Least Significant Bit (simple method)

#!/usr/bin/env python

with open("sample.bmp", "rb") as file:
    data = file.read()

    bits = ""
    for c in data:
        lsb = str(c & 0x1)
        bits += lsb

    bytes = [chr(int(bits[i:i+8], 2)) for i in range(0, len(bits), 8)]
    out = "".join(bytes)
    print(out)