Research map / Image generation / Autoregressive and latent generation
Channel-wise Vector Quantization
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Proposes Channel-wise Vector Quantization (CVQ), which quantizes each channel of a latent map instead of each spatial patch, and a channel-wise autoregressive model (CAR) that generates images via next-channel prediction, reporting 100% codebook usage and competitive text-to-image GenEval/DPG scores.
Problem
Patch-wise vector quantization suffers from low codebook utilization (codebook collapse) and imposes a 2D grid tokenization that is mismatched to unidirectional next-token autoregressive generation.
Approach
Replace patch-wise quantization with channel-wise quantization so each codebook index encodes a whole h×w channel map; channels are then ordered coarse-to-fine via nested channel dropout, yielding a 1D token sequence for next-channel AR prediction.
Key results
- CVQ achieves 100% codebook usage at 16,384 codebook size with rFID 2.60 and PSNR 20.94 at 256 tokens, versus 4.5% usage and rFID 4.84 for vanilla VQ.
- CAR (8B) reaches GenEval 0.79 and DPG 86.72 among unidirectional models, competitive with Infinity and InfinityStar.
- CAR attains MJHQ-30K FID of 6.42, outperforming the standard 2D-token baseline and 1D masked-token baselines reported in the paper.
Surprising findings
- Nested channel dropout hurts patch-wise VQ reconstruction badly (rFID 15.32) while CVQ keeps reconstruction quality under the same dropout.
Limitations
- Fixed token count limits flexibility; at higher resolution with fixed token budget CVQ trades reconstruction fidelity for efficiency.
- Ordering of channels relies on heuristic nested dropout whose theoretical guarantees apply only to semi-linear autoencoders.
- Generation results for the best models rely on a large in-house and web-scale 80M pair training mix that is not released.
Experimental setup
Datasets: ImageNet-1K ImageNet-21K (filtered) LAION-Aesthetics-12M CC12M Megalith-10M BLIP-3o-short BLIP-3o-long 6M in-house aesthetics dataset
Benchmarks: ImageNet-1K GenEval DPG-Bench MJHQ-30K
Metrics: rFID SSIM PSNR codebook usage GenEval overall DPG overall FID
Baselines: VQGAN SimVQ VQ-LC MoVQ TiTok TA-TiTok FlexTok SpectralAR Emu3 NextStep-1 Infinity InfinityStar
Builds on: VQ-VAE VQGAN nested dropout Qwen3 VAR
Closest papers by meaning
- Vision Foundation Models as Effective Visual Tokenizers for Autoregressive Generation (NeurIPS 2025 · similarity 0.90)
- TokenFlow: Unified Image Tokenizer for Multimodal Understanding and Generation (CVPR 2025 · similarity 0.89)
- Image Understanding Makes for A Good Tokenizer for Image Generation (NeurIPS 2024 · similarity 0.89)
- Finite Scalar Quantization: VQ-VAE Made Simple (ICLR 2024 · similarity 0.88)
- UniFlow: A Unified Pixel Flow Tokenizer for Visual Understanding and Generation (ICLR 2026 · similarity 0.88)
- UniTok: a Unified Tokenizer for Visual Generation and Understanding (NeurIPS 2025 · similarity 0.87)
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