try get an image with better quality from any image given by url. uses google's search by image.

enlargeByUrl.py

import urllib, urllib2
from cookielib import CookieJar
from urlparse import urlparse, parse_qs
from bs4 import BeautifulSoup

def toFile(s):
    f = open('dat.html', 'w')
    f.write(s)
    f.close()

def enlargeByUrl(url):
    cj = CookieJar()
    dat = {
    }
    dat = urllib.urlencode(dat)
    opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj))
    opener.addheaders = [('user-agent', 'Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11')]
    #res = opener.open('https://www.google.com/ncr', None, 10)
    #res = opener.open('https://www.google.com/imghp', None, 10)
    res = opener.open('https://www.google.com/searchbyimage?' + urllib.urlencode({'image_url' : url, 'safe' : 'off'}), None, 10)
    soup = BeautifulSoup(''.join(res.read()))
    t = soup.find('a', text = 'All sizes')
    #print 'https://www.google.com' + t['href'] + '&biw=1280&bih=643'
    #print 'https://www.google.com/search?hl=en&safe=off&tbo=d&q=tokyo+juliet+ost&tbm=isch&tbs=simg:CAQSZRpjCxCo1NgEGgIICwwLELCMpwgaPAo6CAESFPgEiQSLBIMEhQTkBeUF_1wT5BMkFGiDne1kJSlZpR4VVucKY_1Cq3xnfJmQamWkedUW6KS8hQCgwLEI6u_1ggaCgoICAESBMKuf2oM&sa=X&ei=NYrIUImRFZHRmAWZloF4&ved=0CCcQ2A4oAA&biw=1280&bih=643&sei=W4rIUNHPLOyKmQXp_IDAAQ'
    res = opener.open('https://www.google.com' + t['href'] + '&biw=1280&bih=760')
    soup = BeautifulSoup(''.join(res.read()))
    t = soup.find('div', class_ = 'rg_di')
    p = urlparse(t.a['href'])
    p = parse_qs(p.query)
    return p['imgurl'][0]

if __name__ == '__main__':
   url = 'http://img3.douban.com/mpic/s1687633.jpg'
#    print urllib.urlencode({'url' : url, 'sag' : 'abc'})
   enlargeByUrl(url)