FreeInv: Free Lunch for Improving DDIM Inversion

Fuente: arXiv
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Main Authors: Bao, Yuxiang, Liu, Huijie, Gao, Xun, Fu, Huan, Kang, Guoliang
Format: Preprint
Published: 2025
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_version_ 1866912725657976832
author Bao, Yuxiang
Liu, Huijie
Gao, Xun
Fu, Huan
Kang, Guoliang
author_facet Bao, Yuxiang
Liu, Huijie
Gao, Xun
Fu, Huan
Kang, Guoliang
contents Naive DDIM inversion process usually suffers from a trajectory deviation issue, i.e., the latent trajectory during reconstruction deviates from the one during inversion. To alleviate this issue, previous methods either learn to mitigate the deviation or design cumbersome compensation strategy to reduce the mismatch error, exhibiting substantial time and computation cost. In this work, we present a nearly free-lunch method (named FreeInv) to address the issue more effectively and efficiently. In FreeInv, we randomly transform the latent representation and keep the transformation the same between the corresponding inversion and reconstruction time-step. It is motivated from a statistical perspective that an ensemble of DDIM inversion processes for multiple trajectories yields a smaller trajectory mismatch error on expectation. Moreover, through theoretical analysis and empirical study, we show that FreeInv performs an efficient ensemble of multiple trajectories. FreeInv can be freely integrated into existing inversion-based image and video editing techniques. Especially for inverting video sequences, it brings more significant fidelity and efficiency improvements. Comprehensive quantitative and qualitative evaluation on PIE benchmark and DAVIS dataset shows that FreeInv remarkably outperforms conventional DDIM inversion, and is competitive among previous state-of-the-art inversion methods, with superior computation efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2503_23035
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FreeInv: Free Lunch for Improving DDIM Inversion
Bao, Yuxiang
Liu, Huijie
Gao, Xun
Fu, Huan
Kang, Guoliang
Computer Vision and Pattern Recognition
Naive DDIM inversion process usually suffers from a trajectory deviation issue, i.e., the latent trajectory during reconstruction deviates from the one during inversion. To alleviate this issue, previous methods either learn to mitigate the deviation or design cumbersome compensation strategy to reduce the mismatch error, exhibiting substantial time and computation cost. In this work, we present a nearly free-lunch method (named FreeInv) to address the issue more effectively and efficiently. In FreeInv, we randomly transform the latent representation and keep the transformation the same between the corresponding inversion and reconstruction time-step. It is motivated from a statistical perspective that an ensemble of DDIM inversion processes for multiple trajectories yields a smaller trajectory mismatch error on expectation. Moreover, through theoretical analysis and empirical study, we show that FreeInv performs an efficient ensemble of multiple trajectories. FreeInv can be freely integrated into existing inversion-based image and video editing techniques. Especially for inverting video sequences, it brings more significant fidelity and efficiency improvements. Comprehensive quantitative and qualitative evaluation on PIE benchmark and DAVIS dataset shows that FreeInv remarkably outperforms conventional DDIM inversion, and is competitive among previous state-of-the-art inversion methods, with superior computation efficiency.
title FreeInv: Free Lunch for Improving DDIM Inversion
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2503.23035