Python将图片转化成文字

import argparse
from PIL import Image
 # 命令行输入参数处理
parser = argparse.ArgumentParser()
# 输入图片
parser.add_argument('file', 
                    help='the input file')
# 输出文件
parser.add_argument('-o', '--output', 
                    help='the output text file')
# 输出字符画宽度
parser.add_argument('-w', '--width',
                    type=int, default=40,
                    help='the width of the output, default is 40')
# 输出字符画高度
parser.add_argument('--height', 
                    type=int, default=40,
                    help='the height of the output, default is 40')
# 获取参数
args = parser.parse_args()
IMG = args.file
WIDTH = args.width
HEIGHT = args.height
OUTPUT = args.output
str = "$@B%8&WM#*oahkbdpqw" \
      "mZO0QLCJUYXzcvunxrjft/\|()" \
      "1{}[]?-_+~<>i!lI;:,\"^`'. "
ascii_char = list(str)
 # 将256 灰度映射到 70 个字符上
def get_char(r, g, b, alpha=256):
    if alpha == 0:
        return " "
    length = len(ascii_char)
    gray = int(0.2126*r + 0.7152*g + 0.0722*b)
     # 每个字符对应的 gray 值区间宽度
    unit = (256.0+1)/length
     # gray值对应到 char_string 中的位置（索引值）
    index = int(gray/unit)
    return ascii_char[index]
if __name__ == "__main__":
    im = Image.open(IMG)
    im = im.resize((WIDTH, HEIGHT), Image.NEAREST)
    txt = ""
    for i in range(HEIGHT):
        for j in range(WIDTH):
            txt += get_char(*im.getpixel((j, i)))
        txt += '\n'
    print(txt)
    if OUTPUT:
        with open(OUTPUT, 'w') as f:
            f.write(txt)
    else:
        with open('output.txt', 'w') as f:
            f.write(txt)