  This work focuses on the combination of White Light (WL) and UV (Ly-alpha)
coronagraphic images to demonstrate the capability to measure the solar wind
speed in the inner corona directly with the ratio between these two images (a
technique called "quick inversion method"), thus avoiding to account for the
line-of-sight (LOS) integration effects in the inversion of data. After a
derivation of the theoretical basis and illustration of the main hypotheses in
the "quick inversion method", the data inversion technique is tested first with
1D radial analytic profiles, and then with 3D numerical MHD simulations, in
order to show the effects of variabilities related with different phases of
solar activity cycle and complex LOS distribution of plasma parameters. The
same technique is also applied to average WL and UV images obtained from real
data acquired by SOHO UVCS and LASCO instruments around the minimum and maximum
of the solar activity cycle. Comparisons between input and output velocities
show overall a good agreement, demonstrating that this method that allows to
infer the solar wind speed with WL-UV image ratio can be complementary to more
complex techniques requiring the full LOS integration. The analysis described
here also allowed us to quantify the possible errors in the outflow speed, and
to identify the coronal regions where the "quick inversion method" performs at
the best. The "quick inversion" applied to real UVCS and LASCO data allowed
also to reconstruct the typical bimodal distribution of fast and slow wind at
solar minimum, and to derive a more complex picture around solar maximum. The
application of the technique shown here will be very important for the future
analyses of data acquired with multichannel WL and UV (Ly-alpha) coronagraphs,
such as Metis on-board Solar Orbiter, LST on-board ASO-S, and any other future
WL and UV Ly-alpha multi-channel coronagraph.
