VLDB 2026 Research / reviewers in the wild / expert
Xu Ouyang
dblp:211/7098
· DBLP profile ↗
14ranked-venue papers
6as first author
10since 2021 · last 2025
0009-0001-5572-9646ORCID · corroborated
Domains — the database's venue-derived domains; a paper can count in several
Artificial intelligence and machine learning · 10 · 5 first-author · 7 since 2021Graphics, computer vision, multimedia, augmented reality and games · 9 · 4 first-author · 6 since 2021Systems, architecture and hardware · 1 · 1 since 2021
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2025 | Low-Bit Quantization Favors Undertrained LLMsabstractLow-bit quantization improves machine learning model efficiency but surprisingly favors undertrained large language models (LLMs).Larger models or those trained on fewer tokens exhibit less quantization-induced degradation (QiD), while smaller, well-trained models face significant performance losses.To gain deeper insights into this trend, we study over 1500+ quantized LLM checkpoints of various sizes and at different training levels (undertrained or fully trained) in a controlled setting, deriving scaling laws for understanding the relationship between QiD and factors: the number of training tokens, model size and bit width.With our derived scaling laws, we propose a novel perspective that we can use QiD to measure an LLM's training levels and determine the number of training tokens required for fully training LLMs of various sizes.Moreover, we use the scaling laws to predict the quantization performance of different-sized LLMs trained with 100 trillion tokens.Our projection shows that the low-bit quantization performance of future models, which are expected to be trained with over 100 trillion tokens, may NOT be desirable.This poses a potential challenge for low-bit quantization in the future and highlights the need for awareness of a model's training level when evaluating lowbit quantization research.To facilitate future research on this problem, we release all the 1500+ quantized checkpoints used in this work at https://huggingface.co/Xu-Ouyang. Xu Ouyang, Tao Ge 0001, Thomas Hartvigsen, Zhisong Zhang, Haitao Mi, Dong Yu 0001 |
ACL (1) | 1 |
| 2025 | SelectFormer in Data Markets: Privacy-Preserving and Efficient Data Selection for Transformers with Multi-Party ComputationabstractCritical to a free data market is $ \textit{private data selection}$, i.e. the model owner selects and then appraises training data from the data owner before both parties commit to a transaction. To keep the data and model private, this process shall evaluate the target model to be trained over Multi-Party Computation (MPC). While prior work suggests that evaluating Transformer-based models over MPC is prohibitively expensive, this paper makes it practical for the purpose of data selection. Our contributions are three: (1) a new pipeline for private data selection over MPC; (2) emulating high-dimensional nonlinear operators with low-dimension MLPs, which are trained on a small sample of the data of interest; (3) scheduling MPC in a parallel, multiphase fashion. We evaluate our method on diverse Transformer models and NLP/CV benchmarks. Compared to directly evaluating the target model over MPC, our method reduces the delay from thousands of hours to tens of hours, while only seeing around 0.20% accuracy degradation from training with the selected data. Xu Ouyang, Felix Xiaozhu Lin, Yangfeng Ji |
ICLR | 1 |
| 2024 | Fine-grained Text to Image Synthesis
Xu Ouyang, Kaiyue Zhu, Gady Agam |
ICPR (24) | 1 |
| 2023 | Efficient NLP Model Finetuning via Multistage Data FilteringabstractAs model finetuning is central to the modern NLP, we set to maximize its efficiency. Motivated by redundancy in training examples and the sheer sizes of pretrained models, we exploit a key opportunity: training only on important data. To this end, we set to filter training examples in a streaming fashion, in tandem with training the target model. Our key techniques are two: (1) automatically determine a training loss threshold for skipping backward training passes; (2) run a meta predictor for further skipping forward training passes. We integrate the above techniques in a holistic, three-stage training pro- cess. On a diverse set of benchmarks, our method reduces the required training examples by up to 5.3× and training time by up to 6.8×, while only seeing minor accuracy degradation. Our method is effective even for training one epoch, where each training example is encountered only once. It is simple to implement and is compatible with the existing finetuning techniques. Code is available at: https://github.com/xo28/efficient-NLP-multistage-training Xu Ouyang, Shahina Mohd Azam Ansari, Felix Xiaozhu Lin, Yangfeng Ji |
IJCAI | 1 |
| 2022 | Contrastive quant: quantization makes stronger contrastive learningabstractContrastive learning learns visual representations by enforcing feature consistency under different augmented views. In this work, we explore contrastive learning from a new perspective. Interestingly, we find that quantization, when properly engineered, can enhance the effectiveness of contrastive learning. To this end, we propose a novel contrastive learning framework, dubbed Contrastive Quant, to encourage feature consistency under both differently augmented inputs via various data transformations and differently augmented weights/activations via various quantization levels. Extensive experiments, built on top of two state-of-the-art contrastive learning methods SimCLR and BYOL, show that Contrastive Quant consistently improves the learned visual representation. Yonggan Fu, Qixuan Yu 0001, Meng Li 0004, Xu Ouyang, Vikas Chandra, Yingyan (Celine) Lin |
