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AJ Piergiovanni

AJ Piergiovanni

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    Preview abstract Effective scaling and a flexible task interface enable large-capacity language models to excel at many tasks. PaLI (Pathways Language and Image model) extends these ideas to the joint modeling of language and vision. PaLI is a model that generates text based on visual and textual inputs. Using this API, PaLI is able to perform many vision, language, and multimodal tasks, across many languages. We train PaLI with two main principles: reuse of pretrained unimodal components, and joint scaling of modalities. Using large-capacity pretrained language models and vision models allows us to capitalize on their existing capabilities, while leveraging the substantial cost of training them. We scale PaLI models across three axes:the language component, the vision component, and the training data that fuses them. For the vision component, we train the largest and best-performing VisionTransformer (ViT) to date. For the data, we build an image-text training set over10B images and covering over 100 languages. PaLI inherits and enhances language-understanding capabilities, and achieves state-of-the-art in multiple vision and language tasks (image classification, image captioning, visual question-answering, scene-text understanding, etc.), based on a simple, modular, and reuse-friendly platform for modeling and scaling. View details
    Joint Adaptive Representations for Image-Language Learning
    Transformers for Vision (T4V) Workshop at the Conference on Computer Vision and Pattern Recognition (CVPR) (2023)
    Preview abstract Image-language transformer models have achieved tremendous success, but they come at high computational costs. We here propose a joint adaptive image-language representation learning, which adaptively and iteratively fuses the multi-modal features. This consistently reduces the model cost and size, allows the model to scale without a large increase in FLOPs or memory, and outperforms bigger and much more expensive models. With only 40M training examples and with 39 GFLOPs our model outperforms many times larger models, some reaching 800 GFLOPs. View details
    Dynamic Pre-training of Vision-Language Models
    Wei Li
    ICLR 2023 Workshop on Multimodal Representation Learning (2023)
    Preview abstract Vision-Language pretraining aims to learn universal cross-modal representations and to create models with broad capabilities. In this paper, we propose a novel dynamic pretraining resampling for a variety of pretraining tasks. Unlike recent large-scale vision-language approaches, we show that a set of diverse self- and weakly-supervised pretraining tasks dynamically sampled according to task difficulty provides strong performance. Further, the approach is sample-efficient, using much less data and compute to address a range of downstream tasks. We show that a single 330M pretrained model using only smaller and publicly accessible datasets, achieves competitive or SOTA performance on three diverse groups of tasks: visual question answering, text-based image localization by referring expressions, and video question answering. View details
    Preview abstract We present F-VLM, a simple open-vocabulary object detection method built upon Frozen Vision and Language Models. F-VLM simplifies the current multi-stage training pipeline by eliminating the need for knowledge distillation or detection-tailored pretraining. Surprisingly, we observe that a frozen VLM: 1) retains the locality-sensitive features necessary for detection, and 2) is a strong region classifier. We finetune only the detector head and combine the detector and VLM outputs for each region at inference time. F-VLM shows compelling scaling behavior and achieves +6.5 mask AP improvement over the previous state of the art on novel categories of LVIS open-vocabulary detection benchmark. In addition, we demonstrate very competitive results on COCO open-vocabulary detection benchmark and cross dataset transfer detection, in addition to significant training speed-up and compute savings. Code will be released at https://sites.google.com/corp/view/f-vlm/home. View details
    Preview abstract The development of language models have moved from encoder-decoder to decoder-only designs. In addition, the common knowledge has it that the two most popular multimodal tasks, the generative and contrastive tasks, tend to conflict with one another, are hard to accommodate in one architecture, and further need complex adaptations for downstream tasks. We propose a novel paradigm of training with a decoder-only model for multimodal tasks, which is surprisingly effective in jointly learning of these disparate vision-language tasks. This is done with a simple model, called MaMMUT. It consists of a single vision encoder and a text decoder, and is able to accommodate contrastive and generative learning by a novel two-pass approach on the text decoder. We demonstrate that joint learning of these diverse objectives is simple, effective, and maximizes the weight-sharing of the model across these tasks. Furthermore, the same architecture enables straightforward extensions to open-vocabulary object detection and video-language tasks. The model tackles a diverse range of tasks, while being modest in capacity. Our model achieves the state of the art on image-text and text-image retrieval, video question answering and open-vocabulary detection tasks, outperforming much larger and more extensively trained foundational models. It shows very competitive results on VQA and Video Captioning, especially considering its capacity. Ablations confirm the flexibility and advantages of our approach. View details
    Diversifying Joint Vision-Language Tokenization Learning
    Vardaan Pahuja
    Transformers for Vision (T4V) Workshop at the Conference on Computer Vision and Pattern Recognition (CVPR) (2023)
