  We demonstrate a new image processing methodology for resolving gas bubbles
travelling through liquid metal from dynamic neutron radiography images with
intrinsically low signal-to-noise ratio. Image pre-processing, denoising and
bubble segmentation are described in detail, with practical recommendations.
Experimental validation is presented - stationary and moving reference bodies
with neutron-transparent cavities are radiographed with imaging conditions
similar to the cases with bubbles in liquid metal. The new methods are applied
to our experimental data from previous and recent imaging campaigns, and the
performance of the methods proposed in this paper is compared against our
previously developed methods. Significant improvements are observed as well as
the capacity to reliably extract physically meaningful information from
measurements performed under highly adverse imaging conditions. The showcased
image processing solution and separate elements thereof are readily extendable
beyond the present application, and have been made open-source.
