diffusers/src/diffusers/image_processor.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.

import warnings
from typing import Union

import numpy as np
import PIL
import torch
from PIL import Image

from .configuration_utils import ConfigMixin, register_to_config
from .utils import CONFIG_NAME, PIL_INTERPOLATION


class VaeImageProcessor(ConfigMixin):
    """
    Image Processor for VAE

    Args:
        do_resize (`bool`, *optional*, defaults to `True`):
            Whether to downscale the image's (height, width) dimensions to multiples of `vae_scale_factor`.
        vae_scale_factor (`int`, *optional*, defaults to `8`):
            VAE scale factor. If `do_resize` is True, the image will be automatically resized to multiples of this
            factor.
        resample (`str`, *optional*, defaults to `lanczos`):
            Resampling filter to use when resizing the image.
        do_normalize (`bool`, *optional*, defaults to `True`):
            Whether to normalize the image to [-1,1]
    """

    config_name = CONFIG_NAME

    @register_to_config
    def __init__(
        self,
        do_resize: bool = True,
        vae_scale_factor: int = 8,
        resample: str = "lanczos",
        do_normalize: bool = True,
    ):
        super().__init__()

    @staticmethod
    def numpy_to_pil(images):
        """
        Convert a numpy image or a batch of images to a PIL image.
        """
        if images.ndim == 3:
            images = images[None, ...]
        images = (images * 255).round().astype("uint8")
        if images.shape[-1] == 1:
            # special case for grayscale (single channel) images
            pil_images = [Image.fromarray(image.squeeze(), mode="L") for image in images]
        else:
            pil_images = [Image.fromarray(image) for image in images]

        return pil_images

    @staticmethod
    def numpy_to_pt(images):
        """
        Convert a numpy image to a pytorch tensor
        """
        if images.ndim == 3:
            images = images[..., None]

        images = torch.from_numpy(images.transpose(0, 3, 1, 2))
        return images

    @staticmethod
    def pt_to_numpy(images):
        """
        Convert a numpy image to a pytorch tensor
        """
        images = images.cpu().permute(0, 2, 3, 1).float().numpy()
        return images

    @staticmethod
    def normalize(images):
        """
        Normalize an image array to [-1,1]
        """
        return 2.0 * images - 1.0

    def resize(self, images: PIL.Image.Image) -> PIL.Image.Image:
        """
        Resize a PIL image. Both height and width will be downscaled to the next integer multiple of `vae_scale_factor`
        """
        w, h = images.size
        w, h = (x - x % self.vae_scale_factor for x in (w, h))  # resize to integer multiple of vae_scale_factor
        images = images.resize((w, h), resample=PIL_INTERPOLATION[self.resample])
        return images

    def preprocess(
        self,
        image: Union[torch.FloatTensor, PIL.Image.Image, np.ndarray],
    ) -> torch.Tensor:
        """
        Preprocess the image input, accepted formats are PIL images, numpy arrays or pytorch tensors"
        """
        supported_formats = (PIL.Image.Image, np.ndarray, torch.Tensor)
        if isinstance(image, supported_formats):
            image = [image]
        elif not (isinstance(image, list) and all(isinstance(i, supported_formats) for i in image)):
            raise ValueError(
                f"Input is in incorrect format: {[type(i) for i in image]}. Currently, we only support {', '.join(supported_formats)}"
            )

        if isinstance(image[0], PIL.Image.Image):
            if self.do_resize:
                image = [self.resize(i) for i in image]
            image = [np.array(i).astype(np.float32) / 255.0 for i in image]
            image = np.stack(image, axis=0)  # to np
            image = self.numpy_to_pt(image)  # to pt

        elif isinstance(image[0], np.ndarray):
            image = np.concatenate(image, axis=0) if image[0].ndim == 4 else np.stack(image, axis=0)
            image = self.numpy_to_pt(image)
            _, _, height, width = image.shape
            if self.do_resize and (height % self.vae_scale_factor != 0 or width % self.vae_scale_factor != 0):
                raise ValueError(
                    f"Currently we only support resizing for PIL image - please resize your numpy array to be divisible by {self.vae_scale_factor}"
                    f"currently the sizes are {height} and {width}. You can also pass a PIL image instead to use resize option in VAEImageProcessor"
                )

        elif isinstance(image[0], torch.Tensor):
            image = torch.cat(image, axis=0) if image[0].ndim == 4 else torch.stack(image, axis=0)
            _, _, height, width = image.shape
            if self.do_resize and (height % self.vae_scale_factor != 0 or width % self.vae_scale_factor != 0):
                raise ValueError(
                    f"Currently we only support resizing for PIL image - please resize your pytorch tensor to be divisible by {self.vae_scale_factor}"
                    f"currently the sizes are {height} and {width}. You can also pass a PIL image instead to use resize option in VAEImageProcessor"
                )

        # expected range [0,1], normalize to [-1,1]
        do_normalize = self.do_normalize
        if image.min() < 0:
            warnings.warn(
                "Passing `image` as torch tensor with value range in [-1,1] is deprecated. The expected value range for image tensor is [0,1] "
                f"when passing as pytorch tensor or numpy Array. You passed `image` with value range [{image.min()},{image.max()}]",
                FutureWarning,
            )
            do_normalize = False

        if do_normalize:
            image = self.normalize(image)

        return image

    def postprocess(
        self,
        image,
        output_type: str = "pil",
    ):
        if isinstance(image, torch.Tensor) and output_type == "pt":
            return image

        image = self.pt_to_numpy(image)

        if output_type == "np":
            return image
        elif output_type == "pil":
            return self.numpy_to_pil(image)
        else:
            raise ValueError(f"Unsupported output_type {output_type}.")