pipeline_kandinsky_inpaint.py

# Copyright 2023 The HuggingFace Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from copy import deepcopy
from typing import Callable, List, Optional, Union

import numpy as np
import PIL.Image
import torch
import torch.nn.functional as F
from packaging import version
from PIL import Image
from transformers import (
    XLMRobertaTokenizer,
)

from ... import __version__
from ...models import UNet2DConditionModel, VQModel
from ...schedulers import DDIMScheduler
from ...utils import (
    logging,
    replace_example_docstring,
)
from ...utils.torch_utils import randn_tensor
from ..pipeline_utils import DiffusionPipeline, ImagePipelineOutput
from .text_encoder import MultilingualCLIP


logger = logging.get_logger(__name__)  # pylint: disable=invalid-name

EXAMPLE_DOC_STRING = """
    Examples:
        ```py
        >>> from diffusers import KandinskyInpaintPipeline, KandinskyPriorPipeline
        >>> from diffusers.utils import load_image
        >>> import torch
        >>> import numpy as np

        >>> pipe_prior = KandinskyPriorPipeline.from_pretrained(
        ...     "kandinsky-community/kandinsky-2-1-prior", torch_dtype=torch.float16
        ... )
        >>> pipe_prior.to("cuda")

        >>> prompt = "a hat"
        >>> image_emb, zero_image_emb = pipe_prior(prompt, return_dict=False)

        >>> pipe = KandinskyInpaintPipeline.from_pretrained(
        ...     "kandinsky-community/kandinsky-2-1-inpaint", torch_dtype=torch.float16
        ... )
        >>> pipe.to("cuda")

        >>> init_image = load_image(
        ...     "https://huggingface.co/datasets/hf-internal-testing/diffusers-images/resolve/main"
        ...     "/kandinsky/cat.png"
        ... )

        >>> mask = np.zeros((768, 768), dtype=np.float32)
        >>> mask[:250, 250:-250] = 1

        >>> out = pipe(
        ...     prompt,
        ...     image=init_image,
        ...     mask_image=mask,
        ...     image_embeds=image_emb,
        ...     negative_image_embeds=zero_image_emb,
        ...     height=768,
        ...     width=768,
        ...     num_inference_steps=50,
        ... )

        >>> image = out.images[0]
        >>> image.save("cat_with_hat.png")
        ```
"""


def get_new_h_w(h, w, scale_factor=8):
    new_h = h // scale_factor**2
    if h % scale_factor**2 != 0:
        new_h += 1
    new_w = w // scale_factor**2
    if w % scale_factor**2 != 0:
        new_w += 1
    return new_h * scale_factor, new_w * scale_factor


def prepare_mask(masks):
    prepared_masks = []
    for mask in masks:
        old_mask = deepcopy(mask)
        for i in range(mask.shape[1]):
            for j in range(mask.shape[2]):
                if old_mask[0][i][j] == 1:
                    continue
                if i != 0:
                    mask[:, i - 1, j] = 0
                if j != 0:
                    mask[:, i, j - 1] = 0
                if i != 0 and j != 0:
                    mask[:, i - 1, j - 1] = 0
                if i != mask.shape[1] - 1:
                    mask[:, i + 1, j] = 0
                if j != mask.shape[2] - 1:
                    mask[:, i, j + 1] = 0
                if i != mask.shape[1] - 1 and j != mask.shape[2] - 1:
                    mask[:, i + 1, j + 1] = 0
        prepared_masks.append(mask)
    return torch.stack(prepared_masks, dim=0)


def prepare_mask_and_masked_image(image, mask, height, width):
    r"""
    Prepares a pair (mask, image) to be consumed by the Kandinsky inpaint pipeline. This means that those inputs will
    be converted to ``torch.Tensor`` with shapes ``batch x channels x height x width`` where ``channels`` is ``3`` for
    the ``image`` and ``1`` for the ``mask``.

    The ``image`` will be converted to ``torch.float32`` and normalized to be in ``[-1, 1]``. The ``mask`` will be
    binarized (``mask > 0.5``) and cast to ``torch.float32`` too.

