A novel method is presented in this paper which aims at achieving grain scale energy balances at finite strain in mechanically-loaded polycrystalline metallic specimens. For this purpose, two complementary imaging techniques were used to investigate material thermo-mechanical behaviour: Digital Image Correlation (DIC) and InfraRed Thermography (IRT) to separately reach the kinematic and the thermal responses of the material. A calorimetric analysis can be conducted by combining these techniques. The aim of this paper is to present and to validate a novel IR data processing method that can be used to perform local thermal field measurements. The procedure was validated on numerical data associated with the response of aluminum polycrystalline aggregates.