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Reference for ultralytics/data/augment.py

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ultralytics.data.augment.BaseTransform

Base class for image transformations.

This is a generic transformation class that can be extended for specific image processing needs. The class is designed to be compatible with both classification and semantic segmentation tasks.

Methods:

Name Description
__init__

Initializes the BaseTransform object.

apply_image

Applies image transformation to labels.

apply_instances

Applies transformations to object instances in labels.

apply_semantic

Applies semantic segmentation to an image.

__call__

Applies all label transformations to an image, instances, and semantic masks.

Source code in ultralytics/data/augment.py
class BaseTransform:
    """
    Base class for image transformations.

    This is a generic transformation class that can be extended for specific image processing needs.
    The class is designed to be compatible with both classification and semantic segmentation tasks.

    Methods:
        __init__: Initializes the BaseTransform object.
        apply_image: Applies image transformation to labels.
        apply_instances: Applies transformations to object instances in labels.
        apply_semantic: Applies semantic segmentation to an image.
        __call__: Applies all label transformations to an image, instances, and semantic masks.
    """

    def __init__(self) -> None:
        """Initializes the BaseTransform object."""
        pass

    def apply_image(self, labels):
        """Applies image transformations to labels."""
        pass

    def apply_instances(self, labels):
        """Applies transformations to object instances in labels."""
        pass

    def apply_semantic(self, labels):
        """Applies semantic segmentation to an image."""
        pass

    def __call__(self, labels):
        """Applies all label transformations to an image, instances, and semantic masks."""
        self.apply_image(labels)
        self.apply_instances(labels)
        self.apply_semantic(labels)

__call__(labels)

Applies all label transformations to an image, instances, and semantic masks.

Source code in ultralytics/data/augment.py
def __call__(self, labels):
    """Applies all label transformations to an image, instances, and semantic masks."""
    self.apply_image(labels)
    self.apply_instances(labels)
    self.apply_semantic(labels)

__init__()

Initializes the BaseTransform object.

Source code in ultralytics/data/augment.py
def __init__(self) -> None:
    """Initializes the BaseTransform object."""
    pass

apply_image(labels)

Applies image transformations to labels.

Source code in ultralytics/data/augment.py
def apply_image(self, labels):
    """Applies image transformations to labels."""
    pass

apply_instances(labels)

Applies transformations to object instances in labels.

Source code in ultralytics/data/augment.py
def apply_instances(self, labels):
    """Applies transformations to object instances in labels."""
    pass

apply_semantic(labels)

Applies semantic segmentation to an image.

Source code in ultralytics/data/augment.py
def apply_semantic(self, labels):
    """Applies semantic segmentation to an image."""
    pass



ultralytics.data.augment.Compose

Class for composing multiple image transformations.

Source code in ultralytics/data/augment.py
class Compose:
    """Class for composing multiple image transformations."""

    def __init__(self, transforms):
        """Initializes the Compose object with a list of transforms."""
        self.transforms = transforms if isinstance(transforms, list) else [transforms]

    def __call__(self, data):
        """Applies a series of transformations to input data."""
        for t in self.transforms:
            data = t(data)
        return data

    def append(self, transform):
        """Appends a new transform to the existing list of transforms."""
        self.transforms.append(transform)

    def insert(self, index, transform):
        """Inserts a new transform to the existing list of transforms."""
        self.transforms.insert(index, transform)

    def __getitem__(self, index: Union[list, int]) -> "Compose":
        """Retrieve a specific transform or a set of transforms using indexing."""
        assert isinstance(index, (int, list)), f"The indices should be either list or int type but got {type(index)}"
        index = [index] if isinstance(index, int) else index
        return Compose([self.transforms[i] for i in index])

    def __setitem__(self, index: Union[list, int], value: Union[list, int]) -> None:
        """Retrieve a specific transform or a set of transforms using indexing."""
        assert isinstance(index, (int, list)), f"The indices should be either list or int type but got {type(index)}"
        if isinstance(index, list):
            assert isinstance(
                value, list
            ), f"The indices should be the same type as values, but got {type(index)} and {type(value)}"
        if isinstance(index, int):
            index, value = [index], [value]
        for i, v in zip(index, value):
            assert i < len(self.transforms), f"list index {i} out of range {len(self.transforms)}."
            self.transforms[i] = v

    def tolist(self):
        """Converts the list of transforms to a standard Python list."""
        return self.transforms

    def __repr__(self):
        """Returns a string representation of the object."""
        return f"{self.__class__.__name__}({', '.join([f'{t}' for t in self.transforms])})"

__call__(data)

Applies a series of transformations to input data.

Source code in ultralytics/data/augment.py
def __call__(self, data):
    """Applies a series of transformations to input data."""
    for t in self.transforms:
        data = t(data)
    return data

__getitem__(index)

Retrieve a specific transform or a set of transforms using indexing.

Source code in ultralytics/data/augment.py
def __getitem__(self, index: Union[list, int]) -> "Compose":
    """Retrieve a specific transform or a set of transforms using indexing."""
    assert isinstance(index, (int, list)), f"The indices should be either list or int type but got {type(index)}"
    index = [index] if isinstance(index, int) else index
    return Compose([self.transforms[i] for i in index])

__init__(transforms)

Initializes the Compose object with a list of transforms.

Source code in ultralytics/data/augment.py
def __init__(self, transforms):
    """Initializes the Compose object with a list of transforms."""
    self.transforms = transforms if isinstance(transforms, list) else [transforms]

__repr__()

Returns a string representation of the object.

Source code in ultralytics/data/augment.py
def __repr__(self):
    """Returns a string representation of the object."""
    return f"{self.__class__.__name__}({', '.join([f'{t}' for t in self.transforms])})"

__setitem__(index, value)

Retrieve a specific transform or a set of transforms using indexing.

Source code in ultralytics/data/augment.py
def __setitem__(self, index: Union[list, int], value: Union[list, int]) -> None:
    """Retrieve a specific transform or a set of transforms using indexing."""
    assert isinstance(index, (int, list)), f"The indices should be either list or int type but got {type(index)}"
    if isinstance(index, list):
        assert isinstance(
            value, list
        ), f"The indices should be the same type as values, but got {type(index)} and {type(value)}"
    if isinstance(index, int):
        index, value = [index], [value]
    for i, v in zip(index, value):
        assert i < len(self.transforms), f"list index {i} out of range {len(self.transforms)}."
        self.transforms[i] = v

append(transform)

Appends a new transform to the existing list of transforms.

Source code in ultralytics/data/augment.py
def append(self, transform):
    """Appends a new transform to the existing list of transforms."""
    self.transforms.append(transform)

insert(index, transform)

Inserts a new transform to the existing list of transforms.

Source code in ultralytics/data/augment.py
def insert(self, index, transform):
    """Inserts a new transform to the existing list of transforms."""
    self.transforms.insert(index, transform)

tolist()

Converts the list of transforms to a standard Python list.

Source code in ultralytics/data/augment.py
def tolist(self):
    """Converts the list of transforms to a standard Python list."""
    return self.transforms



ultralytics.data.augment.BaseMixTransform

Class for base mix (MixUp/Mosaic) transformations.

This implementation is from mmyolo.

Source code in ultralytics/data/augment.py
class BaseMixTransform:
    """
    Class for base mix (MixUp/Mosaic) transformations.

    This implementation is from mmyolo.
    """

    def __init__(self, dataset, pre_transform=None, p=0.0) -> None:
        """Initializes the BaseMixTransform object with dataset, pre_transform, and probability."""
        self.dataset = dataset
        self.pre_transform = pre_transform
        self.p = p

    def __call__(self, labels):
        """Applies pre-processing transforms and mixup/mosaic transforms to labels data."""
        if random.uniform(0, 1) > self.p:
            return labels

        # Get index of one or three other images
        indexes = self.get_indexes()
        if isinstance(indexes, int):
            indexes = [indexes]

        # Get images information will be used for Mosaic or MixUp
        mix_labels = [self.dataset.get_image_and_label(i) for i in indexes]

        if self.pre_transform is not None:
            for i, data in enumerate(mix_labels):
                mix_labels[i] = self.pre_transform(data)
        labels["mix_labels"] = mix_labels

        # Update cls and texts
        labels = self._update_label_text(labels)
        # Mosaic or MixUp
        labels = self._mix_transform(labels)
        labels.pop("mix_labels", None)
        return labels

    def _mix_transform(self, labels):
        """Applies MixUp or Mosaic augmentation to the label dictionary."""
        raise NotImplementedError

    def get_indexes(self):
        """Gets a list of shuffled indexes for mosaic augmentation."""
        raise NotImplementedError

    def _update_label_text(self, labels):
        """Update label text."""
        if "texts" not in labels:
            return labels

        mix_texts = sum([labels["texts"]] + [x["texts"] for x in labels["mix_labels"]], [])
        mix_texts = list({tuple(x) for x in mix_texts})
        text2id = {text: i for i, text in enumerate(mix_texts)}

        for label in [labels] + labels["mix_labels"]:
            for i, cls in enumerate(label["cls"].squeeze(-1).tolist()):
                text = label["texts"][int(cls)]
                label["cls"][i] = text2id[tuple(text)]
            label["texts"] = mix_texts
        return labels

__call__(labels)

Applies pre-processing transforms and mixup/mosaic transforms to labels data.

Source code in ultralytics/data/augment.py
def __call__(self, labels):
    """Applies pre-processing transforms and mixup/mosaic transforms to labels data."""
    if random.uniform(0, 1) > self.p:
        return labels

    # Get index of one or three other images
    indexes = self.get_indexes()
    if isinstance(indexes, int):
        indexes = [indexes]

    # Get images information will be used for Mosaic or MixUp
    mix_labels = [self.dataset.get_image_and_label(i) for i in indexes]

    if self.pre_transform is not None:
        for i, data in enumerate(mix_labels):
            mix_labels[i] = self.pre_transform(data)
    labels["mix_labels"] = mix_labels

    # Update cls and texts
    labels = self._update_label_text(labels)
    # Mosaic or MixUp
    labels = self._mix_transform(labels)
    labels.pop("mix_labels", None)
    return labels

__init__(dataset, pre_transform=None, p=0.0)

Initializes the BaseMixTransform object with dataset, pre_transform, and probability.

Source code in ultralytics/data/augment.py
def __init__(self, dataset, pre_transform=None, p=0.0) -> None:
    """Initializes the BaseMixTransform object with dataset, pre_transform, and probability."""
    self.dataset = dataset
    self.pre_transform = pre_transform
    self.p = p

get_indexes()

Gets a list of shuffled indexes for mosaic augmentation.

Source code in ultralytics/data/augment.py
def get_indexes(self):
    """Gets a list of shuffled indexes for mosaic augmentation."""
    raise NotImplementedError



ultralytics.data.augment.Mosaic

Bases: BaseMixTransform

Mosaic augmentation.

This class performs mosaic augmentation by combining multiple (4 or 9) images into a single mosaic image. The augmentation is applied to a dataset with a given probability.

Attributes:

Name Type Description
dataset

The dataset on which the mosaic augmentation is applied.

imgsz int

Image size (height and width) after mosaic pipeline of a single image. Default to 640.

p float

Probability of applying the mosaic augmentation. Must be in the range 0-1. Default to 1.0.

n int

The grid size, either 4 (for 2x2) or 9 (for 3x3).

Source code in ultralytics/data/augment.py
class Mosaic(BaseMixTransform):
    """
    Mosaic augmentation.

    This class performs mosaic augmentation by combining multiple (4 or 9) images into a single mosaic image.
    The augmentation is applied to a dataset with a given probability.