    Args:
        image (Union[np.array, PIL.Image, torch.Tensor]): The image to inpaint.
            It can be a ``PIL.Image``, or a ``height x width x 3`` ``np.array`` or a ``channels x height x width``
            ``torch.Tensor`` or a ``batch x channels x height x width`` ``torch.Tensor``.
        mask (_type_): The mask to apply to the image, i.e. regions to inpaint.
            It can be a ``PIL.Image``, or a ``height x width`` ``np.array`` or a ``1 x height x width``
            ``torch.Tensor`` or a ``batch x 1 x height x width`` ``torch.Tensor``.
        height (`int`, *optional*, defaults to 512):
            The height in pixels of the generated image.
        width (`int`, *optional*, defaults to 512):
            The width in pixels of the generated image.


    Raises:
        ValueError: ``torch.Tensor`` images should be in the ``[-1, 1]`` range. ValueError: ``torch.Tensor`` mask
        should be in the ``[0, 1]`` range. ValueError: ``mask`` and ``image`` should have the same spatial dimensions.
        TypeError: ``mask`` is a ``torch.Tensor`` but ``image`` is not
            (ot the other way around).

    Returns:
        tuple[torch.Tensor]: The pair (mask, image) as ``torch.Tensor`` with 4
            dimensions: ``batch x channels x height x width``.
    """

    if image is None:
        raise ValueError("`image` input cannot be undefined.")

    if mask is None:
        raise ValueError("`mask_image` input cannot be undefined.")

    if isinstance(image, torch.Tensor):
        if not isinstance(mask, torch.Tensor):
            raise TypeError(f"`image` is a torch.Tensor but `mask` (type: {type(mask)} is not")

        # Batch single image
        if image.ndim == 3:
            assert image.shape[0] == 3, "Image outside a batch should be of shape (3, H, W)"
            image = image.unsqueeze(0)

        # Batch and add channel dim for single mask
        if mask.ndim == 2:
            mask = mask.unsqueeze(0).unsqueeze(0)

        # Batch single mask or add channel dim
        if mask.ndim == 3:
            # Single batched mask, no channel dim or single mask not batched but channel dim
            if mask.shape[0] == 1:
                mask = mask.unsqueeze(0)

            # Batched masks no channel dim
            else:
                mask = mask.unsqueeze(1)

        assert image.ndim == 4 and mask.ndim == 4, "Image and Mask must have 4 dimensions"
        assert image.shape[-2:] == mask.shape[-2:], "Image and Mask must have the same spatial dimensions"
        assert image.shape[0] == mask.shape[0], "Image and Mask must have the same batch size"

        # Check image is in [-1, 1]
        if image.min() < -1 or image.max() > 1:
            raise ValueError("Image should be in [-1, 1] range")

        # Check mask is in [0, 1]
        if mask.min() < 0 or mask.max() > 1:
            raise ValueError("Mask should be in [0, 1] range")

        # Binarize mask
        mask[mask < 0.5] = 0
        mask[mask >= 0.5] = 1

        # Image as float32
        image = image.to(dtype=torch.float32)
    elif isinstance(mask, torch.Tensor):
        raise TypeError(f"`mask` is a torch.Tensor but `image` (type: {type(image)} is not")
    else:
        # preprocess image
        if isinstance(image, (PIL.Image.Image, np.ndarray)):
            image = [image]

        if isinstance(image, list) and isinstance(image[0], PIL.Image.Image):
            # resize all images w.r.t passed height an width
            image = [i.resize((width, height), resample=Image.BICUBIC, reducing_gap=1) for i in image]
            image = [np.array(i.convert("RGB"))[None, :] for i in image]
            image = np.concatenate(image, axis=0)
        elif isinstance(image, list) and isinstance(image[0], np.ndarray):
            image = np.concatenate([i[None, :] for i in image], axis=0)

        image = image.transpose(0, 3, 1, 2)
        image = torch.from_numpy(image).to(dtype=torch.float32) / 127.5 - 1.0

