Female nude - back. The drawing

This is the drawing - the first one I've ever completed with charcoal.
I believe that I changed the original enough, giving also details that were not present in the original picture, and therefore maybe I can call it my own without breaching anything.
It won't matter anyway, given this is a learning project, the results of which are all yet to be established ...
Here is the same picture taken with the new digicam - just to see if there is a difference with this and the previous one taken with the phone.