    Attributes:
        dataset: The dataset on which the mosaic augmentation is applied.
        imgsz (int, optional): Image size (height and width) after mosaic pipeline of a single image. Default to 640.
        p (float, optional): Probability of applying the mosaic augmentation. Must be in the range 0-1. Default to 1.0.
        n (int, optional): The grid size, either 4 (for 2x2) or 9 (for 3x3).
    """

    def __init__(self, dataset, imgsz=640, p=1.0, n=4):
        """Initializes the object with a dataset, image size, probability, and border."""
        assert 0 <= p <= 1.0, f"The probability should be in range [0, 1], but got {p}."
        assert n in {4, 9}, "grid must be equal to 4 or 9."
        super().__init__(dataset=dataset, p=p)
        self.dataset = dataset
        self.imgsz = imgsz
        self.border = (-imgsz // 2, -imgsz // 2)  # width, height
        self.n = n

    def get_indexes(self, buffer=True):
        """Return a list of random indexes from the dataset."""
        if buffer:  # select images from buffer
            return random.choices(list(self.dataset.buffer), k=self.n - 1)
        else:  # select any images
            return [random.randint(0, len(self.dataset) - 1) for _ in range(self.n - 1)]

    def _mix_transform(self, labels):
        """Apply mixup transformation to the input image and labels."""
        assert labels.get("rect_shape", None) is None, "rect and mosaic are mutually exclusive."
        assert len(labels.get("mix_labels", [])), "There are no other images for mosaic augment."
        return (
            self._mosaic3(labels) if self.n == 3 else self._mosaic4(labels) if self.n == 4 else self._mosaic9(labels)
        )  # This code is modified for mosaic3 method.

    def _mosaic3(self, labels):
        """Create a 1x3 image mosaic."""
        mosaic_labels = []
        s = self.imgsz
        for i in range(3):
            labels_patch = labels if i == 0 else labels["mix_labels"][i - 1]
            # Load image
            img = labels_patch["img"]
            h, w = labels_patch.pop("resized_shape")

            # Place img in img3
            if i == 0:  # center
                img3 = np.full((s * 3, s * 3, img.shape[2]), 114, dtype=np.uint8)  # base image with 3 tiles
                h0, w0 = h, w
                c = s, s, s + w, s + h  # xmin, ymin, xmax, ymax (base) coordinates
            elif i == 1:  # right
                c = s + w0, s, s + w0 + w, s + h
            elif i == 2:  # left
                c = s - w, s + h0 - h, s, s + h0

            padw, padh = c[:2]
            x1, y1, x2, y2 = (max(x, 0) for x in c)  # allocate coords

            img3[y1:y2, x1:x2] = img[y1 - padh :, x1 - padw :]  # img3[ymin:ymax, xmin:xmax]
            # hp, wp = h, w  # height, width previous for next iteration

            # Labels assuming imgsz*2 mosaic size
            labels_patch = self._update_labels(labels_patch, padw + self.border[0], padh + self.border[1])
            mosaic_labels.append(labels_patch)
        final_labels = self._cat_labels(mosaic_labels)

        final_labels["img"] = img3[-self.border[0] : self.border[0], -self.border[1] : self.border[1]]
        return final_labels

    def _mosaic4(self, labels):
        """Create a 2x2 image mosaic."""
        mosaic_labels = []
        s = self.imgsz
        yc, xc = (int(random.uniform(-x, 2 * s + x)) for x in self.border)  # mosaic center x, y
        for i in range(4):
            labels_patch = labels if i == 0 else labels["mix_labels"][i - 1]
            # Load image
            img = labels_patch["img"]
            h, w = labels_patch.pop("resized_shape")

            # Place img in img4
            if i == 0:  # top left
                img4 = np.full((s * 2, s * 2, img.shape[2]), 114, dtype=np.uint8)  # base image with 4 tiles
                x1a, y1a, x2a, y2a = max(xc - w, 0), max(yc - h, 0), xc, yc  # xmin, ymin, xmax, ymax (large image)
                x1b, y1b, x2b, y2b = w - (x2a - x1a), h - (y2a - y1a), w, h  # xmin, ymin, xmax, ymax (small image)
            elif i == 1:  # top right
                x1a, y1a, x2a, y2a = xc, max(yc - h, 0), min(xc + w, s * 2), yc
                x1b, y1b, x2b, y2b = 0, h - (y2a - y1a), min(w, x2a - x1a), h
            elif i == 2:  # bottom left
                x1a, y1a, x2a, y2a = max(xc - w, 0), yc, xc, min(s * 2, yc + h)
                x1b, y1b, x2b, y2b = w - (x2a - x1a), 0, w, min(y2a - y1a, h)
            elif i == 3:  # bottom right
                x1a, y1a, x2a, y2a = xc, yc, min(xc + w, s * 2), min(s * 2, yc + h)
                x1b, y1b, x2b, y2b = 0, 0, min(w, x2a - x1a), min(y2a - y1a, h)

            img4[y1a:y2a, x1a:x2a] = img[y1b:y2b, x1b:x2b]  # img4[ymin:ymax, xmin:xmax]
            padw = x1a - x1b
            padh = y1a - y1b

            labels_patch = self._update_labels(labels_patch, padw, padh)
            mosaic_labels.append(labels_patch)
        final_labels = self._cat_labels(mosaic_labels)
        final_labels["img"] = img4
        return final_labels

    def _mosaic9(self, labels):
        """Create a 3x3 image mosaic."""
        mosaic_labels = []
        s = self.imgsz
        hp, wp = -1, -1  # height, width previous
        for i in range(9):
            labels_patch = labels if i == 0 else labels["mix_labels"][i - 1]
            # Load image
            img = labels_patch["img"]
            h, w = labels_patch.pop("resized_shape")

            # Place img in img9
            if i == 0:  # center
                img9 = np.full((s * 3, s * 3, img.shape[2]), 114, dtype=np.uint8)  # base image with 4 tiles
                h0, w0 = h, w
                c = s, s, s + w, s + h  # xmin, ymin, xmax, ymax (base) coordinates
            elif i == 1:  # top
                c = s, s - h, s + w, s
            elif i == 2:  # top right
                c = s + wp, s - h, s + wp + w, s
            elif i == 3:  # right
                c = s + w0, s, s + w0 + w, s + h
            elif i == 4:  # bottom right
                c = s + w0, s + hp, s + w0 + w, s + hp + h
            elif i == 5:  # bottom
                c = s + w0 - w, s + h0, s + w0, s + h0 + h
            elif i == 6:  # bottom left
                c = s + w0 - wp - w, s + h0, s + w0 - wp, s + h0 + h
            elif i == 7:  # left
                c = s - w, s + h0 - h, s, s + h0
            elif i == 8:  # top left
                c = s - w, s + h0 - hp - h, s, s + h0 - hp

            padw, padh = c[:2]
            x1, y1, x2, y2 = (max(x, 0) for x in c)  # allocate coords

            # Image
            img9[y1:y2, x1:x2] = img[y1 - padh :, x1 - padw :]  # img9[ymin:ymax, xmin:xmax]
            hp, wp = h, w  # height, width previous for next iteration

            # Labels assuming imgsz*2 mosaic size
            labels_patch = self._update_labels(labels_patch, padw + self.border[0], padh + self.border[1])
            mosaic_labels.append(labels_patch)
        final_labels = self._cat_labels(mosaic_labels)

        final_labels["img"] = img9[-self.border[0] : self.border[0], -self.border[1] : self.border[1]]
        return final_labels

    @staticmethod
    def _update_labels(labels, padw, padh):
        """Update labels."""
        nh, nw = labels["img"].shape[:2]
        labels["instances"].convert_bbox(format="xyxy")
        labels["instances"].denormalize(nw, nh)
        labels["instances"].add_padding(padw, padh)
        return labels

    def _cat_labels(self, mosaic_labels):
        """Return labels with mosaic border instances clipped."""
        if len(mosaic_labels) == 0:
            return {}
        cls = []
        instances = []
        imgsz = self.imgsz * 2  # mosaic imgsz
        for labels in mosaic_labels:
            cls.append(labels["cls"])
            instances.append(labels["instances"])
        # Final labels
        final_labels = {
            "im_file": mosaic_labels[0]["im_file"],
            "ori_shape": mosaic_labels[0]["ori_shape"],
            "resized_shape": (imgsz, imgsz),
            "cls": np.concatenate(cls, 0),
            "instances": Instances.concatenate(instances, axis=0),
            "mosaic_border": self.border,
        }
        final_labels["instances"].clip(imgsz, imgsz)
        good = final_labels["instances"].remove_zero_area_boxes()
        final_labels["cls"] = final_labels["cls"][good]
        if "texts" in mosaic_labels[0]:
            final_labels["texts"] = mosaic_labels[0]["texts"]
        return final_labels

__init__(dataset, imgsz=640, p=1.0, n=4)

Initializes the object with a dataset, image size, probability, and border.

Source code in ultralytics/data/augment.py
def __init__(self, dataset, imgsz=640, p=1.0, n=4):
    """Initializes the object with a dataset, image size, probability, and border."""
    assert 0 <= p <= 1.0, f"The probability should be in range [0, 1], but got {p}."
    assert n in {4, 9}, "grid must be equal to 4 or 9."
    super().__init__(dataset=dataset, p=p)
    self.dataset = dataset
    self.imgsz = imgsz
    self.border = (-imgsz // 2, -imgsz // 2)  # width, height
    self.n = n

get_indexes(buffer=True)

Return a list of random indexes from the dataset.

Source code in ultralytics/data/augment.py
def get_indexes(self, buffer=True):
    """Return a list of random indexes from the dataset."""
    if buffer:  # select images from buffer
        return random.choices(list(self.dataset.buffer), k=self.n - 1)
    else:  # select any images
        return [random.randint(0, len(self.dataset) - 1) for _ in range(self.n - 1)]



ultralytics.data.augment.MixUp

Bases: BaseMixTransform

Class for applying MixUp augmentation to the dataset.

Source code in ultralytics/data/augment.py
class MixUp(BaseMixTransform):
    """Class for applying MixUp augmentation to the dataset."""

    def __init__(self, dataset, pre_transform=None, p=0.0) -> None:
        """Initializes MixUp object with dataset, pre_transform, and probability of applying MixUp."""
        super().__init__(dataset=dataset, pre_transform=pre_transform, p=p)

    def get_indexes(self):
        """Get a random index from the dataset."""
        return random.randint(0, len(self.dataset) - 1)

    def _mix_transform(self, labels):
        """Applies MixUp augmentation as per https://arxiv.org/pdf/1710.09412.pdf."""
        r = np.random.beta(32.0, 32.0)  # mixup ratio, alpha=beta=32.0
        labels2 = labels["mix_labels"][0]
        labels["img"] = (labels["img"] * r + labels2["img"] * (1 - r)).astype(np.uint8)
        labels["instances"] = Instances.concatenate([labels["instances"], labels2["instances"]], axis=0)
        labels["cls"] = np.concatenate([labels["cls"], labels2["cls"]], 0)
        return labels

__init__(dataset, pre_transform=None, p=0.0)

Initializes MixUp object with dataset, pre_transform, and probability of applying MixUp.

Source code in ultralytics/data/augment.py
def __init__(self, dataset, pre_transform=None, p=0.0) -> None:
    """Initializes MixUp object with dataset, pre_transform, and probability of applying MixUp."""
    super().__init__(dataset=dataset, pre_transform=pre_transform, p=p)

get_indexes()

Get a random index from the dataset.

Source code in ultralytics/data/augment.py
def get_indexes(self):
    """Get a random index from the dataset."""
    return random.randint(0, len(self.dataset) - 1)



ultralytics.data.augment.RandomPerspective

Implements random perspective and affine transformations on images and corresponding bounding boxes, segments, and keypoints. These transformations include rotation, translation, scaling, and shearing. The class also offers the option to apply these transformations conditionally with a specified probability.

Attributes:

Name Type Description
degrees float

Degree range for random rotations.

translate float

Fraction of total width and height for random translation.

scale float

Scaling factor interval, e.g., a scale factor of 0.1 allows a resize between 90%-110%.

shear float

Shear intensity (angle in degrees).

perspective float

Perspective distortion factor.

border tuple

Tuple specifying mosaic border.

pre_transform callable

A function/transform to apply to the image before starting the random transformation.

Methods:

Name Description
affine_transform

Applies a series of affine transformations to the image.

apply_bboxes

Transforms bounding boxes using the calculated affine matrix.

apply_segments

Transforms segments and generates new bounding boxes.

apply_keypoints

Transforms keypoints.

__call__

Main method to apply transformations to both images and their corresponding annotations.

box_candidates

Filters out bounding boxes that don't meet certain criteria post-transformation.

Source code in ultralytics/data/augment.py
class RandomPerspective:
    """
    Implements random perspective and affine transformations on images and corresponding bounding boxes, segments, and
    keypoints. These transformations include rotation, translation, scaling, and shearing. The class also offers the
    option to apply these transformations conditionally with a specified probability.

    Attributes:
        degrees (float): Degree range for random rotations.
        translate (float): Fraction of total width and height for random translation.
        scale (float): Scaling factor interval, e.g., a scale factor of 0.1 allows a resize between 90%-110%.
        shear (float): Shear intensity (angle in degrees).
        perspective (float): Perspective distortion factor.
        border (tuple): Tuple specifying mosaic border.
        pre_transform (callable): A function/transform to apply to the image before starting the random transformation.

    Methods:
        affine_transform(img, border): Applies a series of affine transformations to the image.
        apply_bboxes(bboxes, M): Transforms bounding boxes using the calculated affine matrix.
        apply_segments(segments, M): Transforms segments and generates new bounding boxes.
        apply_keypoints(keypoints, M): Transforms keypoints.
        __call__(labels): Main method to apply transformations to both images and their corresponding annotations.
        box_candidates(box1, box2): Filters out bounding boxes that don't meet certain criteria post-transformation.
    """

    def __init__(
        self, degrees=0.0, translate=0.1, scale=0.5, shear=0.0, perspective=0.0, border=(0, 0), pre_transform=None
    ):
        """Initializes RandomPerspective object with transformation parameters."""

        self.degrees = degrees
        self.translate = translate
        self.scale = scale
        self.shear = shear
        self.perspective = perspective
        self.border = border  # mosaic border
        self.pre_transform = pre_transform

    def affine_transform(self, img, border):
        """
        Applies a sequence of affine transformations centered around the image center.

        Args:
            img (ndarray): Input image.
            border (tuple): Border dimensions.

