Define elements and correct them

Hi all,

This is a phase image reconstructed by NMR.

There are 5 test tubes in this image. One with the largest diameter (marked in blue), and 4 in shorter diameters inside (marked in black). The circular arches are the phase of the molecules.

I need to trace the circular paths, to define them and to correct them inside the 4 test tubes since they underwent a sort of a shift.

I would be happy to get a clue how to manage doing this.

Thanks in advance.