Update README.md

README.md

@@ -99,7 +99,14 @@ A sample image name is "025-95_113-154&383_386&473-386&473_177&454_154&383_363&4
 
 - **Four vertices locations**: The exact (x, y) coordinates of the four vertices of LP in the whole image. These coordinates start from the right-bottom vertex.
 
-- **License plate number**: Each image in CCPD has only one LP. Each LP number is comprised of a Chinese character, a letter, and five letters or numbers.
+- **License plate number**: Each image in CCPD has only one LP. Each LP number is comprised of a Chinese character, a letter, and five letters or numbers. A valid Chinese license plate consists of seven characters: province (1 character), alphabets (1 character), alphabets+digits (5 characters). "0_0_22_27_27_33_16" is the index of each character. The array is defined as follows.
+```
+provinces = ["皖", "沪", "津", "渝", "冀", "晋", "蒙", "辽", "吉", "黑", "苏", "浙", "京", "闽", "赣", "鲁", "豫", "鄂", "湘", "粤", "桂", "琼", "川", "贵", "云", "藏", "陕", "甘", "青", "宁", "新", "警", "学", "O"]
+alphabets = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
+             'X', 'Y', 'Z', 'O']
+ads = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
+       'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'O']
+```
 
 - **Brightness**: The brightness of the license plate region.