    Preview abstract Building joint representations across images and text is an essential step for tasks such as Visual Question Answering and Video Question Answering. In this work, we find that the representations must not only jointly capture features from both modalities but should also be diverse for better generalization performance. To this end, we propose joint vision-language representation learning by diversifying the tokenization learning process, enabling tokens which are sufficiently disentangled from each other to be learned from both modalities. We observe that our approach outperforms the baseline models in a majority of settings and is competitive with state-of-the-art methods. View details
    Preview abstract We present a simple approach which can turn a ViT encoder into an efficient video model, which can seamlessly work with both image and video inputs. By sparsely sampling the inputs, the model is able to do training and inference from both inputs. The model is easily scalable and can be adapted to large-scale pre-trained ViTs without requiring full finetuning. The model achieves SOTA results. View details
    Preview abstract We present Answer-Me, a task-aware multi-task framework which unifies multiple question answering tasks, such as, visual question answering, visual entailment, visual reasoning. In contrast to previous works using contrastive or generative captioning training, we propose a novel and simple recipe to pretrain a vision-language joint model, which is multi-task as well, and uses the entire architecture end-to-end. Our results, which are in the challenging open-vocabulary generative setting, show state-of-the-art performance, zero-shot generalization, robustness to forgetting. View details
    Preview abstract Video question answering is a challenging task that requires understanding jointly the language input, the visual information in individual video frames, as well as the temporal information about the events occurring in the video. In this paper, we propose a novel multi-stream video encoder for video question answering that uses multiple video inputs and a new video-text iterative co-tokenization approach to answer a variety of questions related to videos. We experimentally evaluate the model on several datasets, such as MSRVTT-QA, MSVD-QA, IVQA, outperforming the previous state-of-the-art by large margins. Simultaneously, our model requires only 67 GFLOPs, producing a highly efficient video question answering model. View details
    Preview abstract We present a novel efficient image-language learning model for multi-task visual question answering tasks which works at a fraction of the computational cost. New compact features are learned adaptively to jointly represent the image and language modalities according to the data. Our method outperforms the state-of-the-art multi-task approaches on SNLI-VE and GQA, and works competitively on VQA2.0. The model is highly efficient using 7-10 fewer GFLOPs and scales well to more than twice the input image size. View details
    Preview abstract We present a pre-training approach for vision and language transformer models, which is based on a mixture of diverse tasks. We explore both the use of image-text captioning data in pre-training, which does not need additional supervision, as well as object-aware strategies to pre-train the model. We evaluate the method on a number of text-generative vision+language tasks, such as Visual Question Answering, visual entailment and captioning, and demonstrate large gains over standard pre-training methods. View details
    Preview abstract We propose FindIt, a simple and versatile framework that unifies a variety of visual grounding and localization tasks including referring expression comprehension, text-based localization, and object detection. Key to our architecture is an efficient multi-scale fusion module that unifies the disparate localization requirements across the tasks. In addition, we discover that a standard object detector is surprisingly effective in unifying these tasks without a need for task-specific design, losses, or pre computed detections. Our end-to-end trainable framework responds flexibly and accurately to a wide range of referring expression, localization or detection queries for zero, one, or multiple objects. Jointly trained on these tasks, FindIt outperforms the state of the art on both referring expression and text-based localization, and shows competitive performance on object detection. Finally, FindIt generalizes better to out-of-distribution data and novel categories compared to strong singletask baselines. All of these are accomplished by a single, unified and efficient model View details
    TokenLearner: Adaptive Space-Time Tokenization for Videos
    Michael Ryoo
    Anurag Arnab
    Conference on Neural Information Processing Systems (NeurIPS) (2021)
    Preview abstract In this paper, we present an approach for representation learning from videos. Instead of relying on hand-designed splitting strategies to obtain space-time tokens from videos, our approach learns to mine important tokens in video frames. This results in efficiently and effectively finding a few important visual tokens and enables modeling of pairwise interactions between such tokens over a longer temporal horizon. We introduce a vector transformer to capture such pairwise space-time relations, and a technique to fuse the transformed tokens while learning their spatio-temporal patterns. The proposed approach is designed with the intention to allow the tokenizer to adaptively react to input video frames containing diverse visual content, and then to have the vector transformer and subsequent modules learn the underlying spatio-temporal interactions and long-range dependencies in video inputs. We show the effectiveness of the proposed approach over challenging video classification datasets, outperforming the state-of-the-art, despite using much less compute. We further conduct extensive ablation experiments to study the method. View details
