Ability to change the strength of safety_checker

[suzukimain]

What does this PR do?

Fixes #9003

"""
About safety_Level.
`int` or `float` or one of the following
'WEAK',
'MEDIUM',
'NOMAL',
'STRONG',
'MAX'.
"""

#To see the filter strength.
pipe.filter_level() # 0.0 (default)

#--------------
#If you want to change the intensity.
pipe.safety_checker_level("STRONG")
pipe.filter_level() # 1.0

#--------------
# If numbers are used
pipe.safety_checker_level(3.0)
pipe.filter_level() # 3.0

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[suzukimain]

However, I could not solve the following two problems by myself.

1. regarding the warning message when safety_checker is weakened, the message when safety_checker=None is passed is used as is.
(I was going to put in a modified message, but I was worried, so I decided it was better not to change it and copied it as is.) Resolved in #9404.

---

2. for the number to replace when a string such as 'NOMAL' is entered, I have set the following, but I am not sure if this is the best value.

"WEAK": -1.0
"MEDIUM": -0.5
"NOMAL": 0.0
"STRONG": 0.5
"MAX": 1.0

Please let me know if there are other problems.
thank you

[suzukimain]

Hello, @yiyixuxu
Is there any problem?
I hope to not have caused any inconvenience. thank you for your cooperation.

[yiyixuxu]

Hi @suzukimain
what would be a use case to adjust the strength of safety_checker?

[suzukimain]

Hi, @yiyixuxu

It is intended to be used in classes such as StableDiffusionPipelineSafe and StableDiffusionImg2ImgPipeline, which inherit from DiffusionPipeline and take safety_checker as an argument.
Also, the module name may need to be changed to something more descriptive,
although I couldn't come up with a good idea myself.

pip install git+https://github.com/suzukimain/diffusers@safety_checker

from diffusers import StableDiffusionPipeline
import torch

pipe = StableDiffusionPipeline.from_pretrained(
    "stable-diffusion-v1-5/stable-diffusion-v1-5",
    torch_dtype=torch.float16
    ).to("cuda")

#To see the filter strength.
print(f"Default filter strength: {pipe.filter_level()}") # 0.0

pipe.safety_checker_level("STRONG")

print(f"Filter strength: {pipe.filter_level()}") # 0.5

img=pipe("An image of a squirrel in Picasso style").images[0]
img

[yiyixuxu]

thanks I'm trying to understand whether it would be a common/meaningful use case that people need this feature -
could you explain a little bit?

[suzukimain]

thanks I'm trying to understand whether it would be a common/meaningful use case that people need this feature - could you explain a little bit?

Currently, the safety checker only allows for enabling or disabling its functionality.
This means that when the filtering strength feels too weak, there's no way to increase it, and conversely, when the filtering strength feels too strong, the only option is to disable it.
This can be inconvenient, so it would be beneficial to provide users with the ability to adjust the filtering strength flexibly.
Additionally, it might be helpful to refer to #5623