        # preprocess mask
        if isinstance(mask, (PIL.Image.Image, np.ndarray)):
            mask = [mask]

        if isinstance(mask, list) and isinstance(mask[0], PIL.Image.Image):
            mask = [i.resize((width, height), resample=PIL.Image.LANCZOS) for i in mask]
            mask = np.concatenate([np.array(m.convert("L"))[None, None, :] for m in mask], axis=0)
            mask = mask.astype(np.float32) / 255.0
        elif isinstance(mask, list) and isinstance(mask[0], np.ndarray):
            mask = np.concatenate([m[None, None, :] for m in mask], axis=0)

        mask[mask < 0.5] = 0
        mask[mask >= 0.5] = 1
        mask = torch.from_numpy(mask)

    mask = 1 - mask

    return mask, image


class KandinskyInpaintPipeline(DiffusionPipeline):
    """
    Pipeline for text-guided image inpainting using Kandinsky2.1

    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.)

    Args:
        text_encoder ([`MultilingualCLIP`]):
            Frozen text-encoder.
        tokenizer ([`XLMRobertaTokenizer`]):
            Tokenizer of class
        scheduler ([`DDIMScheduler`]):
            A scheduler to be used in combination with `unet` to generate image latents.
        unet ([`UNet2DConditionModel`]):
            Conditional U-Net architecture to denoise the image embedding.
        movq ([`VQModel`]):
            MoVQ image encoder and decoder
    """

    model_cpu_offload_seq = "text_encoder->unet->movq"

    def __init__(
        self,
        text_encoder: MultilingualCLIP,
        movq: VQModel,
        tokenizer: XLMRobertaTokenizer,
        unet: UNet2DConditionModel,
        scheduler: DDIMScheduler,
    ):
        super().__init__()

        self.register_modules(
            text_encoder=text_encoder,
            movq=movq,
            tokenizer=tokenizer,
            unet=unet,
            scheduler=scheduler,
        )
        self.movq_scale_factor = 2 ** (len(self.movq.config.block_out_channels) - 1)
        self._warn_has_been_called = False

    # Copied from diffusers.pipelines.unclip.pipeline_unclip.UnCLIPPipeline.prepare_latents
    def prepare_latents(self, shape, dtype, device, generator, latents, scheduler):
        if latents is None:
            latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
        else:
            if latents.shape != shape:
                raise ValueError(f"Unexpected latents shape, got {latents.shape}, expected {shape}")
            latents = latents.to(device)

        latents = latents * scheduler.init_noise_sigma
        return latents

    def _encode_prompt(
        self,
        prompt,
        device,
        num_images_per_prompt,
        do_classifier_free_guidance,
        negative_prompt=None,
    ):
        batch_size = len(prompt) if isinstance(prompt, list) else 1
        # get prompt text embeddings
        text_inputs = self.tokenizer(
            prompt,
            padding="max_length",
            max_length=77,
            truncation=True,
            return_attention_mask=True,
            add_special_tokens=True,
            return_tensors="pt",
        )

        text_input_ids = text_inputs.input_ids
        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])
            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}"
            )

        text_input_ids = text_input_ids.to(device)
        text_mask = text_inputs.attention_mask.to(device)

        prompt_embeds, text_encoder_hidden_states = self.text_encoder(
            input_ids=text_input_ids, attention_mask=text_mask
        )

        prompt_embeds = prompt_embeds.repeat_interleave(num_images_per_prompt, dim=0)
        text_encoder_hidden_states = text_encoder_hidden_states.repeat_interleave(num_images_per_prompt, dim=0)
        text_mask = text_mask.repeat_interleave(num_images_per_prompt, dim=0)

        if do_classifier_free_guidance:
            uncond_tokens: List[str]
            if negative_prompt is None:
                uncond_tokens = [""] * batch_size
            elif type(prompt) is not type(negative_prompt):
                raise TypeError(
                    f"`negative_prompt` should be the same type to `prompt`, but got {type(negative_prompt)} !="
                    f" {type(prompt)}."
                )
            elif isinstance(negative_prompt, str):
                uncond_tokens = [negative_prompt]
            elif batch_size != len(negative_prompt):
                raise ValueError(
                    f"`negative_prompt`: {negative_prompt} has batch size {len(negative_prompt)}, but `prompt`:"
                    f" {prompt} has batch size {batch_size}. Please make sure that passed `negative_prompt` matches"
                    " the batch size of `prompt`."
                )
            else:
                uncond_tokens = negative_prompt

