stegno.py

# Python program implementing Image Steganography 
  
# PIL module is used to extract 
# pixels of image and modify it 
from PIL import Image 
  
# Convert encoding data into 8-bit binary 
# form using ASCII value of characters 
def genData(data): 
          
        # list of binary codes 
        # of given data 
        newd = []  
          
        for i in data: 
            newd.append(format(ord(i), '08b')) 
        return newd 
          
# Pixels are modified according to the 
# 8-bit binary data and finally returned 
def modPix(pix, data): 
      
    datalist = genData(data) 
    lendata = len(datalist) 
    imdata = iter(pix) 
  
    for i in range(lendata): 
          
        # Extracting 3 pixels at a time 
        pix = [value for value in imdata.__next__()[:3] +
                                  imdata.__next__()[:3] +
                                  imdata.__next__()[:3]] 
                                      
        # Pixel value should be made  
        # odd for 1 and even for 0 
        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
                  
        # Eigh^th pixel of every set tells  
        # whether to stop ot read further. 
        # 0 means keep reading; 1 means the 
        # message is over. 
        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 modPix(newimg.getdata(), data): 
          
        # Putting modified pixels in the new image 
        newimg.putpixel((x, y), pixel) 
        if (x == w - 1): 
            x = 0
            y += 1
        else: 
            x += 1
              
# Encode data into image 
def encode(imag, texts): 
    #img = input("Enter image name(with extension): ") 
    #image = Image.open(img, 'r')
    image = Image.open(imag,'r') 
      
    #data = input("Enter data to be encoded : ") 
    data = texts
    if (len(data) == 0): 
        raise ValueError('Data is empty') 
          
    newimg = image.copy() 
    encode_enc(newimg, data) 
      
    #new_img_name = "output.png" 
    newimg.save('static/uploads/output.png','PNG') 
  
# Decode the data in the image 
def decode(imag): 
    #img = input("Enter image name(with extension) :") 
    image = Image.open(imag, 'r') 
      
    data = '' 
    imgdata = iter(image.getdata()) 
      
    while (True): 
        pixels = [value for value in imgdata.__next__()[:3] +
                                  imgdata.__next__()[:3] +
                                  imgdata.__next__()[:3]] 
        # string of binary data 
        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 
              
# # Main Function         
# def main(): 
#     a = int(input(":: Welcome to Steganography ::\n"
#                         "1. Encode\n 2. Decode\n")) 
#     if (a == 1): 
#         encode() 
          
#     elif (a == 2): 
#         print("Decoded word- " + decode()) 
#     else: 
#         raise Exception("Enter correct input") 
          
# # Driver Code 
# if __name__ == '__main__' : 
      
#     # Calling main function 
#     main()