XYMasking augmentation (augmentations.dropout.xy_masking)¶

class XYMasking(BaseDropout):
    """Applies masking strips to an image, either horizontally (X axis) or vertically (Y axis),
    simulating occlusions. This transform is useful for training models to recognize images
    with varied visibility conditions. It's particularly effective for spectrogram images,
    allowing spectral and frequency masking to improve model robustness.

    At least one of `max_x_length` or `max_y_length` must be specified, dictating the mask's
    maximum size along each axis.

    Args:
        num_masks_x (int | tuple[int, int]): Number or range of horizontal regions to mask. Defaults to 0.
        num_masks_y (int | tuple[int, int]): Number or range of vertical regions to mask. Defaults to 0.
        mask_x_length (int | tuple[int, int]): Specifies the length of the masks along
            the X (horizontal) axis. If an integer is provided, it sets a fixed mask length.
            If a tuple of two integers (min, max) is provided,
            the mask length is randomly chosen within this range for each mask.
            This allows for variable-length masks in the horizontal direction.
        mask_y_length (int | tuple[int, int]): Specifies the height of the masks along
            the Y (vertical) axis. Similar to `mask_x_length`, an integer sets a fixed mask height,
            while a tuple (min, max) allows for variable-height masks, chosen randomly
            within the specified range for each mask. This flexibility facilitates creating masks of various
            sizes in the vertical direction.
        fill_value (int | float | list[int] | list[float] | str): Value to fill image masks. Defaults to 0.
        mask_fill_value (int | float | list[int] | list[float] | None): Value to fill masks in the mask.
            If `None`, uses mask is not affected. Default: `None`.
        p (float): Probability of applying the transform. Defaults to 0.5.

    Targets:
        image, mask, bboxes, keypoints

    Image types:
        uint8, float32

    Note: Either `max_x_length` or `max_y_length` or both must be defined.
    """

    _targets = (Targets.IMAGE, Targets.MASK, Targets.KEYPOINTS, Targets.BBOXES)

    class InitSchema(BaseTransformInitSchema):
        num_masks_x: NonNegativeIntRangeType
        num_masks_y: NonNegativeIntRangeType
        mask_x_length: NonNegativeIntRangeType
        mask_y_length: NonNegativeIntRangeType

        fill_value: ColorType
        mask_fill_value: ColorType

        @model_validator(mode="after")
        def check_mask_length(self) -> Self:
            if (
                isinstance(self.mask_x_length, int)
                and self.mask_x_length <= 0
                and isinstance(self.mask_y_length, int)
                and self.mask_y_length <= 0
            ):
                msg = "At least one of `mask_x_length` or `mask_y_length` Should be a positive number."
                raise ValueError(msg)
            return self

    def __init__(
        self,
        num_masks_x: ScaleIntType = 0,
        num_masks_y: ScaleIntType = 0,
        mask_x_length: ScaleIntType = 0,
        mask_y_length: ScaleIntType = 0,
        fill_value: ColorType = 0,
        mask_fill_value: ColorType = 0,
        always_apply: bool | None = None,
        p: float = 0.5,
    ):
        super().__init__(p=p, always_apply=always_apply, fill_value=fill_value, mask_fill_value=mask_fill_value)
        self.num_masks_x = cast(tuple[int, int], num_masks_x)
        self.num_masks_y = cast(tuple[int, int], num_masks_y)

        self.mask_x_length = cast(tuple[int, int], mask_x_length)
        self.mask_y_length = cast(tuple[int, int], mask_y_length)

    def validate_mask_length(
        self,
        mask_length: tuple[int, int] | None,
        dimension_size: int,
        dimension_name: str,
    ) -> None:
        """Validate the mask length against the corresponding image dimension size."""
        if mask_length is not None:
            if isinstance(mask_length, (tuple, list)):
                if mask_length[0] < 0 or mask_length[1] > dimension_size:
                    raise ValueError(
                        f"{dimension_name} range {mask_length} is out of valid range [0, {dimension_size}]",
                    )
            elif mask_length < 0 or mask_length > dimension_size:
                raise ValueError(f"{dimension_name} {mask_length} exceeds image {dimension_name} {dimension_size}")

    def get_params_dependent_on_data(
        self,
        params: dict[str, Any],
        data: dict[str, Any],
    ) -> dict[str, np.ndarray]:
        image_shape = params["shape"][:2]

        height, width = image_shape

        self.validate_mask_length(self.mask_x_length, width, "mask_x_length")
        self.validate_mask_length(self.mask_y_length, height, "mask_y_length")

        masks_x = self.generate_masks(self.num_masks_x, image_shape, self.mask_x_length, axis="x")
        masks_y = self.generate_masks(self.num_masks_y, image_shape, self.mask_y_length, axis="y")

        holes = np.array(masks_x + masks_y)
        return {"holes": holes}

    @staticmethod
    def generate_mask_size(mask_length: tuple[int, int]) -> int:
        return random.randint(*mask_length)

    def generate_masks(
        self,
        num_masks: tuple[int, int],
        image_shape: tuple[int, int],
        max_length: tuple[int, int] | None,
        axis: str,
    ) -> list[tuple[int, int, int, int]]:
        if max_length is None or max_length == 0 or isinstance(num_masks, (int, float)) and num_masks == 0:
            return []

        masks = []
        num_masks_integer = num_masks if isinstance(num_masks, int) else random.randint(num_masks[0], num_masks[1])

        height, width = image_shape

        for _ in range(num_masks_integer):
            length = self.generate_mask_size(max_length)

            if axis == "x":
                x_min = random.randint(0, width - length)
                y_min = 0
                x_max, y_max = x_min + length, height
            else:  # axis == 'y'
                y_min = random.randint(0, height - length)
                x_min = 0
                x_max, y_max = width, y_min + length

            masks.append((x_min, y_min, x_max, y_max))
        return masks

    def get_transform_init_args_names(self) -> tuple[str, ...]:
        return (
            "num_masks_x",
            "num_masks_y",
            "mask_x_length",
            "mask_y_length",
            "fill_value",
            "mask_fill_value",
        )