The book "Mathematical Morphology and Its Applications to Signal and Image Processing" presents the thoroughly reviewed contributions from the 12th International Symposium on Mathematical Morphology, which took place in May 2015 in Reykjavik, Iceland. It includes 62 revised full texts selected from 72 submitted papers. The contributions are organized into thematic sections that address various aspects of mathematical morphology, including evaluations and applications, hierarchies, color and multi-valued fields, as well as optimization, calculus, and probabilities. Additionally, topics such as topology, discrete geometry, and algorithms and their implementation are covered. This specialized book is aimed at professionals and students engaged in signal and image processing, providing valuable insights into current research findings and developments in this field.