Learning to Cartoonize Using White-Box Cartoon Representations | Hacker News Reader

Learning to Cartoonize Using White-Box Cartoon Representations

github.com

122 pointsgitgud39 comments

While the results certainly are pretty, I don't see how learning has taken place.

This cartoon filter still has the same issues as previous attempts, which is:

- omitting borders that are semantically important but have a low color gradient

- not collapsing small areas into lines

For the first issue, there's an example image of a picnic on white background. A human cartoonist would most likely draw a full outline around the white spoon, because it is important for conveying the type of object that this is supposed to be. With this algorithm, the spoon gets partially merged with the white background and without the reference photo I would have a hard time identifying it as a spoon.

For the second issue, kook at the photo of the Asian girl with patterned skirt. A human cartoonist would most likely observe the regular grid pattern and replace it with thin lines, thereby communicating that all of it is one same thing. This algorithm, on the other hand, treats each tile of the pattern individually, thereby making it look more like a crystal or crumbled foil.

I personally also prefer white-box algorithms, but there's no denying that creating a cartoon requires a lot of prior knowledge about which features to retain as important and which features to abstract away. As such, I see the real challenge in somehow producing good saliency training data for millions of images. I mean ideally you would want the 5 year video stream plus eye tracking data of a baby starting to grow up...

> For the second issue, kook at the photo of the Asian girl with patterned skirt. A human cartoonist would most likely observe the regular grid pattern and replace it with thin lines, thereby communicating that all of it is one same thing. This algorithm, on the other hand, treats each tile of the pattern individually, thereby making it look more like a crystal or crumbled foil.

Something similar is going on with the photo of the merlion statue. The entire body is scaled, and a cartoonist would definitely represent that. But (because of lighting?), the algorithm renders the tail smooth instead of scaled.

Assume this were a photo in a pictureframe in the background of a bigger picture

This could replace all of the WikiHow illustrators that trace from stock photos, and muddle the waters even more for their copyright status.

https://onezero.medium.com/we-finally-figured-out-who-makes-...

Thank you for that very amusing article.

It's probably much harder to arrange people and objects to reproduce such a scene than to make a basic wikihow-style drawing.

If I understand this right, they've built a 'cartoonify' filter to convert real-world images into cartoon format, and then trained a neural net based on these image pairs? If so, what does the neural net add?

Sorta, it breaks down the images (from anime?) into three representations - surface, structure, and details, and also extracts each of those representations from generated images. Those representations are then cross-checked by the adverserial network, which improves the GAN's anime-esque generation ability.

Kind of agree, I think if they have a good way to create the underlying dataset, a NN to go in the opposite direction might be more interesting.

This would be very similar to the "super-resolution" approach.

E.g.,

https://medium.com/beyondminds/an-introduction-to-super-reso...

I know in the case of physics simulations the neural net can perform better than the classical algorithm. Not sure if that's the case here but just thought it was worth mentioning.

By "perform better" I assume you mean time/memory performance and not accuracy

I could have sworn this kind of thing already exist in some apps. Prism?

Yeah, looks exactly like some of the Prism filtering I've toyed with.

The big question: Does copyright law apply to cartoon version of copyrighted images? Transformative work can circumvent copyright law, but are you allowed to feed copyrighted images into an AI algorithm to create cartooned versions? Who owns the copyright at that point?

I don't see any reason why copyright would not apply. If you take someone else's photograph, change the white balance, and start selling copies of it, that's classic copyright infringement.

As for input data to models, my intuition is that they would be tainted by the copyright of the input images. It's just that nobody has a bot for scanning AI models for their photographs, so you don't see a lot of litigation or DMCA takedown requests here. It's easy when someone just uploads your photo to their website. It's hard when the photo contributes some weights to a neural network.

My main takeaway is that copyright is very imperfect. It doesn't allow for any unsolicited enhancements of someone else's work.

You'll get further issues once Getty Images automatically generates copyrighted images covering as much of the latent space of interesting images as possible.

In principle by the way copyright works this isn't really an issue: if an image is generated independently then copyright does not apply. However, in the event that you wind up with something similar, it becomes something which you would need to prove (and people have lost cases because they could not). On the other hand, such large-scale generation of images will likely be treated differently by the courts than other means of production.

Indeed, people often seem to assume that the output of GANs are free of the copyright of the training data, but this has not been tested in court and I get the impression the legal opinion leans towards that it does, which makes the copyright status of most GANs (and in fact most neural nets) a pretty huge mess.

It's hard to know what would have happened if Shepard Fairey hadn't gotten caught destroying documents, and we don't know the specifics of all of the settlement, but I think it's fair to say he lost that case.

https://en.wikipedia.org/wiki/Barack_Obama_%22Hope%22_poster

Be great to see this in a fragment shader someday.

I really like the cartoonized photos of detailed landscapes.

I think human faces and bokeh could use some improvement.

The former seems especially tricky; showing or hiding certain lines might change the perceived emotion and result in a different image.

To a certain extent, PowerPoint's "Artistic Features" option under "Picture Format" allows for similar effects. The paintbrush options is like this cartoon style. If I had the time, I'd definitely choose this cartoon program, as PowerPoint's effect is not as clean.

I didn't even notice these pictures were "cartoonized" until I zoomed in on my smartphone ...

If you make an imaging effect, please make sure it works at all scales. And I'm also looking at you bokeh-folks ;)

Rotoscope?

yep, this seems exactly the same. It's also fitting the Keanu Reeves is in one of the test images. Scanner darkly was a great film, time for a rewatch

Automated rotoscope.

Those images that don't already work because of their colors and composition have the charme of traced photos.

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