python下調用pytesseract識別某網站驗證碼

一、pytesseract介紹

1、pytesseract說明

pytesseract最新版本0.1.6

Python-tesseract is a wrapper for google's Tesseract-OCR.
# It is also useful as a
stand-alone invocation script to tesseract, as it can read all image types
supported by the Python Imaging Library, including jpeg, png, gif, bmp, tiff,##and . whereas tesseract-ocr by default only supports tiff and bmp.
Additionally, if used as a script, Python-tesseract will print the recognized
text in stead of writing it to a file. Support for recognized##text in stead of writing it to a file. Support for confidence estimates and# #bounding box data is planned for future releases.

翻譯一下大意：

a、Python-tesseract是一個基於google's Tesseract-OCR的獨立封裝包；

b 、Python-tesseract功能是識別圖片檔案中文字，並作為返回參數返回識別結果；

#c、Python-tesseract預設支援tiff、bmp格式圖片，只有在安裝PIL之後，才能支援jpeg、gif 、png等其他圖片格式;

2、pytesseract安裝

INSTALLATION:

Prerequisites:

* Python-tesseract requires python 2.5 or later or python 3.

* You will need the Python Imaging Library (PIL). Under Debian/Ubuntu, this is
the package "python-imaging" or "python3-imaging" for python3.
* Install google tesseract-ocr from
You must be able to invoke the tesseract command as "tesseract". If this
isn't the case, for example because tesseract isn't in your PATH, you will
haveser to tesseract isn't in your PATH, you will
haveser to tesseract isnact_cmser " variable at the top of 'tesseract.py'.
Under Debian/Ubuntu you can use the package "tesseract-ocr".

Installing via pip: 

