init

finetune/mmseg/datasets/transforms/loading.py

@@ -0,0 +1,771 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import warnings
+from pathlib import Path
+from typing import Dict, Optional, Union
+
+import mmcv
+import mmengine.fileio as fileio
+import numpy as np
+from mmcv.transforms import BaseTransform
+from mmcv.transforms import LoadAnnotations as MMCV_LoadAnnotations
+from mmcv.transforms import LoadImageFromFile
+
+from mmseg.registry import TRANSFORMS
+from mmseg.utils import datafrombytes
+
+try:
+    from osgeo import gdal
+except ImportError:
+    gdal = None
+
+
+@TRANSFORMS.register_module()
+class LoadAnnotations(MMCV_LoadAnnotations):
+    """Load annotations for semantic segmentation provided by dataset.
+
+    The annotation format is as the following:
+
+    .. code-block:: python
+
+        {
+            # Filename of semantic segmentation ground truth file.
+            'seg_map_path': 'a/b/c'
+        }
+
+    After this module, the annotation has been changed to the format below:
+
+    .. code-block:: python
+
+        {
+            # in str
+            'seg_fields': List
+             # In uint8 type.
+            'gt_seg_map': np.ndarray (H, W)
+        }
+
+    Required Keys:
+
+    - seg_map_path (str): Path of semantic segmentation ground truth file.
+
+    Added Keys:
+
+    - seg_fields (List)
+    - gt_seg_map (np.uint8)
+
+    Args:
+        reduce_zero_label (bool, optional): Whether reduce all label value
+            by 1. Usually used for datasets where 0 is background label.
+            Defaults to None.
+        imdecode_backend (str): The image decoding backend type. The backend
+            argument for :func:``mmcv.imfrombytes``.
+            See :fun:``mmcv.imfrombytes`` for details.
+            Defaults to 'pillow'.
+        backend_args (dict): Arguments to instantiate a file backend.
+            See https://mmengine.readthedocs.io/en/latest/api/fileio.htm
+            for details. Defaults to None.
+            Notes: mmcv>=2.0.0rc4, mmengine>=0.2.0 required.
+    """
+
+    def __init__(
+        self,
+        reduce_zero_label=None,
+        backend_args=None,
+        imdecode_backend='pillow',
+    ) -> None:
+        super().__init__(
+            with_bbox=False,
+            with_label=False,
+            with_seg=True,
+            with_keypoints=False,
+            imdecode_backend=imdecode_backend,
+            backend_args=backend_args)
+        self.reduce_zero_label = reduce_zero_label
+        if self.reduce_zero_label is not None:
+            warnings.warn('`reduce_zero_label` will be deprecated, '
+                          'if you would like to ignore the zero label, please '
+                          'set `reduce_zero_label=True` when dataset '
+                          'initialized')
+        self.imdecode_backend = imdecode_backend
+
+    def _load_seg_map(self, results: dict) -> None:
+        """Private function to load semantic segmentation annotations.
+
+        Args:
+            results (dict): Result dict from :obj:``mmcv.BaseDataset``.
+
+        Returns:
+            dict: The dict contains loaded semantic segmentation annotations.
+        """
+
+        img_bytes = fileio.get(
+            results['seg_map_path'], backend_args=self.backend_args)
+        gt_semantic_seg = mmcv.imfrombytes(
+            img_bytes, flag='unchanged',
+            backend=self.imdecode_backend).squeeze().astype(np.uint8)
+
+        # reduce zero_label
+        if self.reduce_zero_label is None:
+            self.reduce_zero_label = results['reduce_zero_label']
+        assert self.reduce_zero_label == results['reduce_zero_label'], \
+            'Initialize dataset with `reduce_zero_label` as ' \
+            f'{results["reduce_zero_label"]} but when load annotation ' \
+            f'the `reduce_zero_label` is {self.reduce_zero_label}'
+        if self.reduce_zero_label:
+            # avoid using underflow conversion
+            gt_semantic_seg[gt_semantic_seg == 0] = 255
+            gt_semantic_seg = gt_semantic_seg - 1
+            gt_semantic_seg[gt_semantic_seg == 254] = 255
+        # modify if custom classes
+        if results.get('label_map', None) is not None:
+            # Add deep copy to solve bug of repeatedly
+            # replace `gt_semantic_seg`, which is reported in
+            # https://github.com/open-mmlab/mmsegmentation/pull/1445/
+            gt_semantic_seg_copy = gt_semantic_seg.copy()
+            for old_id, new_id in results['label_map'].items():
+                gt_semantic_seg[gt_semantic_seg_copy == old_id] = new_id
+        results['gt_seg_map'] = gt_semantic_seg
+        results['seg_fields'].append('gt_seg_map')
+
+    def __repr__(self) -> str:
+        repr_str = self.__class__.__name__
+        repr_str += f'(reduce_zero_label={self.reduce_zero_label}, '
+        repr_str += f"imdecode_backend='{self.imdecode_backend}', "
+        repr_str += f'backend_args={self.backend_args})'
+        return repr_str
+
+
+@TRANSFORMS.register_module()
+class LoadImageFromNDArray(LoadImageFromFile):
+    """Load an image from ``results['img']``.
