DeleteSmallComponents

DeleteSmallComponents[image] replaces small connected components in a binary image with background pixels.

DeleteSmallComponents[m] replaces positive integers in a label matrix with 0 if their tally is small.

DeleteSmallComponents[..., n] replaces components consisting of n or fewer elements.

Examples

Remove small components from binary image:

img = Binarize[Import["ExampleData/text.png"]]
DeleteSmallComponents[img]

Specify minimum size:

DeleteSmallComponents[img, 50]

Please visit the official Wolfram Language Reference for more details.