Possible bug with perimeter calculation on composite selections

Posted by Chris Bradhurst on Jan 23, 2009; 12:06pm
URL: http://imagej.273.s1.nabble.com/Possible-bug-with-perimeter-calculation-on-composite-selections-tp3693924.html

Hello All,

I'm getting unexpected results for the perimeter value returned by the
ImageJ measure command (version 1.41o) when applying to composite disjoint
selections.

e.g.:
Just one square selection (20x20 pixels):
Area: 400, Perimeter 80 - as expected.

Hold shift and create an additional non-overlapping 20x20 square:
Area: 800, Perimeter 120 - (should be 160)

Create a third 20x20 non-overlapping square:
Area: 1200, Perimeter 180 - (should be 240)

In each case the area is correct, but the perimeter doesn't seem right when
there is 2 or more squares in the selection.

Any thoughts would be appreciated.

Kind Regards,
-Chris.