Skip to main content

Fine-tuning guide

The guide for high quality avatars and AI photography

When building an app for avatars or professional AI photoshoot, you should consider two aspects

  1. Similarity to the original subject
  2. High quality generation which look professional

Tracking subject similarity

Make sure to test results on a person you closely know and can judge similarity. Create a list of candidate prompts and run them on 2-3 subjects. For each prompt ask the person to rate how many of the images look similar. Finally sum the ratios for each prompt and compare prompts. Improve the prompts or reconsider a different prompt if similarity is low. Alternatively, consider switching to a different base model to match ethnicity or avoid biased models.

Fine-tuning training tips

  1. Enable Face-detection in your account settings page - This will augment the training dataset with face-crops from the original training images. This should increase similarity to the subject but can also cause generations to be more toward close-ups instead of nice medium or long shots. In this case you might need to adjust the prompts to use emphasis weights.
  2. Base model - Select plain SD15 for better resemblance. Select Realistic Vision V5.1 as a base model for nicer pictures. These models are good in realistic results. If you’d like to get generations that are more artistic - consider Deliberate or Reliberate as a base model. For a more diverse ethnically and possibly better similarity to subjects, consider Life Like Ethnicities. Finally, we suggest checking training on SDXL with text-embedding + LoRA.

Prompt generation tips

  1. Set width and height to 512 x 640 - to match Instagram aspect ratio of 4:5 and also create good portraits. Avoid higher aspect ratios as you might get artifacts such as duplicate heads.
  2. Enable face-inpainting - This is one of Astria’s unique features and allows creating long shots while avoiding deformed faces.
  3. Weighted prompts - when a prompt has multiple keywords that collide and reduce similarity - use the parenthesis syntax for emphasis to increase similarity, such as (ohwx man) On the flip side, try to avoid weighted prompts altogether to preserve similarity to subject.
  4. Use Controlnet with input image to preserve composition and create unique long-shots. Enable controlnet_txt2img if you’d like to create more variation and draw more from the prompt. Increase denoising_strength=1