JLT:潜在扩散Transformer中的清洁潜在预测
阅读原文· arxiv.org本文提出JLT,一个基于冻结FLUX.2 VAE编码的130M参数潜在扩散Transformer。研究对比了清洁潜在预测与速度预测DiT在相同表示与训练设置下的表现。分析表明,速度回归继承了各向同性目标协方差下限并放大低方差方向,而清洁预测则能抑制这些方向。在ImageNet 256x256上,JLT-B/1通过classifier-free guidance获得2.50的FID-50K分数,相比速度预测展现出显著优势。研究指出,潜在扩散中的预测目标是与表示相关的几何选择,而非可互换的代数参数化。
Flow matching with clean-data prediction has shown that regressing the clean point can exploit low-dimensional structure more effectively than predicting an ambient noised quantity. We ask whether this principle remains useful after images are mapped into a learned latent space, where compression has already removed much of the raw pixel variability. We introduce JLT, a 130M latent diffusion Transformer over frozen FLUX.2 VAE codes, and compare clean-latent prediction with a matched velocity-prediction DiT under the same representation, backbone, and training settings. Although the three variables x, epsilon, and v are linearly convertible for a fixed corruption time, a local Gaussian analysis shows that velocity regression inherits an isotropic target-covariance floor and amplifies low-variance latent directions, while clean prediction damps them. On ImageNet 256 x 256, JLT-B/1 obtains FID-50K 2.50 with classifier-free guidance, with a large matched-target gap over velocity prediction. These results suggest that prediction targets in latent diffusion are representation-dependent geometric choices, rather than interchangeable algebraic parameterizations.