- Automatic1111 outpainting works well but you need to enable the outpainting script. I would recommend Outpainting MK2. What the author did was just resize with fill which doesn't do any diffusion on the outpainted sections.
- There are much better resizing workflows, at a minumum I would recommend using the "SD Upscale Script". However you can get great results by resizing the image to high-res (4-8k) using lanczos then using inpainting to manually diffuse the image at a much higher resolution with prompt control. In this case "SD Upscale" is fine but the inpaint based upscale works well with complex compositions.
- When training I would typically recommend to keep the background. This allows for a more versitile finetuned model.
- You can get a lot more control of final output by using ControlNet. This is especially great if you have illustration skills. But it is also great to generate varitions in a different style but keep the composition and details. In this case you could have taken a portrait photo of the subject and used ControlNet to adjust the style (without and finetuning required).
