VAE Variational Auto Encoder
In short, it improves the generated images. A VAE is trained for certain aspects of the image, and the default VAE bundled in our UI (vae-ft-mse-840000-ema-pruned) improves the eyes in generated images.
Stable Diffusion UI installs and starts using the vae-ft-mse-840000-ema-pruned VAE file that works with all Stable diffusion models. This uses the official one: https://huggingface.co/stabilityai/sd-vae-ft-mse-original
Put your VAE file ending with .ckpt or .vae.pt inside the models/vae folder, like this:
Then refresh your browser UI. After that, you can select the desired VAE file in Image Settings:
