Marr-Hildreth Enhancement of NDE Images
Karpur, P. K.
Previous publications [1–5] have demonstrated the usefulness of digital image enhancement techniques for improving visual detection and resolution of features in NDE images. Many of the techniques are high-pass spatial domain convolution filters  which are used to enhance the appearance of edges by removing blur. Two of the major advantages of the more popular edge enhancement operators are their ease of implementation and their rapidity of execution . This makes them very useful for rapid “screening” of images. Their major disadvantages are that they emphasize “noise” as well as edges, and some are directionally dependent operators which tend to suppress features that are not aligned in the “preferred” direction.