Google at CVPR 2018

Posted by Christian Howard, Editor-in-Chief, Google AI Communications

This week, Salt Lake City hosts the 2018 Conference on Computer Vision and Pattern Recognition (CVPR 2018), the premier annual computer vision event comprising the main conference and several co-located workshops and tutorials. As a leader in computer vision research and a Diamond Sponsor, Google will have a strong presence at CVPR 2018 — over 200 Googlers will be in attendance to present papers and invited talks at the conference, and to organize and participate in multiple workshops.

If you are attending CVPR this year, please stop by our booth and chat with our researchers who are actively pursuing the next generation of intelligent systems that utilize the latest machine learning techniques applied to various areas of machine perception. Our researchers will also be available to talk about and demo several recent efforts, including the technology behind portrait mode on the Pixel 2 and Pixel 2 XL smartphones, the Open Images V4 dataset and much more.

You can learn more about our research being presented at CVPR 2018 in the list below (Googlers highlighted in blue)

Finance Chair: Ramin Zabih

Area Chairs include: Sameer Agarwal, Aseem Agrawala, Jon Barron, Abhinav Shrivastava, Carl Vondrick, Ming-Hsuan Yang

Unsupervised Discovery of Object Landmarks as Structural Representations
Yuting Zhang, Yijie Guo, Yixin Jin, Yijun Luo, Zhiyuan He, Honglak Lee

DoubleFusion: Real-time Capture of Human Performances with Inner Body Shapes from a Single Depth Sensor
Tao Yu, Zerong Zheng, Kaiwen Guo, Jianhui Zhao, Qionghai Dai, Hao Li, Gerard Pons-Moll, Yebin Liu

Neural Kinematic Networks for Unsupervised Motion Retargetting
Ruben Villegas, Jimei Yang, Duygu Ceylan, Honglak Lee

Burst Denoising with Kernel Prediction Networks
Ben Mildenhall, Jiawen Chen, Jonathan BarronRobert Carroll, Dillon Sharlet, Ren Ng

Quantization and Training of Neural Networks for Efficient Integer-Arithmetic-Only Inference Benoit Jacob, Skirmantas Kligys, Bo Chen, Matthew Tang, Menglong Zhu, Andrew Howard, Dmitry KalenichenkoHartwig Adam

AVA: A Video Dataset of Spatio-temporally Localized Atomic Visual Actions
Chunhui Gu, Chen Sun, David Ross, Carl Vondrick, Caroline Pantofaru, Yeqing Li, Sudheendra Vijayanarasimhan, George Toderici, Susanna Ricco, Rahul Sukthankar, Cordelia Schmid, Jitendra Malik

Focal Visual-Text Attention for Visual Question Answering
Junwei Liang, Lu Jiang, Liangliang Cao, Li-Jia Li, Alexander G. Hauptmann

Inferring Light Fields from Shadows
Manel Baradad, Vickie Ye, Adam Yedida, Fredo Durand, William Freeman, Gregory Wornell, Antonio Torralba

Modifying Non-Local Variations Across Multiple Views
Tal Tlusty, Tomer Michaeli, Tali Dekel, Lihi Zelnik-Manor

Iterative Visual Reasoning Beyond Convolutions
Xinlei Chen, Li-jia Li, Fei-Fei Li, Abhinav Gupta

Unsupervised Training for 3D Morphable Model Regression
Kyle Genova, Forrester Cole, Aaron Maschinot, Daniel Vlasic, Aaron Sarna, William Freeman

Learning Transferable Architectures for Scalable Image Recognition
Barret Zoph, Vijay Vasudevan, Jonathon Shlens, Quoc Le

The iNaturalist Species Classification and Detection Dataset
Grant van Horn, Oisin Mac Aodha, Yang Song, Yin Cui, Chen Sun, Alex Shepard, Hartwig Adam, Pietro Perona, Serge Belongie

Learning Intrinsic Image Decomposition from Watching the World
Zhengqi Li, Noah Snavely

Learning Intelligent Dialogs for Bounding Box Annotation
Ksenia Konyushkova, Jasper Uijlings, Christoph Lampert, Vittorio Ferrari

Revisiting Knowledge Transfer for Training Object Class Detectors
Jasper Uijlings, Stefan Popov, Vittorio Ferrari

Rethinking the Faster R-CNN Architecture for Temporal Action Localization
Yu-Wei Chao, Sudheendra Vijayanarasimhan, Bryan Seybold, David Ross, Jia Deng, Rahul Sukthankar

Hierarchical Novelty Detection for Visual Object Recognition
Kibok Lee, Kimin Lee, Kyle Min, Yuting Zhang, Jinwoo Shin, Honglak Lee

COCO-Stuff: Thing and Stuff Classes in Context
Holger Caesar, Jasper Uijlings, Vittorio Ferrari

Appearance-and-Relation Networks for Video Classification
Limin Wang, Wei Li, Wen Li, Luc Van Gool

MorphNet: Fast & Simple Resource-Constrained Structure Learning of Deep Networks
Ariel Gordon, Elad Eban, Bo Chen, Ofir Nachum, Tien-Ju Yang, Edward Choi

Deformable Shape Completion with Graph Convolutional Autoencoders
Or Litany, Alex Bronstein, Michael Bronstein, Ameesh Makadia

MegaDepth: Learning Single-View Depth Prediction from Internet Photos
Zhengqi Li, Noah Snavely

Unsupervised Discovery of Object Landmarks as Structural Representations
Yuting Zhang, Yijie Guo, Yixin Jin, Yijun Luo, Zhiyuan He, Honglak Lee

Burst Denoising with Kernel Prediction Networks
Ben Mildenhall, Jiawen Chen, Jonathan Barron, Robert Carroll, Dillon Sharlet, Ren Ng

Quantization and Training of Neural Networks for Efficient Integer-Arithmetic-Only Inference Benoit Jacob, Skirmantas Kligys, Bo Chen, Matthew Tang, Menglong Zhu, Andrew Howard, Dmitry Kalenichenko, Hartwig Adam

Pix3D: Dataset and Methods for Single-Image 3D Shape Modeling
Xingyuan Sun, Jiajun Wu, Xiuming Zhang, Zhoutong Zhang, Tianfan Xue, Joshua Tenenbaum, William Freeman

Sparse, Smart Contours to Represent and Edit Images
Tali Dekel, Dilip Krishnan, Chuang Gan, Ce Liu, William Freeman

MaskLab: Instance Segmentation by Refining Object Detection with Semantic and Direction Features
Liang-Chieh Chen, Alexander Hermans, George Papandreou, Florian Schroff, Peng Wang, Hartwig Adam

Large Scale Fine-Grained Categorization and Domain-Specific Transfer Learning
Yin Cui, Yang Song, Chen Sun, Andrew Howard, Serge Belongie

Improved Lossy Image Compression with Priming and Spatially Adaptive Bit Rates for Recurrent Networks
Nick Johnston, Damien Vincent, David Minnen, Michele Covell, Saurabh Singh, Sung Jin Hwang, George Toderici, Troy Chinen, Joel Shor

MobileNetV2: Inverted Residuals and Linear Bottlenecks
Mark Sandler, Andrew Howard, Menglong Zhu, Andrey Zhmoginov, Liang-Chieh Chen

ScanComplete: Large-Scale Scene Completion and Semantic Segmentation for 3D Scans 
Angela Dai, Daniel Ritchie, Martin Bokeloh, Scott Reed, Juergen Sturm, Matthias Nießner

Sim2Real View Invariant Visual Servoing by Recurrent Control
Fereshteh Sadeghi, Alexander Toshev, Eric Jang, Sergey Levine

