Convert all labelme generated json into mask image in every subdirectory

labelme_gen_mask_img.py

# Author : frakw
# Date : 2023-12-04
# Description : Convert all labelme generated json into mask image in every subdirectory
# Usage : python labelme_gen_mask_img.py

import json
import numpy as np
import cv2
import os
import fnmatch
from pathlib import Path

root_dir = './'


def gen_mask_img(json_filename):
    # read json file
    with open(json_filename, "r") as f:
        data = f.read()
    
    # convert str to json objs
    data = json.loads(data)
    
    # get the points 
    points = data["shapes"][0]["points"]
    points = np.array(points, dtype=np.int32)   # tips: points location must be int32
    
    target_dirname = os.path.dirname(json_filename)
    original_img_filename = target_dirname + '/' + data["imagePath"]

    # read image to get shape
    image = cv2.imread(original_img_filename)
    
    # create a blank image
    mask = np.zeros_like(image, dtype=np.uint8)
    
    # fill the contour with 255
    cv2.fillPoly(mask, [points], (255, 255, 255))
    
    json_filename_noex = Path(json_filename).stem
    mask_img_filename = target_dirname + '/' + json_filename_noex + "_mask.png"

    # save the mask 
    cv2.imwrite(mask_img_filename, mask)

def main():
    for dirname, dirnames, filenames in os.walk(root_dir):
        for filename in filenames:
            if fnmatch.fnmatch(filename,"*.json") == True:
                relative_filename = os.path.join(dirname,filename)
                relative_filename = relative_filename.replace("\\","/")
                print("generate mask img for " + relative_filename)
                gen_mask_img(relative_filename)
            else:
                pass

if __name__ == '__main__':
    main()

requirements.txt

numpy==1.26.2
opencv-python==4.8.1.78