Copying linecollections across figures


I’d like to know if there’s some way of copying a LineCollection or a ContourSet (or any other Artist, actually) from one figure to another.

More precisely, I have to figures using identical axes (one being a grayscale image and the other a thresholded version of the image) ; I have written a script to tag parts of the thresholded image (which gives me ContourSets), and I want to copy these to the grayscale image.

Any help would be greatly appreciated.

Thanks in advance,