+
+    Similar with :obj:`LoadImageFromFile`, but the image has been loaded as
+    :obj:`np.ndarray` in ``results['img']``. Can be used when loading image
+    from webcam.
+
+    Required Keys:
+
+    - img
+
+    Modified Keys:
+
+    - img
+    - img_path
+    - img_shape
+    - ori_shape
+
+    Args:
+        to_float32 (bool): Whether to convert the loaded image to a float32
+            numpy array. If set to False, the loaded image is an uint8 array.
+            Defaults to False.
+    """
+
+    def transform(self, results: dict) -> dict:
+        """Transform function to add image meta information.
+
+        Args:
+            results (dict): Result dict with Webcam read image in
+                ``results['img']``.
+
+        Returns:
+            dict: The dict contains loaded image and meta information.
+        """
+
+        img = results['img']
+        if self.to_float32:
+            img = img.astype(np.float32)
+
+        results['img_path'] = None
+        results['img'] = img
+        results['img_shape'] = img.shape[:2]
+        results['ori_shape'] = img.shape[:2]
+        return results
+
+
+@TRANSFORMS.register_module()
+class LoadBiomedicalImageFromFile(BaseTransform):
+    """Load an biomedical mage from file.
+
+    Required Keys:
+
+    - img_path
+
+    Added Keys:
+
+    - img (np.ndarray): Biomedical image with shape (N, Z, Y, X) by default,
+        N is the number of modalities, and data type is float32
+        if set to_float32 = True, or float64 if decode_backend is 'nifti' and
+        to_float32 is False.
+    - img_shape
+    - ori_shape
+
+    Args:
+        decode_backend (str): The data decoding backend type. Options are
+            'numpy'and 'nifti', and there is a convention that when backend is
+            'nifti' the axis of data loaded is XYZ, and when backend is
+            'numpy', the the axis is ZYX. The data will be transposed if the
+            backend is 'nifti'. Defaults to 'nifti'.
+        to_xyz (bool): Whether transpose data from Z, Y, X to X, Y, Z.
+            Defaults to False.
+        to_float32 (bool): Whether to convert the loaded image to a float32
+            numpy array. If set to False, the loaded image is an float64 array.
+            Defaults to True.
+        backend_args (dict, Optional): Arguments to instantiate a file backend.
+            See https://mmengine.readthedocs.io/en/latest/api/fileio.htm
+            for details. Defaults to None.
+            Notes: mmcv>=2.0.0rc4, mmengine>=0.2.0 required.
+    """
+
+    def __init__(self,
+                 decode_backend: str = 'nifti',
+                 to_xyz: bool = False,
+                 to_float32: bool = True,
+                 backend_args: Optional[dict] = None) -> None:
+        self.decode_backend = decode_backend
+        self.to_xyz = to_xyz
+        self.to_float32 = to_float32
+        self.backend_args = backend_args.copy() if backend_args else None
+
+    def transform(self, results: Dict) -> Dict:
+        """Functions to load image.
+
+        Args:
+            results (dict): Result dict from :obj:``mmcv.BaseDataset``.
+
+        Returns:
+            dict: The dict contains loaded image and meta information.
+        """
+
+        filename = results['img_path']
+
+        data_bytes = fileio.get(filename, self.backend_args)
+        img = datafrombytes(data_bytes, backend=self.decode_backend)
+
+        if self.to_float32:
+            img = img.astype(np.float32)
+
+        if len(img.shape) == 3:
+            img = img[None, ...]
