I am trying to fit particles on an image as ellipses. The menu “Set Measurements > Fit Ellipse” looks exactly like what I need, but it only returns “Major”, “Minor” and “Angle” to characterise the fitted ellipses.
The official specs don’t say which information can be used to place the centres of the ellipses.
Is it “Centroid” or “Centre of mass”, or something else?
Note that I am currently using binary images, but I might be using greyscale images soon as well.
Thank you for helping me!
the ImageJ user-documentation says:
Fit ellipse Fits an ellipse to the selection. Uses the headings Major, Minor and Angle. Major and Minor are the primary and secondary axis of the best fitting ellipse. Angle is the angle between the primary axis and a line parallel to the X-axis of the image. The coordinates of the center of the ellipse are displayed as X and Y if Centroid is checked. Note that ImageJ cannot calculate the major and minor axis lengths if Pixel Aspect Ratio in the Analyze▷Set Scale…↓ dialog is not 1.0. There are several ways to view the fitted ellipse: The Edit▷Selection▷Fit Ellipse↑ command replaces an area selection with the best fit ellipse. The DrawEllipse macro draws (destructively) the best fit ellipse and the major and minor axis. Select Ellipses from the Show: drop-down menu in the particle analyzer (Analyze▷Analyze Particles…↑) and it will draw the ellipse for each particle in a separate window.
So the answer is “Centroid” and only form is taken into account, not the greyvalue distribution.