    Tiny Video Networks
    Michael Ryoo
    Applied AI Letters Journal (2021)
    Preview abstract Automatic video understanding is becoming more important for applications where real-time performance is crucial and compute is limited. Yet, accurate solutions so far have been computationally intensive. We propose efficient models for videos - Tiny Video Networks - which are video architectures, automatically designed to comply with fast runtimes and, at the same time are effective at video recognition tasks. The Tiny Video Networks run at faster-than-real-time speeds and demonstrate strong performance across several video benchmarks. These models not only provide new tools for real-time video applications, but also enable fast research and development in video understanding. Code and models are available. View details
    4D-Net for Learned Multi-Modal Alignment
    Michael Ryoo
    International Conference on Computer Vision (ICCV) (2021)
    Preview abstract We present 4D-Net, a 3D object detection approach, which utilizes 3D Point Cloud and RGB sensing information, both in time. We are able to incorporate the 4D information by performing a novel dynamic connection learning across various feature representations and levels of abstraction, as well as by observing geometric constraints. Our approach outperforms the state-of-the-art and strong baselines on the Waymo Open Dataset. 4D-Net is better able to use motion cues and dense image information to detect distant objects more successfully. We will open source the code. View details
    Adaptive Intermediate Representations for Video Understanding
    Juhana Kangaspunta
    Rico Jonschkowski
    Michael Ryoo
    MUltimodal Learning and Applications (MULA) Workshop, CVPR (2021)
    Preview abstract A common strategy to video understanding is to incorporate spatial and motion information by fusing features derived from RGB frames and optical flow. In this work, we introduce a new way to leverage semantic segmentation as an intermediate representation for video understanding and use it in a way that requires no additional labeling. Second, we propose a general framework which learns the intermediate representations (optical flow and semantic segmentation) jointly with the final video understanding task and allows the adaptation of the representations to the end goal. Despite the use of intermediate representations within the network, during inference, no additional data beyond RGB sequences is needed. Finally, we present a way to find the optimal learning configuration by searching the best loss weighting via evolution. We obtain more powerful visual representations for videos which lead to performance gains over the state-of-the-art. View details
    Preview abstract In this paper we address the problem of automatically discovering atomic actions from instructional videos. Instructional videos contain complex activities and are a rich source of information for intelligent agents, such as, autonomous robots or virtual assistants, which can, for example, automatically ‘read’ the steps from an instructional video and execute them. However, videos are rarely annotated with atomic activities, their boundaries or duration. We present an unsupervised approach to learn atomic actions of structured human tasks from a variety of instructional videos. We propose a sequential stochastic autoregressive model for temporal segmentation of videos, which learns to represent and discover the sequential relationship between different atomic actions of the task, and provides automatic and unsupervised self-labeling. View details
    Preview abstract In this paper we address the problem of automatically discovering atomic actions in unsupervised manner from instructional videos, which are rarely annotated with atomic actions. We present an unsupervised approach to learn atomic actions of structured human tasks from a variety of instructional videos based on a sequential stochastic autoregressive model for temporal segmentation of videos. This learns to represent and discover the sequential relationship between different atomic actions of the task, and which provides automatic and unsupervised self-labeling. View details
    Adversarial Generative Grammars for Human Activity Prediction
    Alexander Toshev
    Michael Ryoo
    European Conference on Computer Vision (ECCV) (2020)
    Preview abstract In this paper we propose an adversarial generative grammar model for future prediction. The objective is to learn a model that explicitly captures temporal dependencies, providing a capability to forecast multiple, distinct future activities. Our adversarial grammar is designed so that it can learn stochastic production rules from the data distribution, jointly with its latent non-terminal representations. Being able to select multiple production rules during inference leads to different predicted outcomes, thus efficiently modeling many plausible futures. The adversarial generative grammar is evaluated on the Charades, MultiTHUMOS, Human3.6M, and 50 Salads datasets and on two activity prediction tasks: future 3D human pose prediction and future activity prediction. The proposed adversarial grammar outperforms the state-of-the-art approaches, being able to predict much more accurately and further in the future, than prior work. Code will be open sourced. View details
    Preview abstract This paper proposes a novel algorithm which learns a formal regular grammar from real-world continuous data, such as videos. Learning latent terminals, non-terminals, and production rules directly from continuous data allows the construction of a generative model capturing sequential structures with multiple possibilities. Our model is fully differentiable, and provides easily interpretable results which are important in order to understand the learned structures. It outperforms the state-of-the-art on several challenging datasets and is more accurate for forecasting future activities in videos. We plan to open-source the code at https://sites.google.com/corp/view/differentiable-grammars. View details
