Give more customizable options for safety checker (#815)

* Give more customizable options for safety checker

* Apply suggestions from code review

* Update src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion.py

* Finish

* make style

* Apply suggestions from code review
Co-authored-by: Pedro Cuenca <pedro@huggingface.co>

* up
Co-authored-by: Pedro Cuenca <pedro@huggingface.co>

src/diffusers/pipeline_utils.py

@@ -113,6 +113,9 @@ class DiffusionPipeline(ConfigMixin):
 
         for name, module in kwargs.items():
             # retrieve library
+            if module is None:
+                register_dict = {name: (None, None)}
+            else:
                 library = module.__module__.split(".")[0]
 
                 # check if the module is a pipeline module
@@ -429,6 +432,7 @@ class DiffusionPipeline(ConfigMixin):
 
             is_pipeline_module = hasattr(pipelines, library_name)
             loaded_sub_model = None
+            sub_model_should_be_defined = True
 
             # if the model is in a pipeline module, then we load it from the pipeline
             if name in passed_class_obj:
@@ -449,6 +453,12 @@ class DiffusionPipeline(ConfigMixin):
                             f"{passed_class_obj[name]} is of type: {type(passed_class_obj[name])}, but should be"
                             f" {expected_class_obj}"
                         )
+                elif passed_class_obj[name] is None:
+                    logger.warn(
+                        f"You have passed `None` for {name} to disable its functionality in {pipeline_class}. Note"
+                        f" that this might lead to problems when using {pipeline_class} and is not recommended."
+                    )
+                    sub_model_should_be_defined = False
                 else:
                     logger.warn(
                         f"You have passed a non-standard module {passed_class_obj[name]}. We cannot verify whether it"
@@ -469,7 +479,7 @@ class DiffusionPipeline(ConfigMixin):
                 importable_classes = LOADABLE_CLASSES[library_name]
                 class_candidates = {c: getattr(library, c) for c in importable_classes.keys()}
 
-            if loaded_sub_model is None:
+            if loaded_sub_model is None and sub_model_should_be_defined:
                 load_method_name = None
                 for class_name, class_candidate in class_candidates.items():
                     if issubclass(class_obj, class_candidate):

src/diffusers/pipelines/stable_diffusion/__init__.py

 from dataclasses import dataclass
-from typing import List, Union
+from typing import List, Optional, Union
 
 import numpy as np
 
@@ -20,11 +20,11 @@ class StableDiffusionPipelineOutput(BaseOutput):
             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.
+            (nsfw) content, or `None` if safety checking could not be performed.
     """
 
     images: Union[List[PIL.Image.Image], np.ndarray]
-    nsfw_content_detected: List[bool]
+    nsfw_content_detected: Optional[List[bool]]
 
 
 if is_transformers_available() and is_torch_available():

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion.py

@@ -71,6 +71,16 @@ class StableDiffusionPipeline(DiffusionPipeline):
             new_config["steps_offset"] = 1
             scheduler._internal_dict = FrozenDict(new_config)
 
+        if safety_checker is None:
+            logger.warn(
+                f"You have disabed the safety checker for {self.__class__} by passing `safety_checker=None`. Ensure"
+                " that you abide to the conditions of the Stable Diffusion license and do not expose unfiltered"
+                " results in services or applications open to the public. Both the diffusers team and Hugging Face"
+                " strongly recommend to keep the safety filter enabled in all public facing circumstances, disabling"
+                " it only for use-cases that involve analyzing network behavior or auditing its results. For more"
+                " information, please have a look at https://github.com/huggingface/diffusers/pull/254 ."
+            )
+
         self.register_modules(
             vae=vae,
             text_encoder=text_encoder,
@@ -335,10 +345,15 @@ class StableDiffusionPipeline(DiffusionPipeline):
         # we always cast to float32 as this does not cause significant overhead and is compatible with bfloa16
         image = image.cpu().permute(0, 2, 3, 1).float().numpy()
 
-        safety_checker_input = self.feature_extractor(self.numpy_to_pil(image), return_tensors="pt").to(self.device)
+        if self.safety_checker is not None:
+            safety_checker_input = self.feature_extractor(self.numpy_to_pil(image), return_tensors="pt").to(
+                self.device
+            )
             image, has_nsfw_concept = self.safety_checker(
                 images=image, clip_input=safety_checker_input.pixel_values.to(text_embeddings.dtype)
             )
+        else:
+            has_nsfw_concept = None
 
         if output_type == "pil":
             image = self.numpy_to_pil(image)

