#
Safe Stable Diffusion

Safe Stable Diffusion was proposed in Safe Latent Diffusion: Mitigating Inappropriate Degeneration in Diffusion Models and mitigates the well known issue that models like Stable Diffusion that are trained on unfiltered, web-crawled datasets tend to suffer from inappropriate degeneration. For instance Stable Diffusion may unexpectedly generate nudity, violence, images depicting self-harm, or otherwise offensive content. Safe Stable Diffusion is an extension to the Stable Diffusion that drastically reduces content like this.

The abstract of the paper is the following:

Text-conditioned image generation models have recently achieved astonishing results in image quality and text alignment and are consequently employed in a fast-growing number of applications. Since they are highly data-driven, relying on billion-sized datasets randomly scraped from the internet, they also suffer, as we demonstrate, from degenerated and biased human behavior. In turn, they may even reinforce such biases. To help combat these undesired side effects, we present safe latent diffusion (SLD). Specifically, to measure the inappropriate degeneration due to unfiltered and imbalanced training sets, we establish a novel image generation test bed-inappropriate image prompts (I2P)-containing dedicated, real-world image-to-text prompts covering concepts such as nudity and violence. As our exhaustive empirical evaluation demonstrates, the introduced SLD removes and suppresses inappropriate image parts during the diffusion process, with no additional training required and no adverse effect on overall image quality or text alignment.

Overview:

Pipeline | Tasks | Colab | Demo
--- | --- | --- | ---
pipeline_stable_diffusion_safe.py | Text-to-Image Generation |  |

##
Tips

- Safe Stable Diffusion may also be used with weights of Stable Diffusion.

###
Run Safe Stable Diffusion

Safe Stable Diffusion can be tested very easily with the StableDiffusionPipelineSafe, and the `"AIML-TUDA/stable-diffusion-safe"` checkpoint exactly in the same way it is shown in the Conditional Image Generation Guide.

###
Interacting with the Safety Concept

To check and edit the currently used safety concept, use the `safety_concept` property of StableDiffusionPipelineSafe:

    >>> from diffusers import StableDiffusionPipelineSafe

    >>> pipeline = StableDiffusionPipelineSafe.from_pretrained("AIML-TUDA/stable-diffusion-safe")
    >>> pipeline.safety_concept

For each image generation the active concept is also contained in `StableDiffusionSafePipelineOutput`.

###
Using pre-defined safety configurations

You may use the 4 configurations defined in the Safe Latent Diffusion paper as follows:

    >>> from diffusers import StableDiffusionPipelineSafe
    >>> from diffusers.pipelines.stable_diffusion_safe import SafetyConfig

    >>> pipeline = StableDiffusionPipelineSafe.from_pretrained("AIML-TUDA/stable-diffusion-safe")
    >>> prompt = "the four horsewomen of the apocalypse, painting by tom of finland, gaston bussiere, craig mullins, j. c. leyendecker"
    >>> out = pipeline(prompt=prompt, **SafetyConfig.MAX)

The following configurations are available: `SafetyConfig.WEAK`, `SafetyConfig.MEDIUM`, `SafetyConfig.STRONG`, and `SafetyConfig.MAX`.

###
How to load and use different schedulers

The safe stable diffusion pipeline uses PNDMScheduler scheduler by default. But `diffusers` provides many other schedulers that can be used with the stable diffusion pipeline such as DDIMScheduler, LMSDiscreteScheduler, EulerDiscreteScheduler, EulerAncestralDiscreteScheduler etc. To use a different scheduler, you can either change it via the ConfigMixin.from_config() method or pass the `scheduler` argument to the `from_pretrained` method of the pipeline. For example, to use the EulerDiscreteScheduler, you can do the following:

    >>> from diffusers import StableDiffusionPipelineSafe, EulerDiscreteScheduler

    >>> pipeline = StableDiffusionPipelineSafe.from_pretrained("AIML-TUDA/stable-diffusion-safe")
    >>> pipeline.scheduler = EulerDiscreteScheduler.from_config(pipeline.scheduler.config)

    >>> # or
    >>> euler_scheduler = EulerDiscreteScheduler.from_pretrained("AIML-TUDA/stable-diffusion-safe", subfolder="scheduler")
    >>> pipeline = StableDiffusionPipelineSafe.from_pretrained(
    ...     "AIML-TUDA/stable-diffusion-safe", scheduler=euler_scheduler
    ... )

