Standard diffusion models involve an image transform -- adding Gaussian noise -- and an image restoration operator that inverts this degradation. We observe that the generative behavior of diffusion models is not strongly dependent on the choice of image degradation, and in fact an entire family of generative models can be constructed by varying this choice. Even when using completely deterministic degradations (e.g., blur, masking, and more), the training and test-time update rules that underlie diffusion models can be easily generalized to create generative models. The success of these fully deterministic models calls into question the community's understanding of diffusion models, which relies on noise in either gradient Langevin dynamics or variational inference, and paves the way for generalized diffusion models that invert arbitrary processes. Our code is available at https://github.com/arpitbansal297/Cold-Diffusion-Models

通过改变图像退化处理方法，可以构建一系列生成模型，并且即使使用完全确定性的退化方法，也可以轻松推广扩展扩散模型的训练和测试时间更新规则，为翻转任意过程的扩散模型打下基础，这一成功也质疑了该社区对扩散模型的理解。

冷扩散: 无需噪声即可反转任意图像转换