  We present state-of-the-art calculations of viscous photon emission from
nuclear collisions at RHIC and LHC. Fluctuating initial density profiles are
evolved with event-by-event viscous hydrodynamics. Momentum spectra of thermal
photons radiated by these explosively expanding fireballs and their
$p_T$-differential anisotropic flow coefficients $v_n(p_T)$ are computed, both
with and without accounting for viscous corrections to the standard thermal
emission rates. Viscous corrections to the rates are found to have a larger
effect on the $v_n$ coefficients than the viscous suppression of hydrodynamic
flow anisotropies. The benefits of taking the ratio of elliptic to triangular
flow, $v_2/v_3$, are discussed, and the spacetime regions which contribute
dominantly to the photon flow harmonics are identified. The directed flow $v_1$
of thermal photons is predicted for RHIC and LHC energies.