Alternating-Stereo VINS: Observability Analysis and Performance Evaluation
Mrinal Kanti Paul, Stergios Roumeliotis

Soccer on Your Tabletop
Konstantinos Rematas, Ira Kemelmacher, Brian Curless, Steve Seitz

Unsupervised Learning of Depth and Ego-Motion from Monocular Video Using 3D Geometric Constraints
Reza Mahjourian, Martin Wicke, Anelia Angelova

AVA: A Video Dataset of Spatio-temporally Localized Atomic Visual Actions
Chunhui Gu, Chen Sun, David Ross, Carl Vondrick, Caroline Pantofaru, Yeqing Li, Sudheendra Vijayanarasimhan, George Toderici, Susanna Ricco, Rahul Sukthankar, Cordelia Schmid, Jitendra Malik

Inferring Light Fields from Shadows
Manel Baradad, Vickie Ye, Adam Yedida, Fredo Durand, William Freeman, Gregory Wornell, Antonio Torralba

Modifying Non-Local Variations Across Multiple Views
Tal Tlusty, Tomer Michaeli, Tali Dekel, Lihi Zelnik-Manor

Aperture Supervision for Monocular Depth Estimation
Pratul Srinivasan, Rahul Garg, Neal Wadhwa, Ren Ng, Jonathan Barron

Instance Embedding Transfer to Unsupervised Video Object Segmentation
Siyang Li, Bryan Seybold, Alexey Vorobyov, Alireza Fathi, Qin Huang, C.-C. Jay Kuo

Frame-Recurrent Video Super-Resolution
Mehdi S. M. Sajjadi, Raviteja Vemulapalli, Matthew Brown

Weakly Supervised Action Localization by Sparse Temporal Pooling Network
Phuc Nguyen, Ting Liu, Gautam Prasad, Bohyung Han

Iterative Visual Reasoning Beyond Convolutions
Xinlei Chen, Li-jia Li, Fei-Fei Li, Abhinav Gupta

Learning and Using the Arrow of Time
Donglai Wei, Andrew Zisserman, William Freeman, Joseph Lim

HydraNets: Specialized Dynamic Architectures for Efficient Inference
Ravi Teja Mullapudi, Noam Shazeer, William Mark, Kayvon Fatahalian

Thoracic Disease Identification and Localization with Limited Supervision
Zhe Li, Chong Wang, Mei Han, Yuan Xue, Wei Wei, Li-jia Li, Fei-Fei Li

Inferring Semantic Layout for Hierarchical Text-to-Image Synthesis
Seunghoon Hong, Dingdong Yang, Jongwook Choi, Honglak Lee

Deep Semantic Face Deblurring
Ziyi Shen, Wei-Sheng Lai, Tingfa Xu, Jan Kautz, Ming-Hsuan Yang

Unsupervised Training for 3D Morphable Model Regression
Kyle Genova, Forrester Cole, Aaron Maschinot, Daniel Vlasic, Aaron Sarna, William Freeman

Learning Transferable Architectures for Scalable Image Recognition
Barret Zoph, Vijay Vasudevan, Jonathon Shlens, Quoc Le

Learning Intrinsic Image Decomposition from Watching the World
Zhengqi Li, Noah Snavely

PiCANet: Learning Pixel-wise Contextual Attention for Saliency Detection
Nian Liu, Junwei Han, Ming-Hsuan Yang

Computer Vision for Robotics and Driving
Anelia Angelova, Sanja Fidler

Unsupervised Visual Learning
Pierre Sermanet, Anelia Angelova

UltraFast 3D Sensing, Reconstruction and Understanding of People, Objects and Environments
Sean Fanello, Julien Valentin, Jonathan Taylor, Christoph Rhemann, Adarsh Kowdle, Jürgen SturmChristine Kaeser-Chen, Pavel Pidlypenskyi, Rohit Pandey, Andrea Tagliasacchi, Sameh Khamis, David Kim, Mingsong Dou, Kaiwen Guo, Danhang Tang, Shahram Izadi

Generative Adversarial Networks
Jun-Yan Zhu, Taesung Park, Mihaela Rosca, Phillip Isola, Ian Goodfellow

Continua a leggere

Pubblicato in Senza categoria

Google at NAACL

Posted by Kenton Lee, Research Scientist and Slav Petrov, Principal Scientist, Language Team, Google AI

This week, New Orleans, LA hosted the North American Association of Computational Linguistics (NAACL) conference, a venue for the latest research on computational approaches to understanding natural language. Google once again had a strong presence, presenting our research on a diverse set of topics, including dialog, summarization, machine translation, and linguistic analysis. In addition to contributing publications, Googlers were also involved as committee members, workshop organizers, panelists and presented one of the conference keynotes. We also provided telepresence robots, which enabled researchers who couldn’t attend in person to present their work remotely at the Widening Natural Language Processing Workshop (WiNLP) and several other workshops.

Googler Margaret Mitchell setting up our telepresence robots for remote presenters Diana Gonazelez and Gibran Fuentes Pineda to remotely present their first-place work on visual storytelling from Universidad Nacional Autonoma de Mexico.

This year NAACL also introduced a new Test of Time Award recognizing influential papers published between 2002 and 2012. We are happy and honored to recognize that all three papers receiving the award (listed below with a shot summary) were co-authored by researchers who are now at Google (in blue):

BLEU: a Method for Automatic Evaluation of Machine Translation (2002)
Kishore Papineni, Salim Roukos, Todd Ward, Wei-Jing Zhu
Before the introduction of the BLEU metric, comparing Machine Translation (MT) models required expensive human evaluation. While human evaluation is still the gold standard, the strong correlation of BLEU with human judgment has permitted much faster experiment cycles. BLEU has been a reliable measure of progress, persisting through multiple paradigm shifts in MT.

Discriminative Training Methods for Hidden Markov Models: Theory and Experiments with Perceptron Algorithms (2002)
Michael Collins
The structured perceptron is a generalization of the classical perceptron to structured prediction problems, where the number of possible “labels” for each input is a very large set, and each label has rich internal structure. Canonical examples are speech recognition, machine translation, and syntactic parsing. The structured perceptron was one of the first algorithms proposed for structured prediction, and has been shown to be effective in spite of its simplicity.

Thumbs up?: Sentiment Classification using Machine Learning Techniques (2002)
Bo Pang, Lillian Lee, Shivakumar Vaithyanathan
This paper is amongst the first works in sentiment analysis and helped define the subfield of sentiment and opinion analysis and review mining. The paper introduced a new way to look at document classification, developed the first solutions to it using supervised machine learning methods, and discussed insights and challenges. This paper also had significant data impact — the movie review dataset has supported much of the early work in this area and is still one of the commonly used benchmark evaluation datasets.

If you attended NAACL 2018, we hope that you stopped by the booth to check out some demos, meet our researchers and discuss projects and opportunities at Google that go into solving interesting problems for billions of people. You can learn more about Google research presented at NAACL 2018 below (Googlers highlighted in blue), and visit the Google AI Language Team page.

