Description

• This PR implements the scheduler described in"Beta Sampling is All You Need: Efficient Image Generation Strategy for Diffusion Models using Stepwise Spectral Analysis" (2024, Lee et. al). The basic conclusion of the paper is spending more time at the beginning and end of denoising improves image quality.

• Output images are usually worse than other schedulers at low step count (<= 10), but improved at higher step counts ( >= 20 ).

• Beta scheduler with alpha = beta = 1.0 is supposed to be equivalent to Uniform scheduler, but in practice the Uniform scheduler produces different sigmas / results.

Changes

• Add new scheduler "Beta"
• Adds two options in Sampler Parameters: "Beta scheduler - alpha" and "Beta scheduler - beta"
• Add "Beta schedule alpha" and "Beta schedule beta" to XYZ plot options
• Writes alpha/beta to infotext when scheduler is "Beta"

Additional links:

The authors' paper describing the method:https://arxiv.org/abs/2407.12173

Checklist:

• I have readcontributing wiki page
• I have performed a self-review of my own code
• My code follows thestyle guidelines
• My code passestests

Screenshots/videos:

SD XL