Morphological thinnig algorithm bug

[roymacdonald]

Hi Kyle,
hope you're doing well.
I found a bug in the morphological thinning algo.
Check this screenshot

Probably when using it on images with thin lines it might work but as you can see when lines are wider it doesn't behave well.
What's going on is that the thinning is being done over the original image, thus the evaluation for each pixel is being done over the already modified image generating a wrong evaluation. The fix is quite simple, just create a copy of the original image that's used for evaluation and modify the original.
I have this fix already made. Should I PR?
best

[kylemcdonald]

absolutely! please make a PR!