In this book, several methods for mammogram segmentation, based on pixel intensity, have been presented. In each section, a comprehensive and critical review of existing methods was first undertaken to establish the progress of knowledge in that area and the contemporary state of the art research happening internationally. After the analysis of existing works, methods were proposed. In this book, major emphasize is given to performance evaluation of proposed methods. At the same time different size, shape and types i.e. fatty, fatty-glandular and dense-glandular mammograms were evaluated individually because of their different contrast level and intensity properties. The obtained results have been compared with results of different national and international research in the related field.