DAC | 4 |
| 2022 | SuperTickets: Drawing Task-Agnostic Lottery Tickets from Supernets via Jointly Architecture Searching and Parameter Pruning
Haoran You, Baopu Li, Zhanyi Sun, Xu Ouyang, Yingyan (Celine) Lin |
ECCV (11) | 4 |
| 2022 | Semi-supervised Dual-Domain Adaptation for Semantic SegmentationabstractDeep learning approaches for semantic segmentation rely primarily on supervised learning approaches and require substantial efforts in producing pixel-level annotations. Further, such approaches may perform poorly when applied to unseen image domains. To cope with these limitations, both unsupervised domain adaptation (UDA) with full source supervision but without target supervision and semi-supervised learning (SSL) with partial supervision have been proposed. While such methods are effective at aligning different feature distributions, there is still a need to efficiently exploit unlabeled data to address the performance gap with respect to fully-supervised methods. In this paper we address semi-supervised domain adaptation (SSDA) for semantic segmentation, where a large amount of labeled source data as well as a small amount of labeled target data are available. We propose a novel and effective two-step semi-supervised dual-domain adaptation (SSDDA) approach to address both cross-and intra-domain gaps in semantic segmentation. The proposed framework is comprised of two mixing modules. First, we conduct a cross-domain adaptation via an image-level mixing strategy, which learns to align the distribution shift of features between the source data and target data. Second, intra-domain adaptation is achieved using a separate student-teacher network which is built to generate category-level data augmentation by mixing unlabeled target data in a way that respects predicted object boundaries. We demonstrate that the proposed approach outperforms state-of-the-art methods on two common synthetic-to-real semantic segmentation benchmarks. An extensive ablation study is provided to further validate the effectiveness of our approach. Xu Ouyang, Kaiyue Zhu, Gady Agam |
ICPR | 2 |
| 2021 | ComplexMix: Semi-Supervised Semantic Segmentation Via Mask-Based Data AugmentationabstractSemantic segmentation using convolutional neural networks (CNN) is a crucial component in image analysis. Training a CNN to perform semantic segmentation requires a large amount of labeled data, where the production of such labeled data is both costly and labor intensive. Semi-supervised learning algorithms address this issue by utilizing unlabeled data and so reduce the amount of labeled data needed for training. In particular, data augmentation techniques such as CutMix and ClassMix generate additional training data from existing labeled data. In this paper we propose a new approach for data augmentation, termed ComplexMix, which incorporates aspects of CutMix and ClassMix with improved performance. The proposed approach has the ability to control the complexity of the augmented data while attempting to be semantically-correct and address the tradeoff between complexity and correctness. The proposed ComplexMix approach is evaluated on a standard dataset for semantic segmentation and compared to other state-of-the-art techniques. Experimental results show that our method yields improvement over state-of-the-art methods on standard datasets for semantic image segmentation. Xu Ouyang, Kaiyue Zhu, Gady Agam |
ICIP | 2 |
| 2021 | Drawing Robust Scratch Tickets: Subnetworks with Inborn Robustness Are Found within Randomly Initialized NetworksabstractDeep Neural Networks (DNNs) are known to be vulnerable to adversarial attacks, i.e., an imperceptible perturbation to the input can mislead DNNs trained on clean images into making erroneous predictions. To tackle this, adversarial training is currently the most effective defense method, by augmenting the training set with adversarial samples generated on the fly. \textbf{Interestingly, we discover for the first time that there exist subnetworks with inborn robustness, matching or surpassing the robust accuracy of the adversarially trained networks with comparable model sizes, within randomly initialized networks without any model training}, indicating that adversarial training on model weights is not indispensable towards adversarial robustness. We name such subnetworks Robust Scratch Tickets (RSTs), which are also by nature efficient. Distinct from the popular lottery ticket hypothesis, neither the original dense networks nor the identified RSTs need to be trained. To validate and understand this fascinating finding, we further conduct extensive experiments to study the existence and properties of RSTs under different models, datasets, sparsity patterns, and attacks, drawing insights regarding the relationship between DNNs’ robustness and their initialization/overparameterization. Furthermore, we identify the poor adversarial transferability between RSTs of different sparsity ratios drawn from the same randomly initialized dense network, and propose a Random RST Switch (R2S) technique, which randomly switches between different RSTs, as a novel defense method built on top of RSTs. We believe our findings about RSTs have opened up a new perspective to study model robustness and extend the lottery ticket hypothesis. Yonggan Fu, Qixuan Yu 0001, Yang Zhang 0001, Shang Wu 0003, Xu Ouyang, David D. Cox, Yingyan (Celine) Lin |
