regions

Label the connected components in a binary image. More...

Modules
	regions
	The C++ interface for regions.
	af_regions
	The C interface for regions.

Detailed Description

Label the connected components in a binary image.

Given a binary image (with zero representing background pixels), regions computes a floating point image where each connected component is labeled from 1 to N, the total number of components in the image.

A component is defined as one or more nonzero pixels that are connected by the specified connectivity (either 4-way or 8-way) in two dimensions. The default connectivity is 8-way.

// Make a random array
const int len = 8;
array r = randn(len, len) * 10.0f;

// Convert to a binary image with thresholding
array in = (r > 5.0f);
print(in);
// in =
// 0   0   0   0   1   0   1   0
// 0   0   0   0   0   0   1   1
// 0   1   0   1   0   0   0   0
// 0   0   1   0   1   1   0   1
// 1   1   0   0   0   1   0   1
// 0   0   0   1   0   0   0   1
// 0   0   0   0   1   0   0   1
// 0   1   0   0   0   1   0   0

// Compute the label matrix using 8-way connectivity
print(regions(in));
// 0   0   0   0   4   0   5   0
// 0   0   0   0   0   0   5   5
// 0   1   0   1   0   0   0   0
// 0   0   1   0   1   1   0   6
// 1   1   0   0   0   1   0   6
// 0   0   0   3   0   0   0   6
// 0   0   0   0   3   0   0   6
// 0   2   0   0   0   3   0   0