qr_scan.py

import lxml.html
import requests

FILENAME = '3.png'

r = requests.get('http://www.onlinebarcodereader.com/')
root = lxml.html.fromstring(r.text)

MAX_FILE_SIZE, = root.cssselect('input[name=MAX_FILE_SIZE]')
senderid, = root.cssselect('#senderid')
checksum, = root.cssselect('#checksum')


post_data = {
    'MAX_FILE_SIZE': MAX_FILE_SIZE.get('value'),
    'senderid': senderid.get('value'),
    'checksum': checksum.get('value'),
}
print post_data

r = requests.post('http://www.onlinebarcodereader.com/', post_data, files={
    'userfile': open(FILENAME, 'rb')
})

root = lxml.html.fromstring(r.text)
result, = root.cssselect('#result-raw')
print result.text