ECE 692 – Advanced Topics in Computer Vision Lecture 4 – Morphology 02/09/16

Morphology Pre- and post-processing Morphological filter Extract image components that are useful in the representation and description Boundary Skeleton

Morphological Operators - Dilation 9 8 7 6 5 4 3 2 1 4 3 2 1 -1 -2 -3 -4 -5 9 8 7 6 5 4 3 2 1 Check to see if B needs to be reflected. 0 1 2 3 4 5 6 7 8 9 -5 -4 –3 –2 –1 0 1 2 3 4 0 1 2 3 4 5 6 7 8 9 A = {(2,8),(3,6),(4,4), (5,6),(6,4),(7,6),(8,8)} A+B = {(2,8),(3,6),(4,4), (5,6),(6,4),(7,6),(8,8), (2,9),(3,7),(4,5),(5,7), (6,5),(7,7),(8,9)} B = {(0,0),(0,1)} B: structuring element (s.e) Always includes (0,0)

Morphological Operators - Erosion 9 8 7 6 5 4 3 2 1 9 8 7 6 5 4 3 2 1 2 1 -1 -2 –2 –1 0 1 2 B 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 A-B A

Example Gray-level because of negative values Relief: dilate-original Sunken: erode-original

Other Morphological Operators Opening Closing Application???

Example Opening Closing

Morphological Filter (opening + closing)

Application – Edge Linking

Application

The Hit-or-Miss Transformation B1 or D: shape of interest W: window W-D: window that surrounds D

Some Basic Morphological Algorithms Boundary extraction Hole filling Extraction of connected components Skeletons

Boundary Extraction

Hole Filling X0 is a point within the region with holes. Conditional Dilation

Extraction of Connected Components X0 is a point on the region. Conditional Dilation

Gray-scale Morphology Dilation Finding max in the neighborhood Erosion Finding min in the neighborhood