##
StableDiffusionSafePipelineOutput

###
class diffusers.pipelines.stable_diffusion_safe.StableDiffusionSafePipelineOutput

< source >

( images: typing.Union[typing.List[PIL.Image.Image], numpy.ndarray] nsfw_content_detected: typing.Optional[typing.List[bool]] unsafe_images: typing.Union[typing.List[PIL.Image.Image], numpy.ndarray, NoneType] applied_safety_concept: typing.Optional[str] )

Parameters

- images (`List[PIL.Image.Image]` or `np.ndarray`) — List of denoised PIL images of length `batch_size` or numpy array of shape `(batch_size, height, width, num_channels)`. PIL images or numpy array present the denoised images of the diffusion pipeline.
- nsfw_content_detected (`List[bool]`) — List of flags denoting whether the corresponding generated image likely represents “not-safe-for-work” (nsfw) content, or `None` if safety checking could not be performed.
- images (`List[PIL.Image.Image]` or `np.ndarray`) — List of denoised PIL images that were flagged by the safety checker any may contain “not-safe-for-work” (nsfw) content, or `None` if no safety check was performed or no images were flagged.
- applied_safety_concept (`str`) — The safety concept that was applied for safety guidance, or `None` if safety guidance was disabled

Output class for Safe Stable Diffusion pipelines.

####
__call__

( *args **kwargs )

Call self as a function.

##
StableDiffusionPipelineSafe

###
class diffusers.StableDiffusionPipelineSafe

< source >

( vae: AutoencoderKL text_encoder: CLIPTextModel tokenizer: CLIPTokenizer unet: UNet2DConditionModel scheduler: KarrasDiffusionSchedulers safety_checker: SafeStableDiffusionSafetyChecker feature_extractor: CLIPImageProcessor requires_safety_checker: bool = True )

Parameters

- vae (AutoencoderKL) — Variational Auto-Encoder (VAE) Model to encode and decode images to and from latent representations.
- text_encoder (`CLIPTextModel`) — Frozen text-encoder. Stable Diffusion uses the text portion of CLIP, specifically the clip-vit-large-patch14 variant.
- tokenizer (`CLIPTokenizer`) — Tokenizer of class CLIPTokenizer.
- unet (UNet2DConditionModel) — Conditional U-Net architecture to denoise the encoded image latents.
- scheduler (SchedulerMixin) — A scheduler to be used in combination with `unet` to denoise the encoded image latents. Can be one of DDIMScheduler, LMSDiscreteScheduler, or PNDMScheduler.
- safety_checker (`StableDiffusionSafetyChecker`) — Classification module that estimates whether generated images could be considered offensive or harmful. Please, refer to the model card for details.
- feature_extractor (`CLIPImageProcessor`) — Model that extracts features from generated images to be used as inputs for the `safety_checker`.

Pipeline for text-to-image generation using Safe Latent Diffusion.

The implementation is based on the StableDiffusionPipeline

This model inherits from DiffusionPipeline. Check the superclass documentation for the generic methods the library implements for all the pipelines (such as downloading or saving, running on a particular device, etc.)

####
__call__

< source >

( prompt: typing.Union[str, typing.List[str]] height: typing.Optional[int] = None width: typing.Optional[int] = None num_inference_steps: int = 50 guidance_scale: float = 7.5 negative_prompt: typing.Union[str, typing.List[str], NoneType] = None num_images_per_prompt: typing.Optional[int] = 1 eta: float = 0.0 generator: typing.Union[torch._C.Generator, typing.List[torch._C.Generator], NoneType] = None latents: typing.Optional[torch.FloatTensor] = None output_type: typing.Optional[str] = 'pil' return_dict: bool = True callback: typing.Union[typing.Callable[[int, int, torch.FloatTensor], NoneType], NoneType] = None callback_steps: int = 1 sld_guidance_scale: typing.Optional[float] = 1000 sld_warmup_steps: typing.Optional[int] = 10 sld_threshold: typing.Optional[float] = 0.01 sld_momentum_scale: typing.Optional[float] = 0.3 sld_mom_beta: typing.Optional[float] = 0.4 ) → StableDiffusionPipelineOutput or `tuple`

