In computer vision and image processing, opening is, together with closing, a basic workhorse of morphological noise removal. Opening removes small objects, while closing removes small holes. These techniques can also be used to find specific shapes in an image. Opening can be used to find things into which a specific structuring element can fit (edges, corners, ...).

The Opening (morphology) is the Dilation (morphology) of the Erosion (morphology) of the set A.

O(A,B) = (A - B) + B

where + is the Minkowski addition.