Low frequency rings

Hello,

I’m trying to remove some wide, gradual rings in my images. These are left over after I’ve run Xlib’s stripe removal to get rid of sharper rings. I’d like to segment the dark patches (bubbles) that exist in my solid sample, but the darker sections of the rings are just about as dark as my small bubbles are going to be.

Is there some way to smooth out the rings (stripes in the polar transform, of course), or segment bubbles in spite of them?

Thanks!

heap.tif (3.8 MB)
polar heap.tif (3.8 MB)