Retinal image segmentation is an interdisciplinary field at the intersection of engineering and medicine. This field is intended to develop computational and mathematical models for solving problems pertaining to medical images and their use for biomedical research and clinical care. Every year, many more articles are added in the literature that describe new algorithms in solving the problem. However, the artifacts such as intensity inhomogeneity, poor image contrast, complicated vessel network, various pathologies, etc. make the retinal image segmentation a challenging task.In this context, this book attempts to address different problems in the retinal image segmentation. The pre-processing and vessel extraction are investigated as a cohesive framework in the retinal vessel segmentation process. The study found a flood of new avenues for exploration in the future. The findings of this book could serve as a foundation for researchers looking to improve the efficiency of retinal vessel segmentation.