly image moving
objects is an essential problem for such schemes. Here we present a principle
of single pixel tracking and imaging method. Velocity vector of the object is
obtained from temporal correlation of the bucket signals in a typical
computational ghost imaging system. Then the illumination beam is steered
accordingly. Taking the velocity into account, both trajectory and clear image
of the object are achieved during its evolution. Since tracking is achieved
with bucket signals independently, this scheme is valid for capturing moving
object as fast as its displacement within the interval of every sampling keeps
larger than the resolution of the optical system. Experimentally, our method
works well with the average number of detected photons down to 1.88
photons/speckle.
