Its a mix of Photoshop and Stable diffusion
FOR EDITING EXISTING PHOTO
1. First download a photo and edit the hair to look long. It doesn't have to look good. It is enough if the ai can detect the parts where there is hair like the above picture. I use Photoshop for this.
2. Then in Stable Diffusion, go to img2img section and then to Inpaint.
3. Import the picture there.
4. Then use the draw option to draw only over the face.
5. Below the image u will find 2 options. "Only Masked" & "Not Masked". Select not masked.
6. Then in the denoising slider, set it to 0.30. Setting it higher will alter the image too much. U can experiment with this if u want.
7. In the prompt enter things like "long hair, absurdly long hair, very long hair, thick hair, wavy hair" etc and hit generate.
STABLE DIFFUSION INSTALLATION GUIDE:
PHOTOSHOP HAIR EXTENSION GUIDE: