core/vil/algo/vil_blob.h File Reference

Finds connected regions in a boolean image. More...

#include <vcl_vector.h>
#include <vcl_utility.h>
#include <vil/vil_image_view.h>
#include <vil/vil_chord.h>

Go to the source code of this file.

Typedefs
typedef vcl_vector< vil_chord >	vil_blob_region
	A region is a vector of chords that came from a connected blob.
typedef vcl_vector< vcl_pair < unsigned, unsigned > >	vil_blob_pixel_list
	A pixel list is a vector of <i,j> pixel positions.
Enumerations
enum	vil_blob_connectivity { vil_blob_4_conn, vil_blob_8_conn }
	Specify 4- or 8- neighbour connectivity. More...
Functions
void	vil_blob_labels (const vil_image_view< bool > &src_binary, vil_blob_connectivity conn, vil_image_view< unsigned > &dest_label)
	Produce a label image that enumerates all disjoint blobs in a binary image.
void	vil_blob_labels_to_edge_labels (const vil_image_view< unsigned > &src_label, vil_blob_connectivity conn, vil_image_view< unsigned > &dest_label)
	Set all non-blob-edge pixels in a blob label image to zero.
void	vil_blob_labels_to_regions (const vil_image_view< unsigned > &src_label, vcl_vector< vil_blob_region > &dest_regions)
	Convert a label image into a list of chorded regions.
void	vil_blob_labels_to_pixel_lists (const vil_image_view< unsigned > &src_label, vcl_vector< vil_blob_pixel_list > &dest_pixel_lists)
	Convert a label image into a list of pixel lists.

---

Detailed Description

Finds connected regions in a boolean image.

Author:

Ian Scott Thes functions can be combined to get blobs as images, chorded regions, edge pixels lists, etc. For example to get an edge pixel list of im_binary

 vil_blob_labels(im_binary, vil_blob_4_conn, im_labels);
 vil_blob_labels_to_edge_labels(im_binary, vil_blob_4_conn, im_labels);
 vil_blob_labels_to_pixel_lists(im_edges, pixel_lists);

To get the area of a blob efficiently

 vil_blob_labels(im_binary, vil_blob_4_conn, im_labels);
 vil_blob_labels_to_regions(im_edges, regions);
 unsigned area_of_first_blob = vil_area(regions[0]);

Definition in file vil_blob.h.

---

Typedef Documentation

typedef vcl_vector<vcl_pair<unsigned, unsigned> > vil_blob_pixel_list

A pixel list is a vector of <i,j> pixel positions.

Definition at line 57 of file vil_blob.h.

typedef vcl_vector<vil_chord> vil_blob_region

A region is a vector of chords that came from a connected blob.

Definition at line 48 of file vil_blob.h.

---

Enumeration Type Documentation

enum vil_blob_connectivity

Specify 4- or 8- neighbour connectivity.

Enumerator:

vil_blob_4_conn
vil_blob_8_conn

Definition at line 27 of file vil_blob.h.

---

Function Documentation

void vil_blob_labels	(	const vil_image_view< bool > &	src_binary,
		vil_blob_connectivity	conn,
		vil_image_view< unsigned > &	dest_label
	)

Produce a label image that enumerates all disjoint blobs in a binary image.

Definition at line 81 of file vil_blob.cxx.

void vil_blob_labels_to_edge_labels	(	const vil_image_view< unsigned > &	src_label,
		vil_blob_connectivity	conn,
		vil_image_view< unsigned > &	dest_label
	)

Set all non-blob-edge pixels in a blob label image to zero.

A 4-conn edge is a 4-conn area itself, and not just those pixels which have dissimilar 4-conn neighbours.

Definition at line 197 of file vil_blob.cxx.

void vil_blob_labels_to_pixel_lists	(	const vil_image_view< unsigned > &	src_label,
		vcl_vector< vil_blob_pixel_list > &	dest_pixel_lists
	)

Convert a label image into a list of pixel lists.

A blob label value of n will be returned in dest_pixels_lists[n-1].

Convert a label image into a list of pixel lists.

A blob label value of n will be returned in dest_pixels_lists[n-1]. Note that pixel lists are not ordered.

Definition at line 275 of file vil_blob.cxx.

void vil_blob_labels_to_regions	(	const vil_image_view< unsigned > &	src_label,
		vcl_vector< vil_blob_region > &	dest_regions
	)

Convert a label image into a list of chorded regions.

A blob label value of n will be returned in dest_regions[n-1].

Definition at line 247 of file vil_blob.cxx.