Area Chairs include:
Dan Bikel, Dilek Hakkani-Tur, Zornitsa Kozareva, Marius Pasca, Emily Pitler, Idan Szpektor, Taro Watanabe

Publications Co-Chair
Margaret Mitchell

Google Assistant or My Assistant? Towards Personalized Situated Conversational Agents
Dilek Hakkani-Tür

Bootstrapping a Neural Conversational Agent with Dialogue Self-Play, Crowdsourcing and On-Line Reinforcement Learning
Pararth Shah, Dilek Hakkani-Tür, Bing Liu, Gokhan Tür

SHAPED: Shared-Private Encoder-Decoder for Text Style Adaptation
Ye Zhang, Nan Ding, Radu Soricut

Olive Oil is Made of Olives, Baby Oil is Made for Babies: Interpreting Noun Compounds Using Paraphrases in a Neural Model
Vered Schwartz, Chris Waterson

Are All Languages Equally Hard to Language-Model?
Ryan Cotterell, Sebastian J. Mielke, Jason Eisner, Brian Roark

Self-Attention with Relative Position Representations
Peter Shaw, Jakob Uszkoreit, Ashish Vaswani

Dialogue Learning with Human Teaching and Feedback in End-to-End Trainable Task-Oriented Dialogue Systems
Bing Liu, Gokhan Tür, Dilek Hakkani-Tür, Parath Shah, Larry Heck

Subword & Character Level Models in NLP
Organizers: Manaal Faruqui, Hinrich Schütze, Isabel Trancoso, Yulia Tsvetkov, Yadollah Yaghoobzadeh

Storytelling Workshop
Organizers: Margaret Mitchell, Ishan Misra, Ting-Hao ‘Kenneth’ Huang, Frank Ferraro

Ethics in NLP
Organizers: Michael Strube, Dirk Hovy, Margaret Mitchell, Mark Alfano

Careers in Industry
Participants: Philip Resnik (moderator), Jason Baldridge, Laura Chiticariu, Marie Mateer, Dan Roth

Ethics in NLP
Participants: Dirk Hovy (moderator), Margaret Mitchell, Vinodkumar Prabhakaran, Mark Yatskar, Barbara Plank

Continua a leggere

Pubblicato in Senza categoria

Realtime tSNE Visualizations with TensorFlow.js

Posted by Nicola Pezzotti, Software Engineering Intern, Google Zürich

In recent years, the t-distributed Stochastic Neighbor Embedding (tSNE) algorithm has become one of the most used and insightful techniques for exploratory data analysis of high-dimensional data. Used to interpret deep neural network outputs in tools such as the TensorFlow Embedding Projector and TensorBoard, a powerful feature of tSNE is that it reveals clusters of high-dimensional data points at different scales while requiring only minimal tuning of its parameters. Despite these advantages, the computational complexity of the tSNE algorithm limits its application to relatively small datasets. While several evolutions of tSNE have been developed to address this issue (mainly focusing on the scalability of the similarity computations between data points), they have so far not been enough to provide a truly interactive experience when visualizing the evolution of the tSNE embedding for large datasets.

In “Linear tSNE Optimization for the Web”, we present a novel approach to tSNE that heavily relies on modern graphics hardware. Given the linear complexity of the new approach, our method generates embeddings faster than comparable techniques and can even be executed on the client side in a web browser by leveraging GPU capabilities through WebGL. The combination of these two factors allows for real-time interactive visualization of large, high-dimensional datasets. Furthermore, we are releasing this work as an open source library in the TensorFlow.js family in the hopes that the broader research community finds it useful.

Real-time evolution of the tSNE embedding for the complete MNIST dataset with our technique. The dataset contains images of 60,000 handwritten digits. You can find a live demo here.

The aim of tSNE is to cluster small “neighborhoods” of similar data points while also reducing the overall dimensionality of the data so it is more easily visualized. In other words, the tSNE objective function measures how well these neighborhoods of similar data are preserved in the 2 or 3-dimensional space, and arranges them into clusters accordingly.

In previous work, the minimization of the tSNE objective was performed as a N-body simulation problem, in which points are randomly placed in the embedding space and two different types of forces are applied on each point. Attractive forces bring the points closer to the points that are most similar in the high-dimensional space, while repulsive forces push them away from all the neighbors in the embedding.

While the attractive forces are acting on a small subset of points (i.e., similar neighbors), repulsive forces are in effect from all pairs of points. Due to this, tSNE requires significant computation and many iterations of the objective function, which limits the possible dataset size to just a few hundred data points. To improve over a brute force solution, the Barnes-Hut algorithm was used to approximate the repulsive forces and the gradient of the objective function. This allows scaling of the computation to tens of thousand data points, but it requires more than 15 minutes to compute the MNIST embedding in a C++ implementation.

In our paper, we propose a solution to this scaling problem by approximating the gradient of the objective function using textures that are generated in WebGL. Our technique draws a “repulsive field” at every minimization iteration using a three channel texture, with the 3 components treated as colors and drawn in the RGB channels. The repulsive field is obtained for every point to represent both the horizontal and vertical repulsive force created by the point, and a third component used for normalization. Intuitively, the normalization term ensures that the magnitude of the shifts matches the similarity measure in the high-dimensional space. In addition, the resolution of the texture is adaptively changed to keep the number of pixels drawn constant.

Rendering of the three functions used to approximate the repulsive effect created by a single point. In the above figure the repulsive forces show a point in a blue area is pushed to the left/bottom, while a point in the red area is pushed to the right/top while a point in the white region will not move.

The contribution of every point is then added on the GPU, resulting in a texture similar to those presented in the GIF below, that approximate the repulsive fields. This innovative repulsive field approach turns out to be much more GPU friendly than more commonly used calculation of point-to-point interactions. This is because repulsion for multiple points can be computed at once and in a very fast way in the GPU. In addition, we implemented the computation of the attraction between points in the GPU.

This animation shows the evolution of the tSNE embedding (upper left) and of the scalar fields used to approximate its gradient with normalization term (upper right), horizontal shift (bottom left) and vertical shift (bottom right).

We additionally revised the update of the embedding from an ad-hoc implementation to a series of standard tensor operations that are computed in TensorFlow.js, a JavaScript library to perform tensor computations in the web browser. Our approach, which is released as an open source library in the TensorFlow.js family, allows us to compute the evolution of the tSNE embedding entirely on the GPU while having better computational complexity.

With this implementation, what used to take 15 minutes to calculate (on the MNIST dataset) can now be visualized in real-time and in the web browser. Furthermore this allows real-time visualizations of much larger datasets, a feature that is particularly useful when deep neural output is analyzed. One main limitation of our work is that this technique currently only works for 2D embeddings. However, 2D visualizations are often preferred over 3D ones as they require more interaction to effectively understand cluster results.

Future Work
We believe that having a fast and interactive tSNE implementation that runs in the browser will empower developers of data analytics systems. We are particularly interested in exploring how our implementation can be used for the interpretation of deep neural networks. Additionally, our implementation shows how lateral thinking in using GPU computations (approximating the gradient using RGB texture) can be used to significantly speed up algorithmic computations. In the future we will be exploring how this kind of gradient approximation can be applied not only to speed-up other dimensionality reduction algorithms, but also to implement other N-body simulations in the web browser using TensorFlow.js.

We would like to thank Alexander Mordvintsev, Yannick Assogba, Matt Sharifi, Anna Vilanova, Elmar Eisemann, Nikhil Thorat, Daniel Smilkov, Martin Wattenberg, Fernanda Viegas, Alessio Bazzica, Boudewijn Lelieveldt, Thomas Höllt, Baldur van Lew, Julian Thijssen and Marvin Ritter.

