python生成字母验证图片

from PILimport Image,ImageDraw,ImageFont
import random

def generate_authenticode():
??? letters = random.sample('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789',4)
??? width = 100
??? height = 40
??? im = Image.new("RGB",(width,height),(255,255,255))
??? dr = ImageDraw.Draw(im)
??? font = ImageFont.truetype("/Library/Fonts/arial.ttf",30)
???
??? for iin range(4):
??????? dr.text((5+i*20,5),letters[i],(random.randint(,255),random.randint(,255)),font)
??? del dr

for xin range(width):
??? for yin range(height):
??????? if im.getpixel((x,y)) == (255,255):
??????????? im.putpixel((x,y),255)))

im.save('result.png')

if __name__ =="__main__":

??? generate_authenticode()