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Find connected components in binary image

`CC = bwconncomp(BW)`

`CC = bwconncomp(BW,conn)`

The functions

`bwlabel`

,`bwlabeln`

, and`bwconncomp`

all compute connected components for binary images.`bwconncomp`

replaces the use of`bwlabel`

and`bwlabeln`

. It uses significantly less memory and is sometimes faster than the other functions.Function Input Dimension Output Form Memory Use Connectivity `bwlabel`

2-D Label matrix with double-precision High 4 or 8 `bwlabeln`

N-D Double-precision label matrix High Any `bwconncomp`

N-D `CC`

structLow Any To extract features from a binary image using

`regionprops`

with default connectivity, just pass`BW`

directly into`regionprops`

(i.e.,`regionprops(BW)`

).To compute a label matrix having more memory-efficient data type (e.g.,

`uint8`

versus`double`

), use the`labelmatrix`

function on the output of`bwconncomp`

. See the documentation for each function for more information.

The basic steps in finding the connected components are:

Search for the next unlabeled pixel,

`p`

.Use a flood-fill algorithm to label all the pixels in the connected component containing

`p`

.Repeat steps 1 and 2 until all the pixels are labelled.

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