DDPM: Denoising Diffusion Probabilistic Models
Diffusion Model for Denoising
Paper Title: Denoising Diffusion Probabilistic Models (DDPM)
Paper Source: NIPS, 2020
Paper Address: https://arxiv.org/abs/2006.11239
Paper Code: https://hojonathanho.github.io/diffusion
- for generating models
- Includes forward pass (adds Gaussian noise) and reverse pass (generates data)
- Both forward and reverse are Markov chains
Forward process - add noise
According to the Markov chain, the distribution of time xt is only related to time xt-1.
Indicates the continuous multiplication of at, from a1 to at
Reverse process - denoising
The process from noise to clear picture
reasoning from xt to x0
Use the Bayesian formula to expand:
According to the formula:
, substitute the corresponding values, and use the formula:
to get
where the mean and variance are: