Characterization and Quality Evaluation of Geometric Distortions in Images with Application to Digital Watermarking

The work of this thesis can be seen as a first step towards the characterization and quality evaluation of the class of local geometric distortions. A first step to solve the problems with geometric attacks is the characterization of the class of perceptually admissible distortions. This requires the development of models to treat the distortions from a mathematical point of view. In this context, the first part of the thesis focuses on modeling local geometric transformations from a mathematical point of view. Watermarking is not the only field where an analysis of geometric distortion in images would be useful. In all the applications dealing with geometric distortions the availability of an objective quality metric capable of dealing with this kind of distortions would be of invaluable help. Thus, in the second part of the thesis, two objective quality metrics for the perceptual evaluation of geometrically distorted images have been introduced.