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In the study of image processing a watershed of a grayscale image is analogous to the notion of a catchment basin of a heightmap. In short, a drop of water following the gradient of an image flows along a path to finally reach a local minimum. Intuitively, the watershed of a relief correspond to the limits of the adjacent catchment basins of the drops of water. There are different technical definitions of a watershed. In graphs, watershed lines may be defined on the nodes, on the edges, or hybrid lines on both nodes and edges. Watersheds may also be defined in the continuous domain.〔L. Najman and M. Schmitt. Watershed of a continuous function. In Signal Processing (Special issue on Mathematical Morphology.), Vol. 38 (1994), pages 99–112〕 There are also many different algorithms to compute watersheds. Watershed algorithm is used in image processing primarily for segmentation purposes. Image:Relief of gradient of heart MRI.png|Relief of the gradient magnitude Image:Gradient of MRI heart image.png|Gradient magnitude image Image:Watershed_of_gradient_of_MRI_heart_image.png|Watershed of the gradient Image:Relief view of the watershed of the gradient of an MRI heart image.png|Watershed of the gradient (relief) ==Definitions== A watershed is a basin-like landform defined by highpoints and ridgelines that descend into lower elevations and stream valleys. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Watershed (image processing)」の詳細全文を読む スポンサード リンク
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