Continua a leggere

Pubblicato in Senza categoria

Announcing an updated YouTube-8M, and the 2nd YouTube-8M Large-Scale Video Understanding Challenge and Workshop

Posted by Joonseok Lee, Software Engineer, Google AI

Last year, we organized the first YouTube-8M Large-Scale Video Understanding Challenge with Kaggle, in which 742 teams consisting of 946 individuals from 60 countries used the YouTube-8M dataset (2017 edition) to develop classification algorithms which accurately assign video-level labels. The purpose of the competition was to accelerate improvements in large-scale video understanding, representation learning, noisy data modeling, transfer learning and domain adaptation approaches that can help improve the machine-learning models that classify video. In addition to the competition, we hosted an affiliated workshop at CVPR’17, inviting competition top-performers and researchers and share their ideas on how to advance the state-of-the-art in video understanding.

As a continuation of these efforts to accelerate video understanding, we are excited to announce another update to the YouTube-8M dataset, a new Kaggle video understanding challenge and an affiliated 2nd Workshop on YouTube-8M Large-Scale Video Understanding, to be held at the 2018 European Conference on Computer Vision (ECCV’18).

An Updated YouTube-8M Dataset (2018 Edition)
Our YouTube-8M (2018 edition) features a major improvement in the quality of annotations, obtained using a machine learning system that combines audio-visual content with title, description and other metadata to provide more accurate ground truth annotations. The updated version contains 6.1 million URLs, labeled with a vocabulary of 3,862 visual entities, with each video annotated with one or more labels and an average of 3 labels per video. We have also updated the starter code, with updated instructions for downloading and training TensorFlow video annotation models on the dataset.

The 2nd YouTube-8M Video Understanding Challenge
The 2nd YouTube-8M Video Understanding Challenge invites participants to build audio-visual content classification models using YouTube-8M as training data, and then to label an unknown subset of test videos. Unlike last year, we strictly impose a hard limit on model size, encouraging participants to advance a single model within tight budget rather than assembling as many models as possible. Each of the top 5 teams will be awarded $5,000 to support their travel to Munich to attend ECCV’18. For details, please visit the Kaggle competition page.

The 2nd Workshop on YouTube-8M Large-Scale Video Understanding
To be held at ECCV’18, the workshop will consist of invited talks by distinguished researchers, as well as presentations by top-performing challenge participants in order to facilitate the exchange of ideas. We encourage those who wish to attend to submit papers describing their research, experiments, or applications based on YouTube-8M dataset, including papers summarizing their participation in the challenge above. Please refer to the workshop page for more details.

It is our hope that this update to the dataset, along with the new challenge and workshop, will continue to advance the research in large-scale video understanding. We hope you will join us again!

This post reflects the work of many machine perception researchers including Sami Abu-El-Haija, Ke Chen, Nisarg Kothari, Joonseok Lee, Hanhan Li, Paul Natsev, Sobhan Naderi Parizi, Rahul Sukthankar, George Toderici, Balakrishnan Varadarajan, as well as Sohier Dane, Julia Elliott, Wendy Kan and Walter Reade from Kaggle. We are also grateful for the support and advice from our partners at YouTube.

Continua a leggere

Pubblicato in Senza categoria

Improving Deep Learning Performance with AutoAugment

Posted by Ekin Dogus Cubuk, Google AI Resident and Barret Zoph, Research Scientist, Google Brain Team

The success of deep learning in computer vision can be partially attributed to the availability of large amounts of labeled training data — a model’s performance typically improves as you increase the quality, diversity and the amount of training data. However, collecting enough quality data to train a model to perform well is often prohibitively difficult. One way around this is to hardcode image symmetries into neural network architectures so they perform better or have experts manually design data augmentation methods, like rotation and flipping, that are commonly used to train well-performing vision models. However, until recently, less attention has been paid to finding ways to automatically augment existing data using machine learning. Inspired by the results of our AutoML efforts to design neural network architectures and optimizers to replace components of systems that were previously human designed, we asked ourselves: can we also automate the procedure of data augmentation?

In “AutoAugment: Learning Augmentation Policies from Data”, we explore a reinforcement learning algorithm which increases both the amount and diversity of data in an existing training dataset. Intuitively, data augmentation is used to teach a model about image invariances in the data domain in a way that makes a neural network invariant to these important symmetries, thus improving its performance. Unlike previous state-of-the-art deep learning models that used hand-designed data augmentation policies, we used reinforcement learning to find the optimal image transformation policies from the data itself. The result improved performance of computer vision models without relying on the production of new and ever expanding datasets.

Augmenting Training Data
The idea behind data augmentation is simple: images have many symmetries that don’t change the information present in the image. For example, the mirror reflection of a dog is still a dog. While some of these “invariances” are obvious to humans, many are not. For example, the mixup method augments data by placing images on top of each other during training, resulting in data which improves neural network performance.

Left: An original image from the ImageNet dataset. Right: The same image transformed by a commonly used data augmentation transformation, a horizontal flip about the center.

AutoAugment is an automatic way to design custom data augmentation policies for computer vision datasets, e.g., guiding the selection of basic image transformation operations, such as flipping an image horizontally/vertically, rotating an image, changing the color of an image, etc. AutoAugment not only predicts what image transformations to combine, but also the per-image probability and magnitude of the transformation used, so that the image is not always manipulated in the same way. AutoAugment is able to select an optimal policy from a search space of 2.9 x 1032 image transformation possibilities.

AutoAugment learns different transformations depending on what dataset it is run on. For example, for images involving street view of house numbers (SVHN) which include natural scene images of digits, AutoAugment focuses on geometric transforms like shearing and translation, which represent distortions commonly observed in this dataset. In addition, AutoAugment has learned to completely invert colors which naturally occur in the original SVHN dataset, given the diversity of different building and house numbers materials in the world.

Left: An original image from the SVHN dataset. Right: The same image transformed by AutoAugment. In this case, the optimal transformation was a result of shearing the image and inverting the colors of the pixels.

On CIFAR-10 and ImageNet, AutoAugment does not use shearing because these datasets generally do not include images of sheared objects, nor does it invert colors completely as these transformations would lead to unrealistic images. Instead, AutoAugment focuses on slightly adjusting the color and hue distribution, while preserving the general color properties. This suggests that the actual colors of objects in CIFAR-10 and ImageNet are important, whereas on SVHN only the relative colors are important.

Left: An original image from the ImageNet dataset. Right: The same image transformed by the AutoAugment policy. First, the image contrast is maximized, after which the image is rotated.

Our AutoAugment algorithm found augmentation policies for some of the most well-known computer vision datasets that, when incorporated into the training of the neural network, led to state-of-the-art accuracies. By augmenting ImageNet data we obtain a new state-of-the-art accuracy of 83.54% top1 accuracy and on CIFAR10 we achieve an error rate of 1.48%, which is a 0.83% improvement over the default data augmentation designed by scientists. On SVHN, we improved the state-of-the-art error from 1.30% to 1.02%. Importantly, AutoAugment policies are found to be transferable — the policy found for the ImageNet dataset could also be applied to other vision datasets (Stanford Cars, FGVC-Aircraft, etc.), which in turn improves neural network performance.

We are pleased to see that our AutoAugment algorithm achieved this level of performance on many different competitive computer vision datasets and look forward to seeing future applications of this technology across more computer vision tasks and even in other domains such as audio processing or language models. The policies with the best performance are included in the appendix of the paper, so that researchers can use them to improve their models on relevant vision tasks.

Special thanks to the co-authors of the paper Dandelion Mane, Vijay Vasudevan, and Quoc V. Le. We’d also like to thank Alok Aggarwal, Gabriel Bender, Yanping Huang, Pieter-Jan Kindermans, Simon Kornblith, Augustus Odena, Avital Oliver, and Colin Raffel for their help with this project.

