Show annotations in COCO dataset (multi-polygon and RLE format annos).

show-coco-annos.py

from pycocotools.coco import COCO
import numpy as np
import cv2

import os

coco_dataset_path = "/export/public/MS-COCO-2017/"
coco = COCO(coco_dataset_path + "annotations/instances_val2017.json")


# ============================================================================


ann_ids = coco.getAnnIds(iscrowd=False)
anns = coco.loadAnns(ann_ids)
anns = [ann for ann in anns if len(ann['segmentation']) > 1]
print("num of annotations with more than one polygan:", len(anns))    # 3522

for i, ann in enumerate(anns):
    image_id = ann["image_id"]
    segs = ann["segmentation"]
    bbox = np.array(ann["bbox"])
    bbox[2:4] = bbox[0:2] + bbox[2:4]
    print("BBox[{}] (xyxy):".format(i), bbox.tolist())
    
    image_info = coco.loadImgs(image_id)
    image_path = image_info[0]["file_name"]
    # [0] is required, always return a list
    image_path = os.path.join(coco_dataset_path, "val2017", image_path)
    print(image_path)
    # /export/public/MS-COCO-2017/val2017/000000061108.jpg

    image = cv2.imread(image_path)
    segs = [np.array(seg, np.int32).reshape((1, -1, 2))
            for seg in segs]
    
    for seg in segs: cv2.drawContours(image, seg, -1, (0,255,0), 2)
    # third aug -1 means draw all contours in 3-D array, Or
    # for seg in segs: cv2.fillPoly(image, segm, (0,255,0))
    cv2.rectangle(image, (int(bbox[0]), int(bbox[1])), 
                  (int(bbox[2]), int(bbox[3])), (0,0,255), 2)
    cv2.imshow("polygan label", image)
    cv2.waitKey()

    break


# ============================================================================


ann_ids = coco.getAnnIds(iscrowd=True)
anns = coco.loadAnns(ann_ids)

import pycocotools.mask as mask

for ann in anns:
    image_id = ann["image_id"]
    segm = ann['segmentation']
    bbox = ann['bbox']

    assert sum(segm['counts']) == segm['size'][0] * segm['size'][1]

    # Draw RLE label
    label = np.zeros(segm['size'], np.uint8).reshape(-1)
    ids = 0
    value = 0
    for c in segm['counts']:
        label[ids: ids+c] = value
        value = not value
        ids += c
    label = label.reshape(segm['size'], order='F')
    # order='F' means Fortran memory order
    cv2.imshow("RLE label", label*255)
    cv2.waitKey()

    print('Encoded RLE:', mask.frPyObjects(segm, *segm['size']))
    """
    Encoded RLE: {'size': [240, 320], 'counts': b'`824200N5OI?Y1o3]OfK@;T1m3]OkK\\O9W1k3^OnKXO7[1`3gNTLg0c0ZOYOX1n3IhL>V3DiL=U3FiL;V3HhL8W30cLO[34dLLZ36hLHX38hLHX39fLHZ38eLH\\38cLI]38bLG_3:`LF`3<ZLRN1a1f3U20]Oc0M3N2M3M3M3N2M3J6F:K5L4M3N2M3N2VOWJKk54ZJDj5:g0O1O100O10000000000000000O1000UJCc4=]KEa4;_KF`49aKI]48bKI]47cKK[45eKLZ44fKMY43fK0X40fK5W4LfKa0o3@nKc0Q4_OkKd0T4]OiKf0V4[OfKi0Y4XOcKk0]4VO^Ko0a4RO^Ko0a4QO^KP1b4QO]KP1b4PO]KQ1c4PO\\KP1d4PO\\KQ1c4oN\\KR1d4oN[KQ1e4oN[KQ1e4POYKQ1g4oNYKQ1g4j02J6O1kNWKCi4<ZK]OG]Oo4U1\\KZOHAl4U1^KjNF62Jj4V1gKnNb4m0dKQO]4n0S10kJoNk3Q1SLQOm3o0QLSOo3m0oKXOn3j0PKoNk0>o3h0PLWOQ4i0nKXOR4h0nKWOS4;WK_Oe06U4;XK]O5J14F1m4d0XKCLF`02]4d0XKL:_O_4e0WKL:^O`4f0VKM7]Oe4c0WK00@j4<\\K3H@n4=_KOBAR5?_KN^OAV5`0_KNh42ZKKg44]KFf49Y1O1O1O1O1O1O1000000O10000000000O10000001O00001O00001O001O2N1O2N1O2N4L8ZIVOV6R10000000001O001O0000]OQJFn5:VJBj5>XJ@h5`0YJ@f5`0[J_Oe5a0\\J_Oc5a0^J^Ob5b0_J^O`5b0`J_O_5a0bJ^O^5e0cJXO\\5j0d02N1O5dISOk5[1N1O001O001O1O001O00001O0000000000000000000000000000UOXJNh5MbJN^5OhJMY51kJMU51mJNT50nJ0R50oJNR52PKLP54V1002N1O2N1O2N2hI[OJ0X5f0fJXOJ560X5f0eJ@1LY5Y1bJkN]5e1O2N2N@hJiNW5g0ZKTO@HU5S1\\KTOj4k0WKTOj4k0WKUOi4k0WKTOj4m0UKSOk4m0UKUOi4k0XKVOf4j0P11O3M4L5oJaNg3_1XLcNg3^1WLdNi3[1VLfNk3[1PLiNP4Y1mKhNR4[1kKeNV4]1hKcNX4]1gKcNZ4]1eKcN\\4]1cKdN]4\\1aKeNa4[1]KeNd4`1UKaNm4P23M2N1O2N1O2N3M3M3M1O2M2O1N3N1N3N1N2O1N2N2N2N2N3L3N3L5J7HVi9'}
    """

    image_info = coco.loadImgs(image_id)
    image_path = image_info[0]["file_name"]
    image_path = os.path.join(coco_dataset_path, "val2017", image_path)
    print("image path (crowd label)", image_path)
    # /export/public/MS-COCO-2017/val2017/000000448263.jpg
    image = cv2.imread(image_path)
    cv2.imshow("RLE label", image)
    cv2.waitKey()

    break