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# -*- coding: utf-8 -*- | |
# Copyright (c) Facebook, Inc. and its affiliates. | |
""" | |
Common data processing utilities that are used in a | |
typical object detection data pipeline. | |
""" | |
import logging | |
import numpy as np | |
from typing import List, Union | |
import pycocotools.mask as mask_util | |
import torch | |
from PIL import Image | |
from detectron2.structures import ( | |
BitMasks, | |
Boxes, | |
BoxMode, | |
Instances, | |
Keypoints, | |
PolygonMasks, | |
RotatedBoxes, | |
polygons_to_bitmask, | |
) | |
from detectron2.utils.file_io import PathManager | |
from . import transforms as T | |
from .catalog import MetadataCatalog | |
__all__ = [ | |
"SizeMismatchError", | |
"convert_image_to_rgb", | |
"check_image_size", | |
"transform_proposals", | |
"transform_instance_annotations", | |
"annotations_to_instances", | |
"annotations_to_instances_rotated", | |
"build_augmentation", | |
"build_transform_gen", | |
"create_keypoint_hflip_indices", | |
"filter_empty_instances", | |
"read_image", | |
] | |
class SizeMismatchError(ValueError): | |
""" | |
When loaded image has difference width/height compared with annotation. | |
""" | |
# https://en.wikipedia.org/wiki/YUV#SDTV_with_BT.601 | |
_M_RGB2YUV = [[0.299, 0.587, 0.114], [-0.14713, -0.28886, 0.436], [0.615, -0.51499, -0.10001]] | |
_M_YUV2RGB = [[1.0, 0.0, 1.13983], [1.0, -0.39465, -0.58060], [1.0, 2.03211, 0.0]] | |
# https://www.exiv2.org/tags.html | |
_EXIF_ORIENT = 274 # exif 'Orientation' tag | |
def convert_PIL_to_numpy(image, format): | |
""" | |
Convert PIL image to numpy array of target format. | |
Args: | |
image (PIL.Image): a PIL image | |
format (str): the format of output image | |
Returns: | |
(np.ndarray): also see `read_image` | |
""" | |
if format is not None: | |
# PIL only supports RGB, so convert to RGB and flip channels over below | |
conversion_format = format | |
if format in ["BGR", "YUV-BT.601"]: | |
conversion_format = "RGB" | |
image = image.convert(conversion_format) | |
image = np.asarray(image) | |
# PIL squeezes out the channel dimension for "L", so make it HWC | |
if format == "L": | |
image = np.expand_dims(image, -1) | |
# handle formats not supported by PIL | |
elif format == "BGR": | |
# flip channels if needed | |
image = image[:, :, ::-1] | |
elif format == "YUV-BT.601": | |
image = image / 255.0 | |
image = np.dot(image, np.array(_M_RGB2YUV).T) | |
return image | |
def convert_image_to_rgb(image, format): | |
""" | |
Convert an image from given format to RGB. | |
Args: | |
image (np.ndarray or Tensor): an HWC image | |
format (str): the format of input image, also see `read_image` | |
Returns: | |
(np.ndarray): (H,W,3) RGB image in 0-255 range, can be either float or uint8 | |
""" | |
if isinstance(image, torch.Tensor): | |
image = image.cpu().numpy() | |
if format == "BGR": | |
image = image[:, :, [2, 1, 0]] | |
elif format == "YUV-BT.601": | |
image = np.dot(image, np.array(_M_YUV2RGB).T) | |
image = image * 255.0 | |
else: | |
if format == "L": | |
image = image[:, :, 0] | |
image = image.astype(np.uint8) | |
image = np.asarray(Image.fromarray(image, mode=format).convert("RGB")) | |
return image | |
def _apply_exif_orientation(image): | |
""" | |
Applies the exif orientation correctly. | |
This code exists per the bug: | |
https://github.com/python-pillow/Pillow/issues/3973 | |
with the function `ImageOps.exif_transpose`. The Pillow source raises errors with | |
various methods, especially `tobytes` | |
Function based on: | |
https://github.com/wkentaro/labelme/blob/v4.5.4/labelme/utils/image.py#L59 | |
