Can I section one image based on the intersection of the image with fitted circle/ellipse?

imagej/Fiji has fit circle or fit ellipse capability and I want to see whether I can section the image by the line from centroid to intersection of the fitted circle/ellipse with the real image. I want to do some calculations and processes (like pixel intensity, skletonization ,…) on each section individually. Attached is an example of what I want to do. I fitted the circle by hand just to explain what I want to do.

Hi @Zeynab_Mousavi,

How do you define the direction of your lines ?
Once you know the direction, you can create a image and fill it inside the mask of your circle fit. Then you draw a black line (with makeLine). You can then use Analyse particle to get your sections.


@VirtualSlide I want to section the image by line of symmetry. Based on the geometry, it can have 0,1,2 or more line of symmetry. After sectioning with line of symmetry I want to do calculations on each section separately and take the mean and report that. what you mean by “fill it inside the mask of your circle fit”?


I mean that in a blank image, you can add the ROI of the circle you fitted and fill this ROI with white (run(“Fill”, “slice”);). Then you can draw your black lines of symetry. You’ll then get each of your sections.