+
+        if self.decode_backend == 'nifti':
+            img = img.transpose(0, 3, 2, 1)
+
+        if self.to_xyz:
+            img = img.transpose(0, 3, 2, 1)
+
+        results['img'] = img
+        results['img_shape'] = img.shape[1:]
+        results['ori_shape'] = img.shape[1:]
+        return results
+
+    def __repr__(self):
+        repr_str = (f'{self.__class__.__name__}('
+                    f"decode_backend='{self.decode_backend}', "
+                    f'to_xyz={self.to_xyz}, '
+                    f'to_float32={self.to_float32}, '
+                    f'backend_args={self.backend_args})')
+        return repr_str
+
+
+@TRANSFORMS.register_module()
+class LoadBiomedicalAnnotation(BaseTransform):
+    """Load ``seg_map`` annotation provided by biomedical dataset.
+
+    The annotation format is as the following:
+
+    .. code-block:: python
+
+        {
+            'gt_seg_map': np.ndarray (X, Y, Z) or (Z, Y, X)
+        }
+
+    Required Keys:
+
+    - seg_map_path
+
+    Added Keys:
+
+    - gt_seg_map (np.ndarray): Biomedical seg map with shape (Z, Y, X) by
+        default, and data type is float32 if set to_float32 = True, or
+        float64 if decode_backend is 'nifti' and to_float32 is False.
+
+    Args:
+        decode_backend (str): The data decoding backend type. Options are
+            'numpy'and 'nifti', and there is a convention that when backend is
+            'nifti' the axis of data loaded is XYZ, and when backend is
+            'numpy', the the axis is ZYX. The data will be transposed if the
+            backend is 'nifti'. Defaults to 'nifti'.
+        to_xyz (bool): Whether transpose data from Z, Y, X to X, Y, Z.
+            Defaults to False.
+        to_float32 (bool): Whether to convert the loaded seg map to a float32
+            numpy array. If set to False, the loaded image is an float64 array.
+            Defaults to True.
+        backend_args (dict, Optional): Arguments to instantiate a file backend.
+            See :class:`mmengine.fileio` for details.
+            Defaults to None.
+            Notes: mmcv>=2.0.0rc4, mmengine>=0.2.0 required.
+    """
+
+    def __init__(self,
+                 decode_backend: str = 'nifti',
+                 to_xyz: bool = False,
+                 to_float32: bool = True,
+                 backend_args: Optional[dict] = None) -> None:
+        super().__init__()
+        self.decode_backend = decode_backend
+        self.to_xyz = to_xyz
+        self.to_float32 = to_float32
+        self.backend_args = backend_args.copy() if backend_args else None
+
+    def transform(self, results: Dict) -> Dict:
+        """Functions to load image.
+
+        Args:
+            results (dict): Result dict from :obj:``mmcv.BaseDataset``.
+
+        Returns:
+            dict: The dict contains loaded image and meta information.
+        """
+        data_bytes = fileio.get(results['seg_map_path'], self.backend_args)
+        gt_seg_map = datafrombytes(data_bytes, backend=self.decode_backend)
+
+        if self.to_float32:
+            gt_seg_map = gt_seg_map.astype(np.float32)
+
+        if self.decode_backend == 'nifti':
+            gt_seg_map = gt_seg_map.transpose(2, 1, 0)
+
+        if self.to_xyz:
+            gt_seg_map = gt_seg_map.transpose(2, 1, 0)
+
+        results['gt_seg_map'] = gt_seg_map
+        return results
+
+    def __repr__(self):
+        repr_str = (f'{self.__class__.__name__}('
+                    f"decode_backend='{self.decode_backend}', "
+                    f'to_xyz={self.to_xyz}, '
+                    f'to_float32={self.to_float32}, '
+                    f'backend_args={self.backend_args})')
+        return repr_str
+
+
+@TRANSFORMS.register_module()
+class LoadBiomedicalData(BaseTransform):
+    """Load an biomedical image and annotation from file.
+
+    The loading data format is as the following:
+
+    .. code-block:: python
+
+        {
+            'img': np.ndarray data[:-1, X, Y, Z]
+            'seg_map': np.ndarray data[-1, X, Y, Z]
+        }
+
+
+    Required Keys:
+
+    - img_path
+
+    Added Keys:
+
+    - img (np.ndarray): Biomedical image with shape (N, Z, Y, X) by default,
+        N is the number of modalities.