        Returns:
            img (ndarray): Transformed image.
            M (ndarray): Transformation matrix.
            s (float): Scale factor.
        """

        # Center
        C = np.eye(3, dtype=np.float32)

        C[0, 2] = -img.shape[1] / 2  # x translation (pixels)
        C[1, 2] = -img.shape[0] / 2  # y translation (pixels)

        # Perspective
        P = np.eye(3, dtype=np.float32)
        P[2, 0] = random.uniform(-self.perspective, self.perspective)  # x perspective (about y)
        P[2, 1] = random.uniform(-self.perspective, self.perspective)  # y perspective (about x)

        # Rotation and Scale
        R = np.eye(3, dtype=np.float32)
        a = random.uniform(-self.degrees, self.degrees)
        # a += random.choice([-180, -90, 0, 90])  # add 90deg rotations to small rotations
        s = random.uniform(1 - self.scale, 1 + self.scale)
        # s = 2 ** random.uniform(-scale, scale)
        R[:2] = cv2.getRotationMatrix2D(angle=a, center=(0, 0), scale=s)

        # Shear
        S = np.eye(3, dtype=np.float32)
        S[0, 1] = math.tan(random.uniform(-self.shear, self.shear) * math.pi / 180)  # x shear (deg)
        S[1, 0] = math.tan(random.uniform(-self.shear, self.shear) * math.pi / 180)  # y shear (deg)

        # Translation
        T = np.eye(3, dtype=np.float32)
        T[0, 2] = random.uniform(0.5 - self.translate, 0.5 + self.translate) * self.size[0]  # x translation (pixels)
        T[1, 2] = random.uniform(0.5 - self.translate, 0.5 + self.translate) * self.size[1]  # y translation (pixels)

        # Combined rotation matrix
        M = T @ S @ R @ P @ C  # order of operations (right to left) is IMPORTANT
        # Affine image
        if (border[0] != 0) or (border[1] != 0) or (M != np.eye(3)).any():  # image changed
            if self.perspective:
                img = cv2.warpPerspective(img, M, dsize=self.size, borderValue=(114, 114, 114))
            else:  # affine
                img = cv2.warpAffine(img, M[:2], dsize=self.size, borderValue=(114, 114, 114))
        return img, M, s

    def apply_bboxes(self, bboxes, M):
        """
        Apply affine to bboxes only.

        Args:
            bboxes (ndarray): list of bboxes, xyxy format, with shape (num_bboxes, 4).
            M (ndarray): affine matrix.

        Returns:
            new_bboxes (ndarray): bboxes after affine, [num_bboxes, 4].
        """
        n = len(bboxes)
        if n == 0:
            return bboxes

        xy = np.ones((n * 4, 3), dtype=bboxes.dtype)
        xy[:, :2] = bboxes[:, [0, 1, 2, 3, 0, 3, 2, 1]].reshape(n * 4, 2)  # x1y1, x2y2, x1y2, x2y1
        xy = xy @ M.T  # transform
        xy = (xy[:, :2] / xy[:, 2:3] if self.perspective else xy[:, :2]).reshape(n, 8)  # perspective rescale or affine

        # Create new boxes
        x = xy[:, [0, 2, 4, 6]]
        y = xy[:, [1, 3, 5, 7]]
        return np.concatenate((x.min(1), y.min(1), x.max(1), y.max(1)), dtype=bboxes.dtype).reshape(4, n).T

    def apply_segments(self, segments, M):
        """
        Apply affine to segments and generate new bboxes from segments.

        Args:
            segments (ndarray): list of segments, [num_samples, 500, 2].
            M (ndarray): affine matrix.

        Returns:
            new_segments (ndarray): list of segments after affine, [num_samples, 500, 2].
            new_bboxes (ndarray): bboxes after affine, [N, 4].
        """
        n, num = segments.shape[:2]
        if n == 0:
            return [], segments

        xy = np.ones((n * num, 3), dtype=segments.dtype)
        segments = segments.reshape(-1, 2)
        xy[:, :2] = segments
        xy = xy @ M.T  # transform
        xy = xy[:, :2] / xy[:, 2:3]
        segments = xy.reshape(n, -1, 2)
        bboxes = np.stack([segment2box(xy, self.size[0], self.size[1]) for xy in segments], 0)
        segments[..., 0] = segments[..., 0].clip(bboxes[:, 0:1], bboxes[:, 2:3])
        segments[..., 1] = segments[..., 1].clip(bboxes[:, 1:2], bboxes[:, 3:4])
        return bboxes, segments

    def apply_keypoints(self, keypoints, M):
        """
        Apply affine to keypoints.

        Args:
            keypoints (ndarray): keypoints, [N, 17, 3].
            M (ndarray): affine matrix.

        Returns:
            new_keypoints (ndarray): keypoints after affine, [N, 17, 3].
        """
        n, nkpt = keypoints.shape[:2]
        if n == 0:
            return keypoints
        xy = np.ones((n * nkpt, 3), dtype=keypoints.dtype)
        visible = keypoints[..., 2].reshape(n * nkpt, 1)
        xy[:, :2] = keypoints[..., :2].reshape(n * nkpt, 2)
        xy = xy @ M.T  # transform
        xy = xy[:, :2] / xy[:, 2:3]  # perspective rescale or affine
        out_mask = (xy[:, 0] < 0) | (xy[:, 1] < 0) | (xy[:, 0] > self.size[0]) | (xy[:, 1] > self.size[1])
        visible[out_mask] = 0
        return np.concatenate([xy, visible], axis=-1).reshape(n, nkpt, 3)

    def __call__(self, labels):
        """
        Affine images and targets.

        Args:
            labels (dict): a dict of `bboxes`, `segments`, `keypoints`.
        """
        if self.pre_transform and "mosaic_border" not in labels:
            labels = self.pre_transform(labels)
        labels.pop("ratio_pad", None)  # do not need ratio pad

        img = labels["img"]
        cls = labels["cls"]
        instances = labels.pop("instances")
        # Make sure the coord formats are right
        instances.convert_bbox(format="xyxy")
        instances.denormalize(*img.shape[:2][::-1])

        border = labels.pop("mosaic_border", self.border)
        self.size = img.shape[1] + border[1] * 2, img.shape[0] + border[0] * 2  # w, h
        # M is affine matrix
        # Scale for func:`box_candidates`
        img, M, scale = self.affine_transform(img, border)

        bboxes = self.apply_bboxes(instances.bboxes, M)

        segments = instances.segments
        keypoints = instances.keypoints
        # Update bboxes if there are segments.
        if len(segments):
            bboxes, segments = self.apply_segments(segments, M)

        if keypoints is not None:
            keypoints = self.apply_keypoints(keypoints, M)
        new_instances = Instances(bboxes, segments, keypoints, bbox_format="xyxy", normalized=False)
        # Clip
        new_instances.clip(*self.size)

        # Filter instances
        instances.scale(scale_w=scale, scale_h=scale, bbox_only=True)
        # Make the bboxes have the same scale with new_bboxes
        i = self.box_candidates(
            box1=instances.bboxes.T, box2=new_instances.bboxes.T, area_thr=0.01 if len(segments) else 0.10
        )
        labels["instances"] = new_instances[i]
        labels["cls"] = cls[i]
        labels["img"] = img
        labels["resized_shape"] = img.shape[:2]
        return labels

    def box_candidates(self, box1, box2, wh_thr=2, ar_thr=100, area_thr=0.1, eps=1e-16):
        """
        Compute box candidates based on a set of thresholds. This method compares the characteristics of the boxes
        before and after augmentation to decide whether a box is a candidate for further processing.

        Args:
            box1 (numpy.ndarray): The 4,n bounding box before augmentation, represented as [x1, y1, x2, y2].
            box2 (numpy.ndarray): The 4,n bounding box after augmentation, represented as [x1, y1, x2, y2].
            wh_thr (float, optional): The width and height threshold in pixels. Default is 2.
            ar_thr (float, optional): The aspect ratio threshold. Default is 100.
            area_thr (float, optional): The area ratio threshold. Default is 0.1.
            eps (float, optional): A small epsilon value to prevent division by zero. Default is 1e-16.

        Returns:
            (numpy.ndarray): A boolean array indicating which boxes are candidates based on the given thresholds.
        """
        w1, h1 = box1[2] - box1[0], box1[3] - box1[1]
        w2, h2 = box2[2] - box2[0], box2[3] - box2[1]
        ar = np.maximum(w2 / (h2 + eps), h2 / (w2 + eps))  # aspect ratio
        return (w2 > wh_thr) & (h2 > wh_thr) & (w2 * h2 / (w1 * h1 + eps) > area_thr) & (ar < ar_thr)  # candidates

__call__(labels)

Affine images and targets.

Parameters:

Name Type Description Default
labels dict

a dict of bboxes, segments, keypoints.

required
Source code in ultralytics/data/augment.py
def __call__(self, labels):
    """
    Affine images and targets.

    Args:
        labels (dict): a dict of `bboxes`, `segments`, `keypoints`.
    """
    if self.pre_transform and "mosaic_border" not in labels:
        labels = self.pre_transform(labels)
    labels.pop("ratio_pad", None)  # do not need ratio pad

    img = labels["img"]
    cls = labels["cls"]
    instances = labels.pop("instances")
    # Make sure the coord formats are right
    instances.convert_bbox(format="xyxy")
    instances.denormalize(*img.shape[:2][::-1])

    border = labels.pop("mosaic_border", self.border)
    self.size = img.shape[1] + border[1] * 2, img.shape[0] + border[0] * 2  # w, h
    # M is affine matrix
    # Scale for func:`box_candidates`
    img, M, scale = self.affine_transform(img, border)

    bboxes = self.apply_bboxes(instances.bboxes, M)

    segments = instances.segments
    keypoints = instances.keypoints
    # Update bboxes if there are segments.
    if len(segments):
        bboxes, segments = self.apply_segments(segments, M)

    if keypoints is not None:
        keypoints = self.apply_keypoints(keypoints, M)
    new_instances = Instances(bboxes, segments, keypoints, bbox_format="xyxy", normalized=False)
    # Clip
    new_instances.clip(*self.size)

    # Filter instances
    instances.scale(scale_w=scale, scale_h=scale, bbox_only=True)
    # Make the bboxes have the same scale with new_bboxes
    i = self.box_candidates(
        box1=instances.bboxes.T, box2=new_instances.bboxes.T, area_thr=0.01 if len(segments) else 0.10
    )
    labels["instances"] = new_instances[i]
    labels["cls"] = cls[i]
    labels["img"] = img
    labels["resized_shape"] = img.shape[:2]
    return labels

__init__(degrees=0.0, translate=0.1, scale=0.5, shear=0.0, perspective=0.0, border=(0, 0), pre_transform=None)

Initializes RandomPerspective object with transformation parameters.

Source code in ultralytics/data/augment.py
def __init__(
    self, degrees=0.0, translate=0.1, scale=0.5, shear=0.0, perspective=0.0, border=(0, 0), pre_transform=None
):
    """Initializes RandomPerspective object with transformation parameters."""

    self.degrees = degrees
    self.translate = translate
    self.scale = scale
    self.shear = shear
    self.perspective = perspective
    self.border = border  # mosaic border
    self.pre_transform = pre_transform

affine_transform(img, border)

Applies a sequence of affine transformations centered around the image center.

Parameters:

Name Type Description Default
img ndarray

Input image.

required
border tuple

Border dimensions.

required

Returns:

Name Type Description
img ndarray

Transformed image.

M ndarray

Transformation matrix.

s float

Scale factor.

Source code in ultralytics/data/augment.py
def affine_transform(self, img, border):
    """
    Applies a sequence of affine transformations centered around the image center.

    Args:
        img (ndarray): Input image.
        border (tuple): Border dimensions.

    Returns:
        img (ndarray): Transformed image.
        M (ndarray): Transformation matrix.
        s (float): Scale factor.
    """

    # Center
    C = np.eye(3, dtype=np.float32)

    C[0, 2] = -img.shape[1] / 2  # x translation (pixels)
    C[1, 2] = -img.shape[0] / 2  # y translation (pixels)

    # Perspective
    P = np.eye(3, dtype=np.float32)
    P[2, 0] = random.uniform(-self.perspective, self.perspective)  # x perspective (about y)
    P[2, 1] = random.uniform(-self.perspective, self.perspective)  # y perspective (about x)

    # Rotation and Scale
    R = np.eye(3, dtype=np.float32)
    a = random.uniform(-self.degrees, self.degrees)
    # a += random.choice([-180, -90, 0, 90])  # add 90deg rotations to small rotations
    s = random.uniform(1 - self.scale, 1 + self.scale)
    # s = 2 ** random.uniform(-scale, scale)
    R[:2] = cv2.getRotationMatrix2D(angle=a, center=(0, 0), scale=s)

    # Shear
    S = np.eye(3, dtype=np.float32)
    S[0, 1] = math.tan(random.uniform(-self.shear, self.shear) * math.pi / 180)  # x shear (deg)
    S[1, 0] = math.tan(random.uniform(-self.shear, self.shear) * math.pi / 180)  # y shear (deg)

    # Translation
    T = np.eye(3, dtype=np.float32)
    T[0, 2] = random.uniform(0.5 - self.translate, 0.5 + self.translate) * self.size[0]  # x translation (pixels)
    T[1, 2] = random.uniform(0.5 - self.translate, 0.5 + self.translate) * self.size[1]  # y translation (pixels)

    # Combined rotation matrix
    M = T @ S @ R @ P @ C  # order of operations (right to left) is IMPORTANT
    # Affine image
    if (border[0] != 0) or (border[1] != 0) or (M != np.eye(3)).any():  # image changed
        if self.perspective:
            img = cv2.warpPerspective(img, M, dsize=self.size, borderValue=(114, 114, 114))
        else:  # affine
            img = cv2.warpAffine(img, M[:2], dsize=self.size, borderValue=(114, 114, 114))
    return img, M, s

apply_bboxes(bboxes, M)

Apply affine to bboxes only.

Parameters:

Name Type Description Default
bboxes ndarray

list of bboxes, xyxy format, with shape (num_bboxes, 4).

required
M ndarray

affine matrix.

required

Returns:

Name Type Description
new_bboxes ndarray

bboxes after affine, [num_bboxes, 4].

Source code in ultralytics/data/augment.py
def apply_bboxes(self, bboxes, M):
    """
    Apply affine to bboxes only.

    Args:
        bboxes (ndarray): list of bboxes, xyxy format, with shape (num_bboxes, 4).
        M (ndarray): affine matrix.

    Returns:
        new_bboxes (ndarray): bboxes after affine, [num_bboxes, 4].
    """
    n = len(bboxes)
    if n == 0:
        return bboxes

    xy = np.ones((n * 4, 3), dtype=bboxes.dtype)
    xy[:, :2] = bboxes[:, [0, 1, 2, 3, 0, 3, 2, 1]].reshape(n * 4, 2)  # x1y1, x2y2, x1y2, x2y1
    xy = xy @ M.T  # transform
    xy = (xy[:, :2] / xy[:, 2:3] if self.perspective else xy[:, :2]).reshape(n, 8)  # perspective rescale or affine

    # Create new boxes
    x = xy[:, [0, 2, 4, 6]]
    y = xy[:, [1, 3, 5, 7]]
    return np.concatenate((x.min(1), y.min(1), x.max(1), y.max(1)), dtype=bboxes.dtype).reshape(4, n).T

apply_keypoints(keypoints, M)

Apply affine to keypoints.

Parameters:

Name Type Description Default
keypoints ndarray

keypoints, [N, 17, 3].

required
M ndarray

affine matrix.

required

Returns:

Name Type Description
new_keypoints ndarray

keypoints after affine, [N, 17, 3].

Source code in ultralytics/data/augment.py
def apply_keypoints(self, keypoints, M):
    """
    Apply affine to keypoints.

    Args:
        keypoints (ndarray): keypoints, [N, 17, 3].
        M (ndarray): affine matrix.

    Returns:
        new_keypoints (ndarray): keypoints after affine, [N, 17, 3].
    """
    n, nkpt = keypoints.shape[:2]
    if n == 0:
        return keypoints
    xy = np.ones((n * nkpt, 3), dtype=keypoints.dtype)
    visible = keypoints[..., 2].reshape(n * nkpt, 1)
    xy[:, :2] = keypoints[..., :2].reshape(n * nkpt, 2)
    xy = xy @ M.T  # transform
    xy = xy[:, :2] / xy[:, 2:3]  # perspective rescale or affine
    out_mask = (xy[:, 0] < 0) | (xy[:, 1] < 0) | (xy[:, 0] > self.size[0]) | (xy[:, 1] > self.size[1])
    visible[out_mask] = 0
    return np.concatenate([xy, visible], axis=-1).reshape(n, nkpt, 3)

apply_segments(segments, M)

Apply affine to segments and generate new bboxes from segments.

Parameters:

Name Type Description Default
segments ndarray

list of segments, [num_samples, 500, 2].

required
M ndarray

affine matrix.

required

Returns:

Name Type Description
new_segments ndarray

list of segments after affine, [num_samples, 500, 2].

new_bboxes ndarray

bboxes after affine, [N, 4].

Source code in ultralytics/data/augment.py
def apply_segments(self, segments, M):
    """
    Apply affine to segments and generate new bboxes from segments.

    Args:
        segments (ndarray): list of segments, [num_samples, 500, 2].
        M (ndarray): affine matrix.

    Returns:
        new_segments (ndarray): list of segments after affine, [num_samples, 500, 2].
        new_bboxes (ndarray): bboxes after affine, [N, 4].
    """
    n, num = segments.shape[:2]
    if n == 0:
        return [], segments

    xy = np.ones((n * num, 3), dtype=segments.dtype)
    segments = segments.reshape(-1, 2)
    xy[:, :2] = segments
    xy = xy @ M.T  # transform
    xy = xy[:, :2] / xy[:, 2:3]
    segments = xy.reshape(n, -1, 2)
    bboxes = np.stack([segment2box(xy, self.size[0], self.size[1]) for xy in segments], 0)
    segments[..., 0] = segments[..., 0].clip(bboxes[:, 0:1], bboxes[:, 2:3])
    segments[..., 1] = segments[..., 1].clip(bboxes[:, 1:2], bboxes[:, 3:4])
    return bboxes, segments

box_candidates(box1, box2, wh_thr=2, ar_thr=100, area_thr=0.1, eps=1e-16)

Compute box candidates based on a set of thresholds. This method compares the characteristics of the boxes before and after augmentation to decide whether a box is a candidate for further processing.

Parameters:

Name Type Description Default
box1 ndarray

The 4,n bounding box before augmentation, represented as [x1, y1, x2, y2].

required
box2 ndarray

The 4,n bounding box after augmentation, represented as [x1, y1, x2, y2].

required
wh_thr float

The width and height threshold in pixels. Default is 2.

2
ar_thr float

The aspect ratio threshold. Default is 100.

100
area_thr float

The area ratio threshold. Default is 0.1.

0.1
eps float

A small epsilon value to prevent division by zero. Default is 1e-16.

1e-16

Returns:

Type Description
ndarray

A boolean array indicating which boxes are candidates based on the given thresholds.

Source code in ultralytics/data/augment.py
def box_candidates(self, box1, box2, wh_thr=2, ar_thr=100, area_thr=0.1, eps=1e-16):
    """
    Compute box candidates based on a set of thresholds. This method compares the characteristics of the boxes
    before and after augmentation to decide whether a box is a candidate for further processing.

    Args:
        box1 (numpy.ndarray): The 4,n bounding box before augmentation, represented as [x1, y1, x2, y2].
        box2 (numpy.ndarray): The 4,n bounding box after augmentation, represented as [x1, y1, x2, y2].
        wh_thr (float, optional): The width and height threshold in pixels. Default is 2.
        ar_thr (float, optional): The aspect ratio threshold. Default is 100.
        area_thr (float, optional): The area ratio threshold. Default is 0.1.
        eps (float, optional): A small epsilon value to prevent division by zero. Default is 1e-16.

    Returns:
        (numpy.ndarray): A boolean array indicating which boxes are candidates based on the given thresholds.
    """
    w1, h1 = box1[2] - box1[0], box1[3] - box1[1]
    w2, h2 = box2[2] - box2[0], box2[3] - box2[1]
    ar = np.maximum(w2 / (h2 + eps), h2 / (w2 + eps))  # aspect ratio
    return (w2 > wh_thr) & (h2 > wh_thr) & (w2 * h2 / (w1 * h1 + eps) > area_thr) & (ar < ar_thr)  # candidates



ultralytics.data.augment.RandomHSV

This class is responsible for performing random adjustments to the Hue, Saturation, and Value (HSV) channels of an image.

The adjustments are random but within limits set by hgain, sgain, and vgain.

Source code in ultralytics/data/augment.py
class RandomHSV:
    """
    This class is responsible for performing random adjustments to the Hue, Saturation, and Value (HSV) channels of an
    image.

    The adjustments are random but within limits set by hgain, sgain, and vgain.
    """

    def __init__(self, hgain=0.5, sgain=0.5, vgain=0.5) -> None:
        """
        Initialize RandomHSV class with gains for each HSV channel.

        Args:
            hgain (float, optional): Maximum variation for hue. Default is 0.5.
            sgain (float, optional): Maximum variation for saturation. Default is 0.5.
            vgain (float, optional): Maximum variation for value. Default is 0.5.
        """
        self.hgain = hgain
        self.sgain = sgain
        self.vgain = vgain

    def __call__(self, labels):
        """
        Applies random HSV augmentation to an image within the predefined limits.

        The modified image replaces the original image in the input 'labels' dict.
        """
        img = labels["img"]
        if self.hgain or self.sgain or self.vgain:
            r = np.random.uniform(-1, 1, 3) * [self.hgain, self.sgain, self.vgain] + 1  # random gains
            hue, sat, val = cv2.split(cv2.cvtColor(img, cv2.COLOR_BGR2HSV))
            dtype = img.dtype  # uint8

            x = np.arange(0, 256, dtype=r.dtype)
            lut_hue = ((x * r[0]) % 180).astype(dtype)
            lut_sat = np.clip(x * r[1], 0, 255).astype(dtype)
            lut_val = np.clip(x * r[2], 0, 255).astype(dtype)

            im_hsv = cv2.merge((cv2.LUT(hue, lut_hue), cv2.LUT(sat, lut_sat), cv2.LUT(val, lut_val)))
            cv2.cvtColor(im_hsv, cv2.COLOR_HSV2BGR, dst=img)  # no return needed
        return labels

__call__(labels)

Applies random HSV augmentation to an image within the predefined limits.

The modified image replaces the original image in the input 'labels' dict.

Source code in ultralytics/data/augment.py
def __call__(self, labels):
    """
    Applies random HSV augmentation to an image within the predefined limits.

    The modified image replaces the original image in the input 'labels' dict.
    """
    img = labels["img"]
    if self.hgain or self.sgain or self.vgain:
        r = np.random.uniform(-1, 1, 3) * [self.hgain, self.sgain, self.vgain] + 1  # random gains
        hue, sat, val = cv2.split(cv2.cvtColor(img, cv2.COLOR_BGR2HSV))
        dtype = img.dtype  # uint8

        x = np.arange(0, 256, dtype=r.dtype)
        lut_hue = ((x * r[0]) % 180).astype(dtype)
        lut_sat = np.clip(x * r[1], 0, 255).astype(dtype)
        lut_val = np.clip(x * r[2], 0, 255).astype(dtype)

        im_hsv = cv2.merge((cv2.LUT(hue, lut_hue), cv2.LUT(sat, lut_sat), cv2.LUT(val, lut_val)))
        cv2.cvtColor(im_hsv, cv2.COLOR_HSV2BGR, dst=img)  # no return needed
    return labels

__init__(hgain=0.5, sgain=0.5, vgain=0.5)

Initialize RandomHSV class with gains for each HSV channel.

Parameters:

Name Type Description Default
hgain float

Maximum variation for hue. Default is 0.5.

0.5
sgain float

Maximum variation for saturation. Default is 0.5.

0.5
vgain float

Maximum variation for value. Default is 0.5.

0.5
Source code in ultralytics/data/augment.py
def __init__(self, hgain=0.5, sgain=0.5, vgain=0.5) -> None:
    """
    Initialize RandomHSV class with gains for each HSV channel.

    Args:
        hgain (float, optional): Maximum variation for hue. Default is 0.5.
        sgain (float, optional): Maximum variation for saturation. Default is 0.5.
        vgain (float, optional): Maximum variation for value. Default is 0.5.
    """
    self.hgain = hgain
    self.sgain = sgain
    self.vgain = vgain



ultralytics.data.augment.RandomFlip

Applies a random horizontal or vertical flip to an image with a given probability.

Also updates any instances (bounding boxes, keypoints, etc.) accordingly.

Source code in ultralytics/data/augment.py
class RandomFlip:
    """
    Applies a random horizontal or vertical flip to an image with a given probability.

    Also updates any instances (bounding boxes, keypoints, etc.) accordingly.
    """

    def __init__(self, p=0.5, direction="horizontal", flip_idx=None) -> None:
        """
        Initializes the RandomFlip class with probability and direction.

        Args:
            p (float, optional): The probability of applying the flip. Must be between 0 and 1. Default is 0.5.
            direction (str, optional): The direction to apply the flip. Must be 'horizontal' or 'vertical'.
                Default is 'horizontal'.
            flip_idx (array-like, optional): Index mapping for flipping keypoints, if any.
        """
        assert direction in {"horizontal", "vertical"}, f"Support direction `horizontal` or `vertical`, got {direction}"
        assert 0 <= p <= 1.0

        self.p = p
        self.direction = direction
        self.flip_idx = flip_idx

    def __call__(self, labels):
        """
        Applies random flip to an image and updates any instances like bounding boxes or keypoints accordingly.

        Args:
            labels (dict): A dictionary containing the keys 'img' and 'instances'. 'img' is the image to be flipped.
                           'instances' is an object containing bounding boxes and optionally keypoints.

        Returns:
            (dict): The same dict with the flipped image and updated instances under the 'img' and 'instances' keys.
        """
        img = labels["img"]
        instances = labels.pop("instances")
        instances.convert_bbox(format="xywh")
        h, w = img.shape[:2]
        h = 1 if instances.normalized else h
        w = 1 if instances.normalized else w

        # Flip up-down
        if self.direction == "vertical" and random.random() < self.p:
            img = np.flipud(img)
            instances.flipud(h)
        if self.direction == "horizontal" and random.random() < self.p:
            img = np.fliplr(img)
            instances.fliplr(w)
            # For keypoints
            if self.flip_idx is not None and instances.keypoints is not None:
                instances.keypoints = np.ascontiguousarray(instances.keypoints[:, self.flip_idx, :])
        labels["img"] = np.ascontiguousarray(img)
        labels["instances"] = instances
        return labels

__call__(labels)

Applies random flip to an image and updates any instances like bounding boxes or keypoints accordingly.

Parameters:

Name Type Description Default
labels dict

A dictionary containing the keys 'img' and 'instances'. 'img' is the image to be flipped. 'instances' is an object containing bounding boxes and optionally keypoints.

required

Returns:

Type Description
dict

The same dict with the flipped image and updated instances under the 'img' and 'instances' keys.

Source code in ultralytics/data/augment.py
def __call__(self, labels):
    """
    Applies random flip to an image and updates any instances like bounding boxes or keypoints accordingly.

    Args:
        labels (dict): A dictionary containing the keys 'img' and 'instances'. 'img' is the image to be flipped.
                       'instances' is an object containing bounding boxes and optionally keypoints.

    Returns:
        (dict): The same dict with the flipped image and updated instances under the 'img' and 'instances' keys.
    """
    img = labels["img"]
    instances = labels.pop("instances")
    instances.convert_bbox(format="xywh")
    h, w = img.shape[:2]
    h = 1 if instances.normalized else h
    w = 1 if instances.normalized else w

    # Flip up-down
    if self.direction == "vertical" and random.random() < self.p:
        img = np.flipud(img)
        instances.flipud(h)
    if self.direction == "horizontal" and random.random() < self.p:
        img = np.fliplr(img)
        instances.fliplr(w)
        # For keypoints
        if self.flip_idx is not None and instances.keypoints is not None:
            instances.keypoints = np.ascontiguousarray(instances.keypoints[:, self.flip_idx, :])
    labels["img"] = np.ascontiguousarray(img)
    labels["instances"] = instances
    return labels

__init__(p=0.5, direction='horizontal', flip_idx=None)

Initializes the RandomFlip class with probability and direction.

Parameters:

Name Type Description Default
p float

The probability of applying the flip. Must be between 0 and 1. Default is 0.5.

0.5
direction str

The direction to apply the flip. Must be 'horizontal' or 'vertical'. Default is 'horizontal'.

'horizontal'
flip_idx array - like

Index mapping for flipping keypoints, if any.

None
Source code in ultralytics/data/augment.py
def __init__(self, p=0.5, direction="horizontal", flip_idx=None) -> None:
    """
    Initializes the RandomFlip class with probability and direction.

    Args:
        p (float, optional): The probability of applying the flip. Must be between 0 and 1. Default is 0.5.
        direction (str, optional): The direction to apply the flip. Must be 'horizontal' or 'vertical'.
            Default is 'horizontal'.
        flip_idx (array-like, optional): Index mapping for flipping keypoints, if any.
    """
    assert direction in {"horizontal", "vertical"}, f"Support direction `horizontal` or `vertical`, got {direction}"
    assert 0 <= p <= 1.0

    self.p = p
    self.direction = direction
    self.flip_idx = flip_idx



ultralytics.data.augment.LetterBox

Resize image and padding for detection, instance segmentation, pose.

Source code in ultralytics/data/augment.py
class LetterBox:
    """Resize image and padding for detection, instance segmentation, pose."""

    def __init__(self, new_shape=(640, 640), auto=False, scaleFill=False, scaleup=True, center=True, stride=32):
        """Initialize LetterBox object with specific parameters."""
        self.new_shape = new_shape
        self.auto = auto
        self.scaleFill = scaleFill
        self.scaleup = scaleup
        self.stride = stride
        self.center = center  # Put the image in the middle or top-left

    def __call__(self, labels=None, image=None):
        """Return updated labels and image with added border."""
        if labels is None:
            labels = {}
        img = labels.get("img") if image is None else image
        shape = img.shape[:2]  # current shape [height, width]
        new_shape = labels.pop("rect_shape", self.new_shape)
        if isinstance(new_shape, int):
            new_shape = (new_shape, new_shape)

        # Scale ratio (new / old)
        r = min(new_shape[0] / shape[0], new_shape[1] / shape[1])
        if not self.scaleup:  # only scale down, do not scale up (for better val mAP)
            r = min(r, 1.0)

        # Compute padding
        ratio = r, r  # width, height ratios
        new_unpad = int(round(shape[1] * r)), int(round(shape[0] * r))
        dw, dh = new_shape[1] - new_unpad[0], new_shape[0] - new_unpad[1]  # wh padding
        if self.auto:  # minimum rectangle
            dw, dh = np.mod(dw, self.stride), np.mod(dh, self.stride)  # wh padding
        elif self.scaleFill:  # stretch
            dw, dh = 0.0, 0.0
            new_unpad = (new_shape[1], new_shape[0])
            ratio = new_shape[1] / shape[1], new_shape[0] / shape[0]  # width, height ratios

        if self.center:
            dw /= 2  # divide padding into 2 sides
            dh /= 2

        if shape[::-1] != new_unpad:  # resize
            img = cv2.resize(img, new_unpad, interpolation=cv2.INTER_LINEAR)
        top, bottom = int(round(dh - 0.1)) if self.center else 0, int(round(dh + 0.1))
        left, right = int(round(dw - 0.1)) if self.center else 0, int(round(dw + 0.1))
        img = cv2.copyMakeBorder(
            img, top, bottom, left, right, cv2.BORDER_CONSTANT, value=(114, 114, 114)
        )  # add border
        if labels.get("ratio_pad"):
            labels["ratio_pad"] = (labels["ratio_pad"], (left, top))  # for evaluation

        if len(labels):
            labels = self._update_labels(labels, ratio, dw, dh)
            labels["img"] = img
            labels["resized_shape"] = new_shape
            return labels
        else:
            return img

    def _update_labels(self, labels, ratio, padw, padh):
        """Update labels."""
        labels["instances"].convert_bbox(format="xyxy")
        labels["instances"].denormalize(*labels["img"].shape[:2][::-1])
        labels["instances"].scale(*ratio)
        labels["instances"].add_padding(padw, padh)
        return labels

__call__(labels=None, image=None)

Return updated labels and image with added border.

Source code in ultralytics/data/augment.py
def __call__(self, labels=None, image=None):
    """Return updated labels and image with added border."""
    if labels is None:
        labels = {}
    img = labels.get("img") if image is None else image
    shape = img.shape[:2]  # current shape [height, width]
    new_shape = labels.pop("rect_shape", self.new_shape)
    if isinstance(new_shape, int):
        new_shape = (new_shape, new_shape)

    # Scale ratio (new / old)
    r = min(new_shape[0] / shape[0], new_shape[1] / shape[1])
    if not self.scaleup:  # only scale down, do not scale up (for better val mAP)
        r = min(r, 1.0)

    # Compute padding
    ratio = r, r  # width, height ratios
    new_unpad = int(round(shape[1] * r)), int(round(shape[0] * r))
    dw, dh = new_shape[1] - new_unpad[0], new_shape[0] - new_unpad[1]  # wh padding
    if self.auto:  # minimum rectangle
        dw, dh = np.mod(dw, self.stride), np.mod(dh, self.stride)  # wh padding
    elif self.scaleFill:  # stretch
        dw, dh = 0.0, 0.0
        new_unpad = (new_shape[1], new_shape[0])
        ratio = new_shape[1] / shape[1], new_shape[0] / shape[0]  # width, height ratios

    if self.center:
        dw /= 2  # divide padding into 2 sides
        dh /= 2

    if shape[::-1] != new_unpad:  # resize
        img = cv2.resize(img, new_unpad, interpolation=cv2.INTER_LINEAR)
    top, bottom = int(round(dh - 0.1)) if self.center else 0, int(round(dh + 0.1))
    left, right = int(round(dw - 0.1)) if self.center else 0, int(round(dw + 0.1))
    img = cv2.copyMakeBorder(
        img, top, bottom, left, right, cv2.BORDER_CONSTANT, value=(114, 114, 114)
    )  # add border
    if labels.get("ratio_pad"):
        labels["ratio_pad"] = (labels["ratio_pad"], (left, top))  # for evaluation

    if len(labels):
        labels = self._update_labels(labels, ratio, dw, dh)
        labels["img"] = img
        labels["resized_shape"] = new_shape
        return labels
    else:
        return img

__init__(new_shape=(640, 640), auto=False, scaleFill=False, scaleup=True, center=True, stride=32)

Initialize LetterBox object with specific parameters.

Source code in ultralytics/data/augment.py
def __init__(self, new_shape=(640, 640), auto=False, scaleFill=False, scaleup=True, center=True, stride=32):
    """Initialize LetterBox object with specific parameters."""
    self.new_shape = new_shape
    self.auto = auto
    self.scaleFill = scaleFill
    self.scaleup = scaleup
    self.stride = stride
    self.center = center  # Put the image in the middle or top-left



ultralytics.data.augment.CopyPaste

Implements the Copy-Paste augmentation as described in the paper https://arxiv.org/abs/2012.07177. This class is responsible for applying the Copy-Paste augmentation on images and their corresponding instances.

Source code in ultralytics/data/augment.py
class CopyPaste:
    """
    Implements the Copy-Paste augmentation as described in the paper https://arxiv.org/abs/2012.07177. This class is
    responsible for applying the Copy-Paste augmentation on images and their corresponding instances.
    """

    def __init__(self, p=0.5) -> None:
        """
        Initializes the CopyPaste class with a given probability.

        Args:
            p (float, optional): The probability of applying the Copy-Paste augmentation. Must be between 0 and 1.
                                 Default is 0.5.
        """
        self.p = p

    def __call__(self, labels):
        """
        Applies the Copy-Paste augmentation to the given image and instances.

        Args:
            labels (dict): A dictionary containing:
                           - 'img': The image to augment.
                           - 'cls': Class labels associated with the instances.
                           - 'instances': Object containing bounding boxes, and optionally, keypoints and segments.

        Returns:
            (dict): Dict with augmented image and updated instances under the 'img', 'cls', and 'instances' keys.

        Notes:
            1. Instances are expected to have 'segments' as one of their attributes for this augmentation to work.
            2. This method modifies the input dictionary 'labels' in place.
        """
        im = labels["img"]
        cls = labels["cls"]
        h, w = im.shape[:2]
        instances = labels.pop("instances")
        instances.convert_bbox(format="xyxy")
        instances.denormalize(w, h)
        if self.p and len(instances.segments):
            n = len(instances)
            _, w, _ = im.shape  # height, width, channels
            im_new = np.zeros(im.shape, np.uint8)

            # Calculate ioa first then select indexes randomly
            ins_flip = deepcopy(instances)
            ins_flip.fliplr(w)

            ioa = bbox_ioa(ins_flip.bboxes, instances.bboxes)  # intersection over area, (N, M)
            indexes = np.nonzero((ioa < 0.30).all(1))[0]  # (N, )
            n = len(indexes)
            for j in random.sample(list(indexes), k=round(self.p * n)):
                cls = np.concatenate((cls, cls[[j]]), axis=0)
                instances = Instances.concatenate((instances, ins_flip[[j]]), axis=0)
                cv2.drawContours(im_new, instances.segments[[j]].astype(np.int32), -1, (1, 1, 1), cv2.FILLED)

            result = cv2.flip(im, 1)  # augment segments (flip left-right)
            i = cv2.flip(im_new, 1).astype(bool)
            im[i] = result[i]

        labels["img"] = im
        labels["cls"] = cls
        labels["instances"] = instances
        return labels

__call__(labels)

Applies the Copy-Paste augmentation to the given image and instances.

Parameters:

Name Type Description Default
labels dict

A dictionary containing: - 'img': The image to augment. - 'cls': Class labels associated with the instances. - 'instances': Object containing bounding boxes, and optionally, keypoints and segments.

required

Returns:

Type Description
dict

Dict with augmented image and updated instances under the 'img', 'cls', and 'instances' keys.

Notes
  1. Instances are expected to have 'segments' as one of their attributes for this augmentation to work.
  2. This method modifies the input dictionary 'labels' in place.
Source code in ultralytics/data/augment.py
def __call__(self, labels):
    """
    Applies the Copy-Paste augmentation to the given image and instances.

    Args:
        labels (dict): A dictionary containing:
                       - 'img': The image to augment.
                       - 'cls': Class labels associated with the instances.
                       - 'instances': Object containing bounding boxes, and optionally, keypoints and segments.

    Returns:
        (dict): Dict with augmented image and updated instances under the 'img', 'cls', and 'instances' keys.

    Notes:
        1. Instances are expected to have 'segments' as one of their attributes for this augmentation to work.
        2. This method modifies the input dictionary 'labels' in place.
    """
    im = labels["img"]
    cls = labels["cls"]
    h, w = im.shape[:2]
    instances = labels.pop("instances")
    instances.convert_bbox(format="xyxy")
    instances.denormalize(w, h)
    if self.p and len(instances.segments):
        n = len(instances)
        _, w, _ = im.shape  # height, width, channels
        im_new = np.zeros(im.shape, np.uint8)

        # Calculate ioa first then select indexes randomly
        ins_flip = deepcopy(instances)
        ins_flip.fliplr(w)

        ioa = bbox_ioa(ins_flip.bboxes, instances.bboxes)  # intersection over area, (N, M)
        indexes = np.nonzero((ioa < 0.30).all(1))[0]  # (N, )
        n = len(indexes)
        for j in random.sample(list(indexes), k=round(self.p * n)):
            cls = np.concatenate((cls, cls[[j]]), axis=0)
            instances = Instances.concatenate((instances, ins_flip[[j]]), axis=0)
            cv2.drawContours(im_new, instances.segments[[j]].astype(np.int32), -1, (1, 1, 1), cv2.FILLED)

        result = cv2.flip(im, 1)  # augment segments (flip left-right)
        i = cv2.flip(im_new, 1).astype(bool)
        im[i] = result[i]

    labels["img"] = im
    labels["cls"] = cls
    labels["instances"] = instances
    return labels

__init__(p=0.5)

Initializes the CopyPaste class with a given probability.

Parameters:

Name Type Description Default
p float

The probability of applying the Copy-Paste augmentation. Must be between 0 and 1. Default is 0.5.

0.5
Source code in ultralytics/data/augment.py
def __init__(self, p=0.5) -> None:
    """
    Initializes the CopyPaste class with a given probability.

    Args:
        p (float, optional): The probability of applying the Copy-Paste augmentation. Must be between 0 and 1.
                             Default is 0.5.
    """
    self.p = p



ultralytics.data.augment.Albumentations

Albumentations transformations.

Optional, uninstall package to disable. Applies Blur, Median Blur, convert to grayscale, Contrast Limited Adaptive Histogram Equalization, random change of brightness and contrast, RandomGamma and lowering of image quality by compression.

Source code in ultralytics/data/augment.py
class Albumentations:
    """
    Albumentations transformations.

    Optional, uninstall package to disable. Applies Blur, Median Blur, convert to grayscale, Contrast Limited Adaptive
    Histogram Equalization, random change of brightness and contrast, RandomGamma and lowering of image quality by
    compression.
    """

    def __init__(self, p=1.0):
        """Initialize the transform object for YOLO bbox formatted params."""
        self.p = p
        self.transform = None
        prefix = colorstr("albumentations: ")

        try:
            import albumentations as A

            check_version(A.__version__, "1.0.3", hard=True)  # version requirement

            # List of possible spatial transforms
            spatial_transforms = {
                "Affine",
                "BBoxSafeRandomCrop",
                "CenterCrop",
                "CoarseDropout",
                "Crop",
                "CropAndPad",
                "CropNonEmptyMaskIfExists",
                "D4",
                "ElasticTransform",
                "Flip",
                "GridDistortion",
                "GridDropout",
                "HorizontalFlip",
                "Lambda",
                "LongestMaxSize",
                "MaskDropout",
                "MixUp",
                "Morphological",
                "NoOp",
                "OpticalDistortion",
                "PadIfNeeded",
                "Perspective",
                "PiecewiseAffine",
                "PixelDropout",
                "RandomCrop",
                "RandomCropFromBorders",
                "RandomGridShuffle",
                "RandomResizedCrop",
                "RandomRotate90",
                "RandomScale",
                "RandomSizedBBoxSafeCrop",
                "RandomSizedCrop",
                "Resize",
                "Rotate",
                "SafeRotate",
                "ShiftScaleRotate",
                "SmallestMaxSize",
                "Transpose",
                "VerticalFlip",
                "XYMasking",
            }  # from https://albumentations.ai/docs/getting_started/transforms_and_targets/#spatial-level-transforms

            # Transforms
            T = [
                A.Blur(p=0.01),
                A.MedianBlur(p=0.01),
                A.ToGray(p=0.01),
                A.CLAHE(p=0.01),
                A.RandomBrightnessContrast(p=0.0),
                A.RandomGamma(p=0.0),
                A.ImageCompression(quality_lower=75, p=0.0),
            ]

            # Compose transforms
            self.contains_spatial = any(transform.__class__.__name__ in spatial_transforms for transform in T)
            self.transform = (
                A.Compose(T, bbox_params=A.BboxParams(format="yolo", label_fields=["class_labels"]))
                if self.contains_spatial
                else A.Compose(T)
            )
            LOGGER.info(prefix + ", ".join(f"{x}".replace("always_apply=False, ", "") for x in T if x.p))
        except ImportError:  # package not installed, skip
            pass
        except Exception as e:
            LOGGER.info(f"{prefix}{e}")

    def __call__(self, labels):
        """Generates object detections and returns a dictionary with detection results."""
        if self.transform is None or random.random() > self.p:
            return labels

        if self.contains_spatial:
            cls = labels["cls"]
            if len(cls):
                im = labels["img"]
                labels["instances"].convert_bbox("xywh")
                labels["instances"].normalize(*im.shape[:2][::-1])
                bboxes = labels["instances"].bboxes
                # TODO: add supports of segments and keypoints
                new = self.transform(image=im, bboxes=bboxes, class_labels=cls)  # transformed
                if len(new["class_labels"]) > 0:  # skip update if no bbox in new im
                    labels["img"] = new["image"]
                    labels["cls"] = np.array(new["class_labels"])
                    bboxes = np.array(new["bboxes"], dtype=np.float32)
                labels["instances"].update(bboxes=bboxes)
        else:
            labels["img"] = self.transform(image=labels["img"])["image"]  # transformed

        return labels

__call__(labels)

Generates object detections and returns a dictionary with detection results.

Source code in ultralytics/data/augment.py
def __call__(self, labels):
    """Generates object detections and returns a dictionary with detection results."""
    if self.transform is None or random.random() > self.p:
        return labels

    if self.contains_spatial:
        cls = labels["cls"]
        if len(cls):
            im = labels["img"]
            labels["instances"].convert_bbox("xywh")
            labels["instances"].normalize(*im.shape[:2][::-1])
            bboxes = labels["instances"].bboxes
            # TODO: add supports of segments and keypoints
            new = self.transform(image=im, bboxes=bboxes, class_labels=cls)  # transformed
            if len(new["class_labels"]) > 0:  # skip update if no bbox in new im
                labels["img"] = new["image"]
                labels["cls"] = np.array(new["class_labels"])
                bboxes = np.array(new["bboxes"], dtype=np.float32)
            labels["instances"].update(bboxes=bboxes)
    else:
        labels["img"] = self.transform(image=labels["img"])["image"]  # transformed

    return labels

__init__(p=1.0)

Initialize the transform object for YOLO bbox formatted params.

Source code in ultralytics/data/augment.py
def __init__(self, p=1.0):
    """Initialize the transform object for YOLO bbox formatted params."""
    self.p = p
    self.transform = None
    prefix = colorstr("albumentations: ")

    try:
        import albumentations as A

        check_version(A.__version__, "1.0.3", hard=True)  # version requirement

        # List of possible spatial transforms
        spatial_transforms = {
            "Affine",
            "BBoxSafeRandomCrop",
            "CenterCrop",
            "CoarseDropout",
            "Crop",
            "CropAndPad",
            "CropNonEmptyMaskIfExists",
            "D4",
            "ElasticTransform",
            "Flip",
            "GridDistortion",
            "GridDropout",
            "HorizontalFlip",
            "Lambda",
            "LongestMaxSize",
            "MaskDropout",
            "MixUp",
            "Morphological",
            "NoOp",
            "OpticalDistortion",
            "PadIfNeeded",
            "Perspective",
            "PiecewiseAffine",
            "PixelDropout",
            "RandomCrop",
            "RandomCropFromBorders",
            "RandomGridShuffle",
            "RandomResizedCrop",
            "RandomRotate90",
            "RandomScale",
            "RandomSizedBBoxSafeCrop",
            "RandomSizedCrop",
            "Resize",
            "Rotate",
            "SafeRotate",
            "ShiftScaleRotate",
            "SmallestMaxSize",
            "Transpose",
            "VerticalFlip",
            "XYMasking",
        }  # from https://albumentations.ai/docs/getting_started/transforms_and_targets/#spatial-level-transforms

        # Transforms
        T = [
            A.Blur(p=0.01),
            A.MedianBlur(p=0.01),
            A.ToGray(p=0.01),
            A.CLAHE(p=0.01),
            A.RandomBrightnessContrast(p=0.0),
            A.RandomGamma(p=0.0),
            A.ImageCompression(quality_lower=75, p=0.0),
        ]

        # Compose transforms
        self.contains_spatial = any(transform.__class__.__name__ in spatial_transforms for transform in T)
        self.transform = (
            A.Compose(T, bbox_params=A.BboxParams(format="yolo", label_fields=["class_labels"]))
            if self.contains_spatial
            else A.Compose(T)
        )
        LOGGER.info(prefix + ", ".join(f"{x}".replace("always_apply=False, ", "") for x in T if x.p))
    except ImportError:  # package not installed, skip
        pass
    except Exception as e:
        LOGGER.info(f"{prefix}{e}")



ultralytics.data.augment.Format

Formats image annotations for object detection, instance segmentation, and pose estimation tasks. The class standardizes the image and instance annotations to be used by the collate_fn in PyTorch DataLoader.

Attributes:

Name Type Description
bbox_format str

Format for bounding boxes. Default is 'xywh'.

normalize bool

Whether to normalize bounding boxes. Default is True.

return_mask bool

Return instance masks for segmentation. Default is False.

return_keypoint bool

Return keypoints for pose estimation. Default is False.

mask_ratio int

Downsample ratio for masks. Default is 4.

mask_overlap bool

Whether to overlap masks. Default is True.

batch_idx bool

Keep batch indexes. Default is True.

bgr float

The probability to return BGR images. Default is 0.0.

Source code in ultralytics/data/augment.py
class Format:
    """
    Formats image annotations for object detection, instance segmentation, and pose estimation tasks. The class
    standardizes the image and instance annotations to be used by the `collate_fn` in PyTorch DataLoader.

    Attributes:
        bbox_format (str): Format for bounding boxes. Default is 'xywh'.
        normalize (bool): Whether to normalize bounding boxes. Default is True.
        return_mask (bool): Return instance masks for segmentation. Default is False.
        return_keypoint (bool): Return keypoints for pose estimation. Default is False.
        mask_ratio (int): Downsample ratio for masks. Default is 4.
        mask_overlap (bool): Whether to overlap masks. Default is True.
        batch_idx (bool): Keep batch indexes. Default is True.
        bgr (float): The probability to return BGR images. Default is 0.0.
    """

    def __init__(
        self,
        bbox_format="xywh",
        normalize=True,
        return_mask=False,
        return_keypoint=False,
        return_obb=False,
        mask_ratio=4,
        mask_overlap=True,
        batch_idx=True,
        bgr=0.0,
    ):
        """Initializes the Format class with given parameters."""
        self.bbox_format = bbox_format
        self.normalize = normalize
        self.return_mask = return_mask  # set False when training detection only
        self.return_keypoint = return_keypoint
        self.return_obb = return_obb
        self.mask_ratio = mask_ratio
        self.mask_overlap = mask_overlap
        self.batch_idx = batch_idx  # keep the batch indexes
        self.bgr = bgr

    def __call__(self, labels):
        """Return formatted image, classes, bounding boxes & keypoints to be used by 'collate_fn'."""
        img = labels.pop("img")
        h, w = img.shape[:2]
        cls = labels.pop("cls")
        instances = labels.pop("instances")
        instances.convert_bbox(format=self.bbox_format)
        instances.denormalize(w, h)
        nl = len(instances)

        if self.return_mask:
            if nl:
                masks, instances, cls = self._format_segments(instances, cls, w, h)
                masks = torch.from_numpy(masks)
            else:
                masks = torch.zeros(
                    1 if self.mask_overlap else nl, img.shape[0] // self.mask_ratio, img.shape[1] // self.mask_ratio
                )
            labels["masks"] = masks
        labels["img"] = self._format_img(img)
        labels["cls"] = torch.from_numpy(cls) if nl else torch.zeros(nl)
        labels["bboxes"] = torch.from_numpy(instances.bboxes) if nl else torch.zeros((nl, 4))
        if self.return_keypoint:
            labels["keypoints"] = torch.from_numpy(instances.keypoints)
            if self.normalize:
                labels["keypoints"][..., 0] /= w
                labels["keypoints"][..., 1] /= h
        if self.return_obb:
            labels["bboxes"] = (
                xyxyxyxy2xywhr(torch.from_numpy(instances.segments)) if len(instances.segments) else torch.zeros((0, 5))
            )
        # NOTE: need to normalize obb in xywhr format for width-height consistency
        if self.normalize:
            labels["bboxes"][:, [0, 2]] /= w
            labels["bboxes"][:, [1, 3]] /= h
        # Then we can use collate_fn
        if self.batch_idx:
            labels["batch_idx"] = torch.zeros(nl)
        return labels

    def _format_img(self, img):
        """Format the image for YOLO from Numpy array to PyTorch tensor."""
        if len(img.shape) < 3:
            img = np.expand_dims(img, -1)
        img = img.transpose(2, 0, 1)
        img = np.ascontiguousarray(img[::-1] if random.uniform(0, 1) > self.bgr else img)
        img = torch.from_numpy(img)
        return img

    def _format_segments(self, instances, cls, w, h):
        """Convert polygon points to bitmap."""
        segments = instances.segments
        if self.mask_overlap:
            masks, sorted_idx = polygons2masks_overlap((h, w), segments, downsample_ratio=self.mask_ratio)
            masks = masks[None]  # (640, 640) -> (1, 640, 640)
            instances = instances[sorted_idx]
            cls = cls[sorted_idx]
        else:
            masks = polygons2masks((h, w), segments, color=1, downsample_ratio=self.mask_ratio)

        return masks, instances, cls

__call__(labels)

Return formatted image, classes, bounding boxes & keypoints to be used by 'collate_fn'.

