Robust Latent Matters: Boosting Image Generation with Sampling Error Synthesis
This work addresses a bottleneck in image generation for researchers and practitioners by improving tokenizer robustness and evaluation, though it is incremental as it builds on existing latent space methods.
The paper tackles the discrepancy between reconstruction and generation quality in discrete latent spaces for image generation by proposing a latent perturbation method to simulate sampling errors, leading to a new evaluation metric (pFID) and a plug-and-play tokenizer training scheme that improves generation quality, achieving a gFID of 1.60 with CFG and 3.45 without CFG.
Recent image generation schemes typically capture image distribution in a pre-constructed latent space relying on a frozen image tokenizer. Though the performance of tokenizer plays an essential role to the successful generation, its current evaluation metrics (e.g. rFID) fail to precisely assess the tokenizer and correlate its performance to the generation quality (e.g. gFID). In this paper, we comprehensively analyze the reason for the discrepancy of reconstruction and generation qualities in a discrete latent space, and, from which, we propose a novel plug-and-play tokenizer training scheme to facilitate latent space construction. Specifically, a latent perturbation approach is proposed to simulate sampling noises, i.e., the unexpected tokens sampled, from the generative process. With the latent perturbation, we further propose (1) a novel tokenizer evaluation metric, i.e., pFID, which successfully correlates the tokenizer performance to generation quality and (2) a plug-and-play tokenizer training scheme, which significantly enhances the robustness of tokenizer thus boosting the generation quality and convergence speed. Extensive benchmarking are conducted with 11 advanced discrete image tokenizers with 2 autoregressive generation models to validate our approach. The tokenizer trained with our proposed latent perturbation achieve a notable 1.60 gFID with classifier-free guidance (CFG) and 3.45 gFID without CFG with a $\sim$400M generator. Code: https://github.com/lxa9867/ImageFolder.