ebook that demonstrates the original implementation can be found here: 
Stable Diffusion Upscaler Demo
Available Checkpoints are:
stabilityai/latent-upscaler: stabilityai/sd-x2-latent-upscaler

class diffusers.StableDiffusionLatentUpscalePipeline

<
source
>
(
vae: AutoencoderKL
text_encoder: CLIPTextModel
tokenizer: CLIPTokenizer
unet: UNet2DConditionModel
scheduler: EulerDiscreteScheduler

)


Parameters 

vae (AutoencoderKL) —
Variational Au