MorphologicalComponents

MorphologicalComponents[image] gives an array in which each pixel of image is replaced by an integer index representing the connected foreground image component in which the pixel lies.

MorphologicalComponents[image, t] treats values above t as foreground.

MorphologicalComponents[video, ...] computes connected components in frames of video.

Examples

Find connected components in a binary image:

img = Binarize[ExampleData[{"TestImage", "Blobs"}]];
MorphologicalComponents[img] // Colorize

Please visit the official Wolfram Language Reference for more details.