I had to take a painting and try to re-draw it with a pen for my drawing class this past semester in college. The painting I used as reference was

(A grey Arab by Jacques-Laurent Agasse) this!

I really loved how this came out even though I was sure it would be terrible when I was working on it. I did not trace any part of this in case anyone wanted to know, tracing was not allowed for the project and I hate tracing anyway.