$ sudo apt-get update

$ sudo apt-get install python-dev

$ sudo apt-get install libtiff5-dev libjpeg8-dev zlib1g-dev \
libfreetype6-dev liblcms2-dev libwebp-dev tcl8.6-dev tk8.6-dev python-tk

$ sudo pip install pillow

$ wget http://labfile.oss.aliyuncs.com/courses/364/python_captcha.zip
$ unzip python_captcha.zip
$ cd python_captcha

#-*- coding:utf8 -*-
from PIL import Image

im = Image.open("captcha.gif")
#(将图片转换为8位像素模式)
im = im.convert("P")

#打印颜色直方图
print im.histogram()

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 2, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 2, 1, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0 , 1, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 1, 2, 0, 1, 0, 0, 1, 0, 2, 0, 0, 1, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 3, 1, 3, 3, 0, 0, 0, 0, 0, 0, 1, 0, 3, 2, 132, 1, 1, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 15, 0 , 1, 0, 1, 0, 0, 8, 1, 0, 0, 0, 0, 1, 6, 0, 2, 0, 0, 0, 0, 18, 1, 1, 1, 1, 1, 2, 365, 115, 0, 1, 0, 0, 0, 135, 186, 0, 0, 1, 0, 0, 0, 116, 3, 0, 0, 0, 0, 0, 21, 1, 1, 0, 0, 0, 2, 10, 2, 0, 0, 0, 0, 2, 10, 0, 0, 0, 0, 1, 0, 625]

his = im.histogram()
values = {}

for i in range(256):
 values[i] = his[i]

for j,k in sorted(values.items(),key=lambda x:x[1],reverse = True)[:10]:
 print j,k

255 625
212 365
220 186
219 135
169 132
227 116
213 115
234 21
205 18
184 15

#-*- coding:utf8 -*-
from PIL import Image

im = Image.open("captcha.gif")
im = im.convert("P")
im2 = Image.new("P",im.size,255)


for x in range(im.size[1]):
 for y in range(im.size[0]):
  pix = im.getpixel((y,x))
  if pix == 220 or pix == 227: # these are the numbers to get
   im2.putpixel((y,x),0)

im2.show()

inletter = False
foundletter=False
start = 0
end = 0

letters = []

for y in range(im2.size[0]): 
 for x in range(im2.size[1]):
  pix = im2.getpixel((y,x))
  if pix != 255:
   inletter = True
 if foundletter == False and inletter == True:
  foundletter = True
  start = y

 if foundletter == True and inletter == False:
  foundletter = False
  end = y
  letters.append((start,end))

 inletter=False
print letters

[(6, 14), (15, 25), (27, 35), (37, 46), (48, 56), (57, 67)]

import hashlib
import time

count = 0
for letter in letters:
 m = hashlib.md5()
 im3 = im2.crop(( letter[0] , 0, letter[1],im2.size[1] ))
 m.update("%s%s"%(time.time(),count))
 im3.save("./%s.gif"%(m.hexdigest()))
 count += 1

import math

class VectorCompare:
 #计算矢量大小
 def magnitude(self,concordance):
  total = 0
  for word,count in concordance.iteritems():
   total += count ** 2
  return math.sqrt(total)

 #计算矢量之间的 cos 值
 def relation(self,concordance1, concordance2):
  relevance = 0
  topvalue = 0
  for word, count in concordance1.iteritems():
   if concordance2.has_key(word):
    topvalue += count * concordance2[word]
  return topvalue / (self.magnitude(concordance1) * self.magnitude(concordance2))

#将图片转换为矢量
def buildvector(im):
 d1 = {}
 count = 0
 for i in im.getdata():
  d1[count] = i
  count += 1
 return d1

v = VectorCompare()

iconset = ['0','1','2','3','4','5','6','7','8','9','0','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']

#加载训练集
imageset = []
for letter in iconset:
 for img in os.listdir('./iconset/%s/'%(letter)):
  temp = []
  if img != "Thumbs.db" and img != ".DS_Store":
   temp.append(buildvector(Image.open("./iconset/%s/%s"%(letter,img))))
  imageset.append({letter:temp})


count = 0
#对验证码图片进行切割
for letter in letters:
 m = hashlib.md5()
 im3 = im2.crop(( letter[0] , 0, letter[1],im2.size[1] ))

 guess = []

 #将切割得到的验证码小片段与每个训练片段进行比较
 for image in imageset:
  for x,y in image.iteritems():
   if len(y) != 0:
    guess.append( ( v.relation(y[0],buildvector(im3)),x) )

 guess.sort(reverse=True)
 print "",guess[0]
 count += 1

python crack.py

(0.96376811594202894, '7')
(0.96234028545977002, 's')
(0.9286884286888929, '9')
(0.98350370609844473, 't')
(0.96751165072506273, '9')
(0.96989711688772628, 'j')