https://github.com/python-pillow/Pillow/blob/7.1.2/src/PIL/ImageOps.py#L527 | |
Args: | |
image (PIL.Image): a PIL image | |
Returns: | |
(PIL.Image): the PIL image with exif orientation applied, if applicable | |
""" | |
if not hasattr(image, "getexif"): | |
return image | |
try: | |
exif = image.getexif() | |
except Exception: # https://github.com/facebookresearch/detectron2/issues/1885 | |
exif = None | |
if exif is None: | |
return image | |
orientation = exif.get(_EXIF_ORIENT) | |
method = { | |
2: Image.FLIP_LEFT_RIGHT, | |
3: Image.ROTATE_180, | |
4: Image.FLIP_TOP_BOTTOM, | |
5: Image.TRANSPOSE, | |
6: Image.ROTATE_270, | |
7: Image.TRANSVERSE, | |
8: Image.ROTATE_90, | |
}.get(orientation) | |
if method is not None: | |
return image.transpose(method) | |
return image | |
def read_image(file_name, format=None): | |
""" | |
Read an image into the given format. | |
Will apply rotation and flipping if the image has such exif information. | |
Args: | |
file_name (str): image file path | |
format (str): one of the supported image modes in PIL, or "BGR" or "YUV-BT.601". | |
Returns: | |
image (np.ndarray): | |
an HWC image in the given format, which is 0-255, uint8 for | |
supported image modes in PIL or "BGR"; float (0-1 for Y) for YUV-BT.601. | |
""" | |
with PathManager.open(file_name, "rb") as f: | |
image = Image.open(f) | |
# work around this bug: https://github.com/python-pillow/Pillow/issues/3973 | |
image = _apply_exif_orientation(image) | |
return convert_PIL_to_numpy(image, format) | |
def check_image_size(dataset_dict, image): | |
""" | |
Raise an error if the image does not match the size specified in the dict. | |
""" | |
if "width" in dataset_dict or "height" in dataset_dict: | |
image_wh = (image.shape[1], image.shape[0]) | |
expected_wh = (dataset_dict["width"], dataset_dict["height"]) | |
if not image_wh == expected_wh: | |
raise SizeMismatchError( | |
"Mismatched image shape{}, got {}, expect {}.".format( | |
" for image " + dataset_dict["file_name"] | |
if "file_name" in dataset_dict | |
else "", | |
image_wh, | |
expected_wh, | |
) | |
+ " Please check the width/height in your annotation." | |
) | |
# To ensure bbox always remap to original image size | |
if "width" not in dataset_dict: | |
dataset_dict["width"] = image.shape[1] | |
if "height" not in dataset_dict: | |
dataset_dict["height"] = image.shape[0] | |
def transform_proposals(dataset_dict, image_shape, transforms, *, proposal_topk, min_box_size=0): | |
""" | |
Apply transformations to the proposals in dataset_dict, if any. | |
Args: | |
dataset_dict (dict): a dict read from the dataset, possibly | |
contains fields "proposal_boxes", "proposal_objectness_logits", "proposal_bbox_mode" | |
image_shape (tuple): height, width | |
transforms (TransformList): | |
proposal_topk (int): only keep top-K scoring proposals | |
min_box_size (int): proposals with either side smaller than this | |
threshold are removed | |
The input dict is modified in-place, with abovementioned keys removed. A new | |
key "proposals" will be added. Its value is an `Instances` | |
object which contains the transformed proposals in its field | |
"proposal_boxes" and "objectness_logits". | |
""" | |
if "proposal_boxes" in dataset_dict: | |
# Transform proposal boxes | |
boxes = transforms.apply_box( | |
BoxMode.convert( | |
dataset_dict.pop("proposal_boxes"), | |
dataset_dict.pop("proposal_bbox_mode"), | |
BoxMode.XYXY_ABS, | |
) | |
) | |
boxes = Boxes(boxes) | |
objectness_logits = torch.as_tensor( | |
dataset_dict.pop("proposal_objectness_logits").astype("float32") | |
) | |
boxes.clip(image_shape) | |
keep = boxes.nonempty(threshold=min_box_size) | |
boxes = boxes[keep] | |
objectness_logits = objectness_logits[keep] | |
proposals = Instances(image_shape) | |
proposals.proposal_boxes = boxes[:proposal_topk] | |
proposals.objectness_logits = objectness_logits[:proposal_topk] | |
dataset_dict["proposals"] = proposals | |
def get_bbox(annotation): | |
""" | |
Get bbox from data | |
Args: | |
annotation (dict): dict of instance annotations for a single instance. | |
Returns: | |
bbox (ndarray): x1, y1, x2, y2 coordinates | |
""" | |
# bbox is 1d (per-instance bounding box) | |
bbox = BoxMode.convert(annotation["bbox"], annotation["bbox_mode"], BoxMode.XYXY_ABS) | |
return bbox | |
def transform_instance_annotations( | |
annotation, transforms, image_size, *, keypoint_hflip_indices=None | |
): | |
""" | |
Apply transforms to box, segmentation and keypoints annotations of a single instance. | |
It will use `transforms.apply_box` for the box, and | |
`transforms.apply_coords` for segmentation polygons & keypoints. | |
If you need anything more specially designed for each data structure, | |
you'll need to implement your own version of this function or the transforms. | |
Args: | |
annotation (dict): dict of instance annotations for a single instance. | |
It will be modified in-place. | |
transforms (TransformList or list[Transform]): | |
image_size (tuple): the height, width of the transformed image | |
keypoint_hflip_indices (ndarray[int]): see `create_keypoint_hflip_indices`. | |
Returns: | |
dict: | |
the same input dict with fields "bbox", "segmentation", "keypoints" | |
transformed according to `transforms`. | |
The "bbox_mode" field will be set to XYXY_ABS. | |
""" | |
if isinstance(transforms, (tuple, list)): | |
transforms = T.TransformList(transforms) | |
# bbox is 1d (per-instance bounding box) | |
bbox = BoxMode.convert(annotation["bbox"], annotation["bbox_mode"], BoxMode.XYXY_ABS) | |
# clip transformed bbox to image size | |
bbox = transforms.apply_box(np.array([bbox]))[0].clip(min=0) | |
annotation["bbox"] = np.minimum(bbox, list(image_size + image_size)[::-1]) | |
annotation["bbox_mode"] = BoxMode.XYXY_ABS | |
if "segmentation" in annotation: | |
# each instance contains 1 or more polygons | |
segm = annotation["segmentation"] | |
if isinstance(segm, list): | |
# polygons | |
polygons = [np.asarray(p).reshape(-1, 2) for p in segm] | |
annotation["segmentation"] = [ | |
p.reshape(-1) for p in transforms.apply_polygons(polygons) | |
] | |
elif isinstance(segm, dict): | |
# RLE | |
mask = mask_util.decode(segm) | |
mask = transforms.apply_segmentation(mask) | |
assert tuple(mask.shape[:2]) == image_size | |
annotation["segmentation"] = mask | |
else: | |
raise ValueError( | |
"Cannot transform segmentation of type '{}'!" | |
"Supported types are: polygons as list[list[float] or ndarray]," | |
" COCO-style RLE as a dict.".format(type(segm)) | |
) | |
if "keypoints" in annotation: | |
keypoints = transform_keypoint_annotations( | |
annotation["keypoints"], transforms, image_size, keypoint_hflip_indices | |
) | |
annotation["keypoints"] = keypoints | |
return annotation | |
def transform_keypoint_annotations(keypoints, transforms, image_size, keypoint_hflip_indices=None): | |
""" | |
Transform keypoint annotations of an image. | |
If a keypoint is transformed out of image boundary, it will be marked "unlabeled" (visibility=0) | |
Args: | |
keypoints (list[float]): Nx3 float in Detectron2's Dataset format. | |
Each point is represented by (x, y, visibility). | |
transforms (TransformList): | |