    Preview abstract We present a new method to learn video representations from large-scale unlabeled video data. Ideally, this representation will be generic and transferable, directly usable for new tasks such as action recognition and zero or few-shot learning. We formulate unsupervised representation learning as a multi-modal, multi-task learning problem, where the representations are shared across different modalities via distillation. Further, we introduce the concept of loss function evolution by using an evolutionary search algorithm to automatically find optimal combination of loss functions capturing many (self-supervised) tasks and modalities. Thirdly, we propose an unsupervised representation evaluation metric using distribution matching to a large unlabeled dataset as a prior constraint, based on Zipf's law. This unsupervised constraint, which is not guided by any labeling, produces similar results to weakly-supervised, task-specific ones. The proposed unsupervised representation learning results in a single RGB network and outperforms previous methods. Notably, it is also more effective than several label-based methods (e.g., ImageNet), with the exception of large, fully labeled video datasets View details
    AssembleNet++: Assembling Modality Representations via Attention Connectivity
    Michael Ryoo
    Juhana Kangaspunta
    European Conference on Computer Vision (ECCV) (2020)
    Preview abstract We create a family of powerful video models which are able to: (i) learn interactions between semantic object information and raw appearance and motion features, and (ii) deploy attention in order to better learn the importance of features at each convolutional block of the network. A new network component named peer-attention is introduced, which dynamically learns the attention weights using another block or modality. Even without any pre-training, our models outperform the previous work on standard public activity recognition datasets with continuous videos, establishing new state-of-the-art. We also confirm that our findings of having neural connectivity from the object modality and the use of peer-attention is generally applicable for different existing architectures, improving their performances. View details
    AttentionNAS: Spatiotemporal Attention Cell Search for Video Classification
    Xiaofang Wang
    Xuehan Xiong
    Maxim Neumann
    Michael Ryoo
    Kris Kitani
    Wei Hua
    European Conference on Computer Vision (ECCV) (2020) (to appear)
    Preview abstract Convolutional operations have two limitations: (1) do not explicitly model where to focus as the same filter is applied to all the positions, and (2) are unsuitable for modeling long-range dependencies as they only operate on a small neighborhood. While both limitations can be alleviated by attention operations, many design choices remain to be determined to use attention, especially when applying attention to videos. Towards a principled way of applying attention to videos, we address the task of spatiotemporal attention cell search. We propose a novel search space for spatiotemporal attention cells, which allows the search algorithm to flexibly explore various design choices in the cell. The discovered attention cells can be seamlessly inserted into existing backbone networks, e.g., I3D or S3D, and improve video classification accuracy by more than 2\% on both Kinetics-600 and MiT datasets. The discovered attention cells outperform non-local blocks on both datasets, and demonstrate strong generalization across different modalities, backbones, and datasets. Inserting our attention cells into I3D-R50 yields state-of-the-art performance on both datasets. View details
    Tiny Video Networks: Architecture Search for Efficient Video Models
    Michael Ryoo
    ICML Workshop on Automated Machine Learning (AutoML) (2020)
    Preview abstract Video understanding is a challenging problem with great impact on real-world applications. Yet, solutions so far have been computationally intensive, with the fastest algorithms running at few hundred milliseconds per video snippet on powerful GPUs. We use architecture search to build highly efficient models for videos - Tiny Video Networks - which run at unprecedented speeds and, at the same time, are effective at video recognition tasks. The Tiny Video Networks run faster than real-time e.g., at less than 20 milliseconds per video on a GPU and are much faster than contemporary video models. These models not only provide new tools for real-time applications such as in mobile vision and robotics, but also enable fast research and development for video understanding. The project site is available at https://sites.google.com/view/tinyvideonetworks. View details
    Preview abstract Learning to represent videos is a very challenging task both algorithmically and computationally. Standard video CNN architectures have been designed by directly extending architectures devised for image understanding to include the time dimension, using modules such as 3D convolutions, or by using two-stream design to capture both appearance and motion in videos. We interpret a video CNN as a collection of multi-stream convolutional blocks connected to each other, and propose the approach of automatically finding neural architectures with better connectivity and spatio-temporal interactions for video understanding. This is done by evolving a population of overly-connected architectures guided by connection weight learning. Architectures combining representations that abstract different input types (i.e., RGB and optical flow) at multiple temporal resolutions are searched for, allowing different types or sources of information to interact with each other. Our method, referred to as AssembleNet, outperforms prior approaches on public video datasets, in some cases by a great margin. We obtain 58.6% mAP on Charades and 34.27% accuracy on Moments-in-Time. View details
