4-connectivity and 8-connectivity of components
A pixel is 4-connected to another pixel if they share an adjacent
vertical or horizontal side.
Image[i,j] is 4 connected to the pixels
Image[i+1,j], Image[i-1,j], Image[i,j+1], Image[i,j-1]
A pixel is 8-connected to another pixel if they share an adjacent
vertical or horizontal side OR a diagonal adjacency.
Image[i,j] is 8 connected to the pixels
Image[i+1,j], Image[i-1,j],
Image[i,j+1], Image[i,j-1],
Image[i+1,j+1], Image[i+1,j-1],
Image[i-1,j+1], Image[i-1,j-1]
1. A binary image example:
0 1 0 0 0 0 0 0
0 1 1 0 0 0 0 0
0 0 0 1 0 0 0 0
0 0 0 0 1 1 1 0
0 0 0 0 1 0 1 0
1 1 1 0 1 1 1 0
0 1 1 0 0 0 0 0
0 0 0 0 0 0 0 0
The binary image converted to labeled "4-connected" components:\
0 1 0 0 0 0 0 0
0 1 1 0 0 0 0 0
0 0 0 2 0 0 0 0
0 0 0 0 3 3 3 0
0 0 0 0 3 0 3 0
4 4 4 0 3 3 3 0
0 4 4 0 0 0 0 0
0 0 0 0 0 0 0 0
2. Another binary image:
0 1 0 0 0 1 1 1
0 1 1 0 0 0 1 0
0 0 0 1 0 0 0 0
0 0 0 0 1 1 1 0
0 0 0 0 1 0 1 0
1 1 1 0 1 1 1 0
0 1 1 0 0 0 0 0
0 0 0 0 0 0 4 0
The image converted to labeled "8-connected" components:
0 1 0 0 0 2 2 2
0 1 1 0 0 0 2 0
0 0 0 1 0 0 0 0
0 0 0 0 1 1 1 0
0 0 0 0 1 0 1 0
3 3 3 0 1 1 1 0
0 3 3 0 0 0 0 0
0 0 0 0 0 0 4 0