print('Viewing', db_path)

print('Press ESC to exist or SPACE to advance.')

window_name = 'LSUN'

cv2.namedWindow(window_name)

env = lmdb.open(db_path, map_size=1099511627776,

max_readers=100, readonly=True)

with env.begin(write=False) as txn:

cursor = txn.cursor()

for key, val in cursor:

print('Current key:', key)

img = cv2.imdecode(

numpy.fromstring(val, dtype=numpy.uint8), 1)

cv2.imshow(window_name, img)

c = cv2.waitKey()

if c == 27:

print('Exporting', db_path, 'to', out_dir)

env = lmdb.open(db_path, map_size=1099511627776,

max_readers=100, readonly=True)

count = 0

with env.begin(write=False) as txn:

cursor = txn.cursor()

for key, val in cursor:

key_str = "".join([chr(_) for _ in key])

val_str = "".join([chr(_) for _ in val])

if not flat:

image_out_dir = join(out_dir, '/'.join([chr(_) for _ in key[:6]]))

else:

image_out_dir = out_dir

if not exists(image_out_dir):

os.makedirs(image_out_dir)

image_out_path = join(image_out_dir, key_str + '.webp')

with open(image_out_path, 'wb') as fp:

fp.write(val)

count += 1

if count == limit:

break

if count % 1000 == 0:

parser = argparse.ArgumentParser()

parser.add_argument('command', nargs='?', type=str,

choices=['view', 'export'],

help='view: view the images in the lmdb database '

'interactively.\n'

'export: Export the images in the lmdb databases '

'to a folder. The images are grouped in subfolders'

' determinted by the prefiex of image key.')

parser.add_argument('lmdb_path', nargs='+', type=str,

help='The path to the lmdb database folder. '

'Support multiple database paths.')

parser.add_argument('--out_dir', type=str, default='')

parser.add_argument('--flat', action='store_true',

help='If enabled, the images are imported into output '

'directory directly instead of hierarchical '

'directories.')

args = parser.parse_args()

command = args.command

lmdb_paths = args.lmdb_path

for lmdb_path in lmdb_paths:

if command == 'view':

view(lmdb_path)

elif command == 'export':