Decoding

The following code iterates over all the pixels in encoded_image.png and extracts the binary value of each red pixel.

#Import Image module from PIL library

from PIL import Image

#Path to image containing message here

image = Image.open('encoded_image.png')

#Convert to RGB

rgb_image = image.convert('RGB')

#Assign the image width and height to variables

width, height = image.size

i = 0

output_bits = ""

output_text = ""

#Set up loops to address each pixel in the image

for row in range(height):

    for col in range(width):

      r, g, b = rgb_image.getpixel((col, row))

      bin_r = bin(r)

      output_bits = output_bits + bin_r[-1]

• Add code to read the final bit of this binary value and add it to the end of the output_bits string.

The code below takes the string output_bits and converts each byte into an ASCII character until it reaches a byte with a value of 0. Then the code prints out the decoded hidden message.

end = False

while end == False:

    byte = int(output_bits[:8],2)

    print(byte)

    if byte == 0:

        end = True

    else:

        output_text = output_text + chr(byte)

        output_bits = output_bits[8:]

print(output_text)

• There’s also another message hidden in the image’s green values. Can you modify the code to find this message as well?