We estimate the production rate of photons from the quark-gluon plasma in lattice QCD. The production of weakly-interacting particles from a strongly-interacting medium has applications to particle cosmology and heavy-ion phenomenology. We propose a new observable which gives us better control over the systematic uncertainty in estimating the rate at large photon momenta. The relevant Euclidean vector current correlation functions are computed with $N_\mathrm f =2$ Wilson clover fermions in the relevant chirally-symmetric phase. We investigate discretization effects by employing multiple lattice spacings and applying various strategies for improvement.