Continua a leggere

Pubblicato in Senza categoria

Advances in Semantic Textual Similarity

Posted by Yinfei Yang, Software Engineer and Chris Tar, Engineering Manager, Google AI

The recent rapid progress of neural network-based natural language understanding research, especially on learning semantic text representations, can enable truly novel products such as Smart Compose and Talk to Books. It can also help improve performance on a variety of natural language tasks which have limited amounts of training data, such as building strong text classifiers from as few as 100 labeled examples.

Below, we discuss two papers reporting recent progress on semantic representation research at Google, as well as two new models available for download on TensorFlow Hub that we hope developers will use to build new and exciting applications.

Semantic Textual Similarity
In “Learning Semantic Textual Similarity from Conversations”, we introduce a new way to learn sentence representations for semantic textual similarity. The intuition is that sentences are semantically similar if they have a similar distribution of responses. For example, “How old are you?” and “What is your age?” are both questions about age, which can be answered by similar responses such as “I am 20 years old”. In contrast, while “How are you?” and “How old are you?” contain almost identical words, they have very different meanings and lead to different responses.

Sentences are semantically similar if they can be answered by the same responses. Otherwise, they are semantically different.

In this work, we aim to learn semantic similarity by way of a response classification task: given a conversational input, we wish to classify the correct response from a batch of randomly selected responses. But, the ultimate goal is to learn a model that can return encodings representing a variety of natural language relationships, including similarity and relatedness. By adding another prediction task (In this case, the SNLI entailment dataset) and forcing both through shared encoding layers, we get even better performance on similarity measures such as the STSBenchmark (a sentence similarity benchmark) and CQA task B (a question/question similarity task). This is because logical entailment is quite different from simple equivalence and provides more signal for learning complex semantic representations.

For a given input, classification is considered a ranking problem against potential candidates.

Universal Sentence Encoder
In “Universal Sentence Encoder”, we introduce a model that extends the multitask training described above by adding more tasks, jointly training them with a skip-thought-like model that predicts sentences surrounding a given selection of text. However, instead of the encoder-decoder architecture in the original skip-thought model, we make use of an encode-only architecture by way of a shared encoder to drive the prediction tasks. In this way, training time is greatly reduced while preserving the performance on a variety of transfer tasks including sentiment and semantic similarity classification. The aim is to provide a single encoder that can support as wide a variety of applications as possible, including paraphrase detection, relatedness, clustering and custom text classification.

Pairwise semantic similarity comparison via outputs from TensorFlow Hub Universal Sentence Encoder.

As described in our paper, one version of the Universal Sentence Encoder model uses a deep average network (DAN) encoder, while a second version uses a more complicated self attended network architecture, Transformer.

Multi-task training as described in “Universal Sentence Encoder”. A variety of tasks and task structures are joined by shared encoder layers/parameters (grey boxes).

With the more complicated architecture, the model performs better than the simpler DAN model on a variety of sentiment and similarity classification tasks, and for short sentences is only moderately slower. However, compute time for the model using Transformer increases noticeably as sentence length increases, whereas the compute time for the DAN model stays nearly constant as sentence length is increased.

New Models
In addition to the Universal Sentence Encoder model described above, we are also sharing two new models on TensorFlow Hub: the Universal Sentence Encoder – Large and Universal Sentence Encoder – Lite. These are pretrained Tensorflow models that return a semantic encoding for variable-length text inputs. The encodings can be used for semantic similarity measurement, relatedness, classification, or clustering of natural language text.

  • The Large model is trained with the Transformer encoder described in our second paper. It targets scenarios requiring high precision semantic representations and the best model performance at the cost of speed & size.
  • The Lite model is trained on a Sentence Piece vocabulary instead of words in order to significantly reduce the vocabulary size, which is a major contributor of model size. It targets scenarios where resources like memory and CPU are limited, such as on-device or browser based implementations.

We’re excited to share this research, and these models, with the community. We believe that what we’re showing here is just the beginning, and that there remain important research problems to be addressed, such as extending the techniques to more languages (the models discussed above currently support English). We also hope to further develop this technology so it can understand text at the paragraph or even document level. In achieving these tasks, it may be possible to make an encoder that is truly “universal”.

Daniel Cer, Mario Guajardo-Cespedes, Sheng-Yi Kong, Noah Constant for training the models, Nan Hua, Nicole Limtiaco, Rhomni St. John for transferring tasks, Steve Yuan, Yunhsuan Sung, Brian Strope, Ray Kurzweil for discussion of the model architecture. Special thanks to Sheng-Yi Kong and Noah Constant for training the Lite model.

Continua a leggere

Pubblicato in Senza categoria

Smart Compose: Using Neural Networks to Help Write Emails

Posted by Yonghui Wu, Principal Engineer, Google Brain Team

Last week at Google I/O, we introduced Smart Compose, a new feature in Gmail that uses machine learning to interactively offer sentence completion suggestions as you type, allowing you to draft emails faster. Building upon technology developed for Smart Reply, Smart Compose offers a new way to help you compose messages — whether you are responding to an incoming email or drafting a new one from scratch.

In developing Smart Compose, there were a number of key challenges to face, including:

  • Latency: Since Smart Compose provides predictions on a per-keystroke basis, it must respond ideally within 100ms for the user not to notice any delays. Balancing model complexity and inference speed was a critical issue.
  • Scale: Gmail is used by more than 1.4 billion diverse users. In order to provide auto completions that are useful for all Gmail users, the model has to have enough modeling capacity so that it is able to make tailored suggestions in subtly different contexts.
  • Fairness and Privacy: In developing Smart Compose, we needed to address sources of potential bias in the training process, and had to adhere to the same rigorous user privacy standards as Smart Reply, making sure that our models never expose user’s private information. Furthermore, researchers had no access to emails, which meant they had to develop and train a machine learning system to work on a dataset that they themselves cannot read.

Finding the Right Model
Typical language generation models, such as ngramneural bag-of-words (BoW) and RNN language (RNN-LM) models, learn to predict the next word conditioned on the prefix word sequence. In an email, however, the words a user has typed in the current email composing session is only one “signal” a model can use to predict the next word. In order to incorporate more context about what the user wants to say, our model is also conditioned on the email subject and the previous email body (if the user is replying to an incoming email).

One approach to include this additional context is to cast the problem as a sequence-to-sequence (seq2seq) machine translation task, where the source sequence is the concatenation of the subject and the previous email body (if there is one), and the target sequence is the current email the user is composing. While this approach worked well in terms of prediction quality, it failed to meet our strict latency constraints by orders of magnitude.

To improve on this, we combined a BoW model with an RNN-LM, which is faster than the seq2seq models with only a slight sacrifice to model prediction quality. In this hybrid approach, we encode the subject and previous email by averaging the word embeddings in each field. We then join those averaged embeddings, and feed them to the target sequence RNN-LM at every decoding step, as the model diagram below shows.

Smart Compose RNN-LM model architecture. Subject and previous email message are encoded by averaging the word embeddings in each field. The averaged embeddings are then fed to the RNN-LM at each decoding step.

Accelerated Model Training & Serving
Of course, once we decided on this modeling approach we still had to tune various model hyperparameters and train the models over billions of examples, all of which can be very time-intensive. To speed things up, we used a full TPUv2 Pod to perform experiments. In doing so, we’re able to train a model to convergence in less than a day.

Even after training our faster hybrid model, our initial version of Smart Compose running on a standard CPU had an average serving latency of hundreds of milliseconds, which is still unacceptable for a feature that is trying to save users’ time. Fortunately, TPUs can also be used at inference time to greatly speed up the user experience. By offloading the bulk of the computation onto TPUs, we improved the average latency to tens of milliseconds while also greatly increasing the number of requests that can be served by a single machine.

