Title: LacTok: Latent Consistency Tokenizer for High-resolution Image Reconstruction and Generation by 256 Tokens
Primary area: applications to computer vision, audio, language, and other modalities
Keywords: Tokenizer, consistency model, image generation, image reconstruction

Abstract: Image tokenization has significantly advanced visual generation and multimodal
modeling, particularly when paired with autoregressive models. However, current
methods face challenges in balancing efficiency and fidelity: high-resolution image
reconstruction either requires an excessive number of tokens or compromises
critical details through token reduction. To resolve this, we propose Latent Consistency
Tokenizer (LacTok) that bridges discrete visual tokens with the compact
latent space of pre-trained Latent Diffusion Models (LDMs), enabling efficient
representation of 1024×1024 images using only 256 tokens—a 16× compression
over VQGAN. LacTok integrates a transformer encoder, a quantized codebook,
and a latent consistency decoder. Direct application of LDM as the decoder results
in color and brightness discrepancies; thus, we convert it to latent consistency
decoder, reducing multi-step sampling to 1-2 steps for direct pixel-level supervision.
Experiments demonstrate LacTok’s superiority in high-fidelity reconstruction,
with 10.8 reconstruction Frechet Inception Distance on MSCOCO-2017 5K
benchmark for 1024×1024 image reconstruction. We also extend LacTok to a textto-
image generation model, LacTokGen, working in autoregression. It achieves
0.73 score on GenEval benchmark, surpassing current state-of-the-art methods.

TL;DR: A novel and efficient tokenizer for high-resolution image reconstruction and generation