 Due to the exponential reduction (with respect to distance) of ballistic photons in a scattering medium, often image processing techniques are applied to the raw captured ballistic images, to reconstruct high quality ones.Ballistic imaging modalities aim to reject non-ballistic photons and retain ballistic photons that carry useful information.To perform this task, specific characteristics of ballistic photons vs. non-ballistic photons are used, such as "time of flight" through coherence gated imaging, collimation, wavefront propagation, and polarization.