Parameters

- prompt (`str` or `List[str]`) — The prompt or prompts to guide the image generation.
- height (`int`, optional, defaults to self.unet.config.sample_size * self.vae_scale_factor) — The height in pixels of the generated image.
- width (`int`, optional, defaults to self.unet.config.sample_size * self.vae_scale_factor) — The width in pixels of the generated image.
- num_inference_steps (`int`, optional, defaults to 50) — The number of denoising steps. More denoising steps usually lead to a higher quality image at the expense of slower inference.
- guidance_scale (`float`, optional, defaults to 7.5) — Guidance scale as defined in Classifier-Free Diffusion Guidance. `guidance_scale` is defined as `w` of equation 2. of Imagen Paper. Guidance scale is enabled by setting `guidance_scale > 1`. Higher guidance scale encourages to generate images that are closely linked to the text `prompt`, usually at the expense of lower image quality.
- negative_prompt (`str` or `List[str]`, optional) — The prompt or prompts not to guide the image generation. Ignored when not using guidance (i.e., ignored if `guidance_scale` is less than `1`).
- num_images_per_prompt (`int`, optional, defaults to 1) — The number of images to generate per prompt.
- eta (`float`, optional, defaults to 0.0) — Corresponds to parameter eta (η) in the DDIM paper: https://arxiv.org/abs/2010.02502. Only applies to schedulers.DDIMScheduler, will be ignored for others.
- generator (`torch.Generator`, optional) — One or a list of torch generator(s) to make generation deterministic.
- latents (`torch.FloatTensor`, optional) — Pre-generated noisy latents, sampled from a Gaussian distribution, to be used as inputs for image generation. Can be used to tweak the same generation with different prompts. If not provided, a latents tensor will ge generated by sampling using the supplied random `generator`.
- output_type (`str`, optional, defaults to `"pil"`) — The output format of the generate image. Choose between PIL: `PIL.Image.Image` or `np.array`.
- return_dict (`bool`, optional, defaults to `True`) — Whether or not to return a StableDiffusionPipelineOutput instead of a plain tuple.
- callback (`Callable`, optional) — A function that will be called every `callback_steps` steps during inference. The function will be called with the following arguments: `callback(step: int, timestep: int, latents: torch.FloatTensor)`.
- callback_steps (`int`, optional, defaults to 1) — The frequency at which the `callback` function will be called. If not specified, the callback will be called at every step.
- sld_guidance_scale (`float`, optional, defaults to 1000) — Safe latent guidance as defined in Safe Latent Diffusion. `sld_guidance_scale` is defined as sS of Eq. 6. If set to be less than 1, safety guidance will be disabled.
- sld_warmup_steps (`int`, optional, defaults to 10) — Number of warmup steps for safety guidance. SLD will only be applied for diffusion steps greater than `sld_warmup_steps`. `sld_warmup_steps` is defined as `delta` of Safe Latent Diffusion.
- sld_threshold (`float`, optional, defaults to 0.01) — Threshold that separates the hyperplane between appropriate and inappropriate images. `sld_threshold` is defined as `lamda` of Eq. 5 in Safe Latent Diffusion.
- sld_momentum_scale (`float`, optional, defaults to 0.3) — Scale of the SLD momentum to be added to the safety guidance at each diffusion step. If set to 0.0 momentum will be disabled. Momentum is already built up during warmup, i.e. for diffusion steps smaller than `sld_warmup_steps`. `sld_momentum_scale` is defined as `sm` of Eq. 7 in Safe Latent Diffusion.
- sld_mom_beta (`float`, optional, defaults to 0.4) — Defines how safety guidance momentum builds up. `sld_mom_beta` indicates how much of the previous momentum will be kept. Momentum is already built up during warmup, i.e. for diffusion steps smaller than `sld_warmup_steps`. `sld_mom_beta` is defined as `beta m` of Eq. 8 in Safe Latent Diffusion.

Returns

StableDiffusionPipelineOutput or `tuple`

StableDiffusionPipelineOutput if `return_dict` is True, otherwise a `tuple. When returning a tuple, the first element is a list with the generated images, and the second element is a list of` bool`s denoting whether the corresponding generated image likely represents "not-safe-for-work" (nsfw) content, according to the` safety_checker`.

Function invoked when calling the pipeline for generation.

####
enable_sequential_cpu_offload

< source >

( )

Offloads all models to CPU using accelerate, significantly reducing memory usage. When called, unet, text_encoder, vae and safety checker have their state dicts saved to CPU and then are moved to a `torch.device('meta') and loaded to GPU only when their specific submodule has its` forward` method called.