StableDiffusionLatentUpscalePipeline - positive/negative prompt embeds support (#8947)

* make latent upscaler accept prompt embeds

---------
Co-authored-by: Dhruv Nair <dhruv.nair@gmail.com>
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>
Co-authored-by: YiYi Xu <yixu310@gmail.com>

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion_latent_upscale.py

@@ -33,6 +33,20 @@ from ..pipeline_utils import DiffusionPipeline, ImagePipelineOutput, StableDiffu
 logger = logging.get_logger(__name__)  # pylint: disable=invalid-name
 
 
+# Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion_img2img.retrieve_latents
+def retrieve_latents(
+    encoder_output: torch.Tensor, generator: Optional[torch.Generator] = None, sample_mode: str = "sample"
+):
+    if hasattr(encoder_output, "latent_dist") and sample_mode == "sample":
+        return encoder_output.latent_dist.sample(generator)
+    elif hasattr(encoder_output, "latent_dist") and sample_mode == "argmax":
+        return encoder_output.latent_dist.mode()
+    elif hasattr(encoder_output, "latents"):
+        return encoder_output.latents
+    else:
+        raise AttributeError("Could not access latents of provided encoder_output")
+
+
 # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion_upscale.preprocess
 def preprocess(image):
     warnings.warn(
@@ -105,7 +119,54 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
         self.vae_scale_factor = 2 ** (len(self.vae.config.block_out_channels) - 1)
         self.image_processor = VaeImageProcessor(vae_scale_factor=self.vae_scale_factor, resample="bicubic")
 
-    def _encode_prompt(self, prompt, device, do_classifier_free_guidance, negative_prompt):
+    def _encode_prompt(
+        self,
+        prompt,
+        device,
+        do_classifier_free_guidance,
+        negative_prompt=None,
+        prompt_embeds: Optional[torch.Tensor] = None,
+        negative_prompt_embeds: Optional[torch.Tensor] = None,
+        pooled_prompt_embeds: Optional[torch.Tensor] = None,
+        negative_pooled_prompt_embeds: Optional[torch.Tensor] = None,
+        **kwargs,
+    ):
+        deprecation_message = "`_encode_prompt()` is deprecated and it will be removed in a future version. Use `encode_prompt()` instead. Also, be aware that the output format changed from a concatenated tensor to a tuple."
+        deprecate("_encode_prompt()", "1.0.0", deprecation_message, standard_warn=False)
+
+        (
+            prompt_embeds,
+            negative_prompt_embeds,
+            pooled_prompt_embeds,
+            negative_pooled_prompt_embeds,
+        ) = self.encode_prompt(
+            prompt=prompt,
+            device=device,
+            do_classifier_free_guidance=do_classifier_free_guidance,
+            negative_prompt=negative_prompt,
+            prompt_embeds=prompt_embeds,
+            negative_prompt_embeds=negative_prompt_embeds,
+            pooled_prompt_embeds=pooled_prompt_embeds,
+            negative_pooled_prompt_embeds=negative_pooled_prompt_embeds,
+            **kwargs,
+        )
+
+        prompt_embeds = torch.cat([negative_prompt_embeds, prompt_embeds])
+        pooled_prompt_embeds = torch.cat([negative_pooled_prompt_embeds, pooled_prompt_embeds])
+
+        return prompt_embeds, pooled_prompt_embeds
+
+    def encode_prompt(
+        self,
+        prompt,
+        device,
+        do_classifier_free_guidance,
+        negative_prompt=None,
+        prompt_embeds: Optional[torch.Tensor] = None,
+        negative_prompt_embeds: Optional[torch.Tensor] = None,
+        pooled_prompt_embeds: Optional[torch.Tensor] = None,
+        negative_pooled_prompt_embeds: Optional[torch.Tensor] = None,
+    ):
         r"""
         Encodes the prompt into text encoder hidden states.
 
@@ -119,9 +180,29 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
             negative_prompt (`str` or `List[str]`):
                 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`).
+            prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting. If not
+                provided, text embeddings will be generated from `prompt` input argument.
+            negative_prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated negative text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt
+                weighting. If not provided, negative_prompt_embeds will be generated from `negative_prompt` input
+                argument.
+            pooled_prompt_embeds (`torch.Tensor`, *optional*):
+                Pre-generated pooled text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting.
+                If not provided, pooled text embeddings will be generated from `prompt` input argument.
+            negative_pooled_prompt_embeds (`torch.Tensor`, *optional*):
+                Pre-generated negative pooled text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt
+                weighting. If not provided, pooled negative_prompt_embeds will be generated from `negative_prompt`
+                input argument.
         """
-        batch_size = len(prompt) if isinstance(prompt, list) else 1
+        if prompt is not None and isinstance(prompt, str):
+            batch_size = 1
+        elif prompt is not None and isinstance(prompt, list):
+            batch_size = len(prompt)
+        else:
+            batch_size = prompt_embeds.shape[0]
 
