implementation.py

from PIL import Image


def convert_data(data):
    new_data = []

    for i in data:
        new_data.append(format(ord(i), '08b'))

    return new_data

def mod_pixel(pix, data):
    datalist = convert_data(data)
    lendata = len(datalist)
    imdata = iter(pix)

    for i in range(lendata):
        pix = [value for value in imdata.__next__()[:3] +
               imdata.__next__()[:3] +
               imdata.__next__()[:3]]

        for j in range(0, 8):
            if (datalist[i][j] == '0') and (pix[j] % 2 != 0):
                if (pix[j] % 2 != 0):
                    pix[j] -= 1
            elif (datalist[i][j] == '1') and (pix[j] % 2 == 0):
                pix[j] -= 1

        if (i == lendata - 1):
            if (pix[-1] % 2 == 0):
                pix[-1] -= 1
        else:
            if (pix[-1] % 2 != 0):
                pix[-1] -= 1

        pix = tuple(pix)
        yield pix[0:3]
        yield pix[3:6]
        yield pix[6:9]

def encode_enc(newimg, data):
    w = newimg.size[0]

    (x, y) = (0, 0)

    for pixel in mod_pixel(newimg.getdata(), data):
        newimg.putpixel((x, y), pixel)

        if (x == w - 1):
            x = 0
            y += 1
        else:
            x += 1

def encode():
    img = input("Enter full image name: ")
    image = Image.open(img, 'r')
    data = input("Enter data: ")

    if (len(data) == 0):
        raise ValueError('cannot encode empty')

    newimg = image.copy()

    encode_enc(newimg, data)

    new_img_name = input("Enter full name of encoded image : ")

    newimg.save(new_img_name, str(new_img_name.split(".")[1].upper()))

def decode():
    img = input("Enter full image name :")
    image = Image.open(img, 'r')
    data = ''
    imgdata = iter(image.getdata())

    while (True):
        pixels = [value for value in imgdata.__next__()[:3] +
                  imgdata.__next__()[:3] +
                  imgdata.__next__()[:3]]
        binstr = ''

        for i in pixels[:8]:
            if (i % 2 == 0):
                binstr += '0'
            else:
                binstr += '1'

        data += chr(int(binstr, 2))

        if (pixels[-1] % 2 != 0):
            return data

def main():
    a = input("1. encode \ 2. decode: ")
    
    if (a == '1'):
        encode()
    elif (a == '2'):
        print("Decoded data: " + decode())

if __name__ == '__main__':
    main()