Use row-by-row labeling algorithm to label connected components. The algorithm makes two passes over the image: one pass to record equivalences and assign temporary labels and the second to replace each temporary label by the label of its equivalence class. Based on Linda G. Shapiro, Computer Vision: Theory and Applications. (3.4 Connected Components Labeling), Rosenfeld and Pfaltz (1966). More...

#include <connected_components.h>

Public Member Functions
valarray< int >	compactLabeling ()
	Rearrange the labels to make the label numbers consecutive. More...

	connected_components (valarray< int > m, int rows, int cols, bool zeroAsBg)
	Constructor that initializes the private member variables. More...

void	constructBinaryImages (int robotsLabel)
	Create binary arrays of connected labels. More...

int	getMaxLabel ()
	Get the max label of the labeling process which is in the range [0,max_label]. More...

vector< int >	labeling ()
	Label the connected components. More...

valarray< float >	NormalizedEuclideanDistanceBinary (bool RobotR)
	Calculate the normalized euclidean distance transform of a binary image with foreground pixels set to 1 and background set to 0. More...

int	uf_find (int x, vector< int > parent, vector< int > &label)
	Return the root label (starts from 1 because label array is initialized to 0 at first). The label array records the new label for every root. More...

void	uf_union (int x, int y, vector< int > &parent)
	Combine two labels. More...

Private Member Functions
void	DT1D (vector< float > f, vector< float > &d, vector< int > &v, vector< float > &z)
	DT1D. More...

vector< float >	getVector (valarray< float > A, int row)
	Get a slice of an array. More...

Private Attributes
valarray< int >	BinaryNonRobot
	Binary array of the labels not assigned to a robot. More...

valarray< int >	BinaryRobot
	Binary array of the label assigned to a robot. More...

int	cols
	Number of columns of the image. More...

vector< int >	image
	The image to perform the labeling on. More...

valarray< int >	label2d
	Array of labels. More...

int	next_label = 1
	The current label ID. More...

int	rows
	Number of rows of the image. More...

bool	zeroAsBg
	Whether 0 should be considered or not. More...

Detailed Description

Use row-by-row labeling algorithm to label connected components. The algorithm makes two passes over the image: one pass to record equivalences and assign temporary labels and the second to replace each temporary label by the label of its equivalence class. Based on Linda G. Shapiro, Computer Vision: Theory and Applications. (3.4 Connected Components Labeling), Rosenfeld and Pfaltz (1966).

Definition at line 14 of file connected_components.h.

Constructor & Destructor Documentation

◆ connected_components()

connected_components::connected_components	(	valarray< int >	m,
		int	rows,
		int	cols,
		bool	zeroAsBg
	)

Constructor that initializes the private member variables.

Parameters

m	The matrix containing the data to label.
rows	Number of rows in the matrix.
cols	Number of columns in the matrix.
zeroAsBg	Whether 0 represents background and is ignored.

Definition at line 3 of file connected_components.cpp.

Member Function Documentation

◆ compactLabeling()

valarray< int > connected_components::compactLabeling ( )

Rearrange the labels to make the label numbers consecutive.

Returns: An array of labels.

Definition at line 11 of file connected_components.cpp.

◆ constructBinaryImages()

void connected_components::constructBinaryImages ( int robotsLabel )

Create binary arrays of connected labels.

Parameters

robotsLabel The label to create the binary array for.

Definition at line 138 of file connected_components.cpp.

◆ DT1D()

void connected_components::DT1D	(	vector< float >	f,
		vector< float > &	d,
		vector< int > &	v,
		vector< float > &	z
	)

private

DT1D.

Parameters

f
d
v
z

Definition at line 203 of file connected_components.cpp.

◆ getMaxLabel()

int connected_components::getMaxLabel ( )

Get the max label of the labeling process which is in the range [0,max_label].

Returns: The maximum label.

Definition at line 41 of file connected_components.cpp.

◆ getVector()

vector< float > connected_components::getVector	(	valarray< float >	A,
		int	row
	)

private

Get a slice of an array.

Parameters

A	The array to take the slice from.
row	The index of the slice to take.

Returns: The selected slice.

Definition at line 231 of file connected_components.cpp.

◆ labeling()

vector< int > connected_components::labeling ( )

Label the connected components.

Returns: An array of labels.

Definition at line 46 of file connected_components.cpp.

◆ NormalizedEuclideanDistanceBinary()

valarray< float > connected_components::NormalizedEuclideanDistanceBinary ( bool RobotR )

Calculate the normalized euclidean distance transform of a binary image with foreground pixels set to 1 and background set to 0.

Parameters

RobotR Whether to compute the distances to the robot.

Returns: The distance array.

Definition at line 155 of file connected_components.cpp.

◆ uf_find()

int connected_components::uf_find	(	int	x,
		vector< int >	parent,
		vector< int > &	label
	)

Return the root label (starts from 1 because label array is initialized to 0 at first). The label array records the new label for every root.

Parameters

x	The label to start the search from.
parent	The label hierarchy.
label	The vector of labels.

Returns: The root label.

Definition at line 126 of file connected_components.cpp.

◆ uf_union()

void connected_components::uf_union	(	int	x,
		int	y,
		vector< int > &	parent
	)

Combine two labels.

Parameters

x	The first label.
y	The second label.
parent	The label hierarchy.

Definition at line 113 of file connected_components.cpp.

Member Data Documentation

◆ BinaryNonRobot

valarray<int> connected_components::BinaryNonRobot

private

Binary array of the labels not assigned to a robot.

Definition at line 106 of file connected_components.h.

◆ BinaryRobot

valarray<int> connected_components::BinaryRobot

private

Binary array of the label assigned to a robot.

Definition at line 101 of file connected_components.h.

◆ cols

int connected_components::cols

private

Number of columns of the image.

Definition at line 116 of file connected_components.h.

◆ image

vector<int> connected_components::image

private

The image to perform the labeling on.

Definition at line 126 of file connected_components.h.

◆ label2d

valarray<int> connected_components::label2d

private

Array of labels.

Definition at line 96 of file connected_components.h.

◆ next_label

int connected_components::next_label = 1

private

The current label ID.

Definition at line 121 of file connected_components.h.

◆ rows

int connected_components::rows

private

Number of rows of the image.

Definition at line 111 of file connected_components.h.

◆ zeroAsBg

bool connected_components::zeroAsBg

private

Whether 0 should be considered or not.

Definition at line 131 of file connected_components.h.

The documentation for this class was generated from the following files:

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ connected_components()

Member Function Documentation

◆ compactLabeling()

◆ constructBinaryImages()

◆ DT1D()

◆ getMaxLabel()

◆ getVector()

◆ labeling()

◆ NormalizedEuclideanDistanceBinary()

◆ uf_find()

◆ uf_union()

Member Data Documentation

◆ BinaryNonRobot

◆ BinaryRobot

◆ cols

◆ image

◆ label2d

◆ next_label

◆ rows

◆ zeroAsBg