Neural Network-Generated Illustrations in Allo

Taking, sharing, and viewing selfies has become a daily habit for many — the car selfie, the cute-outfit selfie, the travel selfie, the I-woke-up-like-this selfie. Apart from a social capacity, self-portraiture has long served as a means for self and identity exploration. For some, it’s about figuring out who they are. For others it’s about projecting how they want to be perceived. Sometimes it’s both.

Photography in the form of a selfie is a very direct form of expression. It comes with a set of rules bounded by reality. Illustration, on the other hand, empowers people to define themselves - it’s warmer and less fraught than reality.
Today, Google is introducing a feature in Allo that uses a combination of neural networks and the work of artists to turn your selfie into a personalized sticker pack. Simply snap a selfie, and it’ll return an automatically generated illustrated version of you, on the fly, with customization options to help you personalize the stickers even further.
What makes you, you?
The traditional computer vision approach to mapping selfies to art would be to analyze the pixels of an image and algorithmically determine attribute values by looking at pixel values to measure color, shape, or texture. However, people today take selfies in all types of lighting conditions and poses. And while people can easily pick out and recognize qualitative features, like eye color, regardless of the lighting condition, this is a very complex task for computers. When people look at eye color, they don’t just interpret the pixel values of blue or green, but take into account the surrounding visual context.

In order to account for this, we explored how we could enable an algorithm to pick out qualitative features in a manner similar to the way people do, rather than the traditional approach of hand coding how to interpret every permutation of lighting condition, eye color, etc. While we could have trained a large convolutional neural network from scratch to attempt to accomplish this, we wondered if there was a more efficient way to get results, since we expected that learning to interpret a face into an illustration would be a very iterative process.

That led us to run some experiments, similar to DeepDream, on some of Google's existing more general-purpose computer vision neural networks. We discovered that a few neurons among the millions in these networks were good at focusing on things they weren’t explicitly trained to look at that seemed useful for creating personalized stickers. Additionally, by virtue of being large general-purpose neural networks they had already figured out how to abstract away things they didn’t need. All that was left to do was to provide a much smaller number of human labeled examples to teach the classifiers to isolate out the qualities that the neural network already knew about the image.

To create an illustration of you that captures the qualities that would make it recognizable to your friends, we worked alongside an artistic team to create illustrations that represented a wide variety of features. Artists initially designed a set of hairstyles, for example, that they thought would be representative, and with the help of human raters we used these hairstyles to train the network to match the right illustration to the right selfie. We then asked human raters to judge the sticker output against the input image to see how well it did. In some instances, they determined that some styles were not well represented, so the artists created more that the neural network could learn to identify as well.

Raters were asked to classify hairstyles that the icon on the left resembled closest. Then, once consensus was reached, resident artist Lamar Abrams drew a representation of what they had in common.

Avoiding the uncanny valley
In the study of aesthetics, a well-known problem is the uncanny valley - the hypothesis that human replicas which appear almost, but not exactly, like real human beings can feel repulsive. In machine learning, this could be compounded if were confronted by a computer’s perception of you, versus how you may think of yourself, which can be at odds.

Rather than aim to replicate a person’s appearance exactly, pursuing a lower resolution model, like emojis and stickers, allows the team to explore expressive representation by returning an image that is less about reproducing reality and more about breaking the rules of representation.

The team worked with artist Lamar Abrams to design the features that make up more than 563 quadrillion combinations.

Translating pixels to artistic illustrations
Reconciling how the computer perceives you with how you perceive yourself and what you want to project is truly an artistic exercise. This makes a customization feature that includes different hairstyles, skin tones, and nose shapes, essential. After all, illustration by its very nature can be subjective. Aesthetics are defined by race, culture, and class which can lead to creating zones of exclusion without consciously trying. As such, we strove to create a space for a range of race, age, masculinity, femininity, and/or androgyny. Our teams continue to evaluate the research results to help prevent against incorporating biases while training the system.
Creating a broad palette for identity and sentiment
There is no such thing as a ‘universal aesthetic’ or ‘a singular you’. The way people talk to their parents is different than how they talk to their friends which is different than how they talk to their colleagues. It’s not enough to make an avatar that is a literal representation of yourself when there are many versions of you. To address that, the Allo team is working with a range of artistic voices to help others extend their own voice. This first style that launched today speaks to your sarcastic side but the next pack might be more cute for those sincere moments. Then after that, maybe they’ll turn you into a dog. If emojis broadened the world of communication it’s not hard to imagine how this technology and language evolves. What will be most exciting is listening to what people say with it.

This feature is starting to roll out in Allo today for Android, and will come soon to Allo on iOS.

Acknowledgements
This work was made possible through a collaboration of the Allo Team and Machine Perception researchers at Google. We additionally thank Lamar Abrams, Koji Ashida, Forrester Cole, Jennifer Daniel, Shiraz Fuman, Dilip Krishnan, Inbar Mosseri, Aaron Sarna, Aaron Maschinot and Bhavik Singh.