+        if prompt_embeds is None or pooled_prompt_embeds is None:
             text_inputs = self.tokenizer(
                 prompt,
                 padding="max_length",
@@ -134,8 +215,12 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
 
             untruncated_ids = self.tokenizer(prompt, padding="longest", return_tensors="pt").input_ids
 
-        if untruncated_ids.shape[-1] >= text_input_ids.shape[-1] and not torch.equal(text_input_ids, untruncated_ids):
-            removed_text = self.tokenizer.batch_decode(untruncated_ids[:, self.tokenizer.model_max_length - 1 : -1])
+            if untruncated_ids.shape[-1] >= text_input_ids.shape[-1] and not torch.equal(
+                text_input_ids, untruncated_ids
+            ):
+                removed_text = self.tokenizer.batch_decode(
+                    untruncated_ids[:, self.tokenizer.model_max_length - 1 : -1]
+                )
                 logger.warning(
                     "The following part of your input was truncated because CLIP can only handle sequences up to"
                     f" {self.tokenizer.model_max_length} tokens: {removed_text}"
@@ -145,11 +230,12 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
                 text_input_ids.to(device),
                 output_hidden_states=True,
             )
-        text_embeddings = text_encoder_out.hidden_states[-1]
-        text_pooler_out = text_encoder_out.pooler_output
+            prompt_embeds = text_encoder_out.hidden_states[-1]
+            pooled_prompt_embeds = text_encoder_out.pooler_output
 
         # get unconditional embeddings for classifier free guidance
         if do_classifier_free_guidance:
+            if negative_prompt_embeds is None or negative_pooled_prompt_embeds is None:
                 uncond_tokens: List[str]
                 if negative_prompt is None:
                     uncond_tokens = [""] * batch_size
@@ -184,16 +270,10 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
                     output_hidden_states=True,
                 )
 
-            uncond_embeddings = uncond_encoder_out.hidden_states[-1]
-            uncond_pooler_out = uncond_encoder_out.pooler_output
-
-            # For classifier free guidance, we need to do two forward passes.
-            # Here we concatenate the unconditional and text embeddings into a single batch
-            # to avoid doing two forward passes
-            text_embeddings = torch.cat([uncond_embeddings, text_embeddings])
-            text_pooler_out = torch.cat([uncond_pooler_out, text_pooler_out])
+                negative_prompt_embeds = uncond_encoder_out.hidden_states[-1]
+                negative_pooled_prompt_embeds = uncond_encoder_out.pooler_output
 
-        return text_embeddings, text_pooler_out
+        return prompt_embeds, negative_prompt_embeds, pooled_prompt_embeds, negative_pooled_prompt_embeds
 
     # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.decode_latents
     def decode_latents(self, latents):
@@ -207,12 +287,56 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
         image = image.cpu().permute(0, 2, 3, 1).float().numpy()
         return image
 
-    def check_inputs(self, prompt, image, callback_steps):
-        if not isinstance(prompt, str) and not isinstance(prompt, list):
+    def check_inputs(
+        self,
+        prompt,
+        image,
+        callback_steps,
+        negative_prompt=None,
+        prompt_embeds=None,
+        negative_prompt_embeds=None,
+        pooled_prompt_embeds=None,
+        negative_pooled_prompt_embeds=None,
+    ):
+        if prompt is not None and prompt_embeds is not None:
+            raise ValueError(
+                f"Cannot forward both `prompt`: {prompt} and `prompt_embeds`: {prompt_embeds}. Please make sure to"
+                " only forward one of the two."
+            )
+        elif prompt is None and prompt_embeds is None:
+            raise ValueError(
+                "Provide either `prompt` or `prompt_embeds`. Cannot leave both `prompt` and `prompt_embeds` undefined."
+            )
+        elif prompt is not None and not isinstance(prompt, str) and not isinstance(prompt, list):
             raise ValueError(f"`prompt` has to be of type `str` or `list` but is {type(prompt)}")
 
