Living Lines Animation Style

I watched Glen Keane’s - “The Duet” and realized I would love to do a similar style for a side scroller. What would be the best way to achieve this? Is there a way to do an inverted toon shader that would be lighter on the edges or maybe something similar to the photoshop “edge effect”?

Here is a link to the video. Beautiful animation style and very simple. I’m a minimalist fan anyway though.
Glen Keane - The Duet

Does this achieve the effect you’re after?