Segmentation of a grey lebel image

Dear comunity,

I have the following image composted by many plies. The plies are separated by grey zones made of resin (also called interfaces). Would you suggest an efficient method to separate (segment) the interfaces from the rest of the image (for an exaple, the blue line follows one of the interfaces). Unfortunately, greylevel segmentation does not work properly.

Thank you in advance for your help!

[KALYAN ACHARJYA]

Which part would you like to segment?

Answer 1

[Santi]

Dear Kalyan, the dark grey interfaces that separate the lighter grey plies. For an example, the blue line follows one interface (I want to segment all of them).