For this guide I am going to use my own SD 1.5 base model mix - STABLE v1.3 and A1111
I'm not going to describe in depth each parameter as there are a lot other articles covering that, instead I'll show you my own flow to get nice looking images
--- Generate ---
Let's start with a simple prompt that also implies the diverse set of colors for objects
photo of a woman sasha luss posing on a couch, holding a red cup of coffee, wearing green sporty outfit
Configuration
Steps: 30, Sampler: Euler a, CFG scale: 6, Size: 512x512, Denoising strength: 0.4, Clip skip: 1, Hires upscale: 2, Hires steps: 30, Hires upscaler: 4x_NMKD-Superscale-SP_178000_G
Set Batch count to 4 to find good seed
There is slight difference in resulting images when using Batch size, so it preferable not to use it for precise examples
Let's focus on the fourth image as it well corresponds with the prompt (red cup, green outfit). Before we start with Hires.fix, I'll try to find the best version of the picture to upscale, without levitating cup and thumb.
Change Steps to find better overall composition | Change CFG Scale to fix small details
or
Make X\Y grid on both parameters to quickly find the best result with current settings
I made a grid with settings below and got a composition without levitating cup and thumb:
Steps : 28-32
CFG Scale: 5.8-6.2 (+0.05)
--- Hires.fix ---
Samplers
Restart and DPM2 a Karras with Denoise: 0.4 and Upscale by: 2 are good enough in keeping original details during upscale, this time I picked DPM2 version
Upscalers
Let's compare four most known upscalers
4x_NMKD-Siax_200k
4x_NMKD-Superscale-SP_178000_G
Superscalers tend to be the sharpest, 15000 slightly affecting white balance of the image, Siax adding additional noise and UltraSharp the most blurry.
I chose 4x_NMKD-Superscale-SP_178000_G and Hires.fixed result goes to Img2img for upscale
--- Upscale ---
Configuration
To increase amount of new details during upscale I set CFG Scale: 5 and Denoise: 0.5, also increased steps for the same purpose. Fixed seed will allow to tweak results and Restart sampler will produce enough details and consistent image.
Enabling Tile control net to keep original details
Enabling UltimateSDupscale with Scale: 2 and Tile size: 1024, this will cause some original details loss in favor of new ones.
To keep original as much as possible it is better to use Scale: 1.5, Tile size: 768 and Denoise: 0.3-0.4
This improved overall quality and details
--- Inpaint ---
Fixing hands separately with same configuration and prompt - "perfect female hand"
Sampler: Euler a
CFG Scale : 4
Denoise: 0.4
and this is final image