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion_img2img.py

@@ -83,6 +83,16 @@ class StableDiffusionImg2ImgPipeline(DiffusionPipeline):
             new_config["steps_offset"] = 1
             scheduler._internal_dict = FrozenDict(new_config)
 
+        if safety_checker is None:
+            logger.warn(
+                f"You have disabed the safety checker for {self.__class__} by passing `safety_checker=None`. Ensure"
+                " that you abide to the conditions of the Stable Diffusion license and do not expose unfiltered"
+                " results in services or applications open to the public. Both the diffusers team and Hugging Face"
+                " strongly recommend to keep the safety filter enabled in all public facing circumstances, disabling"
+                " it only for use-cases that involve analyzing network behavior or auditing its results. For more"
+                " information, please have a look at https://github.com/huggingface/diffusers/pull/254 ."
+            )
+
         self.register_modules(
             vae=vae,
             text_encoder=text_encoder,
@@ -359,10 +369,15 @@ class StableDiffusionImg2ImgPipeline(DiffusionPipeline):
         image = (image / 2 + 0.5).clamp(0, 1)
         image = image.cpu().permute(0, 2, 3, 1).numpy()
 
-        safety_checker_input = self.feature_extractor(self.numpy_to_pil(image), return_tensors="pt").to(self.device)
+        if self.safety_checker is not None:
+            safety_checker_input = self.feature_extractor(self.numpy_to_pil(image), return_tensors="pt").to(
+                self.device
+            )
             image, has_nsfw_concept = self.safety_checker(
                 images=image, clip_input=safety_checker_input.pixel_values.to(text_embeddings.dtype)
             )
+        else:
+            has_nsfw_concept = None
 
         if output_type == "pil":
             image = self.numpy_to_pil(image)

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion_inpaint.py

@@ -98,6 +98,16 @@ class StableDiffusionInpaintPipeline(DiffusionPipeline):
             new_config["steps_offset"] = 1
             scheduler._internal_dict = FrozenDict(new_config)
 
+        if safety_checker is None:
+            logger.warn(
+                f"You have disabed the safety checker for {self.__class__} by passing `safety_checker=None`. Ensure"
+                " that you abide to the conditions of the Stable Diffusion license and do not expose unfiltered"
+                " results in services or applications open to the public. Both the diffusers team and Hugging Face"
+                " strongly recommend to keep the safety filter enabled in all public facing circumstances, disabling"
+                " it only for use-cases that involve analyzing network behavior or auditing its results. For more"
+                " information, please have a look at https://github.com/huggingface/diffusers/pull/254 ."
+            )
+
         self.register_modules(
             vae=vae,
             text_encoder=text_encoder,
@@ -382,8 +392,13 @@ class StableDiffusionInpaintPipeline(DiffusionPipeline):
         image = (image / 2 + 0.5).clamp(0, 1)
         image = image.cpu().permute(0, 2, 3, 1).numpy()
 
-        safety_checker_input = self.feature_extractor(self.numpy_to_pil(image), return_tensors="pt").to(self.device)
+        if self.safety_checker is not None:
+            safety_checker_input = self.feature_extractor(self.numpy_to_pil(image), return_tensors="pt").to(
+                self.device
+            )
             image, has_nsfw_concept = self.safety_checker(images=image, clip_input=safety_checker_input.pixel_values)
+        else:
+            has_nsfw_concept = None
 
         if output_type == "pil":
             image = self.numpy_to_pil(image)

tests/test_pipelines.py

@@ -498,6 +498,17 @@ class PipelineFastTests(unittest.TestCase):
         assert isinstance(pipe, StableDiffusionPipeline)
         assert isinstance(pipe.scheduler, LMSDiscreteScheduler)
 
+    def test_stable_diffusion_no_safety_checker(self):
+        pipe = StableDiffusionPipeline.from_pretrained(
+            "hf-internal-testing/tiny-stable-diffusion-lms-pipe", safety_checker=None
+        )
+        assert isinstance(pipe, StableDiffusionPipeline)
+        assert isinstance(pipe.scheduler, LMSDiscreteScheduler)
+        assert pipe.safety_checker is None
+
+        image = pipe("example prompt", num_inference_steps=2).images[0]
+        assert image is not None
+
     def test_stable_diffusion_k_lms(self):
         device = "cpu"  # ensure determinism for the device-dependent torch.Generator
         unet = self.dummy_cond_unet