You are here: Start » Function Reference » Computer Vision » Image Segmentation » SegmentImage_Watersheds

SegmentImage_Watersheds

Header:	AVL.h
Namespace:	avl
Module:	FoundationBasic

Computes dark or bright watershed basins of an image.

Applications: A classic algorithm, useful for segmentation of ball-shaped objects like plant seeds, cells or fruits.

Syntax

void avl::SegmentImage_Watersheds
(
	const avl::Image& inImage,
	atl::Optional<const avl::Region&> inRoi,
	const atl::Array<avl::Region>& inMarkers,
	avl::Polarity::Type inBasinsPolarity,
	atl::Array<avl::Region>& outBasins
)

Parameters

Name	Type	Default	Description
inImage	const Image&		Input image
inRoi	Optional<const Region&>	NIL	Range of pixels to be processed
inMarkers	const Array<Region>&		Local minima markers
inBasinsPolarity	Polarity::Type		Whether to look for bright or dark basins
outBasins	Array<Region>&

Requirements

For input inImage only pixel formats are supported: uint8.

Read more about pixel formats in Image documentation.

Description

This filter segments the image into basins based on a set of markers (inMarkers) and a flooding watersheds implementation for grayscale images.

By default a darker pixel is considered lower but that can be changes using the inBasinsPolarity parameter.

Markers have to be computed beforehand. One way to do that is to detect the ridges of the image and threshold it into a single region, Pass the resulting region into the DistanceTransform filter. Then threshold the distance image and split it into blobs.

Examples

Example image

Computed markers

Basins computed with watersheds

Errors

List of possible exceptions:

Error type	Description
DomainError	No markers present in SegmentImage_Watersheds.
DomainError	Not supported inImage pixel format in SegmentImage_Watersheds. Supported formats: UInt8.