How does a diffusion model generate realistic images?

shreyiot

Member
A diffusion model is a type of generative model that has gained significant attention for its ability to generate high-quality, realistic images. The basic idea behind diffusion models is to gradually add noise to an image and then learn how to reverse this process, ultimately generating new data points (images) from random noise.


The process works in two stages: forward diffusion and reverse diffusion.


  1. Forward Diffusion: In the forward process, the model starts with a real image and progressively adds noise over several steps. This noise addition is done in such a way that after enough iterations, the image becomes completely random noise. Mathematically, this can be viewed as a sequence of increasingly noisy images that resemble the original image, but with less detail.
  2. Reverse Diffusion: The model then learns to reverse this process. It trains on pairs of noisy images (from different steps of the forward diffusion) and learns how to "denoise" the image at each step, recovering the original image from the noise. The key is that the model doesn’t learn to generate images directly from noise at first but instead learns how to transform random noise into structured data by reversing the noise addition process step by step.

Diffusion models typically leverage neural networks to model the reverse process, where each step learns how to reduce the noise and bring the image closer to a realistic sample. By performing this over multiple steps, the model can generate sharp, high-fidelity images from initial random noise.


The main advantage of diffusion models over other generative models like GANs (Generative Adversarial Networks) is that they are less prone to mode collapse and are capable of generating more stable, diverse, and high-quality outputs.


For those looking to dive deeper into this topic, a Generative AI certification course can provide in-depth knowledge on the fundamentals and applications of these powerful models.
 
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