Source code in ultralytics/data/augment.py
def __call__(self, labels):
    """Return formatted image, classes, bounding boxes & keypoints to be used by 'collate_fn'."""
    img = labels.pop("img")
    h, w = img.shape[:2]
    cls = labels.pop("cls")
    instances = labels.pop("instances")
    instances.convert_bbox(format=self.bbox_format)
    instances.denormalize(w, h)
    nl = len(instances)

    if self.return_mask:
        if nl:
            masks, instances, cls = self._format_segments(instances, cls, w, h)
            masks = torch.from_numpy(masks)
        else:
            masks = torch.zeros(
                1 if self.mask_overlap else nl, img.shape[0] // self.mask_ratio, img.shape[1] // self.mask_ratio
            )
        labels["masks"] = masks
    labels["img"] = self._format_img(img)
    labels["cls"] = torch.from_numpy(cls) if nl else torch.zeros(nl)
    labels["bboxes"] = torch.from_numpy(instances.bboxes) if nl else torch.zeros((nl, 4))
    if self.return_keypoint:
        labels["keypoints"] = torch.from_numpy(instances.keypoints)
        if self.normalize:
            labels["keypoints"][..., 0] /= w
            labels["keypoints"][..., 1] /= h
    if self.return_obb:
        labels["bboxes"] = (
            xyxyxyxy2xywhr(torch.from_numpy(instances.segments)) if len(instances.segments) else torch.zeros((0, 5))
        )
    # NOTE: need to normalize obb in xywhr format for width-height consistency
    if self.normalize:
        labels["bboxes"][:, [0, 2]] /= w
        labels["bboxes"][:, [1, 3]] /= h
    # Then we can use collate_fn
    if self.batch_idx:
        labels["batch_idx"] = torch.zeros(nl)
    return labels

__init__(bbox_format='xywh', normalize=True, return_mask=False, return_keypoint=False, return_obb=False, mask_ratio=4, mask_overlap=True, batch_idx=True, bgr=0.0)

Initializes the Format class with given parameters.

Source code in ultralytics/data/augment.py
def __init__(
    self,
    bbox_format="xywh",
    normalize=True,
    return_mask=False,
    return_keypoint=False,
    return_obb=False,
    mask_ratio=4,
    mask_overlap=True,
    batch_idx=True,
    bgr=0.0,
):
    """Initializes the Format class with given parameters."""
    self.bbox_format = bbox_format
    self.normalize = normalize
    self.return_mask = return_mask  # set False when training detection only
    self.return_keypoint = return_keypoint
    self.return_obb = return_obb
    self.mask_ratio = mask_ratio
    self.mask_overlap = mask_overlap
    self.batch_idx = batch_idx  # keep the batch indexes
    self.bgr = bgr



ultralytics.data.augment.RandomLoadText

Randomly sample positive texts and negative texts and update the class indices accordingly to the number of samples.

Attributes:

Name Type Description
prompt_format str

Format for prompt. Default is '{}'.

neg_samples tuple[int]

A ranger to randomly sample negative texts, Default is (80, 80).

max_samples int

The max number of different text samples in one image, Default is 80.

padding bool

Whether to pad texts to max_samples. Default is False.

padding_value str

The padding text. Default is "".

Source code in ultralytics/data/augment.py
class RandomLoadText:
    """
    Randomly sample positive texts and negative texts and update the class indices accordingly to the number of samples.

    Attributes:
        prompt_format (str): Format for prompt. Default is '{}'.
        neg_samples (tuple[int]): A ranger to randomly sample negative texts, Default is (80, 80).
        max_samples (int): The max number of different text samples in one image, Default is 80.
        padding (bool): Whether to pad texts to max_samples. Default is False.
        padding_value (str): The padding text. Default is "".
    """

    def __init__(
        self,
        prompt_format: str = "{}",
        neg_samples: Tuple[int, int] = (80, 80),
        max_samples: int = 80,
        padding: bool = False,
        padding_value: str = "",
    ) -> None:
        """Initializes the RandomLoadText class with given parameters."""
        self.prompt_format = prompt_format
        self.neg_samples = neg_samples
        self.max_samples = max_samples
        self.padding = padding
        self.padding_value = padding_value

    def __call__(self, labels: dict) -> dict:
        """Return updated classes and texts."""
        assert "texts" in labels, "No texts found in labels."
        class_texts = labels["texts"]
        num_classes = len(class_texts)
        cls = np.asarray(labels.pop("cls"), dtype=int)
        pos_labels = np.unique(cls).tolist()

        if len(pos_labels) > self.max_samples:
            pos_labels = set(random.sample(pos_labels, k=self.max_samples))

        neg_samples = min(min(num_classes, self.max_samples) - len(pos_labels), random.randint(*self.neg_samples))
        neg_labels = [i for i in range(num_classes) if i not in pos_labels]
        neg_labels = random.sample(neg_labels, k=neg_samples)

        sampled_labels = pos_labels + neg_labels
        random.shuffle(sampled_labels)

        label2ids = {label: i for i, label in enumerate(sampled_labels)}
        valid_idx = np.zeros(len(labels["instances"]), dtype=bool)
        new_cls = []
        for i, label in enumerate(cls.squeeze(-1).tolist()):
            if label not in label2ids:
                continue
            valid_idx[i] = True
            new_cls.append([label2ids[label]])
        labels["instances"] = labels["instances"][valid_idx]
        labels["cls"] = np.array(new_cls)

        # Randomly select one prompt when there's more than one prompts
        texts = []
        for label in sampled_labels:
            prompts = class_texts[label]
            assert len(prompts) > 0
            prompt = self.prompt_format.format(prompts[random.randrange(len(prompts))])
            texts.append(prompt)

        if self.padding:
            valid_labels = len(pos_labels) + len(neg_labels)
            num_padding = self.max_samples - valid_labels
            if num_padding > 0:
                texts += [self.padding_value] * num_padding

        labels["texts"] = texts
        return labels

__call__(labels)

Return updated classes and texts.

Source code in ultralytics/data/augment.py
def __call__(self, labels: dict) -> dict:
    """Return updated classes and texts."""
    assert "texts" in labels, "No texts found in labels."
    class_texts = labels["texts"]
    num_classes = len(class_texts)
    cls = np.asarray(labels.pop("cls"), dtype=int)
    pos_labels = np.unique(cls).tolist()

    if len(pos_labels) > self.max_samples:
        pos_labels = set(random.sample(pos_labels, k=self.max_samples))

    neg_samples = min(min(num_classes, self.max_samples) - len(pos_labels), random.randint(*self.neg_samples))
    neg_labels = [i for i in range(num_classes) if i not in pos_labels]
    neg_labels = random.sample(neg_labels, k=neg_samples)

    sampled_labels = pos_labels + neg_labels
    random.shuffle(sampled_labels)

    label2ids = {label: i for i, label in enumerate(sampled_labels)}
    valid_idx = np.zeros(len(labels["instances"]), dtype=bool)
    new_cls = []
    for i, label in enumerate(cls.squeeze(-1).tolist()):
        if label not in label2ids:
            continue
        valid_idx[i] = True
        new_cls.append([label2ids[label]])
    labels["instances"] = labels["instances"][valid_idx]
    labels["cls"] = np.array(new_cls)

    # Randomly select one prompt when there's more than one prompts
    texts = []
    for label in sampled_labels:
        prompts = class_texts[label]
        assert len(prompts) > 0
        prompt = self.prompt_format.format(prompts[random.randrange(len(prompts))])
        texts.append(prompt)

    if self.padding:
        valid_labels = len(pos_labels) + len(neg_labels)
        num_padding = self.max_samples - valid_labels
        if num_padding > 0:
            texts += [self.padding_value] * num_padding

    labels["texts"] = texts
    return labels

__init__(prompt_format='{}', neg_samples=(80, 80), max_samples=80, padding=False, padding_value='')

Initializes the RandomLoadText class with given parameters.

Source code in ultralytics/data/augment.py
def __init__(
    self,
    prompt_format: str = "{}",
    neg_samples: Tuple[int, int] = (80, 80),
    max_samples: int = 80,
    padding: bool = False,
    padding_value: str = "",
) -> None:
    """Initializes the RandomLoadText class with given parameters."""
    self.prompt_format = prompt_format
    self.neg_samples = neg_samples
    self.max_samples = max_samples
    self.padding = padding
    self.padding_value = padding_value



ultralytics.data.augment.ClassifyLetterBox

YOLOv8 LetterBox class for image preprocessing, designed to be part of a transformation pipeline, e.g., T.Compose([LetterBox(size), ToTensor()]).

Attributes:

Name Type Description
h int

Target height of the image.

w int

Target width of the image.

auto bool

If True, automatically solves for short side using stride.

stride int

The stride value, used when 'auto' is True.

Source code in ultralytics/data/augment.py
class ClassifyLetterBox:
    """
    YOLOv8 LetterBox class for image preprocessing, designed to be part of a transformation pipeline, e.g.,
    T.Compose([LetterBox(size), ToTensor()]).

    Attributes:
        h (int): Target height of the image.
        w (int): Target width of the image.
        auto (bool): If True, automatically solves for short side using stride.
        stride (int): The stride value, used when 'auto' is True.
    """

    def __init__(self, size=(640, 640), auto=False, stride=32):
        """
        Initializes the ClassifyLetterBox class with a target size, auto-flag, and stride.

        Args:
            size (Union[int, Tuple[int, int]]): The target dimensions (height, width) for the letterbox.
            auto (bool): If True, automatically calculates the short side based on stride.
            stride (int): The stride value, used when 'auto' is True.
        """
        super().__init__()
        self.h, self.w = (size, size) if isinstance(size, int) else size
        self.auto = auto  # pass max size integer, automatically solve for short side using stride
        self.stride = stride  # used with auto

    def __call__(self, im):
        """
        Resizes the image and pads it with a letterbox method.

        Args:
            im (numpy.ndarray): The input image as a numpy array of shape HWC.

        Returns:
            (numpy.ndarray): The letterboxed and resized image as a numpy array.
        """
        imh, imw = im.shape[:2]
        r = min(self.h / imh, self.w / imw)  # ratio of new/old dimensions
        h, w = round(imh * r), round(imw * r)  # resized image dimensions

        # Calculate padding dimensions
        hs, ws = (math.ceil(x / self.stride) * self.stride for x in (h, w)) if self.auto else (self.h, self.w)
        top, left = round((hs - h) / 2 - 0.1), round((ws - w) / 2 - 0.1)

        # Create padded image
        im_out = np.full((hs, ws, 3), 114, dtype=im.dtype)
        im_out[top : top + h, left : left + w] = cv2.resize(im, (w, h), interpolation=cv2.INTER_LINEAR)
        return im_out

__call__(im)

Resizes the image and pads it with a letterbox method.

Parameters:

Name Type Description Default
im ndarray

The input image as a numpy array of shape HWC.

required

Returns:

Type Description
ndarray

The letterboxed and resized image as a numpy array.

Source code in ultralytics/data/augment.py
def __call__(self, im):
    """
    Resizes the image and pads it with a letterbox method.

    Args:
        im (numpy.ndarray): The input image as a numpy array of shape HWC.

    Returns:
        (numpy.ndarray): The letterboxed and resized image as a numpy array.
    """
    imh, imw = im.shape[:2]
    r = min(self.h / imh, self.w / imw)  # ratio of new/old dimensions
    h, w = round(imh * r), round(imw * r)  # resized image dimensions

    # Calculate padding dimensions
    hs, ws = (math.ceil(x / self.stride) * self.stride for x in (h, w)) if self.auto else (self.h, self.w)
    top, left = round((hs - h) / 2 - 0.1), round((ws - w) / 2 - 0.1)

    # Create padded image
    im_out = np.full((hs, ws, 3), 114, dtype=im.dtype)
    im_out[top : top + h, left : left + w] = cv2.resize(im, (w, h), interpolation=cv2.INTER_LINEAR)
    return im_out

__init__(size=(640, 640), auto=False, stride=32)

Initializes the ClassifyLetterBox class with a target size, auto-flag, and stride.

Parameters:

Name Type Description Default
size Union[int, Tuple[int, int]]

The target dimensions (height, width) for the letterbox.

(640, 640)
auto bool

If True, automatically calculates the short side based on stride.

False
stride int

The stride value, used when 'auto' is True.

32
Source code in ultralytics/data/augment.py
def __init__(self, size=(640, 640), auto=False, stride=32):
    """
    Initializes the ClassifyLetterBox class with a target size, auto-flag, and stride.

    Args:
        size (Union[int, Tuple[int, int]]): The target dimensions (height, width) for the letterbox.
        auto (bool): If True, automatically calculates the short side based on stride.
        stride (int): The stride value, used when 'auto' is True.
    """
    super().__init__()
    self.h, self.w = (size, size) if isinstance(size, int) else size
    self.auto = auto  # pass max size integer, automatically solve for short side using stride
    self.stride = stride  # used with auto



ultralytics.data.augment.CenterCrop

YOLOv8 CenterCrop class for image preprocessing, designed to be part of a transformation pipeline, e.g., T.Compose([CenterCrop(size), ToTensor()]).

Source code in ultralytics/data/augment.py
class CenterCrop:
    """YOLOv8 CenterCrop class for image preprocessing, designed to be part of a transformation pipeline, e.g.,
    T.Compose([CenterCrop(size), ToTensor()]).
    """

    def __init__(self, size=640):
        """Converts an image from numpy array to PyTorch tensor."""
        super().__init__()
        self.h, self.w = (size, size) if isinstance(size, int) else size

    def __call__(self, im):
        """
        Resizes and crops the center of the image using a letterbox method.

        Args:
            im (numpy.ndarray): The input image as a numpy array of shape HWC.

        Returns:
            (numpy.ndarray): The center-cropped and resized image as a numpy array.
        """
        imh, imw = im.shape[:2]
        m = min(imh, imw)  # min dimension
        top, left = (imh - m) // 2, (imw - m) // 2
        return cv2.resize(im[top : top + m, left : left + m], (self.w, self.h), interpolation=cv2.INTER_LINEAR)

__call__(im)

Resizes and crops the center of the image using a letterbox method.

Parameters:

Name Type Description Default
im ndarray

The input image as a numpy array of shape HWC.

required

Returns:

Type Description
ndarray

The center-cropped and resized image as a numpy array.