+    - gt_seg_map (np.ndarray, optional): Biomedical seg map with shape
+        (Z, Y, X) by default.
+    - img_shape
+    - ori_shape
+
+    Args:
+        with_seg (bool): Whether to parse and load the semantic segmentation
+            annotation. Defaults to False.
+        decode_backend (str): The data decoding backend type. Options are
+            'numpy'and 'nifti', and there is a convention that when backend is
+            'nifti' the axis of data loaded is XYZ, and when backend is
+            'numpy', the the axis is ZYX. The data will be transposed if the
+            backend is 'nifti'. Defaults to 'nifti'.
+        to_xyz (bool): Whether transpose data from Z, Y, X to X, Y, Z.
+            Defaults to False.
+        backend_args (dict, Optional): Arguments to instantiate a file backend.
+            See https://mmengine.readthedocs.io/en/latest/api/fileio.htm
+            for details. Defaults to None.
+            Notes: mmcv>=2.0.0rc4, mmengine>=0.2.0 required.
+    """
+
+    def __init__(self,
+                 with_seg=False,
+                 decode_backend: str = 'numpy',
+                 to_xyz: bool = False,
+                 backend_args: Optional[dict] = None) -> None:  # noqa
+        self.with_seg = with_seg
+        self.decode_backend = decode_backend
+        self.to_xyz = to_xyz
+        self.backend_args = backend_args.copy() if backend_args else None
+
+    def transform(self, results: Dict) -> Dict:
+        """Functions to load image.
+
+        Args:
+            results (dict): Result dict from :obj:``mmcv.BaseDataset``.
+
+        Returns:
+            dict: The dict contains loaded image and meta information.
+        """
+        data_bytes = fileio.get(results['img_path'], self.backend_args)
+        data = datafrombytes(data_bytes, backend=self.decode_backend)
+        # img is 4D data (N, X, Y, Z), N is the number of protocol
+        img = data[:-1, :]
+
+        if self.decode_backend == 'nifti':
+            img = img.transpose(0, 3, 2, 1)
+
+        if self.to_xyz:
+            img = img.transpose(0, 3, 2, 1)
+
+        results['img'] = img
+        results['img_shape'] = img.shape[1:]
+        results['ori_shape'] = img.shape[1:]
+
+        if self.with_seg:
+            gt_seg_map = data[-1, :]
+            if self.decode_backend == 'nifti':
+                gt_seg_map = gt_seg_map.transpose(2, 1, 0)
+
+            if self.to_xyz:
+                gt_seg_map = gt_seg_map.transpose(2, 1, 0)
+            results['gt_seg_map'] = gt_seg_map
+        return results
+
+    def __repr__(self) -> str:
+        repr_str = (f'{self.__class__.__name__}('
+                    f'with_seg={self.with_seg}, '
+                    f"decode_backend='{self.decode_backend}', "
+                    f'to_xyz={self.to_xyz}, '
+                    f'backend_args={self.backend_args})')
+        return repr_str
+
+
+@TRANSFORMS.register_module()
+class InferencerLoader(BaseTransform):
+    """Load an image from ``results['img']``.
+
+    Similar with :obj:`LoadImageFromFile`, but the image has been loaded as
+    :obj:`np.ndarray` in ``results['img']``. Can be used when loading image
+    from webcam.
+
+    Required Keys:
+
+    - img
+
+    Modified Keys:
+
+    - img
+    - img_path
+    - img_shape
+    - ori_shape
+
+    Args:
+        to_float32 (bool): Whether to convert the loaded image to a float32
+            numpy array. If set to False, the loaded image is an uint8 array.
+            Defaults to False.
+    """
+
+    def __init__(self, **kwargs) -> None:
+        super().__init__()
+        self.from_file = TRANSFORMS.build(
+            dict(type='LoadImageFromFile', **kwargs))
+        self.from_ndarray = TRANSFORMS.build(
+            dict(type='LoadImageFromNDArray', **kwargs))
+
+    def transform(self, single_input: Union[str, np.ndarray, dict]) -> dict:
+        """Transform function to add image meta information.
+
+        Args:
+            results (dict): Result dict with Webcam read image in
+                ``results['img']``.
+
+        Returns:
+            dict: The dict contains loaded image and meta information.
