Important analyses of the core LHCb physics program rely on calorimetry to identify photons, high-energy neutral pions and electrons. For this purpose, the LHCb calorimeter system is composed of a scintillating pad plane, a preshower detector, an electromagnetic and a hadronic sampling calorimeters. The interaction of a given particle in these detectors leaves a specific signature. This is exploited for particle identification (PID) by combining calorimeters and tracking information into multivariate classifiers.

In this contribution, we focus on the identification of photons against high-energy neutral pions, electrons and hadronic backgrounds. Neutral particles reconstruction process at LHCb is succinctly explained and PID performances on Run 1 data is shown. Discrepancies with simulation predictions are then discussed, with special emphasis on the methods to correctly estimate PID cut efficiencies by means of large calibration samples of abundant beauty and charm decays to final states with photons or neutral pions. Finally, the technical aspects of the collection of these samples in Run 2 are presented.