Re-imagine the Negative Prompt Algorithm: Transform 2D Diffusion into 3D, alleviate Janus problem and Beyond

TL;DR

This paper introduces Perp-Neg, a novel algorithm leveraging geometrical properties of score space to improve negative prompts in diffusion models, enhancing 2D and 3D image generation and addressing the Janus problem without requiring model training.

Contribution

We propose Perp-Neg, a geometry-based negative prompt method that improves image editing and view conditioning in 2D and 3D diffusion models without additional training.

Findings

Perp-Neg effectively removes unwanted concepts in 2D image generation.

It enables flexible view conditioning in 3D diffusion models.

The method successfully addresses the Janus problem in text-to-3D generation.

Abstract

Although text-to-image diffusion models have made significant strides in generating images from text, they are sometimes more inclined to generate images like the data on which the model was trained rather than the provided text. This limitation has hindered their usage in both 2D and 3D applications. To address this problem, we explored the use of negative prompts but found that the current implementation fails to produce desired results, particularly when there is an overlap between the main and negative prompts. To overcome this issue, we propose Perp-Neg, a new algorithm that leverages the geometrical properties of the score space to address the shortcomings of the current negative prompts algorithm. Perp-Neg does not require any training or fine-tuning of the model. Moreover, we experimentally demonstrate that Perp-Neg provides greater flexibility in generating images by enabling users to edit out unwanted concepts from the initially generated images in 2D cases. Furthermore, to extend the application of Perp-Neg to 3D, we conducted a thorough exploration of how Perp-Neg can be used in 2D to condition the diffusion model to generate desired views, rather than being biased toward the canonical views. Finally, we applied our 2D intuition to integrate Perp-Neg with the state-of-the-art text-to-3D (DreamFusion) method, effectively addressing its Janus (multi-head) problem. Our project page is available at https://Perp-Neg.github.io/