            uncond_input = self.tokenizer(
                uncond_tokens,
                padding="max_length",
                max_length=77,
                truncation=True,
                return_attention_mask=True,
                add_special_tokens=True,
                return_tensors="pt",
            )
            uncond_text_input_ids = uncond_input.input_ids.to(device)
            uncond_text_mask = uncond_input.attention_mask.to(device)

            negative_prompt_embeds, uncond_text_encoder_hidden_states = self.text_encoder(
                input_ids=uncond_text_input_ids, attention_mask=uncond_text_mask
            )

            # duplicate unconditional embeddings for each generation per prompt, using mps friendly method

            seq_len = negative_prompt_embeds.shape[1]
            negative_prompt_embeds = negative_prompt_embeds.repeat(1, num_images_per_prompt)
            negative_prompt_embeds = negative_prompt_embeds.view(batch_size * num_images_per_prompt, seq_len)

            seq_len = uncond_text_encoder_hidden_states.shape[1]
            uncond_text_encoder_hidden_states = uncond_text_encoder_hidden_states.repeat(1, num_images_per_prompt, 1)
            uncond_text_encoder_hidden_states = uncond_text_encoder_hidden_states.view(
                batch_size * num_images_per_prompt, seq_len, -1
            )
            uncond_text_mask = uncond_text_mask.repeat_interleave(num_images_per_prompt, dim=0)

            # done duplicates

            # 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
            prompt_embeds = torch.cat([negative_prompt_embeds, prompt_embeds])
            text_encoder_hidden_states = torch.cat([uncond_text_encoder_hidden_states, text_encoder_hidden_states])

            text_mask = torch.cat([uncond_text_mask, text_mask])

        return prompt_embeds, text_encoder_hidden_states, text_mask

    @torch.no_grad()
    @replace_example_docstring(EXAMPLE_DOC_STRING)
    def __call__(
        self,
        prompt: Union[str, List[str]],
        image: Union[torch.FloatTensor, PIL.Image.Image],
        mask_image: Union[torch.FloatTensor, PIL.Image.Image, np.ndarray],
        image_embeds: torch.FloatTensor,
        negative_image_embeds: torch.FloatTensor,
        negative_prompt: Optional[Union[str, List[str]]] = None,
        height: int = 512,
        width: int = 512,
        num_inference_steps: int = 100,
        guidance_scale: float = 4.0,
        num_images_per_prompt: int = 1,
        generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
        latents: Optional[torch.FloatTensor] = None,
        output_type: Optional[str] = "pil",
        callback: Optional[Callable[[int, int, torch.FloatTensor], None]] = None,
        callback_steps: int = 1,
        return_dict: bool = True,
    ):
        """
        Function invoked when calling the pipeline for generation.

        Args:
            prompt (`str` or `List[str]`):
                The prompt or prompts to guide the image generation.
            image (`torch.FloatTensor`, `PIL.Image.Image` or `np.ndarray`):
                `Image`, or tensor representing an image batch, that will be used as the starting point for the
                process.
            mask_image (`PIL.Image.Image`,`torch.FloatTensor` or `np.ndarray`):
                `Image`, or a tensor representing an image batch, to mask `image`. White pixels in the mask will be
                repainted, while black pixels will be preserved. You can pass a pytorch tensor as mask only if the
                image you passed is a pytorch tensor, and it should contain one color channel (L) instead of 3, so the
                expected shape would be either `(B, 1, H, W,)`, `(B, H, W)`, `(1, H, W)` or `(H, W)` If image is an PIL
                image or numpy array, mask should also be a either PIL image or numpy array. If it is a PIL image, it
                will be converted to a single channel (luminance) before use. If it is a nummpy array, the expected
                shape is `(H, W)`.
            image_embeds (`torch.FloatTensor` or `List[torch.FloatTensor]`):
                The clip image embeddings for text prompt, that will be used to condition the image generation.
            negative_image_embeds (`torch.FloatTensor` or `List[torch.FloatTensor]`):
                The clip image embeddings for negative text prompt, will be used to condition the image generation.
            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`).
            height (`int`, *optional*, defaults to 512):
                The height in pixels of the generated image.
            width (`int`, *optional*, defaults to 512):
                The width in pixels of the generated image.
            num_inference_steps (`int`, *optional*, defaults to 100):
                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 4.0):
                Guidance scale as defined in [Classifier-Free Diffusion Guidance](https://arxiv.org/abs/2207.12598).
                `guidance_scale` is defined as `w` of equation 2. of [Imagen
                Paper](https://arxiv.org/pdf/2205.11487.pdf). 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.
            num_images_per_prompt (`int`, *optional*, defaults to 1):
                The number of images to generate per prompt.
            generator (`torch.Generator` or `List[torch.Generator]`, *optional*):
                One or a list of [torch generator(s)](https://pytorch.org/docs/stable/generated/torch.Generator.html)
                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`), `"np"`
                (`np.array`) or `"pt"` (`torch.Tensor`).
            callback (`Callable`, *optional*):
                A function that calls every `callback_steps` steps during inference. The function is 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 is called. If not specified, the callback is called at
                every step.
            return_dict (`bool`, *optional*, defaults to `True`):
                Whether or not to return a [`~pipelines.ImagePipelineOutput`] instead of a plain tuple.

        Examples:

        Returns:
            [`~pipelines.ImagePipelineOutput`] or `tuple`
        """
        if not self._warn_has_been_called and version.parse(version.parse(__version__).base_version) < version.parse(
            "0.23.0.dev0"
        ):
            logger.warn(
                "Please note that the expected format of `mask_image` has recently been changed. "
                "Before diffusers == 0.19.0, Kandinsky Inpainting pipelines repainted black pixels and preserved black pixels. "
                "As of diffusers==0.19.0 this behavior has been inverted. Now white pixels are repainted and black pixels are preserved. "
                "This way, Kandinsky's masking behavior is aligned with Stable Diffusion. "
                "THIS means that you HAVE to invert the input mask to have the same behavior as before as explained in https://github.com/huggingface/diffusers/pull/4207. "
                "This warning will be surpressed after the first inference call and will be removed in diffusers>0.23.0"
            )
            self._warn_has_been_called = True

        # Define call parameters
        if isinstance(prompt, str):
            batch_size = 1
        elif isinstance(prompt, list):
            batch_size = len(prompt)
        else:
            raise ValueError(f"`prompt` has to be of type `str` or `list` but is {type(prompt)}")

        device = self._execution_device

        batch_size = batch_size * num_images_per_prompt
        do_classifier_free_guidance = guidance_scale > 1.0

        prompt_embeds, text_encoder_hidden_states, _ = self._encode_prompt(
            prompt, device, num_images_per_prompt, do_classifier_free_guidance, negative_prompt
        )

        if isinstance(image_embeds, list):
            image_embeds = torch.cat(image_embeds, dim=0)
        if isinstance(negative_image_embeds, list):
            negative_image_embeds = torch.cat(negative_image_embeds, dim=0)

        if do_classifier_free_guidance:
            image_embeds = image_embeds.repeat_interleave(num_images_per_prompt, dim=0)
            negative_image_embeds = negative_image_embeds.repeat_interleave(num_images_per_prompt, dim=0)

            image_embeds = torch.cat([negative_image_embeds, image_embeds], dim=0).to(
                dtype=prompt_embeds.dtype, device=device
            )

