  Ablation fronts and shocks are two radiative/hydrodynamic features ubiquitous
in inertial confinement fusion (ICF). A specially designed shock-tube
experiment was tested on the OMEGA laser facility to observe these two features
evolve at once and to assess thermodynamical and radiative properties. It is a
basic science experiment aimed at improving our understanding of shocked and
ablated matter which is critical to ICF design. At all time, these two moving
"interfaces" separate the tube into three distinct zones where matter is either
ablated, shocked or unshocked. The {\it simple-flux} or {\it double-flux}
experiments, respectively one or two halfraum-plus-tube, have been thought up
to observe and image these zones using x-ray and visible image diagnostic. The
possibility of observing all three regions at once was instrumental in our new
radiographic image processing used to remove the backlighter background
otherwise detrimental to quantitative measurement. By so doing, after
processing the radiographic images of the 15 shots accumulated during the 2013
and 2015 campaigns, a quantitative comparison between experiments and our
radiative hydrocode simulations was made possible. Several points of the
principal Hugoniot of the aerogel used as a light material in the shock-tube
were inferred from that comparison. Most surprisingly, rapid variations of
relative-transmission in the ablated region were observed during radiographic
irradiations while it remained constant in the shocked region. This effect
might be attributed to the spectral distribution variability of the backlighter
during the radiographic pulse. Numerically, that distribution is strongly
dependent upon NLTE models and it could potentially be used as a mean to
discriminate among them.
