  An overwhelming fraction of photons from relativistic heavy ion collisions
has its origin in the decay of $\pi^0$ and $\eta$ mesons. We calculate the
azimuthal asymmetry of the decay photons for several azimuthally asymmetric
pion distributions. We find that the $k_T$ dependence of the elliptic flow
parameter$v_2$ for the decay photons closely follows the elliptic flow
parameter $v_2^{\pi^0}$ evaluated at $p_T \approx k_T+\delta$, where
$\delta\approx$ 0.1 -- 0.2 GeV, for typical pion distributions measured in
nucleus-nucleus collisions at relativistic energies. Similar results are
obtained for photons from the 2-$\gamma$ decay of $\eta$ mesons. Assuming that
the flow of $\pi^0$ is similar to those for $\pi^+$ and $\pi^-$ for which
independent measurements would be generally available, this ansatz can help in
identifying additional sources for photons. Taken along with quark number
scaling suggested by the recombination model, it may help to estimate $v_2$ of
the parton distributions in terms of azimuthal asymmetry of the decay photons
at large $k_T$.
