Photon and diphoton production at ATLAS

We present the latest ATLAS measurement of the cross section for the inclusive production of isolated prompt photons of $pp$ collisions at a centre-of-mass energy $\sqrt{s}$ = 7 TeV, as well as the measurement of diphoton production. Photon candidates are identified by combining information from the calorimeters and from the inner tracker. Residual background in the selected sample is estimated from data, based on the observed distribution of the transverse isolation energy in a narrow cone around the photon candidate. The results are compared to predictions from next-to-leading order perturbative QCD calculations.