labelImg: Convert annotations in JSON to YOLO format

json2yolo.py

import glob
import json
import cv2

LUT = {"class0": 0, "class1": 1, "class2": 2}

for each_file in glob.glob("data/*.json"):
	with open(each_file) as json_file:
		data = json.load(json_file)[0]

		print(data["image"])
		img = cv2.imread("data/" + data["image"])
		height = img.shape[0]
		width = img.shape[1]

		print(height, width)

		label = data["annotations"][0]['label']
		x = data["annotations"][0]['coordinates']['x']
		y = data["annotations"][0]['coordinates']['y']
		annotation_width = data["annotations"][0]['coordinates']['width']
		annotation_height = data["annotations"][0]['coordinates']['height']

		annotation_yolo = f"{LUT[label]} {x/width} {y/height} {annotation_width/width} {annotation_height/height}"
		print(annotation_yolo)

		with open(data["image"][:-3] + "txt", 'w') as txt_file:
			txt_file.write(annotation_yolo)