image_size (tuple): the height, width of the transformed image | |
keypoint_hflip_indices (ndarray[int]): see `create_keypoint_hflip_indices`. | |
When `transforms` includes horizontal flip, will use the index | |
mapping to flip keypoints. | |
""" | |
# (N*3,) -> (N, 3) | |
keypoints = np.asarray(keypoints, dtype="float64").reshape(-1, 3) | |
keypoints_xy = transforms.apply_coords(keypoints[:, :2]) | |
# Set all out-of-boundary points to "unlabeled" | |
inside = (keypoints_xy >= np.array([0, 0])) & (keypoints_xy <= np.array(image_size[::-1])) | |
inside = inside.all(axis=1) | |
keypoints[:, :2] = keypoints_xy | |
keypoints[:, 2][~inside] = 0 | |
# This assumes that HorizFlipTransform is the only one that does flip | |
do_hflip = sum(isinstance(t, T.HFlipTransform) for t in transforms.transforms) % 2 == 1 | |
# Alternative way: check if probe points was horizontally flipped. | |
# probe = np.asarray([[0.0, 0.0], [image_width, 0.0]]) | |
# probe_aug = transforms.apply_coords(probe.copy()) | |
# do_hflip = np.sign(probe[1][0] - probe[0][0]) != np.sign(probe_aug[1][0] - probe_aug[0][0]) # noqa | |
# If flipped, swap each keypoint with its opposite-handed equivalent | |
if do_hflip: | |
if keypoint_hflip_indices is None: | |
raise ValueError("Cannot flip keypoints without providing flip indices!") | |
if len(keypoints) != len(keypoint_hflip_indices): | |
raise ValueError( | |
"Keypoint data has {} points, but metadata " | |
"contains {} points!".format(len(keypoints), len(keypoint_hflip_indices)) | |
) | |
keypoints = keypoints[np.asarray(keypoint_hflip_indices, dtype=np.int32), :] | |
# Maintain COCO convention that if visibility == 0 (unlabeled), then x, y = 0 | |
keypoints[keypoints[:, 2] == 0] = 0 | |
return keypoints | |
def annotations_to_instances(annos, image_size, mask_format="polygon"): | |
""" | |
Create an :class:`Instances` object used by the models, | |
from instance annotations in the dataset dict. | |
Args: | |
annos (list[dict]): a list of instance annotations in one image, each | |
element for one instance. | |
image_size (tuple): height, width | |
Returns: | |
Instances: | |
It will contain fields "gt_boxes", "gt_classes", | |
"gt_masks", "gt_keypoints", if they can be obtained from `annos`. | |
This is the format that builtin models expect. | |
""" | |
boxes = ( | |
np.stack( | |
[BoxMode.convert(obj["bbox"], obj["bbox_mode"], BoxMode.XYXY_ABS) for obj in annos] | |
) | |
if len(annos) | |
else np.zeros((0, 4)) | |
) | |
target = Instances(image_size) | |
target.gt_boxes = Boxes(boxes) | |
classes = [int(obj["category_id"]) for obj in annos] | |
classes = torch.tensor(classes, dtype=torch.int64) | |
target.gt_classes = classes | |
if len(annos) and "segmentation" in annos[0]: | |
segms = [obj["segmentation"] for obj in annos] | |
if mask_format == "polygon": | |
try: | |
masks = PolygonMasks(segms) | |
except ValueError as e: | |
raise ValueError( | |
"Failed to use mask_format=='polygon' from the given annotations!" | |
) from e | |
else: | |
assert mask_format == "bitmask", mask_format | |
masks = [] | |
for segm in segms: | |
if isinstance(segm, list): | |
# polygon | |
masks.append(polygons_to_bitmask(segm, *image_size)) | |
elif isinstance(segm, dict): | |
# COCO RLE | |
masks.append(mask_util.decode(segm)) | |
elif isinstance(segm, np.ndarray): | |
assert segm.ndim == 2, "Expect segmentation of 2 dimensions, got {}.".format( | |
segm.ndim | |
) | |
# mask array | |
masks.append(segm) | |
else: | |
raise ValueError( | |
"Cannot convert segmentation of type '{}' to BitMasks!" | |
