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Abdullah Rashwan

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5 papers

2 author rows

TMLR Journal 2024 Journal Article

Greedy Growing Enables High-Resolution Pixel-Based Diffusion Models

Cristina Nader Vasconcelos
Abdullah Rashwan
Austin Waters
Trevor Walker
Keyang Xu
Jimmy Yan
Rui Qian
Yeqing Li

We address the long-standing problem of how to learn effective pixel-based image diffusion models at scale, introducing a remarkably simple greedy method for stable training of large-scale, high-resolution models. without the needs for cascaded super-resolution components.The key insight stems from careful pre-training of core components, namely, those responsible for text-to-image alignment vs. high resolution rendering. We first demonstrate the benefits of scaling a Shallow UNet, with no down(up)-sampling enc(dec)oder. Scaling its deep core layers is shown to improve alignment, object structure, and composition. Building on this core model, we propose a greedy algorithm that grows the architecture into high resolution end-to-end models, while preserving the integrity of the pre-trained representation,stabilizing training, and reducing the need for large high-resolution datasets. This enables a single stage model capable of generating high-resolution images without the need of a super-resolution cascade. Our key results rely on public datasets and show that we are able to train non-cascaded models up to 8B parameters with no further regularization schemes.Vermeer, our full pipeline model trained with internal datasets to produce 1024×1024 images, without cascades, is preferred by 44.0% vs. 21.4% human evaluators over SDXL.

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NeurIPS Conference 2024 Conference Paper

Subject-driven Text-to-Image Generation via Preference-based Reinforcement Learning

Yanting Miao
William Loh
Suraj Kothawade
Pascal Poupart
Abdullah Rashwan
Yeqing Li

Text-to-image generative models have recently attracted considerable interest, enabling the synthesis of high-quality images from textual prompts. However, these models often lack the capability to generate specific subjects from given reference images or to synthesize novel renditions under varying conditions. Methods like DreamBooth and Subject-driven Text-to-Image (SuTI) have made significant progress in this area. Yet, both approaches primarily focus on enhancing similarity to reference images and require expensive setups, often overlooking the need for efficient training and avoiding overfitting to the reference images. In this work, we present the $\lambda$-Harmonic reward function, which provides a reliable reward signal and enables early stopping for faster training and effective regularization. By combining the Bradley-Terry preference model, the $\lambda$-Harmonic reward function also provides preference labels for subject-driven generation tasks. We propose Reward Preference Optimization (RPO), which offers a simpler setup (requiring only 3\% of the negative samples used by DreamBooth) and fewer gradient steps for fine-tuning. Unlike most existing methods, our approach does not require training a text encoder or optimizing text embeddings and achieves text-image alignment by fine-tuning only the U-Net component. Empirically, $\lambda$-Harmonic proves to be a reliable approach for model selection in subject-driven generation tasks. Based on preference labels and early stopping validation from the $\lambda$-Harmonic reward function, our algorithm achieves a state-of-the-art CLIP-I score of 0. 833 and a CLIP-T score of 0. 314 on DreamBench.

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NeurIPS Conference 2023 Conference Paper

DaTaSeg: Taming a Universal Multi-Dataset Multi-Task Segmentation Model

Xiuye Gu
Yin Cui
Jonathan Huang
Abdullah Rashwan
Xuan Yang
Xingyi Zhou
Golnaz Ghiasi
Weicheng Kuo

Observing the close relationship among panoptic, semantic and instance segmentation tasks, we propose to train a universal multi-dataset multi-task segmentation model: DaTaSeg. We use a shared representation (mask proposals with class predictions) for all tasks. To tackle task discrepancy, we adopt different merge operations and post-processing for different tasks. We also leverage weak-supervision, allowing our segmentation model to benefit from cheaper bounding box annotations. To share knowledge across datasets, we use text embeddings from the same semantic embedding space as classifiers and share all network parameters among datasets. We train DaTaSeg on ADE semantic, COCO panoptic, and Objects365 detection datasets. DaTaSeg improves performance on all datasets, especially small-scale datasets, achieving 54. 0 mIoU on ADE semantic and 53. 5 PQ on COCO panoptic. DaTaSeg also enables weakly-supervised knowledge transfer on ADE panoptic and Objects365 instance segmentation. Experiments show DaTaSeg scales with the number of training datasets and enables open-vocabulary segmentation through direct transfer. In addition, we annotate an Objects365 instance segmentation set of 1, 000 images and release it as a public evaluation benchmark on https: //laoreja. github. io/dataseg.

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UAI Conference 2020 Conference Paper

Batch norm with entropic regularization turns deterministic autoencoders into generative models

Amur Ghose
Abdullah Rashwan
Pascal Poupart

The variational autoencoder is a well defined deep generative model that utilizes an encoder-decoder framework where an encoding neural network outputs a non-deterministic code for reconstructing an input. The encoder achieves this by sampling from a distribution for every input, instead of outputting a deterministic code per input. The great advantage of this process is that it allows the use of the network as a generative model for sampling from the data distribution beyond provided samples for training. We show in this work that utilizing batch normalization as a source for non-determinism suffices to turn deterministic autoencoders into generative models on par with variational ones, so long as we add a suitable entropic regularization to the training objective.

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NeurIPS Conference 2018 Conference Paper

Online Structure Learning for Feed-Forward and Recurrent Sum-Product Networks

Agastya Kalra
Abdullah Rashwan
Wei-Shou Hsu
Pascal Poupart
Prashant Doshi
Georgios Trimponias

Sum-product networks have recently emerged as an attractive representation due to their dual view as a special type of deep neural network with clear semantics and a special type of probabilistic graphical model for which inference is always tractable. Those properties follow from some conditions (i. e. , completeness and decomposability) that must be respected by the structure of the network. As a result, it is not easy to specify a valid sum-product network by hand and therefore structure learning techniques are typically used in practice. This paper describes a new online structure learning technique for feed-forward and recurrent SPNs. The algorithm is demonstrated on real-world datasets with continuous features for which it is not clear what network architecture might be best, including sequence datasets of varying length.

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