How to determine two unequal radius

Good day everyone,

I am new in Fiji (imageJ) and I am trying to use Fiji (imageJ) to work on some flame (combustion) high speed camera images as shown below. I would like to determine the radius (R1) or (R2) as shown in the image. Please can someone kindly advise on how to go about it.



please upload a raw image, the white circle is your marker? or on the image?

Thanks yxdragon.

The white circle is the edge of the image. It’s on the image not a white marker.


so the red and green marker?
please upload a raw image. how many images do you have?
you want measure by hand? or use some method to process automatic?

Thanks yxdragon,

I have a lot of images so I want to compute it automatically, however, if its not possible to determine it automatically you can show me the manual means. The red and green are marker lines. Attached are some of the raw images. Note some of the images don’t have the white marker.


So I think it is a mixed problem.

  1. how to detect the goal
    some image with white contours is easy to segment, but the third image with no contour, there is no easy method to segment.

  2. measure
    some image with black line, but some image not. and how to define the R, the max vertical distance? or the max inscribed circle?

maybe you need classify your images, and process them by different method. Here I give your some advice to treat some specific image. I use ImagePy, you can get it free, (imagej has the similar method, so if you use imagej, you can also reference these method)

  1. how to extract a white contours?
    threshold > fill holes > filter region by area and solidity

  2. how to measure the max height
    region analysis then you can got the maxy and miny, max height = maxy - miny,
    and you can also get the cov ellipse. the major, minor axis may be meanful for you.

  3. how to measre the max inscribed circle?
    distance transform, and find local max point, the pixel value is the max inscribed circle radius.

  4. how to split from the black line
    extract the goal > mask the raw image > threshold > watershed
    then you can measure the max height, major, minor axis, or max inscribed circle like upon!

the method upon in ImagePy support sequence process, but you need put the same type together in a folder. then import them as sequence. then you can process all images at one time.

a tips: please save your image in png or bmp, tif. (jpg would lost some detail)

Thanks yxdragon,

I will have a look at it.