Fairness and Privacy
Fairness in machine learning is very important, as language understanding models can reflect human cognitive biases resulting in unwanted word associations and sentence completions. As Caliskan et al. point out in their recent paper “Semantics derived automatically from language corpora contain human-like biases”, these associations are deeply entangled in natural language data, which presents a considerable challenge to building any language model. We are actively researching ways to continue to reduce potential biases in our training procedures. Also, since Smart Compose is trained on billions of phrases and sentences, similar to the way spam machine learning models are trained, we have done extensive testing to make sure that only common phrases used by multiple users are memorized by our model, using findings from this paper.

Future work
We are constantly working on improving the suggestion quality of the language generation model by following state-of-the-art architectures (e.g., Transformer, RNMT+, etc.) and experimenting with most recent and advanced training techniques. We will deploy those more advanced models to production once our strict latency constraints can be met. We are also working on incorporating personal language models, designed to more accurately emulate an individual’s style of writing into our system.

Smart Compose language generation model was developed by Benjamin Lee, Mia Chen, Gagan Bansal, Justin Lu, Jackie Tsay, Kaushik Roy, Tobias Bosch, Yinan Wang, Matthew Dierker, Katherine Evans, Thomas Jablin, Dehao Chen, Vinu Rajashekhar, Akshay Agrawal, Yuan Cao, Shuyuan Zhang, Xiaobing Liu, Noam Shazeer, Andrew Dai, Zhifeng Chen, Rami Al-Rfou, DK Choe, Yunhsuan Sung, Brian Strope, Timothy Sohn, Yonghui Wu, and many others.

Continua a leggere

Pubblicato in Senza categoria

Automatic Photography with Google Clips

Posted by Aseem Agarwala, Research Scientist, Clips Content Team Lead

To me, photography is the simultaneous recognition, in a fraction of a second, of the significance of an event as well as of a precise organization of forms which give that event its proper expression.
Henri Cartier-Bresson

The last few years have witnessed a Cambrian-like explosion in AI, with deep learning methods enabling computer vision algorithms to recognize many of the elements of a good photograph: people, smiles, pets, sunsets, famous landmarks and more. But, despite these recent advancements, automatic photography remains a very challenging problem. Can a camera capture a great moment automatically?

Recently, we released Google Clips, a new, hands-free camera that automatically captures interesting moments in your life. We designed Google Clips around three important principles:

  • We wanted all computations to be performed on-device. In addition to extending battery life and reducing latency, on-device processing means that none of your clips leave the device unless you decide to save or share them, which is a key privacy control.
  • We wanted the device to capture short videos, rather than single photographs. Moments with motion can be more poignant and true-to-memory, and it is often easier to shoot a video around a compelling moment than it is to capture a perfect, single instant in time.
  • We wanted to focus on capturing candid moments of people and pets, rather than the more abstract and subjective problem of capturing artistic images. That is, we did not attempt to teach Clips to think about composition, color balance, light, etc.; instead, Clips focuses on selecting ranges of time containing people and animals doing interesting activities.

Learning to Recognize Great Moments
How could we train an algorithm to recognize interesting moments? As with most machine learning problems, we started with a dataset. We created a dataset of thousands of videos in diverse scenarios where we imagined Clips being used. We also made sure our dataset represented a wide range of ethnicities, genders, and ages. We then hired expert photographers and video editors to pore over this footage to select the best short video segments. These early curations gave us examples for our algorithms to emulate. However, it is challenging to train an algorithm solely from the subjective selection of the curators — one needs a smooth gradient of labels to teach an algorithm to recognize the quality of content, ranging from “perfect” to “terrible.”

To address this problem, we took a second data-collection approach, with the goal of creating a continuous quality score across the length of a video. We split each video into short segments (similar to the content Clips captures), randomly selected pairs of segments, and asked human raters to select the one they prefer.

We took this pairwise comparison approach, instead of having raters score videos directly, because it is much easier to choose the better of a pair than it is to specify a number. We found that raters were very consistent in pairwise comparisons, and less so when scoring directly. Given enough pairwise comparisons for any given video, we were able to compute a continuous quality score over the entire length. In this process, we collected over 50,000,000 pairwise comparisons on clips sampled from over 1,000 videos. That’s a lot of human effort!

Training a Clips Quality Model
Given this quality score training data, our next step was to train a neural network model to estimate the quality of any photograph captured by the device. We started with the basic assumption that knowing what’s in the photograph (e.g., people, dogs, trees, etc.) will help determine “interestingness”. If this assumption is correct, we could learn a function that uses the recognized content of the photograph to predict its quality score derived above from human comparisons.

To identify content labels in our training data, we leveraged the same Google machine learning technology that powers Google image search and Google Photos, which can recognize over 27,000 different labels describing objects, concepts, and actions. We certainly didn’t need all these labels, nor could we compute them all on device, so our expert photographers selected the few hundred labels they felt were most relevant to predicting the “interestingness” of a photograph. We also added the labels most highly correlated with the rater-derived quality scores.

Once we had this subset of labels, we then needed to design a compact, efficient model that could predict them for any given image, on-device, within strict power and thermal limits. This presented a challenge, as the deep learning techniques behind computer vision typically require strong desktop GPUs, and algorithms adapted to run on mobile devices lag far behind state-of-the-art techniques on desktop or cloud. To train this on-device model, we first took a large set of photographs and again used Google’s powerful, server-based recognition models to predict label confidence for each of the “interesting” labels described above. We then trained a MobileNet Image Content Model (ICM) to mimic the predictions of the server-based model. This compact model is capable of recognizing the most interesting elements of photographs, while ignoring non-relevant content.

The final step was to predict a single quality score for an input photograph from its content predicted by the ICM, using the 50M pairwise comparisons as training data. This score is computed with a piecewise linear regression model that combines the output of the ICM into a frame quality score. This frame quality score is averaged across the video segment to form a moment score. Given a pairwise comparison, our model should compute a moment score that is higher for the video segment preferred by humans. The model is trained so that its predictions match the human pairwise comparisons as well as possible.

Diagram of the training process for generating frame quality scores. Piecewise linear regression maps from an ICM embedding to a score which, when averaged across a video segment, yields a moment score. The moment score of the preferred segment should be higher.

This process allowed us to train a model that combines the power of Google image recognition technology with the wisdom of human raters–represented by 50 million opinions on what makes interesting content!

While this data-driven score does a great job of identifying interesting (and non-interesting) moments, we also added some bonuses to our overall quality score for phenomena that we know we want Clips to capture, including faces (especially recurring and thus “familiar” ones), smiles, and pets. In our most recent release, we added bonuses for certain activities that customers particularly want to capture, such as hugs, kisses, jumping, and dancing. Recognizing these activities required extensions to the ICM model.

Shot Control
Given this powerful model for predicting the “interestingness” of a scene, the Clips camera can decide which moments to capture in real-time. Its shot control algorithms follow three main principles:

  1. Respect Power & Thermals: We want the Clips battery to last roughly three hours, and we don’t want the device to overheat — the device can’t run at full throttle all the time. Clips spends much of its time in a low-power mode that captures one frame per second. If the quality of that frame exceeds a threshold set by how much Clips has recently shot, it moves into a high-power mode, capturing at 15 fps. Clips then saves a clip at the first quality peak encountered.
  2. Avoid Redundancy: We don’t want Clips to capture all of its moments at once, and ignore the rest of a session. Our algorithms therefore cluster moments into visually similar groups, and limit the number of clips in each cluster.
  3. The Benefit of Hindsight: It’s much easier to determine which clips are the best when you can examine the totality of clips captured. Clips therefore captures more moments than it intends to show to the user. When clips are ready to be transferred to the phone, the Clips device takes a second look at what it has shot, and only transfers the best and least redundant content.

