The paper "The Watershed Transform: Definitions, Algorithms and Parallelization Strategies" by Roerdink and Meijster provides a comprehensive review of the watershed transform, a method widely used for image segmentation in mathematical morphology. The authors discuss various definitions of the watershed transform and associated sequential algorithms, emphasizing the distinction between definition, algorithm specification, and implementation. They highlight common issues in the literature, such as the lack of clarity in definitions and the need for careful distinction between algorithm specification and implementation. The paper also surveys approaches for parallelizing sequential watershed algorithms, noting the challenges due to the non-local nature of the watershed transform. It discusses the difficulty in parallelizing algorithms that depend on the order of pixel processing, especially in asynchronous environments. The authors provide examples and illustrations to explain the differences between various definitions and implementations of the watershed transform, and they present several algorithms for both sequential and parallel implementations. Key points include: - **Definitions**: The paper introduces different definitions of the watershed transform, including those based on topographical distances and algorithmic definitions like simulated immersion. - **Sequential Algorithms**: It reviews existing watershed algorithms, such as the Vincent-Soille algorithm, and discusses its implementation and limitations. - **Parallelization**: The authors explore parallelization strategies, noting the challenges and proposing methods to address them, particularly in the context of digital images with plateaus. The paper aims to provide a clear and critical overview of the watershed transform, helping researchers and practitioners better understand and implement this method for image segmentation.The paper "The Watershed Transform: Definitions, Algorithms and Parallelization Strategies" by Roerdink and Meijster provides a comprehensive review of the watershed transform, a method widely used for image segmentation in mathematical morphology. The authors discuss various definitions of the watershed transform and associated sequential algorithms, emphasizing the distinction between definition, algorithm specification, and implementation. They highlight common issues in the literature, such as the lack of clarity in definitions and the need for careful distinction between algorithm specification and implementation. The paper also surveys approaches for parallelizing sequential watershed algorithms, noting the challenges due to the non-local nature of the watershed transform. It discusses the difficulty in parallelizing algorithms that depend on the order of pixel processing, especially in asynchronous environments. The authors provide examples and illustrations to explain the differences between various definitions and implementations of the watershed transform, and they present several algorithms for both sequential and parallel implementations. Key points include: - **Definitions**: The paper introduces different definitions of the watershed transform, including those based on topographical distances and algorithmic definitions like simulated immersion. - **Sequential Algorithms**: It reviews existing watershed algorithms, such as the Vincent-Soille algorithm, and discusses its implementation and limitations. - **Parallelization**: The authors explore parallelization strategies, noting the challenges and proposing methods to address them, particularly in the context of digital images with plateaus. The paper aims to provide a clear and critical overview of the watershed transform, helping researchers and practitioners better understand and implement this method for image segmentation.