The use of non-destructive measurement techniques by means of Infra-Red Thermography (IT) allows a fast and simple evaluation and control of all types of materials and processes without any contact. For this reason, the general objective of this thesis was to better understand the different stages of digital treatment of thermograms, to apply this new knowledge to real problems and to find solutions for any deficiencies. These stages consist of the conditioning of the thermal images (preprocessing) as a previous step to digital treatment (processing), where the identification of the defects present in the material is improved, thus allowing a subsequent analysis and characterization (postprocessing). The fields of application covered by these contributions are varied: evaluation and inspection processes of welding, testing of composite materials for the aeronautics industry and applications in the field of contaminant detection in the environment and in the military textile industry. This doctoral thesis was done in the Photonics Engineering Group (GIF) of the Department of Electronic Technology and Systems and Automation Engineering (TEISA) of the University of Cantabria.