stable-diffusion-webui-hires-fix-progressive

A progressive upscaling-img2img version of hires.fix, extension script for AUTOMATIC1111/stable-diffusion-webui.

Highres.fix pipline gives us an inspirable way to sketch-and-refine an image, we could make it even further~

⚠ This is possibly obsolete, try use multidiffusion-upscaler-for-automatic1111 for img2img upscale instead :)

Examples

⚪ progressive vs. official

official
hires steps	10	20	30	60	90	120
progressive
iter * step	4*3=12	4*5=20	4*8=32	4*15=60	4*23=92	4*30=120

ℹ It is found that original hires.fix sometimes suffers from color red-shift, on the contratry, the progressive version suffers from blue-shift. I don't know why though...

⚪ balancing iter and step

progressive
iter * step = 120	1 * 120	2 * 60	3 * 40	4 * 30	6 * 20	8 * 15	10 * 12

1x120:

2x60:

3x40:

4x30:

6x20:

8x15:

10x12:

raw lowres (txt2img ouput)	raw highres (upscale only)

Commom parameters for above demo images:

Steps: 20
Sampler: Euler a
CFG scale: 7
Seed: 1919810                 
Size: 512 x 512
Target size: 1024 x 1024
Upscaler: Lanczos
Denoising strength: 0.5

How it works

⚪ How the original hires.fix works?

It takes three steps:

• Several steps of txt2img to sketch a low resolution image
• One step upscale the low resolution image to a higher target resoultion
• Yet another several steps of img2img to refine the high resolution image

⚪ How a progressive hires.fix works?

Just make the upscale & img2img step repeatible and progressive:

• Several steps of txt2img to sketch a low resolution image
• Repeat the follwing steps until reaching the target resoultion
  • Upscale low resolution image to some higher itermediate resoultion
  • Small steps of img2img on the higher resolution image

Options

• upscale_*
  • upscaler: (categorical), upscaleing method same as in hires.fix
  • resize_mode:
  • target_(width|height): (int), final image resolution
• img2img_*
  • iter: (int), the repeated upscale-img2img iteration
  • step: (int), img2img steps per iteration
  • denoise_strength: (float), denoise strength for img2img
  • prompt: (string), use another prompt for img2img, default to the main prompt box

Installation

Easiest way to install it is to:

1. Go to the "Extensions" tab in the webui, switch to the "Install from URL" tab
2. Paste https://github.com/Kahsolt/stable-diffusion-webui-hires-fix-progressive.git into "URL for extension's git repository" and click install

Manual install:

1. Copy this repo folder to the 'extensions' folder of https://github.com/AUTOMATIC1111/stable-diffusion-webui

by Armit 2023/01/12