Python将图片转换为字符画的方法

# coding:utf-8 
 
# 为一张图片生成对应的字符集图片 
 
from PIL import Image 
import argparse 
 
# 命令行输入参数处理 
parser = argparse.ArgumentParser() 
 
parser.add_argument('file')   # 输入文件 
parser.add_argument('-o','--output')  # 输出文件 
parser.add_argument('--width',type=int,default=80) # 输出字符画宽 
parser.add_argument('--height',default=80) # 输出字符画高 
 
# 获取参数 
args = parser.parse_args() 
 
IMG = args.file 
WIDTH = args.width 
HEIGHT = args.height 
OUTPUT = args.output 
 
ascii_char = list("$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/|()1{}[]?-_+~<>i!lI;:,"^`'. ") 
 
 
# 将256灰度映射到70个字符上 
def get_char(r,b,g,alpha=256): 
  if alpha == 0: 
    return ' ' 
  length = len(ascii_char) 
  gray = int(0.2126 * r + 0.7152 * g + 0.0722 * b) 
 
  unit = (256.0 + 1)/length 
  return ascii_char[int(gray/unit)] 
 
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 
 
  # 字符画输出到文件 
  if OUTPUT: 
    with open(OUTPUT,'w') as f: 
      f.write(txt) 
  else: 
    with open("output.txt",'w') as f: 
      f.write(txt)