ReGain: training-free fix restores subject fidelity lost from personalizing on synthetic images

UIUC-CS · hf · 2026-10-09

UIUC researchers show that DreamBooth personalization on diffusion-generated synthetic images degrades subject fidelity with oversaturated colors and excess high-frequency detail. They trace the cause to classifier-free guidance: the angle between conditional and unconditional noise predictions inflates toward high frequencies.

ReGain is a training-free, sampling-time correction that measures how much each frequency band of guidance is inflated relative to the base model and scales it down, requiring no real photos. On SD v1.5 it closes 51-64% of the subject-fidelity gap (DINO, DINOv2, CLIP-I), also improves SDXL and SD 3.5, and preserves text alignment on all three backbones.

Original post →

More from Research

Research channel →