#See the [pytesseract package page]

```
$> sudo pip install pytesseract

翻譯一下：

a、Python-tesseract支援python2.5及更高版本;

b、Python-tesseract需要安裝PIL（Python Imaging Library） ，來支援更多的圖片格式；

c、Python-tesseract需要安裝tesseract-ocr安裝套件。

綜上，Pytesseract原理：

1、上一篇部落格文章提到，執行命令列tesseract.exe 1.png output -l eng ，可以辨識1.png中文字，並且把辨識結果輸出到output.txt中；

2、Pytesseract對上述過程進行了二次封裝，自動呼叫tesseract.exe，並讀取output.txt檔案的內容，作為函數的回傳值進行返回。

二、pytesseract使用

USAGE:

``
#> try:
> import Image
> except ImportError:
> ; from PIL import Image
> import pytesseract
> print(pytesseract.image_to_string(Image.open('test.png')))
> print(pytesseract.image_to_string(Image.opening(Image.opening(Image). 'test-european.jpg'),))

可以看到：

1、核心程式碼就是image_to_string函數，該函數也支援-l eng 參數，支援-psm 參數。

用法：

image_to_string(Image.open('test.png'),lang="eng" config="-psm 7")

2、pytesseract裡呼叫了image，所以才需要PIL，其實tesseract.exe本身是支援jpeg、png等圖片格式的。

實例代碼，識別某公共網站的驗證碼(大家千萬別幹壞事啊，思慮再三，最後還是隱掉網站域名，大家去找別的網站試試吧…)：

#-*-coding=utf-8-*-
__author__='zhongtang'
 
import urllib
import urllib2
import cookielib
import math
import random
import time
import os
import htmltool
from pytesseract import *
from PIL import Image
from PIL import ImageEnhance
import re
 
class orclnypcg:
  def __init__(self):
    self.baseUrl='http://jbywcg.****.com.cn'
    self.ht=htmltool.htmltool()
    self.curPath=self.ht.getPyFileDir()
    self.authCode=''
     
  def initUrllib2(self):
    try:
      cookie = cookielib.CookieJar()
      cookieHandLer = urllib2.HTTPCookieProcessor(cookie)
      httpHandLer=urllib2.HTTPHandler(debuglevel=0)
      httpsHandLer=urllib2.HTTPSHandler(debuglevel=0)
    except:
      raise
    else:
       opener = urllib2.build_opener(cookieHandLer,httpHandLer,httpsHandLer)
       opener.addheaders = [('User-Agent','Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11')]
       urllib2.install_opener(opener)
        
  def urllib2Navigate(self,url,data={}):      #定义连接函数，有超时重连功能
    tryTimes = 0
    while True:
      if (tryTimes>20):
        print u"多次尝试仍无法链接网络，程序终止"
        break
      try:
        if (data=={}):
          req = urllib2.Request(url)
        else:
          req = urllib2.Request(url,urllib.urlencode(data))
        response =urllib2.urlopen(req)
        bodydata = response.read()
        headerdata = response.info()
        if headerdata.get('Content-Encoding')=='gzip':
          rdata = StringIO.StringIO(bodydata)
          gz = gzip.GzipFile(fileobj=rdata)
          bodydata = gz.read()
          gz.close()
        tryTimes = tryTimes +1
      except urllib2.HTTPError, e:
       print 'HTTPError[%s]\n' %e.code        
      except urllib2.URLError, e:
       print 'URLError[%s]\n' %e.reason  
      except socket.error:
        print u"连接失败，尝试重新连接"
      else:
        break
    return bodydata,headerdata
   
  def randomCodeOcr(self,filename):
    image = Image.open(filename)
    #使用ImageEnhance可以增强图片的识别率
    #enhancer = ImageEnhance.Contrast(image)
    #enhancer = enhancer.enhance(4)
    image = image.convert('L')
    ltext = ''
    ltext= image_to_string(image)
    #去掉非法字符，只保留字母数字
    ltext=re.sub("\W", "", ltext)
    print u'[%s]识别到验证码:[%s]!!!' %(filename,ltext)
    image.save(filename)
    #print ltext
    return ltext
 
  def getRandomCode(self):
    #开始获取验证码
    #http://jbywcg.****.com.cn/CommonPage/Code.aspx?0.9409255818463862
    i = 0
    while ( i<=100):
      i += 1
      #拼接验证码Url
      randomUrlNew=&#39;%s/CommonPage/Code.aspx?%s&#39; %(self.baseUrl,random.random())
      #拼接验证码本地文件名
      filename= &#39;%s.png&#39; %(i)
      filename= os.path.join(self.curPath,filename)
      jpgdata,jpgheader = self.urllib2Navigate(randomUrlNew)
      if len(jpgdata)<= 0 :
        print u&#39;获取验证码出错！\n&#39;
        return False
      f = open(filename, &#39;wb&#39;)
      f.write(jpgdata)
      #print u"保存图片:",fileName
      f.close()
      self.authCode = self.randomCodeOcr(filename)
 
 
#主程序开始
orcln=orclnypcg()
orcln.initUrllib2()
orcln.getRandomCode()

三、pytesseract程式碼最佳化

上述程式在windows平台運行時，會發現有黑色的控制台視窗一閃而過的畫面，不太友善。

稍微修改了pytesseract.py（C:\Python27\Lib\site-packages\pytesseract目錄下），把上述過程進行了隱藏。

# modified by zhongtang hide console window

# new code
IS_WIN32 = 'win32' in str(sys.platform).lower()
if IS_WIN32:
   startupinfo = subprocess .STARTUPINFO()
   startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
   startupinfo.wShowWindow = subprocess.SW_HIDE
   procm = subprocess.Pinfo(com =startupinfo)
'''
# old code
proc = subprocess.Popen(command,
   stderr=subprocess.PIPE)
'''
## modified end

為了方便初學者，把pytesseract.py也貼出來，高手自行忽略。

#!/usr/bin/env python
'''
Python-tesseract is an optical character recognition (OCR) tool for python.
That is, it will recognize and "read" the text embedded in images.
 
Python-tesseract is a wrapper for google's Tesseract-OCR
( http://code.google.com/p/tesseract-ocr/ ). It is also useful as a
stand-alone invocation script to tesseract, as it can read all image types
supported by the Python Imaging Library, including jpeg, png, gif, bmp, tiff,
and others, whereas tesseract-ocr by default only supports tiff and bmp.
Additionally, if used as a script, Python-tesseract will print the recognized
text in stead of writing it to a file. Support for confidence estimates and
bounding box data is planned for future releases.
 
 
USAGE:
```
 > try:
 >   import Image
 > except ImportError:
 >   from PIL import Image
 > import pytesseract
 > print(pytesseract.image_to_string(Image.open('test.png')))
 > print(pytesseract.image_to_string(Image.open('test-european.jpg'),))
```
 
INSTALLATION:
 
Prerequisites:
* Python-tesseract requires python 2.5 or later or python 3.
* You will need the Python Imaging Library (PIL). Under Debian/Ubuntu, this is
 the package "python-imaging" or "python3-imaging" for python3.
* Install google tesseract-ocr from http://code.google.com/p/tesseract-ocr/ .
 You must be able to invoke the tesseract command as "tesseract". If this
 isn't the case, for example because tesseract isn't in your PATH, you will
 have to change the "tesseract_cmd" variable at the top of 'tesseract.py'.
 Under Debian/Ubuntu you can use the package "tesseract-ocr".
  
Installing via pip:  
See the [pytesseract package page](https://pypi.python.org/pypi/pytesseract)   
$> sudo pip install pytesseract  
 
Installing from source:  
$> git clone git@github.com:madmaze/pytesseract.git  
$> sudo python setup.py install  
 
 
LICENSE:
Python-tesseract is released under the GPL v3.
 
CONTRIBUTERS:
- Originally written by [Samuel Hoffstaetter](https://github.com/hoffstaetter) 
- [Juarez Bochi](https://github.com/jbochi)
- [Matthias Lee](https://github.com/madmaze)
- [Lars Kistner](https://github.com/Sr4l)
 
'''
 
# CHANGE THIS IF TESSERACT IS NOT IN YOUR PATH, OR IS NAMED DIFFERENTLY
tesseract_cmd = 'tesseract'
 
try:
  import Image
except ImportError:
  from PIL import Image
import subprocess
import sys
import tempfile
import os
import shlex
 
__all__ = ['image_to_string']
 
def run_tesseract(input_filename, output_filename_base,, boxes=False, config=None):
  '''
  runs the command:
    `tesseract_cmd` `input_filename` `output_filename_base`
   
  returns the exit status of tesseract, as well as tesseract's stderr output
 
  '''
  command = [tesseract_cmd, input_filename, output_filename_base]
   
  if lang is not None:
    command += ['-l', lang]
 
  if boxes:
    command += ['batch.nochop', 'makebox']
     
  if config:
    command += shlex.split(config)
     
  # modified by zhongtang hide console window
  # new code
  IS_WIN32 = 'win32' in str(sys.platform).lower()
  if IS_WIN32:
    startupinfo = subprocess.STARTUPINFO()
    startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
    startupinfo.wShowWindow = subprocess.SW_HIDE
  proc = subprocess.Popen(command,
      stderr=subprocess.PIPE,startupinfo=startupinfo)
  '''
  # old code
  proc = subprocess.Popen(command,
      stderr=subprocess.PIPE)
  '''
  # modified end
   
  return (proc.wait(), proc.stderr.read())
 
def cleanup(filename):
  ''' tries to remove the given filename. Ignores non-existent files '''
  try:
    os.remove(filename)
  except OSError:
    pass
 
def get_errors(error_string):
  '''
  returns all lines in the error_string that start with the string "error"
 
  '''
 
  lines = error_string.splitlines()
  error_lines = tuple(line for line in lines if line.find('Error') >= 0)
  if len(error_lines) > 0:
    return '\n'.join(error_lines)
  else:
    return error_string.strip()
 
def tempnam():
  ''' returns a temporary file-name '''
  tmpfile = tempfile.NamedTemporaryFile(prefix="tess_")
  return tmpfile.name
 
class TesseractError(Exception):
  def __init__(self, status, message):
    self.status = status
    self.message = message
    self.args = (status, message)
 
def image_to_string(image,, boxes=False, config=None):
  '''
  Runs tesseract on the specified image. First, the image is written to disk,
  and then the tesseract command is run on the image. Resseract's result is
  read, and the temporary files are erased.
   
  also supports boxes and config.
   
  if boxes=True
    "batch.nochop makebox" gets added to the tesseract call
  if config is set, the config gets appended to the command.
    ex: config="-psm 6"
 
  '''
 
  if len(image.split()) == 4:
    # In case we have 4 channels, lets discard the Alpha.
    # Kind of a hack, should fix in the future some time.
    r, g, b, a = image.split()
    image = Image.merge("RGB", (r, g, b))
   
  input_file_name = '%s.bmp' % tempnam()
  output_file_name_base = tempnam()
  if not boxes:
    output_file_name = '%s.txt' % output_file_name_base
  else:
    output_file_name = '%s.box' % output_file_name_base
  try:
    image.save(input_file_name)
    status, error_string = run_tesseract(input_file_name,
                       output_file_name_base,
                       lang=lang,
                       boxes=boxes,
                       config=config)
    if status:
      #print 'test' , status,error_string
      errors = get_errors(error_string)
      raise TesseractError(status, errors)
    f = open(output_file_name)
    try:
      return f.read().strip()
    finally:
      f.close()
  finally:
    cleanup(input_file_name)
    cleanup(output_file_name)
 
def main():
  if len(sys.argv) == 2:
    filename = sys.argv[1]
    try:
      image = Image.open(filename)
      if len(image.split()) == 4:
        # In case we have 4 channels, lets discard the Alpha.
        # Kind of a hack, should fix in the future some time.
        r, g, b, a = image.split()
        image = Image.merge("RGB", (r, g, b))
    except IOError:
      sys.stderr.write('ERROR: Could not open file "%s"\n' % filename)
      exit(1)
    print(image_to_string(image))
  elif len(sys.argv) == 4 and sys.argv[1] == '-l':
   .argv[2]
    filename = sys.argv[3]
    try:
      image = Image.open(filename)
    except IOError:
      sys.stderr.write('ERROR: Could not open file "%s"\n' % filename)
      exit(1)
    print(image_to_string(image,))
  else:
    sys.stderr.write('Usage: python pytesseract.py [-l language] input_file\n')
    exit(2)
 
if __name__ == '__main__':
  main()

以上…

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