Posted by
Michael Schmid on
Sep 17, 2009; 2:56pm
URL: http://imagej.273.s1.nabble.com/Automatic-location-of-spots-at-intersections-of-arcs-of-spots-Laue-camera-tp3691082p3691085.html
Hi Alan,
use Process>Binary<Find Maxima to create an image with one point per
maximum.
Then Analyze>Tool>Save XY Coordinates to export the list.
Finding the arcs automatically will be much more difficult.
Assuming that the arcs are ellipses, it would be possible if you
write a Hough transform that takes advantage of the fact that all all
ellipses have a vertex at the origin, so there are only 3 parameters
for the ellipse (angle, a, b). Usually, a Hough transform with 3
parameters should be possible (4 parameters would be too much).
(See the Wikipedia entry for Hough transform).
Hope this helps,
Michael
________________________________________________________________
On 17 Sep 2009, at 16:33, Alan Hewat wrote:
> I am interested in the possibility of the automatic measurement of the
> co-ordinates of isolated spots in an image, and eventually of spots
> that lie at the intersection of arcs of spots, such as shown by the
> numbered spots on
http://www.neutronoptics.com/resources/oe-laue.jpg>
> This is a back-scattered Laue X-ray diffraction pattern, and is used
> to determine the orientation of the crystal by solving for the (h,k,l)
> indices of the diffraction spots; the spots at arc intersections
> normally have low indices.
> ______________________________________________
> Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
> <
[hidden email]> +33.476.98.41.68
>
http://www.NeutronOptics.com/hewat> ______________________________________________