F-MDM: Rethinking image denoising with a feature map-based Poisson–Gaussian Mixture Diffusion Model

In image-denoising tasks, the diffusion model has shown great potential. Usually, the diffusion model uses a real scene’s noise-free and clean image dataset as the starting point for diffusion. When the denoising network trained on this dataset is applied to image denoising in other scenes, the generalization of the denoising network will decrease due to changes in scene priors. In order to improve generalization, we hope to find a clean image dataset that not only has rich scene priors but also has a certain scene independence. The VGG-16 network is a network trained from a large number of images. After the real scene images are processed through the VGG-16 convolution layer, the shallow feature maps obtained have scene priors and break free from the scene dependency caused by minor details. This paper uses the shallow feature maps of VGG-16 as a clean image dataset for the diffusion model, and the results of denoising experiments are surprising. Furthermore, considering that the noise of the image mainly includes Gaussian noise and Poisson noise, the classical diffusion model uses Gaussian noise for diffusion to improve the interpretability of the model. We introduce a novel Poisson–Gaussian noise mixture for the diffusion process, and the theoretical derivation is given. Finally, we propose a Poisson–Gaussian Denoising Mixture Diffusion Model based on Feature maps (F-MDM). Experiments demonstrate that our method exhibits excellent generalization ability compared to some other advanced algorithms.