DistanceTransform

DistanceTransform[image] gives the distance transform of image, in which the value of each pixel is replaced by its distance to the nearest background pixel.

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

Examples

DistanceTransform[Binarize[ExampleData[{"TestImage", "Lena"}]]]

Please visit the official Wolfram Language Reference for more details.