SONIC: Spectral Optimization of Noise for Inpainting with Consistency

TL;DR

SONIC introduces a training-free inpainting method that optimizes initial seed noise in the spectral domain, improving results with minimal optimization steps and outperforming existing techniques.

Contribution

The paper presents a novel spectral optimization approach for seed noise in training-free inpainting, eliminating the need for specialized models.

Findings

Outperforms state-of-the-art inpainting methods

Requires only a few tens of optimization steps

Effective across various inpainting tasks

Abstract

We propose a novel training-free method for inpainting with off-the-shelf text-to-image models. While guidance-based methods in theory allow generic models to be used for inverse problems such as inpainting, in practice, their effectiveness is limited, leading to the necessity of specialized inpainting-specific models. In this work, we argue that the missing ingredient for training-free inpainting is the optimization (guidance) of the initial seed noise. We propose to optimize the initial seed noise to approximately match the unmasked parts of the data - with as few as a few tens of optimization steps. We then apply conventional training-free inpainting methods on top of our optimized initial seed noise. Critically, we propose two core ideas to effectively implement this idea: (i) to avoid the costly unrolling required to relate the initial noise and the generated outcome, we perform linear approximation; and (ii) to stabilize the optimization, we optimize the initial seed noise in the spectral domain. We demonstrate the effectiveness of our method on various inpainting tasks, outperforming the state of the art. Project page: https://ubc-vision.github.io/sonic/