The following is a quotation from an Image processing textbook:
The connectivity relationship between a center pixel and its eight neighbors can be quantified by the concept of a pixel bond, the sum of the bond weights between the center pixel and each of its neighbors. Each four-connected neighbor has a bond of two, and each eight-connected neighbor has a bond of one.
I am searching different sources to understand what is pixel bond. How four-connected neighbor has two and eight connected has one.
What exactly is the bond weight?
(The passage from this book seems to also be available via Google Books)