A new thermography method is presented to measure the absolute temperature history in dynamic experiments of very short duration. By superposing a known infrared radiation to the naturally emitted specimen radiation, both the specimen's emissivity and temperature are determined from the measurements of a custom-made detector array. As a result, this method can be used without prior knowledge of the specimen's optical properties. At the same time, the temperature measurement accuracy is substantially improved in comparison with other established methods. Since the specimen's emissivity is measured in addition to the temperature, this method may also be used to study the coupling between the evolution of the optical and mechanical properties under dynamic loading.