+        if negative_prompt is not None and negative_prompt_embeds is not None:
+            raise ValueError(
+                f"Cannot forward both `negative_prompt`: {negative_prompt} and `negative_prompt_embeds`:"
+                f" {negative_prompt_embeds}. Please make sure to only forward one of the two."
+            )
+
+        if prompt_embeds is not None and negative_prompt_embeds is not None:
+            if prompt_embeds.shape != negative_prompt_embeds.shape:
+                raise ValueError(
+                    "`prompt_embeds` and `negative_prompt_embeds` must have the same shape when passed directly, but"
+                    f" got: `prompt_embeds` {prompt_embeds.shape} != `negative_prompt_embeds`"
+                    f" {negative_prompt_embeds.shape}."
+                )
+
+        if prompt_embeds is not None and pooled_prompt_embeds is None:
+            raise ValueError(
+                "If `prompt_embeds` are provided, `pooled_prompt_embeds` also have to be passed. Make sure to generate `pooled_prompt_embeds` from the same text encoder that was used to generate `prompt_embeds`."
+            )
+
+        if negative_prompt_embeds is not None and negative_pooled_prompt_embeds is None:
+            raise ValueError(
+                "If `negative_prompt_embeds` are provided, `negative_pooled_prompt_embeds` also have to be passed. Make sure to generate `negative_pooled_prompt_embeds` from the same text encoder that was used to generate `negative_prompt_embeds`."
+            )
+
         if (
             not isinstance(image, torch.Tensor)
+            and not isinstance(image, np.ndarray)
             and not isinstance(image, PIL.Image.Image)
             and not isinstance(image, list)
         ):
@@ -222,10 +346,14 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
 
         # verify batch size of prompt and image are same if image is a list or tensor
         if isinstance(image, (list, torch.Tensor)):
+            if prompt is not None:
                 if isinstance(prompt, str):
                     batch_size = 1
                 else:
                     batch_size = len(prompt)
+            else:
+                batch_size = prompt_embeds.shape[0]
+
             if isinstance(image, list):
                 image_batch_size = len(image)
             else:
@@ -261,13 +389,17 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
     @torch.no_grad()
     def __call__(
         self,
-        prompt: Union[str, List[str]],
+        prompt: Union[str, List[str]] = None,
         image: PipelineImageInput = None,
         num_inference_steps: int = 75,
         guidance_scale: float = 9.0,
         negative_prompt: Optional[Union[str, List[str]]] = None,
         generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
         latents: Optional[torch.Tensor] = None,
+        prompt_embeds: Optional[torch.Tensor] = None,
+        negative_prompt_embeds: Optional[torch.Tensor] = None,
+        pooled_prompt_embeds: Optional[torch.Tensor] = None,
+        negative_pooled_prompt_embeds: Optional[torch.Tensor] = None,
         output_type: Optional[str] = "pil",
         return_dict: bool = True,
         callback: Optional[Callable[[int, int, torch.Tensor], None]] = None,
@@ -359,10 +491,22 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
         """
 
         # 1. Check inputs
-        self.check_inputs(prompt, image, callback_steps)
+        self.check_inputs(
+            prompt,
+            image,
+            callback_steps,
+            negative_prompt,
+            prompt_embeds,
+            negative_prompt_embeds,
+            pooled_prompt_embeds,
+            negative_pooled_prompt_embeds,
+        )
 
         # 2. Define call parameters
+        if prompt is not None:
             batch_size = 1 if isinstance(prompt, str) else len(prompt)
+        else:
+            batch_size = prompt_embeds.shape[0]
         device = self._execution_device
         # here `guidance_scale` is defined analog to the guidance weight `w` of equation (2)
         # of the Imagen paper: https://arxiv.org/pdf/2205.11487.pdf . `guidance_scale = 1`
@@ -373,16 +517,32 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
             prompt = [""] * batch_size
 
         # 3. Encode input prompt
-        text_embeddings, text_pooler_out = self._encode_prompt(
-            prompt, device, do_classifier_free_guidance, negative_prompt
+        (
+            prompt_embeds,
+            negative_prompt_embeds,
+            pooled_prompt_embeds,
+            negative_pooled_prompt_embeds,
+        ) = self.encode_prompt(
+            prompt,
+            device,
+            do_classifier_free_guidance,
+            negative_prompt,
+            prompt_embeds,
+            negative_prompt_embeds,
+            pooled_prompt_embeds,
+            negative_pooled_prompt_embeds,
         )
 
+        if do_classifier_free_guidance:
+            prompt_embeds = torch.cat([negative_prompt_embeds, prompt_embeds])
+            pooled_prompt_embeds = torch.cat([negative_pooled_prompt_embeds, pooled_prompt_embeds])
+
         # 4. Preprocess image
         image = self.image_processor.preprocess(image)
-        image = image.to(dtype=text_embeddings.dtype, device=device)
+        image = image.to(dtype=prompt_embeds.dtype, device=device)
         if image.shape[1] == 3:
             # encode image if not in latent-space yet
-            image = self.vae.encode(image).latent_dist.sample() * self.vae.config.scaling_factor
+            image = retrieve_latents(self.vae.encode(image), generator=generator) * self.vae.config.scaling_factor
 