+        """
+        if isinstance(single_input, str):
+            inputs = dict(img_path=single_input)
+        elif isinstance(single_input, np.ndarray):
+            inputs = dict(img=single_input)
+        elif isinstance(single_input, dict):
+            inputs = single_input
+        else:
+            raise NotImplementedError
+
+        if 'img' in inputs:
+            return self.from_ndarray(inputs)
+        return self.from_file(inputs)
+
+
+@TRANSFORMS.register_module()
+class LoadSingleRSImageFromFile(BaseTransform):
+    """Load a Remote Sensing mage from file.
+
+    Required Keys:
+
+    - img_path
+
+    Modified Keys:
+
+    - img
+    - img_shape
+    - ori_shape
+
+    Args:
+        to_float32 (bool): Whether to convert the loaded image to a float32
+            numpy array. If set to False, the loaded image is a float64 array.
+            Defaults to True.
+    """
+
+    def __init__(self, to_float32: bool = True):
+        self.to_float32 = to_float32
+
+        if gdal is None:
+            raise RuntimeError('gdal is not installed')
+
+    def transform(self, results: Dict) -> Dict:
+        """Functions to load image.
+
+        Args:
+            results (dict): Result dict from :obj:``mmcv.BaseDataset``.
+
+        Returns:
+            dict: The dict contains loaded image and meta information.
+        """
+
+        filename = results['img_path']
+        ds = gdal.Open(filename)
+        if ds is None:
+            raise Exception(f'Unable to open file: {filename}')
+        img = np.einsum('ijk->jki', ds.ReadAsArray())
+
+        if self.to_float32:
+            img = img.astype(np.float32)
+
+        results['img'] = img
+        results['img_shape'] = img.shape[:2]
+        results['ori_shape'] = img.shape[:2]
+        return results
+
+    def __repr__(self):
+        repr_str = (f'{self.__class__.__name__}('
+                    f'to_float32={self.to_float32})')
+        return repr_str
+
+
+@TRANSFORMS.register_module()
+class LoadMultipleRSImageFromFile(BaseTransform):
+    """Load two Remote Sensing mage from file.
+
+    Required Keys:
+
+    - img_path
+    - img_path2
+
+    Modified Keys:
+
+    - img
+    - img2
+    - img_shape
+    - ori_shape
+
+    Args:
+        to_float32 (bool): Whether to convert the loaded image to a float32
+            numpy array. If set to False, the loaded image is a float64 array.
+            Defaults to True.
+    """
+
+    def __init__(self, to_float32: bool = True):
+        if gdal is None:
+            raise RuntimeError('gdal is not installed')
+        self.to_float32 = to_float32
+
+    def transform(self, results: Dict) -> Dict:
+        """Functions to load image.
+
+        Args:
+            results (dict): Result dict from :obj:``mmcv.BaseDataset``.
+
+        Returns:
+            dict: The dict contains loaded image and meta information.
+        """
+
+        filename = results['img_path']
+        filename2 = results['img_path2']
+
+        ds = gdal.Open(filename)
+        ds2 = gdal.Open(filename2)
+
+        if ds is None:
+            raise Exception(f'Unable to open file: {filename}')
+        if ds2 is None:
+            raise Exception(f'Unable to open file: {filename2}')
+
+        img = np.einsum('ijk->jki', ds.ReadAsArray())
+        img2 = np.einsum('ijk->jki', ds2.ReadAsArray())
+
+        if self.to_float32:
+            img = img.astype(np.float32)
+            img2 = img2.astype(np.float32)
+
+        if img.shape != img2.shape:
+            raise Exception(f'Image shapes do not match:'
+                            f' {img.shape} vs {img2.shape}')
+
+        results['img'] = img
+        results['img2'] = img2
+        results['img_shape'] = img.shape[:2]
+        results['ori_shape'] = img.shape[:2]
+        return results
+
+    def __repr__(self):
+        repr_str = (f'{self.__class__.__name__}('
+                    f'to_float32={self.to_float32})')
+        return repr_str
+
+
+@TRANSFORMS.register_module()
+class LoadDepthAnnotation(BaseTransform):
+    """Load ``depth_map`` annotation provided by depth estimation dataset.
+
+    The annotation format is as the following:
+
+    .. code-block:: python
+
+        {
+            'gt_depth_map': np.ndarray [Y, X]
+        }
+
+    Required Keys:
+
+    - seg_depth_path
+
+    Added Keys:
+
+    - gt_depth_map (np.ndarray): Depth map with shape (Y, X) by
+        default, and data type is float32 if set to_float32 = True.
