Convert a binary file into a binary string and back

data-to-binary-string.py

import struct

def data_to_binary_string(input_filename):
    binary_string = ''

    file = open(input_filename, 'rb')

    bytes = file.read(1024)
    while len(bytes):
        binary_string = binary_string + ''.join(['{0:0>8b}'.format(ord(b)) for b in bytes])
        bytes = file.read(1024)

    return binary_string

def binary_string_to_data(binary_string, ouput_filename):
    bytes = []

    for i in range(0, len(binary_string) / 8):
        bytes.append(int(binary_string[i*8:(i+1)*8], 2))

    data = struct.pack('{0}B'.format(len(bytes)), *bytes)

    file = open(ouput_filename, 'wb')
    file.write(data)
    file.close()

binary_string = data_to_binary_string('dapa.jpg')
binary_string_to_data(binary_string, 'new-dapa.jpg')