Watermarking in Diffusion Model: Gaussian Shading with Exact Diffusion Inversion via Coupled Transformations (EDICT)
Krishna Panthi
TL;DR
This work addresses watermark fidelity in diffusion-based image generation by tackling the inexact inversion of Gaussian Shading with standard DDIM methods. It introduces Exact Diffusion Inversion via Coupled Transformations (EDICT) to derive exact inverse mappings using two coupled latents $x$ and $y$, which denoise each other in an alternating fashion during the forward pass and reintroduce noise in the reverse pass. The approach duplicates the watermark-infused latent, enabling reciprocal denoising and more precise watermark recovery, and claims to be the first integration of EDICT with Gaussian Shading. Experiments on Stable Diffusion 2.1 show a modest but statistically significant improvement in watermark recovery fidelity across several image-manipulation scenarios, without requiring model retraining; the method is roughly 2× slower and has some limitations under certain perturbations, suggesting avenues for speedups and broader applicability.
Abstract
This paper introduces a novel approach to enhance the performance of Gaussian Shading, a prevalent watermarking technique, by integrating the Exact Diffusion Inversion via Coupled Transformations (EDICT) framework. While Gaussian Shading traditionally embeds watermarks in a noise latent space, followed by iterative denoising for image generation and noise addition for watermark recovery, its inversion process is not exact, leading to potential watermark distortion. We propose to leverage EDICT's ability to derive exact inverse mappings to refine this process. Our method involves duplicating the watermark-infused noisy latent and employing a reciprocal, alternating denoising and noising scheme between the two latents, facilitated by EDICT. This allows for a more precise reconstruction of both the image and the embedded watermark. Empirical evaluation on standard datasets demonstrates that our integrated approach yields a slight, yet statistically significant improvement in watermark recovery fidelity. These results highlight the potential of EDICT to enhance existing diffusion-based watermarking techniques by providing a more accurate and robust inversion mechanism. To the best of our knowledge, this is the first work to explore the synergy between EDICT and Gaussian Shading for digital watermarking, opening new avenues for research in robust and high-fidelity watermark embedding and extraction.