         # 5. set timesteps
         self.scheduler.set_timesteps(num_inference_steps, device=device)
@@ -400,17 +560,17 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
         inv_noise_level = (noise_level**2 + 1) ** (-0.5)
 
         image_cond = F.interpolate(image, scale_factor=2, mode="nearest") * inv_noise_level[:, None, None, None]
-        image_cond = image_cond.to(text_embeddings.dtype)
+        image_cond = image_cond.to(prompt_embeds.dtype)
 
         noise_level_embed = torch.cat(
             [
-                torch.ones(text_pooler_out.shape[0], 64, dtype=text_pooler_out.dtype, device=device),
-                torch.zeros(text_pooler_out.shape[0], 64, dtype=text_pooler_out.dtype, device=device),
+                torch.ones(pooled_prompt_embeds.shape[0], 64, dtype=pooled_prompt_embeds.dtype, device=device),
+                torch.zeros(pooled_prompt_embeds.shape[0], 64, dtype=pooled_prompt_embeds.dtype, device=device),
             ],
             dim=1,
         )
 
-        timestep_condition = torch.cat([noise_level_embed, text_pooler_out], dim=1)
+        timestep_condition = torch.cat([noise_level_embed, pooled_prompt_embeds], dim=1)
 
         # 6. Prepare latent variables
         height, width = image.shape[2:]
@@ -420,7 +580,7 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
             num_channels_latents,
             height * 2,  # 2x upscale
             width * 2,
-            text_embeddings.dtype,
+            prompt_embeds.dtype,
             device,
             generator,
             latents,
@@ -454,7 +614,7 @@ class StableDiffusionLatentUpscalePipeline(DiffusionPipeline, StableDiffusionMix
                 noise_pred = self.unet(
                     scaled_model_input,
                     timestep,
-                    encoder_hidden_states=text_embeddings,
+                    encoder_hidden_states=prompt_embeds,
                     timestep_cond=timestep_condition,
                 ).sample
 

tests/pipelines/stable_diffusion_2/test_stable_diffusion_latent_upscale.py

@@ -178,6 +178,46 @@ class StableDiffusionLatentUpscalePipelineFastTests(
         max_diff = np.abs(image_slice.flatten() - expected_slice).max()
         self.assertLessEqual(max_diff, 1e-3)
 
+    def test_stable_diffusion_latent_upscaler_negative_prompt(self):
+        device = "cpu"  # ensure determinism for the device-dependent torch.Generator
+        components = self.get_dummy_components()
+        sd_pipe = StableDiffusionLatentUpscalePipeline(**components)
+        sd_pipe = sd_pipe.to(device)
+        sd_pipe.set_progress_bar_config(disable=None)
+
+        inputs = self.get_dummy_inputs(device)
+        negative_prompt = "french fries"
+        output = sd_pipe(**inputs, negative_prompt=negative_prompt)
+        image = output.images
+        image_slice = image[0, -3:, -3:, -1]
+
+        assert image.shape == (1, 256, 256, 3)
+        expected_slice = np.array(
+            [0.43865365, 0.404124, 0.42618454, 0.44333526, 0.40564927, 0.43818694, 0.4411913, 0.43404633, 0.46392226]
+        )
+
+        assert np.abs(image_slice.flatten() - expected_slice).max() < 1e-3
+
+    def test_stable_diffusion_latent_upscaler_multiple_init_images(self):
+        device = "cpu"  # ensure determinism for the device-dependent torch.Generator
+        components = self.get_dummy_components()
+        sd_pipe = StableDiffusionLatentUpscalePipeline(**components)
+        sd_pipe = sd_pipe.to(device)
+        sd_pipe.set_progress_bar_config(disable=None)
+
+        inputs = self.get_dummy_inputs(device)
+        inputs["prompt"] = [inputs["prompt"]] * 2
+        inputs["image"] = inputs["image"].repeat(2, 1, 1, 1)
+        image = sd_pipe(**inputs).images
+        image_slice = image[-1, -3:, -3:, -1]
+
+        assert image.shape == (2, 256, 256, 3)
+        expected_slice = np.array(
+            [0.38730142, 0.35695046, 0.40646142, 0.40967226, 0.3981609, 0.4195988, 0.4248805, 0.430259, 0.45694894]
+        )
+
+        assert np.abs(image_slice.flatten() - expected_slice).max() < 1e-3
+
     def test_attention_slicing_forward_pass(self):
         super().test_attention_slicing_forward_pass(expected_max_diff=7e-3)