understanding selection coordinates

Posted by Neil Fazel on Feb 16, 2014; 1:10am
URL: http://imagej.273.s1.nabble.com/understanding-selection-coordinates-tp5006538.html

I have sampled the pixels on a 32-bit grayscale image (attached) using a selection and a macro call to getSelectionCoordinates(). (The selection itself was created using the Contour Plotter plugin for a contour with grayscale value of 157 on another image of same size.)

I am now inspecting the values of the pixels crossed by the selection. In the array returned by getSelectionCoordinates(), some pixels show up twice. How is that possible? Isn't a selection supposed to cross each pixel only once?

I have also magnified the image so I can see the individual pixels and the selection that goes through them. (An image for this is attached.) How do the values returned by getSelectionCoordinates() relate to the points on the selection, i.e. when I see a little white dot on the selection (see attached image), how do I know which pixel it refers to?

Thanks,
Neil

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