fix: support for loading playground v2.5 single file checkpoint.

[sayakpaul]

What does this PR do?

Fixes: #7221.

Code to test:

from diffusers import StableDiffusionXLPipeline, EDMDPMSolverMultistepScheduler
import torch

url = "https://huggingface.co/playgroundai/playground-v2.5-1024px-aesthetic/blob/main/playground-v2.5-1024px-aesthetic.safetensors"
pipeline = StableDiffusionXLPipeline.from_single_file(url)

pipeline.to(device="cuda", dtype=torch.float16)

prompt = "Astronaut in a jungle, cold color palette, muted colors, detailed, 8k"
image  = pipeline(prompt=prompt, guidance_scale=3.0).images[0]
image.save("playground_test_image.png")

We need to be careful when loading the FP16 checkpoint. See internal thread: https://huggingface.slack.com/archives/C03HBN1C8CW/p1709703331962229. Currently, we parse it correctly from the single file checkpoint. However, when using the diffusers format, if someone specifies variant="fp16" it is going to incorrectly fetch the mean and std corresponding to the FP32 variant. During inference, it doesn't cause a huge problem, but it does when fine-tuning with the FP16 variant.

[HuggingFaceDocBuilderDev]

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[sayakpaul]

@DN6 I have addressed your comments. The code snippet posted in the OP generates:

[sayakpaul]

@DN6 done.

[nicksonredfield]

@DN6 done.

is it possible to push this fix to A1111? really need it, tks!

[sayakpaul]

@DN6 up for another review :-)

[nicksonredfield]

@DN6 up for another review :-)

Recently I've been using the PG2 model for character and scene design for my novel, creating some great images, and I've found that the DPMA sampler and high amount of cue words are only available in the A1111 webui to realize the full potential of the PG model, and I was very eager to continue my creations with PG2.5 when it was released. But I found that comfyUI couldn't release its potential and the A1111 was buggy running the model.

I'm not a developer, so I can't understand the details of what you guys are discussing, and I don't know if you guys will push this fix to the A1111 branch, so if this model is able to run in A1111, I hope to let me know here or on HG's model release page.

My creations stem from your support and it is much appreciated.

[sayakpaul]

I'm not a developer, so I can't understand the details of what you guys are discussing, and I don't know if you guys will push this fix to the A1111 branch, so if this model is able to run in A1111, I hope to let me know here or on HG's model release page.

We won't be able to push the fix for now.

[nicksonredfield]

I'm not a developer, so I can't understand the details of what you guys are discussing, and I don't know if you guys will push this fix to the A1111 branch, so if this model is able to run in A1111, I hope to let me know here or on HG's model release page.

We won't be able to push the fix for now.

tks for reply, I would be very thankful if it could be done later, looking forward that.

[sayakpaul]

Gonna merge this after the CI is complete. @DN6 do you want me to add a slow test?