N2 and N3 are your local coordinates.
If your blob is contained in the rectangular area, let's say (left, top, right, bottom): 10, 20, 20, 30
The absolute (meaning relative to the entire image) coordinates will range between 10 and 20 for x and 20 and 30 for y.
Since we are only looking at that rectangular area, the local coordinates will range between 0 and 10 for x and 0 and 10 for y.
In your screenshots, the VI has finished executing, so I would assume, that the last blob evaluated is 50 pixels wide and 56 pixels high.
