| """Load annotation-only COCO TSVs and download original images on demand.""" |
| import argparse |
| from concurrent.futures import ThreadPoolExecutor |
| import hashlib |
| import io |
| import json |
| import os |
| from pathlib import Path |
| import tempfile |
| from urllib.request import urlopen |
| from PIL import Image |
|
|
|
|
| class CocoKeypointsDataset: |
| def __init__(self, root, images, positive_only=False): |
| self.root, self.images = Path(root), Path(images) |
| index = 'train.positive.annotations.tsv.lineidx' if positive_only else 'train.annotations.tsv.lineidx' |
| self.offsets = [int(x) for x in (self.root / index).read_text().splitlines()] |
|
|
| def __len__(self): |
| return len(self.offsets) |
|
|
| def annotation(self, index): |
| with (self.root / 'train.annotations.tsv').open('rb') as stream: |
| stream.seek(self.offsets[index]) |
| key, payload = stream.readline().split(b'\t', 1) |
| row = json.loads(payload) |
| if int(key) != row['image']['id']: |
| raise ValueError('Image ID mismatch') |
| return row |
|
|
| def ensure_image(self, row): |
| meta = row['image'] |
| filename = meta['file_name'] |
| if Path(filename).name != filename: |
| raise ValueError('Unsafe image filename') |
| target = self.images / 'train2017' / filename |
| def validate(data): |
| if hashlib.sha256(data).hexdigest() != meta['sha256']: |
| raise ValueError(f'Image checksum mismatch: {filename}') |
| with Image.open(io.BytesIO(data)) as im: |
| im.load() |
| if im.size != (meta['width'], meta['height']): |
| raise ValueError(f'Image dimensions mismatch: {filename}') |
| if target.exists(): |
| validate(target.read_bytes()) |
| return target |
| url = 'https://s3.amazonaws.com/images.cocodataset.org/train2017/' + filename |
| with urlopen(url, timeout=60) as response: |
| data = response.read() |
| validate(data) |
| target.parent.mkdir(parents=True, exist_ok=True) |
| fd, temporary = tempfile.mkstemp(prefix='.' + filename, dir=target.parent) |
| try: |
| with os.fdopen(fd, 'wb') as stream: |
| stream.write(data) |
| os.replace(temporary, target) |
| finally: |
| Path(temporary).unlink(missing_ok=True) |
| return target |
|
|
| def __getitem__(self, index): |
| annotation = self.annotation(index) |
| path = self.ensure_image(annotation) |
| with Image.open(path) as source: |
| image = source.convert('RGB') |
| image.info.pop('exif', None) |
| return {'image': image, 'annotation': annotation, 'image_path': str(path)} |
|
|
|
|
| if __name__ == '__main__': |
| parser = argparse.ArgumentParser(description=__doc__) |
| parser.add_argument('--root', type=Path, default=Path(__file__).resolve().parent / 'coco') |
| parser.add_argument('--images', type=Path, required=True) |
| parser.add_argument('--positive-only', action='store_true') |
| parser.add_argument('--workers', type=int, default=8) |
| parser.add_argument('--limit', type=int, default=0, help='0 downloads all selected images') |
| args = parser.parse_args() |
| if args.workers < 1 or args.limit < 0: |
| parser.error('workers must be positive and limit nonnegative') |
| dataset = CocoKeypointsDataset(args.root, args.images, args.positive_only) |
| count = min(args.limit, len(dataset)) if args.limit else len(dataset) |
| def download(index): |
| return dataset.ensure_image(dataset.annotation(index)) |
| with ThreadPoolExecutor(max_workers=args.workers) as pool: |
| for i, path in enumerate(pool.map(download, range(count)), 1): |
| if i % 1000 == 0 or i == count: |
| print(f'{i}/{count} images ready', flush=True) |
|
|
