DDIM Inversion and Editing

Key Insight

To edit a real photo with a diffusion model you first need the noise that would regenerate it — and DDIM inversion finds it by running the deterministic DDIM sampler backwards, adding noise along the same path the model would later remove. Once you hold that starting noise you change the prompt and denoise forward again: because the trajectory is largely shared, the new image keeps the original's layout and pose while swapping the content you re-described. The imperfection you will see — inversion drifts, so the reconstruction is never pixel-perfect — is exactly the gap that follow-up methods like null-text inversion were built to close.