Source code in ultralytics/data/augment.py
def __call__(self, im):
    """
    Resizes and crops the center of the image using a letterbox method.

    Args:
        im (numpy.ndarray): The input image as a numpy array of shape HWC.

    Returns:
        (numpy.ndarray): The center-cropped and resized image as a numpy array.
    """
    imh, imw = im.shape[:2]
    m = min(imh, imw)  # min dimension
    top, left = (imh - m) // 2, (imw - m) // 2
    return cv2.resize(im[top : top + m, left : left + m], (self.w, self.h), interpolation=cv2.INTER_LINEAR)

__init__(size=640)

Converts an image from numpy array to PyTorch tensor.

Source code in ultralytics/data/augment.py
def __init__(self, size=640):
    """Converts an image from numpy array to PyTorch tensor."""
    super().__init__()
    self.h, self.w = (size, size) if isinstance(size, int) else size



ultralytics.data.augment.ToTensor

YOLOv8 ToTensor class for image preprocessing, i.e., T.Compose([LetterBox(size), ToTensor()]).

Source code in ultralytics/data/augment.py
class ToTensor:
    """YOLOv8 ToTensor class for image preprocessing, i.e., T.Compose([LetterBox(size), ToTensor()])."""

    def __init__(self, half=False):
        """Initialize YOLOv8 ToTensor object with optional half-precision support."""
        super().__init__()
        self.half = half

    def __call__(self, im):
        """
        Transforms an image from a numpy array to a PyTorch tensor, applying optional half-precision and normalization.

        Args:
            im (numpy.ndarray): Input image as a numpy array with shape (H, W, C) in BGR order.

        Returns:
            (torch.Tensor): The transformed image as a PyTorch tensor in float32 or float16, normalized to [0, 1].
        """
        im = np.ascontiguousarray(im.transpose((2, 0, 1))[::-1])  # HWC to CHW -> BGR to RGB -> contiguous
        im = torch.from_numpy(im)  # to torch
        im = im.half() if self.half else im.float()  # uint8 to fp16/32
        im /= 255.0  # 0-255 to 0.0-1.0
        return im

__call__(im)

Transforms an image from a numpy array to a PyTorch tensor, applying optional half-precision and normalization.

Parameters:

Name Type Description Default
im ndarray

Input image as a numpy array with shape (H, W, C) in BGR order.

required

Returns:

Type Description
Tensor

The transformed image as a PyTorch tensor in float32 or float16, normalized to [0, 1].

Source code in ultralytics/data/augment.py
def __call__(self, im):
    """
    Transforms an image from a numpy array to a PyTorch tensor, applying optional half-precision and normalization.

    Args:
        im (numpy.ndarray): Input image as a numpy array with shape (H, W, C) in BGR order.

    Returns:
        (torch.Tensor): The transformed image as a PyTorch tensor in float32 or float16, normalized to [0, 1].
    """
    im = np.ascontiguousarray(im.transpose((2, 0, 1))[::-1])  # HWC to CHW -> BGR to RGB -> contiguous
    im = torch.from_numpy(im)  # to torch
    im = im.half() if self.half else im.float()  # uint8 to fp16/32
    im /= 255.0  # 0-255 to 0.0-1.0
    return im

__init__(half=False)

Initialize YOLOv8 ToTensor object with optional half-precision support.

Source code in ultralytics/data/augment.py
def __init__(self, half=False):
    """Initialize YOLOv8 ToTensor object with optional half-precision support."""
    super().__init__()
    self.half = half



ultralytics.data.augment.v8_transforms(dataset, imgsz, hyp, stretch=False)

Convert images to a size suitable for YOLOv8 training.

Source code in ultralytics/data/augment.py
def v8_transforms(dataset, imgsz, hyp, stretch=False):
    """Convert images to a size suitable for YOLOv8 training."""
    pre_transform = Compose(
        [
            Mosaic(dataset, imgsz=imgsz, p=hyp.mosaic),
            CopyPaste(p=hyp.copy_paste),
            RandomPerspective(
                degrees=hyp.degrees,
                translate=hyp.translate,
                scale=hyp.scale,
                shear=hyp.shear,
                perspective=hyp.perspective,
                pre_transform=None if stretch else LetterBox(new_shape=(imgsz, imgsz)),
            ),
        ]
    )
    flip_idx = dataset.data.get("flip_idx", [])  # for keypoints augmentation
    if dataset.use_keypoints:
        kpt_shape = dataset.data.get("kpt_shape", None)
        if len(flip_idx) == 0 and hyp.fliplr > 0.0:
            hyp.fliplr = 0.0
            LOGGER.warning("WARNING ⚠️ No 'flip_idx' array defined in data.yaml, setting augmentation 'fliplr=0.0'")
        elif flip_idx and (len(flip_idx) != kpt_shape[0]):
            raise ValueError(f"data.yaml flip_idx={flip_idx} length must be equal to kpt_shape[0]={kpt_shape[0]}")

    return Compose(
        [
            pre_transform,
            MixUp(dataset, pre_transform=pre_transform, p=hyp.mixup),
            Albumentations(p=1.0),
            RandomHSV(hgain=hyp.hsv_h, sgain=hyp.hsv_s, vgain=hyp.hsv_v),
            RandomFlip(direction="vertical", p=hyp.flipud),
            RandomFlip(direction="horizontal", p=hyp.fliplr, flip_idx=flip_idx),
        ]
    )  # transforms



ultralytics.data.augment.classify_transforms(size=224, mean=DEFAULT_MEAN, std=DEFAULT_STD, interpolation=Image.BILINEAR, crop_fraction=DEFAULT_CROP_FRACTION)

Classification transforms for evaluation/inference. Inspired by timm/data/transforms_factory.py.

Parameters:

Name Type Description Default
size int

image size

224
mean tuple

mean values of RGB channels

DEFAULT_MEAN
std tuple

std values of RGB channels

DEFAULT_STD
interpolation InterpolationMode

interpolation mode. default is T.InterpolationMode.BILINEAR.

BILINEAR
crop_fraction float

fraction of image to crop. default is 1.0.

DEFAULT_CROP_FRACTION

Returns:

Type Description
Compose

torchvision transforms

Source code in ultralytics/data/augment.py
def classify_transforms(
    size=224,
    mean=DEFAULT_MEAN,
    std=DEFAULT_STD,
    interpolation=Image.BILINEAR,
    crop_fraction: float = DEFAULT_CROP_FRACTION,
):
    """
    Classification transforms for evaluation/inference. Inspired by timm/data/transforms_factory.py.

    Args:
        size (int): image size
        mean (tuple): mean values of RGB channels
        std (tuple): std values of RGB channels
        interpolation (T.InterpolationMode): interpolation mode. default is T.InterpolationMode.BILINEAR.
        crop_fraction (float): fraction of image to crop. default is 1.0.

    Returns:
        (T.Compose): torchvision transforms
    """
    import torchvision.transforms as T  # scope for faster 'import ultralytics'

    if isinstance(size, (tuple, list)):
        assert len(size) == 2
        scale_size = tuple(math.floor(x / crop_fraction) for x in size)
    else:
        scale_size = math.floor(size / crop_fraction)
        scale_size = (scale_size, scale_size)

    # Aspect ratio is preserved, crops center within image, no borders are added, image is lost
    if scale_size[0] == scale_size[1]:
        # Simple case, use torchvision built-in Resize with the shortest edge mode (scalar size arg)
        tfl = [T.Resize(scale_size[0], interpolation=interpolation)]
    else:
        # Resize the shortest edge to matching target dim for non-square target
        tfl = [T.Resize(scale_size)]
    tfl += [T.CenterCrop(size)]

    tfl += [
        T.ToTensor(),
        T.Normalize(
            mean=torch.tensor(mean),
            std=torch.tensor(std),
        ),
    ]

    return T.Compose(tfl)



ultralytics.data.augment.classify_augmentations(size=224, mean=DEFAULT_MEAN, std=DEFAULT_STD, scale=None, ratio=None, hflip=0.5, vflip=0.0, auto_augment=None, hsv_h=0.015, hsv_s=0.4, hsv_v=0.4, force_color_jitter=False, erasing=0.0, interpolation=Image.BILINEAR)

Classification transforms with augmentation for training. Inspired by timm/data/transforms_factory.py.

Parameters:

Name Type Description Default
size int

image size

224
scale tuple

scale range of the image. default is (0.08, 1.0)

None
ratio tuple

aspect ratio range of the image. default is (3./4., 4./3.)

None
mean tuple

mean values of RGB channels

DEFAULT_MEAN
std tuple

std values of RGB channels

DEFAULT_STD
hflip float

probability of horizontal flip

0.5
vflip float

probability of vertical flip

0.0
auto_augment str

auto augmentation policy. can be 'randaugment', 'augmix', 'autoaugment' or None.

None
hsv_h float

image HSV-Hue augmentation (fraction)

0.015
hsv_s float

image HSV-Saturation augmentation (fraction)

0.4
hsv_v float

image HSV-Value augmentation (fraction)

0.4
force_color_jitter bool

force to apply color jitter even if auto augment is enabled

False
erasing float

probability of random erasing

0.0
interpolation InterpolationMode

interpolation mode. default is T.InterpolationMode.BILINEAR.

BILINEAR

Returns:

Type Description
Compose

torchvision transforms

Source code in ultralytics/data/augment.py
def classify_augmentations(
    size=224,
    mean=DEFAULT_MEAN,
    std=DEFAULT_STD,
    scale=None,
    ratio=None,
    hflip=0.5,
    vflip=0.0,
    auto_augment=None,
    hsv_h=0.015,  # image HSV-Hue augmentation (fraction)
    hsv_s=0.4,  # image HSV-Saturation augmentation (fraction)
    hsv_v=0.4,  # image HSV-Value augmentation (fraction)
    force_color_jitter=False,
    erasing=0.0,
    interpolation=Image.BILINEAR,
):
    """
    Classification transforms with augmentation for training. Inspired by timm/data/transforms_factory.py.

    Args:
        size (int): image size
        scale (tuple): scale range of the image. default is (0.08, 1.0)
        ratio (tuple): aspect ratio range of the image. default is (3./4., 4./3.)
        mean (tuple): mean values of RGB channels
        std (tuple): std values of RGB channels
        hflip (float): probability of horizontal flip
        vflip (float): probability of vertical flip
        auto_augment (str): auto augmentation policy. can be 'randaugment', 'augmix', 'autoaugment' or None.
        hsv_h (float): image HSV-Hue augmentation (fraction)
        hsv_s (float): image HSV-Saturation augmentation (fraction)
        hsv_v (float): image HSV-Value augmentation (fraction)
        force_color_jitter (bool): force to apply color jitter even if auto augment is enabled
        erasing (float): probability of random erasing
        interpolation (T.InterpolationMode): interpolation mode. default is T.InterpolationMode.BILINEAR.

    Returns:
        (T.Compose): torchvision transforms
    """
    # Transforms to apply if Albumentations not installed
    import torchvision.transforms as T  # scope for faster 'import ultralytics'

    if not isinstance(size, int):
        raise TypeError(f"classify_transforms() size {size} must be integer, not (list, tuple)")
    scale = tuple(scale or (0.08, 1.0))  # default imagenet scale range
    ratio = tuple(ratio or (3.0 / 4.0, 4.0 / 3.0))  # default imagenet ratio range
    primary_tfl = [T.RandomResizedCrop(size, scale=scale, ratio=ratio, interpolation=interpolation)]
    if hflip > 0.0:
        primary_tfl += [T.RandomHorizontalFlip(p=hflip)]
    if vflip > 0.0:
        primary_tfl += [T.RandomVerticalFlip(p=vflip)]

    secondary_tfl = []
    disable_color_jitter = False
    if auto_augment:
        assert isinstance(auto_augment, str)
        # color jitter is typically disabled if AA/RA on,
        # this allows override without breaking old hparm cfgs
        disable_color_jitter = not force_color_jitter

        if auto_augment == "randaugment":
            if TORCHVISION_0_11:
                secondary_tfl += [T.RandAugment(interpolation=interpolation)]
            else:
                LOGGER.warning('"auto_augment=randaugment" requires torchvision >= 0.11.0. Disabling it.')

        elif auto_augment == "augmix":
            if TORCHVISION_0_13:
                secondary_tfl += [T.AugMix(interpolation=interpolation)]
            else:
                LOGGER.warning('"auto_augment=augmix" requires torchvision >= 0.13.0. Disabling it.')

        elif auto_augment == "autoaugment":
            if TORCHVISION_0_10:
                secondary_tfl += [T.AutoAugment(interpolation=interpolation)]
            else:
                LOGGER.warning('"auto_augment=autoaugment" requires torchvision >= 0.10.0. Disabling it.')

        else:
            raise ValueError(
                f'Invalid auto_augment policy: {auto_augment}. Should be one of "randaugment", '
                f'"augmix", "autoaugment" or None'
            )

    if not disable_color_jitter:
        secondary_tfl += [T.ColorJitter(brightness=hsv_v, contrast=hsv_v, saturation=hsv_s, hue=hsv_h)]

    final_tfl = [
        T.ToTensor(),
        T.Normalize(mean=torch.tensor(mean), std=torch.tensor(std)),
        T.RandomErasing(p=erasing, inplace=True),
    ]

    return T.Compose(primary_tfl + secondary_tfl + final_tfl)





Created 2023-11-12, Updated 2024-06-02
Authors: glenn-jocher (6), Burhan-Q (1), Laughing-q (1)