    Evolving Losses for Video Representation Learning
    Michael Ryoo
    Bay Area Machine Learning Symposium (BayLearn) (2019)
    Preview abstract We present a new method to learn video representations from unlabeled data. We formulate our unsupervised representation learning as a multi-modal, multi-task learning problem. We also introduce the concept of finding a better loss function to train such multi-task multi-modal representation space using an evolutionary algorithm; our method automatically searches over different combinations of loss functions capturing multiple (self-supervised) tasks and modalities View details
    Evolving Losses for Unlabeled Video Representation Learning
    Michael Ryoo
    CVPR 2019 Workshop on Learning from Unlabeled Videos (2019)
    Preview abstract We present a new method to learn video representations from large-scale unlabeled video data. We formulate our unsupervised representation learning as a multi-modal, multi-task learning problem, where the representations are also shared across different modalities via distillation. Our formulation allows for the distillation of audio, optical flow and temporal information into a single, RGB-based convolutional neural network. We also compare the effects of using additional unlabeled video data and evaluate our representation learning on standard public video datasets. We newly introduce the concept of using an evolutionary algorithm to obtain a better multi-modal, multi-task loss function to train the network. AutoML has successfully been applied to architecture search and data augmentation. Here we extend the concept of AutoML to unsupervised representation learning by automatically finding the optimal weighting of tasks for representation learning. View details
    EvaNet: A Family of Diverse, Fast and Accurate Video Architectures
    Alexander Toshev
    Michael Ryoo
    Bay Area Machine Learning Symposium (BayLearn) (2019)
    Preview abstract We present a novel evolutionary algorithm that automatically constructs architectures of layers exploring space-time interactions for videos. The discovered architectures are accurate, diverse and efficient. Ensembling such models leads to further accuracy gains and yields faster and more accurate solutions than previous state-of-the-art models. Evolved models can be used across datasets and to build more powerful models for video understanding. View details
    Evolving Space-Time Neural Architectures for Videos
    Alexander Toshev
    Michael Ryoo
    International Conference on Computer Vision (ICCV) (2019)
    Preview abstract We present a new method for finding video CNN architectures that capture rich spatio-temporal information in videos. Previous work, taking advantage of 3D convolutions, obtained promising results by manually designing video CNN architectures. We here develop a novel evolutionary search algorithm that automatically explores models with different types and combinations of layers to jointly learn interactions between spatial and temporal aspects of video representations. We demonstrate the generality of this algorithm by applying it to two meta-architectures, obtaining new architectures superior to manually designed architectures: EvaNet. Further, we propose a new component, the iTGM layer, which more efficiently utilizes its parameters to allow learning of space-time interactions over longer time horizons. The iTGM layer is often preferred by the evolutionary algorithm and allows building cost-efficient networks. The proposed approach discovers new and diverse video architectures that were previously unknown. More importantly they are both more accurate and faster than prior models, and outperform the state-of-the-art results on multiple datasets we test, including HMDB, Kinetics, and Moments in Time. We will open source the code and models, to encourage future model development at https://sites.google.com/corp/view/evanet-video. . View details
    Learning Differentiable Grammars for Videos
    Michael Ryoo
    Bay Area Machine Learning Symposium (BayLearn) (2019)
    Preview abstract This paper proposes a novel algorithm which learns a formal regular grammar from real-world continuous data, such as videos. Learning latent terminals, nonterminals, and production rules directly from continuous data allows the construction of a generative model capturing sequential structures with multiple possibilities. Our model is fully differentiable, and provides easily interpretable results which are important in order to understand the learned structures. It outperforms the state-of-the-art on several challenging datasets and is more accurate for forecasting future activities in videos. View details
    Preview abstract In this paper, we present a new method for evolving video CNN models to find architectures that more optimally captures rich spatio-temporal information in videos. Previous work, taking advantage of 3D convolutional layers, obtained promising results by manually designing CNN architectures for videos. We here develop an evolutionary algorithm that automatically explores models with different types and combinations of space-time convolutional layers to jointly capture various spatial and temporal aspects of video representations. We further propose a new key component in video model evolution, the iTGM layer, which more efficiently utilizes its parameters to allow learning of space-time interactions over longer time horizons. The experiments confirm the advantages of our video CNN architecture evolution, with results outperforming previous stateof-the-art models. Our algorithm discovers new and interesting video architecture structures. View details
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