Test on a folder got error.

[sibadakesi]

 if os.path.isdir(args.imgs[0]):   # Maybe args.imgs.
        imgs = find_recursive(args.imgs[0])
    else:
        imgs = [args.imgs]

and "find_recursive"

def find_recursive(root_dir):
    files = []
    filenames = os.listdir(root_dir)
    for filename in filenames:
        files.append(os.path.join(root_dir, filename))
    return files

[owenzlz]

if os.path.isdir(args.imgs): # Maybe args.imgs.
imgs = find_recursive(args.imgs)
else:
imgs = [args.imgs]

Change to the above should work.