bwlabel()- clarification and manipulation

I didnt understand the terms 4- connected objects and 8- connected bjects put in the econd argument of the function

Another question is- How does matlab determine the numbering of the objects? Can I use matlab to start numbering from the middle of the matrix? It doesn't matter to me if I need to use another function

Matar Maoz

Answer 1

[David Young]

See also http://en.wikipedia.org/wiki/Pixel_connectivity.

The ordering is arbitrary in bwlabel - and if you think about images with complex, arbitrary-shaped regions, it's clear that it would be very difficult to offer anything else in a general function.

You can use regionprops to find region centres, compute the distances od these from the image centre, then use sort to put the regions in order, and relabel.

Answer 2

[Sean de Wolski]

1) 4-connected means the (2d) pixels must be sharing a side 8-connected means the (2d) pixels can be sharing a side or a corner

2) As far as labeling order, I don't know if there is a stock way to do that.