"Supported types are: polygons as list[list[float] or ndarray]," | |
" COCO-style RLE as a dict, or a binary segmentation mask " | |
" in a 2D numpy array of shape HxW.".format(type(segm)) | |
) | |
# torch.from_numpy does not support array with negative stride. | |
masks = BitMasks( | |
torch.stack([torch.from_numpy(np.ascontiguousarray(x)) for x in masks]) | |
) | |
target.gt_masks = masks | |
if len(annos) and "keypoints" in annos[0]: | |
kpts = [obj.get("keypoints", []) for obj in annos] | |
target.gt_keypoints = Keypoints(kpts) | |
return target | |
def annotations_to_instances_rotated(annos, image_size): | |
""" | |
Create an :class:`Instances` object used by the models, | |
from instance annotations in the dataset dict. | |
Compared to `annotations_to_instances`, this function is for rotated boxes only | |
Args: | |
annos (list[dict]): a list of instance annotations in one image, each | |
element for one instance. | |
image_size (tuple): height, width | |
Returns: | |
Instances: | |
Containing fields "gt_boxes", "gt_classes", | |
if they can be obtained from `annos`. | |
This is the format that builtin models expect. | |
""" | |
boxes = [obj["bbox"] for obj in annos] | |
target = Instances(image_size) | |
boxes = target.gt_boxes = RotatedBoxes(boxes) | |
boxes.clip(image_size) | |
classes = [obj["category_id"] for obj in annos] | |
classes = torch.tensor(classes, dtype=torch.int64) | |
target.gt_classes = classes | |
return target | |
def filter_empty_instances( | |
instances, by_box=True, by_mask=True, box_threshold=1e-5, return_mask=False | |
): | |
""" | |
Filter out empty instances in an `Instances` object. | |
Args: | |
instances (Instances): | |
by_box (bool): whether to filter out instances with empty boxes | |
by_mask (bool): whether to filter out instances with empty masks | |
box_threshold (float): minimum width and height to be considered non-empty | |
return_mask (bool): whether to return boolean mask of filtered instances | |
Returns: | |
Instances: the filtered instances. | |
tensor[bool], optional: boolean mask of filtered instances | |
""" | |
assert by_box or by_mask | |
r = [] | |
if by_box: | |
r.append(instances.gt_boxes.nonempty(threshold=box_threshold)) | |
if instances.has("gt_masks") and by_mask: | |
r.append(instances.gt_masks.nonempty()) | |
# TODO: can also filter visible keypoints | |
if not r: | |
return instances | |
m = r[0] | |
for x in r[1:]: | |
m = m & x | |
if return_mask: | |
return instances[m], m | |
return instances[m] | |
def create_keypoint_hflip_indices(dataset_names: Union[str, List[str]]) -> List[int]: | |
""" | |
Args: | |
dataset_names: list of dataset names | |
Returns: | |
list[int]: a list of size=#keypoints, storing the | |
horizontally-flipped keypoint indices. | |
""" | |
if isinstance(dataset_names, str): | |
dataset_names = [dataset_names] | |
check_metadata_consistency("keypoint_names", dataset_names) | |
check_metadata_consistency("keypoint_flip_map", dataset_names) | |
meta = MetadataCatalog.get(dataset_names[0]) | |
names = meta.keypoint_names | |
# TODO flip -> hflip | |
flip_map = dict(meta.keypoint_flip_map) | |
flip_map.update({v: k for k, v in flip_map.items()}) | |
flipped_names = [i if i not in flip_map else flip_map[i] for i in names] | |
flip_indices = [names.index(i) for i in flipped_names] | |
return flip_indices | |
def get_fed_loss_cls_weights(dataset_names: Union[str, List[str]], freq_weight_power=1.0): | |
""" | |
Get frequency weight for each class sorted by class id. | |
We now calcualte freqency weight using image_count to the power freq_weight_power. | |
Args: | |
