Keeping Intersection of an Image Only

[Anysja]

I am trying to take a black and white image, place red lines over the top and keep only the part of the red line that intersects with the black.

Original Image:    
Final Image:    

Is there a way to program this in Python?

Thank you!

[Larz60+]

don't post the same question in multiple threads. We read them all. If your's hasn't been responded to right away, it may because someone is trying to solve before responding.
Multiple posts are clutter.

[Anysja]

Sorry, I just thought I posted the first one in the wrong thread.

[metulburr]

we can move threads

[Anysja]

I figured it out. I just search every pixel and if it is black I draw a line in a canvas at that same coordinate. It replicates the image, leaving only the black portion. This is exactly what I want.