NeurIPS | 5 |
| 2021 | Accelerated WGAN update strategy with loss change rate balancingabstractOptimizing the discriminator in Generative Adversarial Networks (GANs) to completion in the inner training loop is computationally prohibitive, and on finite datasets would result in overfitting. To address this, a common update strategy is to alternate between k optimization steps for the discriminator D and one optimization step for the generator G. This strategy is repeated in various GAN algorithms where k is selected empirically. In this paper, we show that this update strategy is not optimal in terms of accuracy and convergence speed, and propose a new update strategy for networks with Wasserstein GAN (WGAN) group related loss functions (e.g. WGAN, WGAN-GP, Deblur GAN, and Super resolution GAN). The proposed update strategy is based on a loss change ratio comparison of G and D. We demonstrate that the proposed strategy improves both convergence speed and accuracy. Xu Ouyang, Gady Agam |
WACV | 1 |
| 2018 | MFCNET: End-to-End Approach for Change Detection in ImagesabstractChange detection is an important task in computer vision and video processing. Due to unimportant or nuisance forms of change, traditional methods require sophisticated image preprocessing and possibly manual interaction. In this work, we propose an end-to-end approach for change detection to identify temporal changes in multiple images. Our approach feeds a pair of images into a deep convolutional neural network combining the model of MatchNet [1] and the Fully Convolutional Network [2] modified to reduce the number of parameters. We train and evaluate the proposed approach using a subset of frames from the Change Detection challenge 2014 dataset (CDnet 2014). Experimental evaluation comparing the performance of the proposed approach with several known approaches shows that the proposed approach outperforms existing methods. Xu Ouyang, Gady Agam |
ICIP | 2 |
| 2018 | Generating Image Sequence from Description with LSTM Conditional GANabstractGenerating images from word descriptions is a challenging task. Generative adversarial networks(GANs) are shown to be able to generate realistic images of real-life objects. In this paper, we propose a new neural network architecture of LSTM Conditional Generative Adversarial Networks to generate images of real-life objects. Our proposed model is trained on the Oxford-102 Flowers and Caltech-UCSD Birds-200-2011 datasets. We demonstrate that our proposed model produces the better results surpassing other state-of-art approaches. Xu Ouyang, Gady Agam |
ICPR | 1 |
| 2018 | Layered Optical Flow Estimation Using a Deep Neural Network with a Soft MaskabstractUsing a layered representation for motion estimation has the advantage of being able to cope with discontinuities and occlusions. In this paper, we learn to estimate optical flow by combining a layered motion representation with deep learning. Instead of pre-segmenting the image to layers, the proposed approach automatically generates a layered representation of optical flow using the proposed soft-mask module. The essential components of the soft-mask module are maxout and fuse operations, which enable a disjoint layered representation of optical flow and more accurate flow estimation. We show that by using masks the motion estimate results in a quadratic function of input features in the output layer. The proposed soft-mask module can be added to any existing optical flow estimation networks by replacing their flow output layer. In this work, we use FlowNet as the base network to which we add the soft-mask module. The resulting network is tested on three well-known benchmarks with both supervised and unsupervised flow estimation tasks. Evaluation results show that the proposed network achieve better results compared with the original FlowNet. Xu Ouyang, Gady Agam |
IJCAI | 3 |
| 2017 | Lecture Vdeo Indexing Using Boosted Margin Maximizing Neural NetworksabstractThis paper presents a novel approach for lecture video indexing using a boosted deep convolutional neural network system. The indexing is performed by matching high quality slide images, for which text is either known or extracted, to lower resolution video frames with possible noise, perspective distortion, and occlusions. We propose a deep neural network integrated with a boosting framework composed of two sub-networks targeting feature extraction and similarity determination to perform the matching. The trained network is given as input a pair of slide image and a candidate video frame image and produces the similarity between them. A boosting framework is integrated into our proposed network during the training process. Experimental results show that the proposed approach is much more capable of handling occlusion, spatial transformations, and other types of noises when compared with known approaches. Xu Ouyang, Gady Agam |
ICMLA | 3 |