Machine Learning Fairness
In addition to making sure our video dataset represented a diverse population, we also constructed several other tests to assess the fairness of our algorithms. We created controlled datasets by sampling subjects from different genders and skin tones in a balanced manner, while keeping variables like content type, duration, and environmental conditions constant. We then used this dataset to test that our algorithms had similar performance when applied to different groups. To help detect any regressions in fairness that might occur as we improved our moment quality models, we added fairness tests to our automated system. Any change to our software was run across this battery of tests, and was required to pass. It is important to note that this methodology can’t guarantee fairness, as we can’t test for every possible scenario and outcome. However, we believe that these steps are an important part of our long-term work to achieve fairness in ML algorithms.

Most machine learning algorithms are designed to estimate objective qualities – a photo contains a cat, or it doesn’t. In our case, we aim to capture a more elusive and subjective quality – whether a personal photograph is interesting, or not. We therefore combine the objective, semantic content of photographs with subjective human preferences to build the AI behind Google Clips. Also, Clips is designed to work alongside a person, rather than autonomously; to get good results, a person still needs to be conscious of framing, and make sure the camera is pointed at interesting content. We’re happy with how well Google Clips performs, and are excited to continue to improve our algorithms to capture that “perfect” moment!

The algorithms described here were conceived and implemented by a large group of Google engineers, research scientists, and others. Figures were made by Lior Shapira. Thanks to Lior and Juston Payne for video content.

Continua a leggere

Pubblicato in Senza categoria

Custom On-Device ML Models with Learn2Compress

Posted by Sujith Ravi, Senior Staff Research Scientist, Google Expander Team

Successful deep learning models often require significant amounts of computational resources, memory and power to train and run, which presents an obstacle if you want them to perform well on mobile and IoT devices. On-device machine learning allows you to run inference directly on the devices, with the benefits of data privacy and access everywhere, regardless of connectivity. On-device ML systems, such as MobileNets and ProjectionNets, address the resource bottlenecks on mobile devices by optimizing for model efficiency. But what if you wanted to train your own customized, on-device models for your personal mobile application?

Yesterday at Google I/O, we announced ML Kit to make machine learning accessible for all mobile developers. One of the core ML Kit capabilities that will be available soon is an automatic model compression service powered by “Learn2Compress” technology developed by our research team. Learn2Compress enables custom on-device deep learning models in TensorFlow Lite that run efficiently on mobile devices, without developers having to worry about optimizing for memory and speed. We are pleased to make Learn2Compress for image classification available soon through ML Kit. Learn2Compress will be initially available to a small number of developers, and will be offered more broadly in the coming months. You can sign up here if you are interested in using this feature for building your own models.

How it Works
Learn2Compress generalizes the learning framework introduced in previous works like ProjectionNet and incorporates several state-of-the-art techniques for compressing neural network models. It takes as input a large pre-trained TensorFlow model provided by the user, performs training and optimization and automatically generates ready-to-use on-device models that are smaller in size, more memory-efficient, more power-efficient and faster at inference with minimal loss in accuracy.

Learn2Compress for automatically generating on-device ML models.

To do this, Learn2Compress uses multiple neural network optimization and compression techniques including:

  • Pruning reduces model size by removing weights or operations that are least useful for predictions (e.g.low-scoring weights). This can be very effective especially for on-device models involving sparse inputs or outputs, which can be reduced up to 2x in size while retaining 97% of the original prediction quality.
  • Quantization techniques are particularly effective when applied during training and can improve inference speed by reducing the number of bits used for model weights and activations. For example, using 8-bit fixed point representation instead of floats can speed up the model inference, reduce power and further reduce size by 4x.
  • Joint training and distillation approaches follow a teacher-student learning strategy — we use a larger teacher network (in this case, user-provided TensorFlow model) to train a compact student network (on-device model) with minimal loss in accuracy.
    Joint training and distillation approach to learn compact student models.

    The teacher network can be fixed (as in distillation) or jointly optimized, and even train multiple student models of different sizes simultaneously. So instead of a single model, Learn2Compress generates multiple on-device models in a single shot, at different sizes and inference speeds, and lets the developer pick one best suited for their application needs.

These and other techniques like transfer learning also make the compression process more efficient and scalable to large-scale datasets.

How well does it work?
To demonstrate the effectiveness of Learn2Compress, we used it to build compact on-device models of several state-of-the-art deep networks used in image and natural language tasks such as MobileNets, NASNet, Inception, ProjectionNet, among others. For a given task and dataset, we can generate multiple on-device models at different inference speeds and model sizes.

Accuracy at various sizes for Learn2Compress models and full-sized baseline networks on CIFAR-10 (left) and ImageNet (right) image classification tasks. Student networks used to produce the compressed variants for CIFAR-10 and ImageNet are modeled using NASNet and MobileNet-inspired architectures, respectively.

For image classification, Learn2Compress can generate small and fast models with good prediction accuracy suited for mobile applications. For example, on ImageNet task, Learn2Compress achieves a model 22x smaller than Inception v3 baseline and 4x smaller than MobileNet v1 baseline with just 4.6-7% drop in accuracy. On CIFAR-10, jointly training multiple Learn2Compress models with shared parameters, takes only 10% more time than training a single Learn2Compress large model, but yields 3 compressed models that are upto 94x smaller in size and upto 27x faster with up to 36x lower cost and good prediction quality (90-95% top-1 accuracy).

Computation cost and average prediction latency (on Pixel phone) for baseline and Learn2Compress models on CIFAR-10 image classification task. Learn2Compress-optimized models use NASNet-style network architecture.

We are also excited to see how well this performs on developer use-cases. For example, Fishbrain, a social platform for fishing enthusiasts, used Learn2Compress to compress their existing image classification cloud model (80MB+ in size and 91.8% top-3 accuracy) to a much smaller on-device model, less than 5MB in size, with similar accuracy. In some cases, we observe that it is possible for the compressed models to even slightly outperform the original large model’s accuracy due to better regularization effects.

We will continue to improve Learn2Compress with future advances in ML and deep learning, and extend to more use-cases beyond image classification. We are excited and looking forward to make this available soon through ML Kit’s compression service on the Cloud. We hope this will make it easy for developers to automatically build and optimize their own on-device ML models so that they can focus on building great apps and cool user experiences involving computer vision, natural language and other machine learning applications.

I would like to acknowledge our core contributors Gaurav Menghani, Prabhu Kaliamoorthi and Yicheng Fan along with Wei Chai, Kang Lee, Sheng Xu and Pannag Sanketi. Special thanks to Dave Burke, Brahim Elbouchikhi, Hrishikesh Aradhye, Hugues Vincent, and Arun Venkatesan from the Android team; Sachin Kotwani, Wesley Tarle, Pavel Jbanov and from the Firebase team; Andrei Broder, Andrew Tomkins, Robin Dua, Patrick McGregor, Gaurav Nemade, the Google Expander team and TensorFlow team.

Continua a leggere

Pubblicato in Senza categoria

Google Duplex: An AI System for Accomplishing Real-World Tasks Over the Phone

Posted by Yaniv Leviathan, Principal Engineer and Yossi Matias, Vice President, Engineering, Google

A long-standing goal of human-computer interaction has been to enable people to have a natural conversation with computers, as they would with each other. In recent years, we have witnessed a revolution in the ability of computers to understand and to generate natural speech, especially with the application of deep neural networks (e.g., Google voice search, WaveNet). Still, even with today’s state of the art systems, it is often frustrating having to talk to stilted computerized voices that don’t understand natural language. In particular, automated phone systems are still struggling to recognize simple words and commands. They don’t engage in a conversation flow and force the caller to adjust to the system instead of the system adjusting to the caller.

