id_card_dob_extractor.py

"""
Filename: id_card_dob_extractor.py

This script extracts the date of birth (DOB) from the front image of an ID card. The image
is converted to grayscale and optical character recognition (OCR) is used to extract
all the text information. Then, a regular expression (regex) is used to find the 
DOB in the format dd-mm-yyyy.

Author: Siddharth Kumar (www.siddharthsah.com)
Last Updated: July 28, 2023
"""

import re
import cv2
import pytesseract

def extract_text_from_image(image_path):
    """
    Reads an image, converts it to grayscale, and extracts all text information.

    Args:
        image_path: Path to the image file.

    Returns:
        A string containing all the text information in the image.
    """
    img = cv2.imread(image_path)
    if img is None:
        raise ValueError(f"Image couldn't be read, check the path: {image_path}")

    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    return pytesseract.image_to_string(gray)


def extract_dob_from_text(text):
    """
    Uses a regex to find the DOB in the extracted text.

    Args:
        text: A string of text extracted from an image.

    Returns:
        The DOB found in the text.
    """
    # Split the text into an array of words
    words = text.split()

    # Search for the DOB in the array of words
    for word in words:
        match = re.match("^(0[1-9]|[12][0-9]|3[01])[- /.](0[1-9]|1[012])[- /.](19|20)\d\d$", word)
        if match:
            return word  # Return the DOB

    # If no DOB was found, return None
    return None


def main():
    """
    Main function that reads the front image of an ID card, extracts the text, 
    and finds the DOB.
    """
    image_path = './output/5_1.jpg'
    text = extract_text_from_image(image_path)
    dob = extract_dob_from_text(text)

    if dob:
        print(f"DOB found: {dob}")
    else:
        print("No DOB found in the ID card image.")


if __name__ == '__main__':
    main()