arXiv Computer Vision

Improving Flexible Image Tokenizers for Autoregressive Image Generation

The paper introduces ReToK, a flexible image tokenizer that uses redundant token padding and hierarchical semantic regularization to better utilize all tokens in autoregressive image generation. By activating tail tokens more frequently and aligning early token features with a pre‑trained vision model while gradually reducing regularization, ReToK mitigates the information concentration problem of traditional nested dropout tokenizers. Experiments on ImageNet 256×256 show that ReToK outperforms both flexible and fixed‑length tokenizers in generation quality.

arXiv AI
Oct 5

VTBench: Evaluating Visual Tokenizers for Autoregressive Image Generation

VTBench is a new benchmark that evaluates visual tokenizers (VTs) used in autoregressive image generation. It assesses VTs on image reconstruction, detail preservation, and text preservation across diverse scenarios, revealing that continuous VAEs outperform discrete VTs in maintaining spatial structure and semantic detail. The study also explores GPT‑4o’s potential autoregressive behavior and releases the benchmark publicly to encourage development of robust, open‑source VTs.

By Huawei Lin, Tony Geng, Zhaozhuo Xu, Weijie Zhao
arXiv Computer Vision
Aug 27

Efficient Training with Foresight: Multi-Token Auxiliary Supervision for Autoregressive Image Generation

The paper introduces MTAR, a training framework for autoregressive image generation that enhances performance through multi-token prediction, token-level contrastive regularization, and semantic dropping. These components address sparse supervision, improve representation discriminability, and accelerate training without affecting inference. On ImageNet, MTAR outperforms LlamaGen with lower FID and faster training, achieving comparable results in only a third of the iterations.

By Guo Niu, Xiongfei Yao, Teng Wang, Nannan Zhu
arXiv Computer Vision
2d ago

MoETok: Sparse Expert Routing for 1D Visual Tokenizers

MoETok introduces a sparse expert routing mechanism for 1D visual tokenizers, enabling distinct Content and Detail queries to specialize in high‑level semantics and fine‑grained visual details, respectively. By jointly optimizing reconstruction and semantic objectives, the router learns role‑specialized processing paths that improve reconstruction, semantic representation, and autoregressive generation across various model scales and token budgets. On ImageNet, MoETok achieves state‑of‑the‑art class‑conditional generation within the 1D tokenizer family and, when scaled to a unified autoregressive model, matches or surpasses diffusion‑based models on benchmarks such as DPG‑Bench, GenEval2, and WISE.

By Jiahao Guo, Bao Tang, Haoxiang Cao, Jingfeng Yao, Bo Li, Wenyu Liu, Kun Gai, Changqian Yu, Xinggang Wang
arXiv Computer Vision
Oct 8

QuadTok: Quadtree Visual Tokenizer for Autoregressive Image Generation

QuadTok introduces a quadtree-based visual tokenizer that replaces traditional 2D grids or 1D token sequences with a hierarchical structure, allowing dynamic allocation of tokens to visually complex regions while using coarser resolution for homogeneous areas. The tokenizer, trained on ImageNet, reduces token usage by about 10% compared to a fixed 256-token grid and retains comparable reconstruction fidelity. Leveraging the tree’s natural causality, a 947 M GPT-style model conditioned on a quadtree topology achieves a 2.08 gFID on ImageNet 256×256 and supports zero‑shot spatially controlled image generation.

By Yucheng Mao, Zeyuan Chen, Xiaojun Shan, Xiang Zhang, Divyansh Srivastava, Bingnan Li, Zhuowen Tu
arXiv AI
Jun 16

Token Reduction Should Go Beyond Efficiency in Generative Models -- From Vision, Language to Multimodality

arXiv:2505. 18227v4 Announce Type: replace-cross Abstract: In Transformer architectures, tokens\textemdash discrete units derived from raw data\textemdash are formed by segmenting inputs into fixed-length chunks.

By Zhenglun Kong, Yize Li, Fanhu Zeng, Lei Xin, Shvat Messica, Xue Lin, Pu Zhao, Manolis Kellis, Hao Tang, Marinka Zitnik
arXiv Machine Learning
Sep 3

DynaTokens: Controlling Token Dynamics for Continual Video-Language Understanding

The paper introduces DynaTokens, a transformer-based token generator that produces fine‑tuning tokens on demand for continual VideoQA with multimodal large language models. It uses shared generation weights and meta‑learning‑inspired regularisers to reduce task interference and forgetting, connecting the objective to sharpness‑aware optimisation for flatter cross‑task minima. Experiments on standard continual VideoQA benchmarks show that DynaTokens achieves higher average accuracy, lower forgetting, better zero‑shot generalisation, and robust cross‑modal transfer in a new ImageQA→VideoQA protocol.

By Toan Nguyen, Yang Liu, Celso De Melo, Flora D. Salim