Today we announce Google Duplex, a new technology for conducting natural conversations to carry out “real world” tasks over the phone. The technology is directed towards completing specific tasks, such as scheduling certain types of appointments. For such tasks, the system makes the conversational experience as natural as possible, allowing people to speak normally, like they would to another person, without having to adapt to a machine.

One of the key research insights was to constrain Duplex to closed domains, which are narrow enough to explore extensively. Duplex can only carry out natural conversations after being deeply trained in such domains. It cannot carry out general conversations.

Here are examples of Duplex making phone calls (using different voices):

Duplex scheduling a hair salon appointment:
Duplex calling a restaurant:

While sounding natural, these and other examples are conversations between a fully automatic computer system and real businesses.

The Google Duplex technology is built to sound natural, to make the conversation experience comfortable. It’s important to us that users and businesses have a good experience with this service, and transparency is a key part of that. We want to be clear about the intent of the call so businesses understand the context. We’ll be experimenting with the right approach over the coming months.

Conducting Natural Conversations
There are several challenges in conducting natural conversations: natural language is hard to understand, natural behavior is tricky to model, latency expectations require fast processing, and generating natural sounding speech, with the appropriate intonations, is difficult.

When people talk to each other, they use more complex sentences than when talking to computers. They often correct themselves mid-sentence, are more verbose than necessary, or omit words and rely on context instead; they also express a wide range of intents, sometimes in the same sentence, e.g., “So umm Tuesday through Thursday we are open 11 to 2, and then reopen 4 to 9, and then Friday, Saturday, Sunday we… or Friday, Saturday we’re open 11 to 9 and then Sunday we’re open 1 to 9.”

Example of complex statement:

In natural spontaneous speech people talk faster and less clearly than they do when they speak to a machine, so speech recognition is harder and we see higher word error rates. The problem is aggravated during phone calls, which often have loud background noises and sound quality issues.

In longer conversations, the same sentence can have very different meanings depending on context. For example, when booking reservations “Ok for 4” can mean the time of the reservation or the number of people. Often the relevant context might be several sentences back, a problem that gets compounded by the increased word error rate in phone calls.

Deciding what to say is a function of both the task and the state of the conversation. In addition, there are some common practices in natural conversations — implicit protocols that include elaborations (“for next Friday” “for when?” “for Friday next week, the 18th.”), syncs (“can you hear me?”), interruptions (“the number is 212-” “sorry can you start over?”), and pauses (“can you hold? [pause] thank you!” different meaning for a pause of 1 second vs 2 minutes).

Enter Duplex
Google Duplex’s conversations sound natural thanks to advances in understanding, interacting, timing, and speaking.

At the core of Duplex is a recurrent neural network (RNN) designed to cope with these challenges, built using TensorFlow Extended (TFX). To obtain its high precision, we trained Duplex’s RNN on a corpus of anonymized phone conversation data. The network uses the output of Google’s automatic speech recognition (ASR) technology, as well as features from the audio, the history of the conversation, the parameters of the conversation (e.g. the desired service for an appointment, or the current time of day) and more. We trained our understanding model separately for each task, but leveraged the shared corpus across tasks. Finally, we used hyperparameter optimization from TFX to further improve the model.

Incoming sound is processed through an ASR system. This produces text that is analyzed with context data and other inputs to produce a response text that is read aloud through the TTS system.
Duplex handling interruptions:
Duplex elaborating:
Duplex responding to a sync:

Sounding Natural
We use a combination of a concatenative text to speech (TTS) engine and a synthesis TTS engine (using Tacotron and WaveNet) to control intonation depending on the circumstance.

The system also sounds more natural thanks to the incorporation of speech disfluencies (e.g. “hmm”s and “uh”s). These are added when combining widely differing sound units in the concatenative TTS or adding synthetic waits, which allows the system to signal in a natural way that it is still processing. (This is what people often do when they are gathering their thoughts.) In user studies, we found that conversations using these disfluencies sound more familiar and natural.

Also, it’s important for latency to match people’s expectations. For example, after people say something simple, e.g., “hello?”, they expect an instant response, and are more sensitive to latency. When we detect that low latency is required, we use faster, low-confidence models (e.g. speech recognition or endpointing). In extreme cases, we don’t even wait for our RNN, and instead use faster approximations (usually coupled with more hesitant responses, as a person would do if they didn’t fully understand their counterpart). This allows us to have less than 100ms of response latency in these situations. Interestingly, in some situations, we found it was actually helpful to introduce more latency to make the conversation feel more natural — for example, when replying to a really complex sentence.

System Operation
The Google Duplex system is capable of carrying out sophisticated conversations and it completes the majority of its tasks fully autonomously, without human involvement. The system has a self-monitoring capability, which allows it to recognize the tasks it cannot complete autonomously (e.g., scheduling an unusually complex appointment). In these cases, it signals to a human operator, who can complete the task.

To train the system in a new domain, we use real-time supervised training. This is comparable to the training practices of many disciplines, where an instructor supervises a student as they are doing their job, providing guidance as needed, and making sure that the task is performed at the instructor’s level of quality. In the Duplex system, experienced operators act as the instructors. By monitoring the system as it makes phone calls in a new domain, they can affect the behavior of the system in real time as needed. This continues until the system performs at the desired quality level, at which point the supervision stops and the system can make calls autonomously.

Benefits for Businesses and Users
Businesses that rely on appointment bookings supported by Duplex, and are not yet powered by online systems, can benefit from Duplex by allowing customers to book through the Google Assistant without having to change any day-to-day practices or train employees. Using Duplex could also reduce no-shows to appointments by reminding customers about their upcoming appointments in a way that allows easy cancellation or rescheduling.

Duplex calling a restaurant:

In another example, customers often call businesses to inquire about information that is not available online such as hours of operation during a holiday. Duplex can call the business to inquire about open hours and make the information available online with Google, reducing the number of such calls businesses receive, while at the same time, making the information more accessible to everyone. Businesses can operate as they always have, there’s no learning curve or changes to make to benefit from this technology.

Duplex asking for holiday hours:

For users, Google Duplex is making supported tasks easier. Instead of making a phone call, the user simply interacts with the Google Assistant, and the call happens completely in the background without any user involvement.

A user asks the Google Assistant for an appointment, which the Assistant then schedules by having Duplex call the business.

Another benefit for users is that Duplex enables delegated communication with service providers in an asynchronous way, e.g., requesting reservations during off-hours, or with limited connectivity. It can also help address accessibility and language barriers, e.g., allowing hearing-impaired users, or users who don’t speak the local language, to carry out tasks over the phone.

This summer, we’ll start testing the Duplex technology within the Google Assistant, to help users make restaurant reservations, schedule hair salon appointments, and get holiday hours over the phone.

Yaniv Leviathan, Google Duplex lead, and Matan Kalman, engineering manager on the project, enjoying a meal booked through a call from Duplex.
Duplex calling to book the above meal:

Allowing people to interact with technology as naturally as they interact with each other has been a long standing promise. Google Duplex takes a step in this direction, making interaction with technology via natural conversation a reality in specific scenarios. We hope that these technology advances will ultimately contribute to a meaningful improvement in people’s experience in day-to-day interactions with computers.

Continua a leggere

Pubblicato in Senza categoria