  We present the results of our lattice QCD study of the $\pi\gamma\to\pi\pi$
process, where the $\rho$ resonance appears as an enhancement in the transition
amplitude. We use $N_f=2+1$ clover fermions on a lattice of $L=3.6$ fm and a
pion mass of $320$ MeV. Using a combination of forward, stochastic, and
sequential propagators, we calculate the two-point and three-point functions
that allow us to determine the $\pi\gamma\to\pi\pi$ matrix elements for several
values of the invariant mass $s$ and momentum transfer $q^2$. To fit the $q^2$
and $s$ dependence of the $\pi\gamma\to\pi\pi$ amplitude, we explore a set of
general parametrizations based on a Taylor expansion. By analytic continuation
to the complex pole corresponding to the $\rho$ resonance, we determine the
resonant form factors and calculate the radiative decay width of the $\rho$.
