Re: draw contour for given pixel value

Posted by Michael Schmid on
URL: http://imagej.273.s1.nabble.com/draw-contour-for-given-pixel-value-tp5003651p5003657.html

Hi Neil,

simply use the Wand tool. It's probably best to set a slight tolerance (1 or 2) and 8-connected mode in its options.

The Wand selects a single pixel value (with some tolerance if specified), so in principle it will select a ring around the maximum. The ImageJ built-in Wand will always include 'inner hole' in the selection, however, so you get everything inside selected as well.

By the way, you can then very easily fit an ellipse to the shape: Have 'Fit Ellipse' enabled in 'Set Measurement' and use 'Measure'.

Michael
________________________________________________________________
On Jun 26, 2013, at 17:44, Neil Fazel wrote:

> For an image with almost elliptic intensity contours, is there a way to draw a selection for a contour corresponding to a given pixel value? For example, I would click on a pixel and it would start from there and trace an almost elliptical contour having that pixel's value.  Since the selection would be almost elliptic but not completely, the elliptical selection tool, or oval profiling macro, can't be used.
>
> I have attached an example of such an image.
>
> Thanks,
> Neil

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