albumentations: Incorrect number of masks returned after augmentation

🐛 Bug

Describe the bug Incorrect number of masks returned after augmentation. It happend when some boxes goes outside of image. Number of boxes changed but masks stays the same.

To Reproduce

from albumentations import *
from albumentations import __version__ as ver


transform_generator = Compose([
        ShiftScaleRotate(p=1.0, shift_limit=0.1, scale_limit=0.2, rotate_limit=45, border_mode=cv2.BORDER_REFLECT),
    ], bbox_params={'format': 'pascal_voc',
                    'min_area': 0,
                    'min_visibility': 0.0,
                    'label_fields': ['labels']}, p=1.0)


def albu_bug():
    print('Albu ver: {}'.format(ver))
    image = np.zeros((500, 500, 3), dtype=np.uint8)
    mask1 = np.zeros((500, 500, 3), dtype=np.uint8)
    mask2 = np.zeros((500, 500, 3), dtype=np.uint8)
    mask3 = np.zeros((500, 500, 3), dtype=np.uint8)
    mask1[0:10, 0:10] = 255
    mask2[-10:, -10:] = 255
    mask3[250:260, 250:260] = 255

    ann = dict()
    ann['image'] = image.copy()
    ann['masks'] = [mask1, mask2, mask3]
    ann['labels'] = np.array([0, 0, 0])
    ann['bboxes'] = np.array([[0, 0, 10, 10], [490, 490, 500, 500], [250, 250, 260, 260]])

    for i in range(10):
        augm = transform_generator(**ann)
        print(len(ann['masks']), len(ann['labels']), len(ann['bboxes']))
        print(len(augm['masks']), len(augm['labels']), len(augm['bboxes']))


if __name__ == '__main__':
    albu_bug()

Expected behavior Masks corrsponding to removed boxes must be also removed

Environment

• Albumentations version (e.g., 0.1.8): 0.5.2
• Python version (e.g., 3.7): 3.7
• OS (e.g., Linux): Win10
• How you installed albumentations (conda, pip, source): pip