The infrared thermography (IRT) technique has shown great potential with many applications in a variety of fields, such as aerospace, petroleum, civil engineering, and so forth. This chapter is designed to provide an overview of the method of IRT in non-destructive material evaluation. It begins with the general introduction and development of the IRT. It follows the basic principles of the electromagnetic spectrum and radiative energy concepts. Following the introduction of different types of thermography, applications in the non-destructive testing fields are provided. The next section focuses on recent trends and developments, in particular the integration of IRT with other technologies namely ultrasonic, acoustic emission, and so on. By assigning a data analysis section, data processing techniques are described by dividing them into two conventional and advanced categories. The numerical modeling and simulation of the IRT inspection process are then presented as beneficial applications. In addition, the relevant standards have been specified in a short separate section. To testify to the effectiveness of the IRT, a case study of a steel sample inspection is provided at the end of the chapter itself.

Inspection of cultural heritage objects plays nowadays paramount importance around the world. Non-destructive inspection is a must and a necessity in order to preserve the integrity of the artwork without losing any precious material composing it. The use of thermal non-destructive inspection is a good idea since, by exploiting the 3D diffusion inside the object, triggered by external radiation, surface and subsurface defects may be revealed. To do this, the long-wave infrared (LWIR) spectrum is usually exploited in combination with a thermal camera. In the cultural heritage field, the main problem to solve to detect as much as possible thermal imprints linked to invisible defects is the minimisation of the impact of emissivity variations caused by pigments composing the colours. A simple, effective, solid, and optimized method for decorated paintings is here applied right after some preliminary results. It is based on active thermography as the modality of inspection, and a thermal stimulus provoked by halogen lamps; thermal images recorded on a panel painting including man-made defects have been analysed and processed in MATLAB® environment. After extraction of de-nosing functions based on the heating and cooling steps, two methods are proposed to enhance the de-noised thermograms. Then, popular methods of Pulsed Phase Thermography (PPT) and the Principal Component Thermography (PCT) are applied. In the end, after minimizing the effect of emissivity variation, an optimization fusion proposal through post-processing the emissivity adjusted thermograms is provided. A brief but exhaustive review introduce and guide the readers towards the problem for which the authors took a step ahead via a proposal based on image fusion.