RegionBinarize
RegionBinarize[image, marker, d] gives a binary version of image that includes the foreground pixels of marker and also connected regions whose pixel values are within a distance d.
RegionBinarize[image, marker, d, {t1, t2}]grows regions in marker by adding pixels whose average intensity is also constrained within an interval {t1, t2}.
Examples
img = ExampleData[{"TestImage", "Lena"}];
marker = Binarize[img, 0.8];
RegionBinarize[img, marker, 0.1]Please visit the official Wolfram Language Reference for more details.