Safe Image Generation via Lightweight Concept Erasure in Diffusion Models

Text-to-image diffusion models have achieved remarkable progress in image synthesis, but their potential misuse for generating unauthorized or harmful content has raised growing safety concerns. This has created an urgent need for safe diffusion-based image generation methods that can selectively suppress sensitive concepts while preserving the model's general generative capability. Existing concept erasure approaches typically rely on either model fine-tuning or closed-form editing. However, they often suffer from two major limitations: (1 insufficient or excessive erasure, where the former fails to suppress target concepts and the latter disrupts benign semantics; and (2 degradation of non-target concepts, where removing target concepts undermines the generation of unrelated concepts, especially in multi-concept scenarios. To address these issues, we propose the Singular Value Eraser (SVEraser), a lightweight concept erasure module that removes specific concepts by optimizing singular-value offsets of weight matrices. Operating in a compact yet expressive singular-value space, SVEraser enables precise concept removal while reducing side effects on unrelated content. Moreover, once trained for different concepts, multiple SVErasers can be flexibly combined for multi-concept erasure. To further reduce interference, we introduce an eraser activation mechanism that adaptively selects the appropriate SVErasers during inference based on the input prompt. Extensive experiments on copyrighted objects, artistic styles, and explicit content demonstrate that our method achieves accurate target concept removal while preserving non-target semantics, providing a practical and reliable solution for safe diffusion-based image generation.