Radius of Curvature using Fiji

Hi! I am very new to Fiji (just downloaded it), so I don’t know how to use it.

For my research, I am trying to use pictures to find the radius of curvature of white “cloud-like” paths. In the picture, I am trying to find the radius of curvature of the path circled in yellow.

Ideally, I would like some kind of program that could turn the image into a graph. In other words, if the object I am taking a picture of has the dimensions of 25cm x 25cm, I would like to be able to tell Fiji that the image is 25cm by 25cm and then Fiji creates a 25cm by 25cm graph in the xy-plane where I could click anywhere on the image and Fiji would tell me my location/coordinates on the graph in terms of cm. From there, I would be able to plot the points of a path and find the radius of curvature of that path.

Does anyone know how I would go about doing something like this? Is ImageJ/Fiji the best program to use for something like this? Again, I have no Fiji/ImageJ experience; nor do I have any coding experience. It would be amazing if someone could help me out.

Thank you!!