yellow_plate.py

import os
import cv2
import numpy as np
from PIL import Image, ImageFont, ImageDraw


class Draw:
    _font = [
        ImageFont.truetype(os.path.join(os.path.dirname(__file__), "res/eng_92.ttf"), 126),
        ImageFont.truetype(os.path.join(os.path.dirname(__file__), "res/zh_cn_92.ttf"), 95)
    ]
    _bg = cv2.resize(cv2.imread(os.path.join(os.path.dirname(__file__), "res/yellow_bg.png")), (440, 140))

    def __call__(self, plate):
        if len(plate) != 7:
            print("ERROR: Invalid length")
            return None
        fg = self._draw_fg(plate)
        return cv2.cvtColor(cv2.bitwise_and(fg, self._bg), cv2.COLOR_BGR2RGB)

    def _draw_char(self, ch):
        img = Image.new("RGB", (45 if ch.isupper() or ch.isdigit() else 95, 140), (255, 255, 255))
        draw = ImageDraw.Draw(img)
        draw.text(
            (0, -11 if ch.isupper() or ch.isdigit() else 3), ch,
            fill = (0, 0, 0),
            font = self._font[0 if ch.isupper() or ch.isdigit() else 1]
        )
        if img.width > 45:
            img = img.resize((45, 140))
        return np.array(img)

    def _draw_fg(self, plate):
        img = np.array(Image.new("RGB", (440, 140), (255, 255, 255)))
        offset = 15
        img[0:140, offset:offset+45] = self._draw_char(plate[0])
        offset = offset + 45 + 12
        img[0:140, offset:offset+45] = self._draw_char(plate[1])
        offset = offset + 45 + 34
        for i in range(2, len(plate)):
            img[0:140, offset:offset+45] = self._draw_char(plate[i])
            offset = offset + 45 + 12
        return img


if __name__ == "__main__":
    import argparse
    import matplotlib.pyplot as plt

    parser = argparse.ArgumentParser(description="Generate a yellow plate.")
    parser.add_argument("plate", help="license plate number (default: 京A12345)", type=str, nargs="?", default="京A12345")
    args = parser.parse_args()

    draw = Draw()
    plate = draw(args.plate)
    plt.imshow(plate)
    plt.show()