+    - depth_rescale_factor (float): The rescale factor of depth map, which
+        can be used to recover the original value of depth map.
+
+    Args:
+        decode_backend (str): The data decoding backend type. Options are
+            'numpy', 'nifti', and 'cv2'. Defaults to 'cv2'.
+        to_float32 (bool): Whether to convert the loaded depth map to a float32
+            numpy array. If set to False, the loaded image is an uint16 array.
+            Defaults to True.
+        depth_rescale_factor (float): Factor to rescale the depth value to
+            limit the range. Defaults to 1.0.
+        backend_args (dict, Optional): Arguments to instantiate a file backend.
+            See :class:`mmengine.fileio` for details.
+            Defaults to None.
+            Notes: mmcv>=2.0.0rc4, mmengine>=0.2.0 required.
+    """
+
+    def __init__(self,
+                 decode_backend: str = 'cv2',
+                 to_float32: bool = True,
+                 depth_rescale_factor: float = 1.0,
+                 backend_args: Optional[dict] = None) -> None:
+        super().__init__()
+        self.decode_backend = decode_backend
+        self.to_float32 = to_float32
+        self.depth_rescale_factor = depth_rescale_factor
+        self.backend_args = backend_args.copy() if backend_args else None
+
+    def transform(self, results: Dict) -> Dict:
+        """Functions to load depth map.
+
+        Args:
+            results (dict): Result dict from :obj:``mmcv.BaseDataset``.
+
+        Returns:
+            dict: The dict contains loaded depth map.
+        """
+        data_bytes = fileio.get(results['depth_map_path'], self.backend_args)
+        gt_depth_map = datafrombytes(data_bytes, backend=self.decode_backend)
+
+        if self.to_float32:
+            gt_depth_map = gt_depth_map.astype(np.float32)
+
+        gt_depth_map *= self.depth_rescale_factor
+        results['gt_depth_map'] = gt_depth_map
+        results['seg_fields'].append('gt_depth_map')
+        results['depth_rescale_factor'] = self.depth_rescale_factor
+        return results
+
+    def __repr__(self):
+        repr_str = (f'{self.__class__.__name__}('
+                    f"decode_backend='{self.decode_backend}', "
+                    f'to_float32={self.to_float32}, '
+                    f'backend_args={self.backend_args})')
+        return repr_str
+
+
+@TRANSFORMS.register_module()
+class LoadImageFromNpyFile(LoadImageFromFile):
+    """Load an image from ``results['img_path']``.
+
+    Required Keys:
+
+    - img_path
+
+    Modified Keys:
+
+    - img
+    - img_shape
+    - ori_shape
+
+    Args:
+        to_float32 (bool): Whether to convert the loaded image to a float32
+            numpy array. If set to False, the loaded image is an uint8 array.
+            Defaults to False.
+    """
+
+    def transform(self, results: dict) -> Optional[dict]:
+        """Functions to load image.
+
+        Args:
+            results (dict): Result dict from
+                :class:`mmengine.dataset.BaseDataset`.
+
+        Returns:
+            dict: The dict contains loaded image and meta information.
+        """
+
+        filename = results['img_path']
+
+        try:
+            if Path(filename).suffix in ['.npy', '.npz']:
+                img = np.load(filename)
+            else:
+                if self.file_client_args is not None:
+                    file_client = fileio.FileClient.infer_client(
+                        self.file_client_args, filename)
+                    img_bytes = file_client.get(filename)
+                else:
+                    img_bytes = fileio.get(
+                        filename, backend_args=self.backend_args)
+                img = mmcv.imfrombytes(
+                    img_bytes,
+                    flag=self.color_type,
+                    backend=self.imdecode_backend)
+        except Exception as e:
+            if self.ignore_empty:
+                return None
+            else:
+                raise e
+
+        # in some cases, images are not read successfully, the img would be
+        # `None`, refer to https://github.com/open-mmlab/mmpretrain/issues/1427
+        assert img is not None, f'failed to load image: {filename}'
+        if self.to_float32:
+            img = img.astype(np.float32)
+
+        results['img'] = img
+        results['img_shape'] = img.shape[:2]
+        results['ori_shape'] = img.shape[:2]
+        return results