Image Steganography

ImageProcessingScripts/Image Steganography/README.md

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+
+# Image Steganography
+
+
+## Description
+
+Image Steganography refers to the process of hiding data within an image file. The image selected for this purpose is called the cover-image and the image obtained after steganography is called the stego-image.
+
+### How it is done?
+
+The idea behind Image Steganography is simple. Images are composed of digital data (pixels), which describes what’s inside the picture, usually the colors of all the pixels. Since we know every image is made up of pixels and every pixel contains 3-values (red, green, blue). In image steganography, a message is embedded into an image by altering the values of some pixels, which are chosen by an encryption algorithm. The recipient of the image must be aware of the same algorithm in order to known which pixels he or she must select to extract the message.
+
+Every byte of data is converted to its 8-bit binary code using ASCII values. Now pixels are read from left to right in a group of 3 containing a total of 9 values. The first 8-values are used to store binary data. The value is made odd if 1 occurs and even if 0 occurs.
+To decode, three pixels are read at a time, till the last value is odd, which means the message is over. Every 3-pixels contain a binary data, which can be extracted by the same encoding logic. If the value if odd the binary bit is 1 else 0.
+
+
+## Library imported :
+
+Image library of Python Imaging Library(PIL) module - is used to extract pixels of image
+
+
+## Output :
+Encoding Screenshot:
+![Encoding Image](Images/encoding_ss.png)
+
+Decoding Screenshot:
+![Decoding Image](Images/decoding_ss.png)
+
+
+## Author : Shaik Imranuddin 
+
+

ImageProcessingScripts/Image Steganography/image_steganography.py

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+
+
+# PIL module is used to extract pixels of image and modify it
+from PIL import Image
+
+# Convert the secret data into 8-bit binary value by using the ASCII value
+def genData(data):
+
+binLst = [] #list to store binary data
+
+for i in data:
+binLst.append(format(ord(i), '08b')) #Converting and appending binary data
+return binLst
+
+# Pixels are modified according to the 8-bit binary data and finally returned
+def modPixel(pix, data):
+
+datalist = genData(data)
+lendata = len(datalist)
+igdata = iter(pix)
+
+for i in range(lendata):
+
+# Extracting 3 pixels at a time
+pix = [value for value in igdata.__next__()[:3] + igdata.__next__()[:3] + igdata.__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):
+pix[j] -= 1
+
+elif (datalist[i][j] == '1' and pix[j] % 2 == 0):
+if(pix[j] != 0):
+pix[j] -= 1
+else:
+pix[j] += 1
+
+# Eighth pixel of every set tells us whether to stop or read further.
+# 0 means keep reading; 1 means the message is over.
+if (i == lendata - 1):
+if (pix[-1] % 2 == 0):
+if(pix[-1] != 0):
+pix[-1] -= 1
+else:
+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 modPixel(newimg.getdata(), data):
+
+# Putting modified pixels with encoded data in the new image
+newimg.putpixel((x, y), pixel)
+if (x == w - 1):
+x = 0
+y += 1
+else:
+x += 1
+
+
+# Method to encode data into image
+def encode():
+img = input("Enter image name(with extension) in which data is to be encoded : ")
+image = Image.open("Images/"+img, 'r')
+
+data = input("Enter the data to be encoded : ")
+if (len(data) == 0):
+raise ValueError('Data is empty')
+
+newimg = image.copy()
+encode_enc(newimg, data)
+
+en_img = input("Enter the name of new encoded image(with extension) : ")
+newimg.save("Images/"+en_img, str(en_img.split(".")[1].upper()))
+
+
+# Method to decode the data present in the image
+def decode():
+img = input("Enter image name(with extension) from which data is to be dencoded : ")
+image = Image.open("Images/"+img, 'r')
+
+data = ''
+imgdata = iter(image.getdata())
+
+while (True):
+pixels = [value for value in imgdata.__next__()[:3] + imgdata.__next__()[:3] + imgdata.__next__()[:3]]
+
+# string to store converted binary data
+binstr = ''
+
+#converting the binary data into ASCII value
+for i in pixels[:8]:
+if (i % 2 == 0):
+binstr += '0'
+else:
+binstr += '1'
+
+#Converting ASCII value to form a string i.e secret data
+data += chr(int(binstr, 2))
+if (pixels[-1] % 2 != 0):
+image.show() #shows the image which contains the secret data
+return data
+
+# Main Function
+def main():
+ch = int(input("\n:: Welcome to Image Steganography ::\n"
+" 1. Encode the data\n 2. Decode the data\n"
+"\nSelect your choice : "))
+if (ch == 1):
+encode()
+print("\n*** Encoding secret data into image Successful ***\n")
+
+elif (ch == 2):
+print("Decoded Message : " + decode())
+print("\n*** Decoding secret data from image Successful ***\n")
+else:
+raise Exception("Invalid input")
+
+# Driver Code
+if __name__ == '__main__' :
+
+# Calling main function
+main()
+
+