        # preprocess image and mask
        mask_image, image = prepare_mask_and_masked_image(image, mask_image, height, width)

        image = image.to(dtype=prompt_embeds.dtype, device=device)
        image = self.movq.encode(image)["latents"]

        mask_image = mask_image.to(dtype=prompt_embeds.dtype, device=device)

        image_shape = tuple(image.shape[-2:])
        mask_image = F.interpolate(
            mask_image,
            image_shape,
            mode="nearest",
        )
        mask_image = prepare_mask(mask_image)
        masked_image = image * mask_image

        mask_image = mask_image.repeat_interleave(num_images_per_prompt, dim=0)
        masked_image = masked_image.repeat_interleave(num_images_per_prompt, dim=0)
        if do_classifier_free_guidance:
            mask_image = mask_image.repeat(2, 1, 1, 1)
            masked_image = masked_image.repeat(2, 1, 1, 1)

        self.scheduler.set_timesteps(num_inference_steps, device=device)
        timesteps_tensor = self.scheduler.timesteps

        num_channels_latents = self.movq.config.latent_channels

        # get h, w for latents
        sample_height, sample_width = get_new_h_w(height, width, self.movq_scale_factor)

        # create initial latent
        latents = self.prepare_latents(
            (batch_size, num_channels_latents, sample_height, sample_width),
            text_encoder_hidden_states.dtype,
            device,
            generator,
            latents,
            self.scheduler,
        )

        # Check that sizes of mask, masked image and latents match with expected
        num_channels_mask = mask_image.shape[1]
        num_channels_masked_image = masked_image.shape[1]
        if num_channels_latents + num_channels_mask + num_channels_masked_image != self.unet.config.in_channels:
            raise ValueError(
                f"Incorrect configuration settings! The config of `pipeline.unet`: {self.unet.config} expects"
                f" {self.unet.config.in_channels} but received `num_channels_latents`: {num_channels_latents} +"
                f" `num_channels_mask`: {num_channels_mask} + `num_channels_masked_image`: {num_channels_masked_image}"
                f" = {num_channels_latents+num_channels_masked_image+num_channels_mask}. Please verify the config of"
                " `pipeline.unet` or your `mask_image` or `image` input."
            )

        for i, t in enumerate(self.progress_bar(timesteps_tensor)):
            # expand the latents if we are doing classifier free guidance
            latent_model_input = torch.cat([latents] * 2) if do_classifier_free_guidance else latents
            latent_model_input = torch.cat([latent_model_input, masked_image, mask_image], dim=1)

            added_cond_kwargs = {"text_embeds": prompt_embeds, "image_embeds": image_embeds}
            noise_pred = self.unet(
                sample=latent_model_input,
                timestep=t,
                encoder_hidden_states=text_encoder_hidden_states,
                added_cond_kwargs=added_cond_kwargs,
                return_dict=False,
            )[0]

            if do_classifier_free_guidance:
                noise_pred, variance_pred = noise_pred.split(latents.shape[1], dim=1)
                noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
                _, variance_pred_text = variance_pred.chunk(2)
                noise_pred = noise_pred_uncond + guidance_scale * (noise_pred_text - noise_pred_uncond)
                noise_pred = torch.cat([noise_pred, variance_pred_text], dim=1)

            if not (
                hasattr(self.scheduler.config, "variance_type")
                and self.scheduler.config.variance_type in ["learned", "learned_range"]
            ):
                noise_pred, _ = noise_pred.split(latents.shape[1], dim=1)

            # compute the previous noisy sample x_t -> x_t-1
            latents = self.scheduler.step(
                noise_pred,
                t,
                latents,
                generator=generator,
            ).prev_sample

            if callback is not None and i % callback_steps == 0:
                step_idx = i // getattr(self.scheduler, "order", 1)
                callback(step_idx, t, latents)

        # post-processing
        image = self.movq.decode(latents, force_not_quantize=True)["sample"]

        self.maybe_free_model_hooks()

        if output_type not in ["pt", "np", "pil"]:
            raise ValueError(f"Only the output types `pt`, `pil` and `np` are supported not output_type={output_type}")

        if output_type in ["np", "pil"]:
            image = image * 0.5 + 0.5
            image = image.clamp(0, 1)
            image = image.cpu().permute(0, 2, 3, 1).float().numpy()

        if output_type == "pil":
            image = self.numpy_to_pil(image)

        if not return_dict:
            return (image,)

        return ImagePipelineOutput(images=image)