class mmedit.datasets.transforms.Resize(keys: Union[str, List[str]] = 'img', scale=None, keep_ratio=False, size_factor=None, max_size=None, interpolation='bilinear', backend=None, output_keys=None)[source]

Resize data to a specific size for training or resize the images to fit the network input regulation for testing.

When used for resizing images to fit network input regulation, the case is that a network may have several downsample and then upsample operation, then the input height and width should be divisible by the downsample factor of the network. For example, the network would downsample the input for 5 times with stride 2, then the downsample factor is 2^5 = 32 and the height and width should be divisible by 32.

Required keys are the keys in attribute “keys”, added or modified keys are “keep_ratio”, “scale_factor”, “interpolation” and the keys in attribute “keys”.

Required Keys:

  • Required keys are the keys in attribute “keys”

Modified Keys:

  • Modified the keys in attribute “keys” or save as new key ([OUT_KEY])

Added Keys:

  • [OUT_KEY]_shape

  • keep_ratio

  • scale_factor

  • interpolation

All keys in “keys” should have the same shape. “test_trans” is used to record the test transformation to align the input’s shape.

  • keys (str | list[str]) – The image(s) to be resized.

  • scale (float | tuple[int]) – If scale is tuple[int], target spatial size (h, w). Otherwise, target spatial size is scaled by input size. Note that when it is used, size_factor and max_size are useless. Default: None

  • keep_ratio (bool) – If set to True, images will be resized without changing the aspect ratio. Otherwise, it will resize images to a given size. Default: False. Note that it is used together with scale.

  • size_factor (int) – Let the output shape be a multiple of size_factor. Default:None. Note that when it is used, scale should be set to None and keep_ratio should be set to False.

  • max_size (int) – The maximum size of the longest side of the output. Default:None. Note that it is used together with size_factor.

  • interpolation (str) – Algorithm used for interpolation: “nearest” | “bilinear” | “bicubic” | “area” | “lanczos”. Default: “bilinear”.

  • backend (str | None) – The image resize backend type. Options are cv2, pillow, None. If backend is None, the global imread_backend specified by mmcv.use_backend() will be used. Default: None.

  • output_keys (list[str] | None) – The resized images. Default: None Note that if it is not None, its length should be equal to keys.

transform(results: Dict) Dict[source]

Transform function to resize images.


results (dict) – A dict containing the necessary information and data for augmentation.


A dict containing the processed data and information.

Return type


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