watersheds_marker — Extract watersheds and combine basins based on markers.
watersheds_marker segments an image based on the topology of
the gray values and returns the resulting regions in
The image is interpreted as a “mountain range”.
Higher gray values correspond to “mountains”, while lower gray
values correspond to “valleys”.
The image, interpreted in this particular way, is flooded, starting with the
regions defined in
Markers, until the entire image is filled.
Thus, each pixel is assigned to the marker to which it has the path
with the lowest maximum height.
If this is the case for multiple markers, the pixel is assigned to either
The resulting basins, one per input region in
Markers, are returned
Basins. Note that some of those regions might be empty.
This can happen if, for example, two marker regions are in the same
watershed basin. If a pixel is contained in multiple marker regions, only
the last marker region is used as seed for that pixel. It is advised that
the marker regions do not overlap.
The flooding is performed only for the domain of
Parts of the marker regions outside the domain of
Image are ignored.
It is advisable to apply a smoothing operator (e.g.,
gauss_filter) to the input image
To segment an image, it is also often reasonable to run an edge extractor
edges_color) on the image,
and pass the resulting amplitude image to
If the image contains many fine structures or is noisy, many watershed regions need to be processed internally, and thus the runtime increases considerably.
→object (byte / uint2 / real)
Initial markers from which to flood the image.
Basins for all markers.
read_image (Image, 'printer_chip/printer_chip_01') edges_image (Image, ImaAmp, ImaDir, 'canny', 1, 'nms', 20, 40) * Compute background marker full_domain (ImaAmp, ImageFull) erosion_circle (Image, RegionErosion, 2.5) difference (Image, RegionErosion, Boundary) * Compute foreground markers threshold (Image, Region, 200, 255) erosion_circle (Region, RegionErosion1, 7.5) connection (RegionErosion1, ConnectedRegions) select_shape (ConnectedRegions, SelectedRegions, 'area', 'and', 1500, 99999) * Apply marker-based watersheds concat_obj (Boundary, SelectedRegions, MarkerRegions) watersheds_marker (ImageFull, MarkerRegions, Basins) * Display results dev_display (Image) dev_set_color (['#FF000055', '#00FF0055', '#0000FF55', '#FF00FF55', '#FFFF0055', '#00FFFF55', '#80FF0055', '#0080FF55']) dev_display (MarkerRegions) dev_set_draw ('fill') dev_display (Basins)
If all input parameters are valid,
watersheds_marker returns TRUE.
If necessary, an exception is raised.