How to select edge/ black lines in an image only?

[rich2005]

Not going to be easy with that sort of image.

You can get this: https://i.imgur.com/wOJDoMw.jpg using the median blur filter Filters -> Blur -> Median Blur Settings as shown
Repeat the filter again using the same parameters : https://i.imgur.com/1rhpQoA.jpg Some of the noise gone.
Gives this: https://i.imgur.com/U1nsudc.png You will still need to do a bit of touch-up.