  We present an image processing algorithm developed for quantitative analysis
of directional solidification of metal alloys in thin cells using X-ray
imaging. Our methodology allows to identify the fluid volume, fluid channels
and cavities, and to separate them from the solidified structures. It also
allows morphological analysis within the solid fraction, including automatic
decomposition into dominant grains by orientation and connectivity. In
addition, the interplay between solidification and convection can be studied by
characterizing convection plumes in the fluid, and solute concentrations above
the developing solidification front. The image filters used enable the
developed code (open-source) to work reliably even for single images with low
signal-to-noise ratio, low contrast-to-noise ratio, and low image resolution.
This is demonstrated by applying the code to several dynamic in situ X-ray
imaging experiments with a solidifying gallium-indium alloy in a thin cell.
Grain (and global) dendrite orientation statistics, convective plume
parameterization, etc. can be obtained from the code output. The limitations of
the presented approach are also explained.