dataset_names: list of dataset names | |
freq_weight_power: power value | |
""" | |
if isinstance(dataset_names, str): | |
dataset_names = [dataset_names] | |
check_metadata_consistency("class_image_count", dataset_names) | |
meta = MetadataCatalog.get(dataset_names[0]) | |
class_freq_meta = meta.class_image_count | |
class_freq = torch.tensor( | |
[c["image_count"] for c in sorted(class_freq_meta, key=lambda x: x["id"])] | |
) | |
class_freq_weight = class_freq.float() ** freq_weight_power | |
return class_freq_weight | |
def gen_crop_transform_with_instance(crop_size, image_size, instance): | |
""" | |
Generate a CropTransform so that the cropping region contains | |
the center of the given instance. | |
Args: | |
crop_size (tuple): h, w in pixels | |
image_size (tuple): h, w | |
instance (dict): an annotation dict of one instance, in Detectron2's | |
dataset format. | |
""" | |
crop_size = np.asarray(crop_size, dtype=np.int32) | |
bbox = BoxMode.convert(instance["bbox"], instance["bbox_mode"], BoxMode.XYXY_ABS) | |
center_yx = (bbox[1] + bbox[3]) * 0.5, (bbox[0] + bbox[2]) * 0.5 | |
assert ( | |
image_size[0] >= center_yx[0] and image_size[1] >= center_yx[1] | |
), "The annotation bounding box is outside of the image!" | |
assert ( | |
image_size[0] >= crop_size[0] and image_size[1] >= crop_size[1] | |
), "Crop size is larger than image size!" | |
min_yx = np.maximum(np.floor(center_yx).astype(np.int32) - crop_size, 0) | |
max_yx = np.maximum(np.asarray(image_size, dtype=np.int32) - crop_size, 0) | |
max_yx = np.minimum(max_yx, np.ceil(center_yx).astype(np.int32)) | |
y0 = np.random.randint(min_yx[0], max_yx[0] + 1) | |
x0 = np.random.randint(min_yx[1], max_yx[1] + 1) | |
return T.CropTransform(x0, y0, crop_size[1], crop_size[0]) | |
def check_metadata_consistency(key, dataset_names): | |
""" | |
Check that the datasets have consistent metadata. | |
Args: | |
key (str): a metadata key | |
dataset_names (list[str]): a list of dataset names | |
Raises: | |
AttributeError: if the key does not exist in the metadata | |
ValueError: if the given datasets do not have the same metadata values defined by key | |
""" | |
if len(dataset_names) == 0: | |
return | |
logger = logging.getLogger(__name__) | |
entries_per_dataset = [getattr(MetadataCatalog.get(d), key) for d in dataset_names] | |
for idx, entry in enumerate(entries_per_dataset): | |
if entry != entries_per_dataset[0]: | |
logger.error( | |
"Metadata '{}' for dataset '{}' is '{}'".format(key, dataset_names[idx], str(entry)) | |
) | |
logger.error( | |
"Metadata '{}' for dataset '{}' is '{}'".format( | |
key, dataset_names[0], str(entries_per_dataset[0]) | |
) | |
) | |
raise ValueError("Datasets have different metadata '{}'!".format(key)) | |
def build_augmentation(cfg, is_train): | |
""" | |
Create a list of default :class:`Augmentation` from config. | |
Now it includes resizing and flipping. | |
Returns: | |
list[Augmentation] | |
""" | |
if is_train: | |
min_size = cfg.INPUT.MIN_SIZE_TRAIN | |
max_size = cfg.INPUT.MAX_SIZE_TRAIN | |
sample_style = cfg.INPUT.MIN_SIZE_TRAIN_SAMPLING | |
else: | |
min_size = cfg.INPUT.MIN_SIZE_TEST | |
max_size = cfg.INPUT.MAX_SIZE_TEST | |
sample_style = "choice" | |
augmentation = [T.ResizeShortestEdge(min_size, max_size, sample_style)] | |
if is_train and cfg.INPUT.RANDOM_FLIP != "none": | |
augmentation.append( | |
T.RandomFlip( | |
horizontal=cfg.INPUT.RANDOM_FLIP == "horizontal", | |
vertical=cfg.INPUT.RANDOM_FLIP == "vertical", | |
) | |
) | |
return augmentation | |
build_transform_gen = build_augmentation | |
""" | |
Alias for backward-compatibility. | |
""" | |